Harnessing Mechanical Energy for Catalysis: Mechanisms, Materials, and Applications of the Emerging Piezocatalysis Frontier

Abstract

Driven by the urgent global water remediation demands, piezocatalysis, as an emerging green tech, has quickly become a massive research hotspot. Piezocatalysis breaks free from the high energy costs and strict operating conditions that often hold back traditional catalysts by directly converting mechanical energy into usable chemical energy. This review systematically tracks the design progress of piezocatalytic materials. This work provides an in‐depth analysis of the dynamic mechanisms revealing how mechanical stress induces endogenous polarization fields to precisely regulate charge separation and reactive oxygen species (ROS) generation. We heavily focus on what is happening at the nanoscale‐morphology tweaks, interface engineering, and polarization enhancement by tracing the evolutionary path of these materials. This article shed light on how active sites dynamically adapt under stress by pairing density functional theory calculations with in situ characterization. Finally, we map out the road ahead, tackling the macrolevel engineering challenges of mitigating nanomaterial fatigue, improving anticorrosion performance in complex waters, and designing viable continuous‐flow reactors.

This review highlights piezocatalysis converting mechanical to chemical energy for water remediation. Stress‐induced polarization in piezoelectrics drives charge separation and reactive oxygen species (ROS) generation. It traces material design from bulk to nanoscale, emphasizing morphology, interfaces, and polarization. In situ characterization and challenges are discussed, providing ideas to practical applications.

1. Introduction

Catalytic technology, as a cornerstone of the modern chemical industry, plays an indispensable role in energy conversion, environmental protection, and chemical synthesis [1, 2, 3, 4, 5]. It has been estimated that more than 90% of industrial chemical processes involve catalysts. From petroleum cracking and fertilizer production to automotive exhaust purification, catalytic technologies have profoundly influenced the sustainable development of the global economy and environment [6, 7, 8, 9]. Conventional catalytic technologies, including photocatalysis, electrocatalysis, and thermocatalysis, have achieved remarkable progress in pollutant degradation, hydrogen production, and carbon‐neutral energy conversion [10, 11, 12, 13, 14]. However, these catalytic systems generally rely on continuous external energy inputs, such as light irradiation, electrical power, or thermal energy, which limits their applicability in decentralized, low‐energy, or light‐deficient environments. Meanwhile, mechanical energy, including vibrations, acoustic waves, water flow, wind fluctuations, friction, and human motion, is ubiquitous in both natural and industrial settings yet remains largely underutilized [15]. Therefore, the efficient conversion of such low‐grade mechanical energy into usable chemical energy has emerged as a critical scientific challenge in the fields of sustainable catalysis and energy utilization.

Compared with conventional catalytic technologies, piezocatalysis offers a promising pathway to overcome existing technological limitations owing to its unique energy conversion mechanism [16,  17]. Piezocatalysis utilizes piezoelectric polarization induced by mechanical deformation to drive redox reactions. Under external mechanical stimulation, noncentrosymmetric piezoelectric materials generate transient polarization charges and internal electric fields, leading to band bending and charge carrier separation, as illustrated in Figure 1. The resulting electrons and holes can subsequently participate in interfacial reduction and oxidation reactions, enabling applications such as pollutant degradation, ROS generation, water splitting, and energy conversion [18, 19]. Unlike conventional photocatalysis, which relies heavily on photon absorption, piezocatalysis can directly harvest ambient mechanical energy without requiring external electrical infrastructure or stable illumination conditions [20, 21, 22]. This distinctive capability creates new opportunities for decentralized environmental remediation, self‐powered catalysis, and low‐frequency energy harvesting systems [23, 24].

FIGURE 1.

(a) Schematic diagram of piezoelectric catalysis principle. (b) Schematic diagrams depicting the potential distribution on piezoelectrics through bending. (c) Band diagram of unstrained and (d) strained insulating piezoelectric. The piezopotential has changed the energy state across the material, allowing electron transfer between piezoelectric/solution interface. Reproduced with permission [9]. Copyright 2020, Wiley‐VCH GmbH.

In recent years, rapid progress has been made in the development of piezoelectric catalytic materials and multifield coupling systems. Various piezoelectric materials, including BaTiO₃, ZnO, BiFeO₃, MoS₂, PVDF‐based polymers, and emerging low‐dimensional materials [25, 26, 27, 28], as shown in Figure 2, exhibit promising piezocatalytic performance in pollutant degradation and hydrogen evolution reactions. Structural engineering strategies, such as defect modulation, heterostructure construction, morphology control, and interface modulation, significantly improve charge separation efficiency and catalytic activity [29, 30, 31, 32, 33]. In addition, combining piezoelectric catalysis with photocatalysis, thermal catalysis, friction analysis, and advanced oxidation processes further expands its application scope and improves energy utilization efficiency [34, 35, 36, 37].

FIGURE 2.

Schematic representation on the mechanism of piezocatalysis. (a) Before contact‐Pt metal and BaTiO₃. (b) After contact‐Pt metal and BaTiO₃ with band bending due to intrinsic polarization. (c) Band tilting due to exert mechanical input energy (i.e., during ultrasonication). Piezoelectric photocatalytic degradation performance of BTO with different morphologies: (d) BTO‐NPs, (e) BTO‐Nf, and (f) BTO‐Nc. Reproduced with permission [25, 28]. Copyright 2024, Wiley‐VCH GmbH; Copyright 2023, MDPI.

Despite these advances, the fundamental mechanisms and practical implementation of piezocatalysis remain far from fully understood. One of the major challenges lies in distinguishing genuine piezoelectric effects from other mechanically induced physicochemical phenomena, particularly acoustic cavitation and triboelectric charge generation in ultrasound‐driven or frictional systems. In many reported systems, ROS may partially originate from sonochemical effects rather than intrinsic piezoelectric polarization, leading to mechanistic ambiguity [38]. In addition, piezoelectric polarization under oscillatory mechanical stimulation is inherently dynamic rather than static. The transient evolution of piezopotential, periodic band bending, interfacial charge redistribution, and time‐dependent adsorption energetics remain insufficiently understood [39, 40]. The lack of quantitative understanding regarding the relationship among mechanical excitation, polarization response, carrier dynamics, and catalytic activity continues to hinder the rational design of efficient piezocatalytic systems [16].

From an engineering perspective, most current studies rely on high‐frequency ultrasonic excitation under laboratory conditions, whereas realistic environmental mechanical energy sources are typically broadband, low‐frequency, stochastic, and spatially heterogeneous [41, 42]. Therefore, translating laboratory‐scale piezocatalytic systems into practical environmental and energy applications remains highly challenging. Additional issues, including catalyst fatigue, structural instability, polarization attenuation, inefficient stress transfer, catalyst recovery, and the absence of standardized evaluation protocols [16,  43], further restrict large‐scale implementation.

In this review, we systematically summarize recent advances in piezocatalysis from the perspectives of fundamental mechanisms, material design, catalytic applications, characterization techniques, and engineering challenges. Particular emphasis is placed on dynamic polarization behavior, interfacial charge regulation, distinctions among piezocatalysis, sonochemistry, and tribocatalysis, as well as structure–activity relationships in emerging piezoelectric materials. Furthermore, current limitations and future research directions toward practical self‐powered catalytic systems are critically discussed. We anticipate that this review will provide deeper mechanistic insights and theoretical guidance for the rational development of next‐generation piezocatalytic technologies.

2. Principle of Piezocatalysis

2.1. Definition

Piezoelectric materials with noncentrosymmetric crystal structures undergo lattice‐level atomic displacement when subjected to mechanical stress [44]. This structural deformation induces a spatial separation of positive and negative charge centers, establishing an internal electric field, as shown in Figure 3a, that serves as the primary driver for catalytic reactions [45, 46, 47]. Crucially, the polarity and magnitude of this endogenous field are dynamically responsive, shifting in tandem with the direction and amplitude of the applied mechanical stimuli. This fundamental transduction of mechanical energy into chemical potential, rooted in the classic piezoelectric effect discovered by the Curie brothers [48], has established a novel paradigm in heterogeneous catalysis.

FIGURE 3.

Illustration of different types of piezocatalytic mechanisms. (a) “Top‐to‐bottom” electric potential difference due to bulk polarization of a piezocatalyst under stress. Reproduced with permission [44]. Copyright 2021, Elsevier. (b) Energy band theory and (c) screening charge theory.

For piezoelectric semiconductors like ZnO, BaTiO₃, and BiFeO₃, the underlying physics is typically described through energy band theory. Under mechanical load, asymmetric crystal deformation reconfigures the bulk electronic band structure [49], inducing macroscopic band tilting that aligns with the energetic requirements of target redox couples (Figure 3b). The resulting piezopotential propels intrinsic carriers toward the material surface, suppressing electron–hole recombination and accelerating interfacial redox kinetics [16, 50]. Moreover, reversing the stress direction can mitigate the depolarization field, effectively causing the energy bands to bend in the opposite orientation.

Crucially, unlike the static band alignment characteristic of conventional heterojunctions, the piezopotential‐induced band bending under cyclic or oscillatory stress is highly dynamic and time‐variant. As the applied mechanical stress periodically fluctuates, the conduction and valence band edges shift dynamically in both space and time [51]. This shifting generates a continuously fluctuating internal electric field that periodically modulates the surface electronic structures, thereby modifying the adsorption energies and chemical bonding configurations of surface‐bound reactants. During the peak strain phase, the instantaneous surface piezopotential elevates the local conduction band edge based on its intrinsic band alignment, effectively lowering the activation energy barrier for electron injection into adsorbed O₂ molecules and accelerating their reduction to superoxide radicals (·O₂ ^–) [18]. Conversely, upon stress relaxation or reversal, the electric field diminishes or flips, drastically decreasing the chemisorption strength of the generated intermediates. This continuous dynamic reconfiguration systematically prevents active‐site poisoning by accelerating product desorption, thereby sustaining a highly active, nonequilibrium surface state throughout the entire mechanical oscillation cycle [52].

In contrast, piezoelectric insulators and polymers, which lack continuous energy bands or possess wide band gaps, are more accurately described by the screening charge mechanism. In these systems, catalytic activity stems from the adsorption and release of external screening charges [53]. Continuous external forces disrupt the electronic equilibrium between internal carriers and external screening charges established during piezoelectric polarization (as illustrated in Figure 3c). Mechanical forces disrupt the electronic equilibrium between internal polarization and external surface charges, triggering the release of these charges to generate ROS. As the material relaxes and polarization is restored, charges from the electrolyte are readsorbed, creating a continuous charge flux driven by periodic mechanical energy.

Following the pioneering work of Wang’s group [54], which realized nanogenerators based on piezoelectric materials, continuous exploration of piezoelectric systems has substantially expanded the application scope of piezocatalysis. In recent years, piezocatalytic applications have evolved from organic dye degradation and efficient hydrogen production via water splitting to more advanced fields, including greenhouse gas conversion and tumor inhibition. Representative piezocatalytic materials such as BaTiO₃ [55], ZnO [48], and KNbO₃ [20] have been extensively employed to drive advanced oxidation reactions for the degradation of organic pollutants. By constructing heterojunctions, SrZrO₃ and BaZrO₃ have achieved synergistic piezophotocatalytic water splitting with markedly enhanced hydrogen evolution efficiency [56]. Furthermore, two‐dimensional (2D) Co‐NC@BiFeO₃ nanosheets, incorporating highly active Co–N–C sites, significantly promoted charge carrier separation and migration under piezophotocatalytic conditions, enabling efficient CO₂ reduction [57]. Pyroxene‐type narrow‐bandgap piezoelectric Cu₂XSnS₄ demonstrated that the layered morphology of 2D nanosheets facilitates mechanical deformation to trigger the piezoelectric effect, thereby substantially reducing the mechanical energy input required for catalytic reactions [58]. In the biomedical field, Pu et al. designed an injectable hydrogel (DBG), coloading 2D BiFeO₃ (BFO) nanosheets and 2‐deoxyglucose (2‐DG), which generated abundant ROS while simultaneously inhibiting N‐glycosylation of tumor cells upon ultrasound stimulation, remodeling the tumor immune microenvironment, suppressing tumor growth, and inducing immune memory to prevent metastasis [59]. With the rapid development of piezocharge‐driven catalytic chemical reactions [60] in environmental science, an increasing number of piezoelectric materials are being explored for applications in environmental remediation, renewable energy conversion, and emerging biotechnological fields [61].

2.2. Comparison With Traditional Catalysis

Piezocatalysis has recently attracted considerable research interest alongside traditional energy‐driven catalytic processes such as photocatalysis, electrocatalysis, and thermocatalysis (as illustrated in Figure 4a–c) 62]. While all of these processes are fundamentally driven by an input of energy to facilitate chemical transformations, they differ markedly in their energy sources, charge carrier generation mechanisms, and catalytic driving forces. Conventional photocatalysis relies on the absorption of photons by a semiconductor to generate electron–hole pairs, which subsequently participate in redox reactions [59]. The clean and sustainable nature of solar energy endows photocatalysis with broad potential for applications including pollutant degradation, water splitting, and CO₂ conversion. However, its strong dependence on light irradiation limits its performance under weak or absent illumination, and the rapid recombination of photogenerated charge carriers constrains both efficiency and stability in practical systems [43]. By contrast, electrocatalysis is driven by an externally applied potential that governs electron transfer pathways and reaction kinetics with high precision [49]. This high degree of control has made electrocatalysis a mainstay in industrial applications. The continuous and stable external power supply results in persistently high energy consumption throughout the system, and stringent demands on electrode materials and system stability often present practical challenges [63]. Thermocatalysis uses high temperatures to provide the thermal energy required to overcome activation barriers [64]. Although it enables high reaction rates and remains indispensable in chemical manufacturing, its inherently high energy demand and tendency toward unwanted side reactions pose sustainability concerns under current carbon‐neutral policies.

FIGURE 4.

Mechanism of traditional catalytic processes. (a) Thermocatalysis. (b) Photocatalysis. (c) Electrocatalysis. (d) Typical mechanical excitation modes for driving piezocatalytic water treatment processes. Reproduced with permission [64]. Copyright 2024, Elsevier.

From a mechanistic perspective, piezocatalysis shares the central role of charge carriers in driving redox reactions with photocatalysis and electrocatalysis. But the difference is piezocatalysis does not require external light or electrical power. Instead, it directly harnesses ambient mechanical energy, such as ultrasonic vibration, air bubbling, water‐vortex disturbance, and ball milling to drive chemical reactions through the deformation‐induced piezoelectric effect [64] (as illustrated in Figure 4d). The mechanical stress on a piezoelectric material generates an internal polarization field that can directly induce catalytic reactions.

The internally generated electric field induced by the piezoelectric effect serves as the intrinsic driving force of the catalytic process. This built‐in field not only enables piezocatalysis to proceed independently but also plays a critical role in suppressing charge carrier recombination and regulating interfacial charge migration in hybrid catalytic systems. Importantly, the synergistic interaction between piezocatalysis and conventional catalytic pathways is not a simple additive effect; it arises from the cooperative regulation of built‐in electric fields and optimized interfacial charge dynamics [65]. Such synergistic strategies effectively compensate for the limitations of traditional catalysis, particularly with respect to energy utilization efficiency and carrier recombination losses, while simultaneously expanding the functional scope of piezocatalytic systems. Owing to these multidimensional synergistic gains, piezocoupled catalytic systems have emerged as one of the most promising and rapidly evolving research directions in contemporary catalysis.

2.3. Kinetics and Rate‐Determining Steps in Piezocatalysis

The fundamental physical and chemical time scales involved in piezocatalytic processes differ significantly. Stress‐induced lattice deformation, the establishment of a spontaneous polarization field, and the separation and migration of charge carriers are electrodynamic processes driven by Maxwell displacement currents [66]. These processes typically occur within an extremely short time frame (less than 1 ps) [67]. Conversely, interfacial chemical conversion processes proceed much more slowly. These processes include reactant diffusion, chemical adsorption, multistep proton‐coupled electron transfer (PCET), and product desorption [52]. Their time scales generally range from microseconds to milliseconds (μs to s timescale) [67]. Therefore, particularly under low‐to‐medium frequency stimuli, either surface chemical redox reactions or mass transport acts as the rate‐determining step (RDS) for the entire process.

In current piezocatalysis research, the development of reaction kinetic models is at a critical transition stage. It is moving from macroscopic empirical fitting toward intrinsic multifield coupling. Currently, the pseudo‐first‐order kinetic model, $ln\left(C_0/C\right)=kt$ [68], is the most widely applied due to its mathematical simplicity and intuitive quantitative comparison. However, this model fails to explicitly incorporate core physical parameters into the reaction rate equation. These missing parameters include the applied mechanical stress, the intrinsic piezoelectric tensor, and the built‐in piezoelectric field. Consequently, the empirical model severely lacks the physical depth required to elucidate the mechanical‐to‐chemical energy conversion mechanism.

To overcome this limitation, some frontier studies have introduced electrocatalysis‐analogous kinetic models, such as the Butler–Volmer model, which treats the strain‐induced transient piezoelectric potential difference as an endogenous overpotential for interfacial charge transfer [69]. It successfully bridges the gap between solid mechanics and interfacial electrochemistry at a fundamental physicochemical level. Furthermore, it quantitatively confirms that the microscopic mechanism of piezopotential‐driven reactions highly aligns with traditional electrocatalysis. Thus, it can accurately describe the variation of current density under specific physical bending conditions. Nevertheless, its assumptions regarding physical boundary conditions are relatively stringent. This makes it exceedingly difficult to apply in ultrasonic powder suspension systems, which possess highly complex fluid dynamic environments.

The future development of piezocatalytic kinetics urgently requires a comprehensive upgrade. It must transition from simple chemical reaction kinetics to interdisciplinary, quantitative physical models. On one hand, precise mathematical relationships between mechanical energy input and catalytic yield must be established. On the other hand, dynamic strain‐electric field‐coupled adsorption free energy models need to be developed [70]. The periodic analysis of the adsorption energy of key reaction intermediates and the reduction of activation energy barriers induced by dynamic band‐bending under the alternating piezoelectric field reveals the dynamic evolution of the RDS.

3. Piezocatalytic Materials

3.1. Material Evolution and Structural Tuning

Inorganic piezoelectric catalysts represented the first wave of systematic exploration in this field. These materials, such as ZnO [71], BaTiO₃ (BTO) [72], NaNbO₃ [73], and BiFeO₃ [74], typically possess well‐defined noncentrosymmetric crystal structures, enabling the generation of a stable piezoelectric polarization field under applied mechanical stress, which drives electron–hole separation and subsequently induces reactive species formation. It is shown that the nontraditional ferroelectric system materials can still achieve effective free radical generation and dye degradation as long as they have sufficient lattice distortion and stress response ability, which expands the family of viable inorganic piezoelectric materials. Concurrently, this dependency underscores the necessity of high‐intensity external stimuli.

While materials like BaTiO₃ are regarded as benchmarks, pristine nanoparticles often struggle with rapid carrier recombination, which hampers their overall efficiency. BTO nanoparticles often suffer from rapid electron–hole recombination during piezocatalytic processes, which limits their effective catalytic performance [43, 75, 76]. This emphasizes that only high piezoelectric coefficient does not unilaterally guarantee superior catalytic performance; rather, it necessitates auxiliary strategies such as defect engineering or heterojunction construction.

In this situation, organic and organic–inorganic composite piezoelectric materials have attracted considerable attention for piezocatalytic applications. Polyvinylidene fluoride (PVDF) and its derivatives are particularly promising due to their inherent flexibility, facile processability, and tunable piezoelectric phases, especially the electroactive β phase, which is critical for efficient mechanical‐to‐electric energy conversion [20, 77, 78]. Pristine PVDF typically exhibits a mixed structure of multiple crystalline phases, so increasing the proportion of the β‐phase remains a core objective in designing piezoelectric composites [79]. However, this factor alone cannot produce a significant macroscopic piezoelectric effect. Internal dipoles must distribute uniformly and align directionally within the crystalline regions to form domain structures, thereby uniformizing the material’s polarization and enhancing the piezoelectric response [80]. In practice, mechanical stretching and external electrical poling are the key methods to achieve this directional dipole alignment. The synergy of these two strategy significantly boosts the material’s intrinsic piezoelectric response and piezocatalytic activity by stabilizing the polarization direction.

However, pristine PVDF often shows limited piezocatalytic performance due to low β‐phase content Recent composite strategies, such as incorporating nanostructured fillers or polar functional groups, have been shown to dramatically increase the β phase content and enhance piezoelectric performance [81]. For example, rGO‐PVDF composite system achieves high β‐phase content and strong piezoelectric conversion properties by inducing lattice constant and cell volume changes in PVDF through heat treatment [82].

Meanwhile, the field is currently transitioning toward flexible and biointegrated systems to overcome the inherent brittleness and potential toxicity of traditional ceramics. The natural origin and excellent biocompatibility of biobased materials endow them with inherent degradability, sustainability, and multifunctionality, which has significantly accelerated the integration of piezocatalytic technologies across sensors, actuators, energy harvesting, and tissue engineering [83]. Traditional single‐component inorganic piezoelectric materials are gradually evolving toward composite, flexible, and biointegrated systems (as illustrated in Figure 5) [84]. Emerging trends emphasize the intelligent synthesis of catalysts through AI‐driven design and additive manufacturing. Although the intrinsic correlation between piezoelectric output and catalytic active sites in different material systems remains unclear, personalized and intelligent synthesis of piezocatalytic materials through rational design, high‐resolution additive manufacturing, and in situ self‐assembly will become a major trend.

FIGURE 5.

Schematic diagram of Piezoelectric material development trend and molecular structure. (a) ZnO. (b) Perovskite. (c) PVDF. (d) PVDF‐TrFE. (e) Biobased piezoelectrics. Reproduced with permission [84]. Copyright 2025, American Chemical Society. (f) Future piezoelectrics. Reproduced with permission [85]. Copyright 2025, Wiley‐VCH GmbH.

3.2. Material Performance and Structural Optimization

In piezocatalytic systems, the crystal structure not only determines whether a material exhibits a piezoelectric response but also directly influences the magnitude and spatial orientation of the piezopotential. By modulating lattice distortions and local asymmetry, researchers can now precisely regulate the spatial orientation of the piezopotential and the resulting charge migration pathways [74, 85]. Piezopotential governs charge separation and transfer under mechanical deformation [86], while heterostructuring and defect engineering further extend these effects by modulating band alignment and interface energetics.

Beyond intrinsic structural parameters, oxygen vacancy modulation has emerged as a potent tool for tuning both polarization behavior and surface kinetics [87]. In BTO nanostructures, these vacancies strengthen local dipoles and boost surface electron density, facilitating the generation of ·O₂ ^– and singlet oxygen (¹O₂) [88]. Furthermore, geometric optimization plays a vital role; for instance, tuning nanoparticle diameters to achieve mechanical resonance under specific low‐frequency excitations can substantially amplify the output potential [89]. This suggests that maximizing efficiency requires a synergetic alignment between the material’s geometry and the mode of mechanical excitation.

These findings indicate that the enhancement of piezocatalytic performance arises from the synergistic interplay among strengthened polarization, modified surface electronic structure, and adsorbate activation, rather than solely from an increased piezoelectric coefficient. In addition to compositional and defect engineering, size effects also exert a significant influence on piezoelectric output. As the thickness of 2D nanosheets approaches the single‐ or few‐layer limit, their mechanical bending stiffness decreases sharply [90]. This structural flexibility allows even minuscule ambient forces to induce significant lattice strain and strain gradients. Consequently, the piezoelectric potential is substantially enhanced through the synergistic interplay of the piezoelectric and flexoelectric effects [91]. However, an inherent size limitation exists. If the nanoparticle diameter or the nanosheet thickness falls below the ferroelectric correlation length, the depolarization field becomes dominant. This dominance leads to a severe weakening or even a complete loss of spontaneous polarization. Therefore, smaller nanosheets with optimal structural compliance can generate a stronger piezoelectric potential [83]. This enhanced potential subsequently achieves a significant dynamic reduction in the interfacial charge‐transfer resistance [16].

Doping strategies further enable simultaneous band structure modulation and polarization enhancement. Transition‐metal dopants such as Fe in Bi₂WO₆ introduce localized d‐states that strengthen internal fields and significantly accelerate the activation of peroxymonosulfate (PMS) [92]. As a result, the degradation rate of refractory organic pollutants is significantly improved. Nb doping in SrTiO₃ forms defect dipoles and defect dipole clusters, which effectively enhance the dielectric constant while partially trapping charge carriers. This significantly reduces dielectric loss and promotes the generation of oxygen vacancies [93]. Nonmetal dopants have been shown to increase local polarization without compromising lattice stability, thereby improving ROS production for environmental applications.

In‐plane polarized materials, such as Bi₂WO₆, induce a transient piezoelectric field parallel to their basal planes, driving the lateral separation of electrons and holes across distinct surface facets [94]. This behavior uniquely benefits 2D nanostructures with exposed lateral active sites. Conversely, out‐of‐plane polarized systems like BaTiO₃ project an electric field vector normal to the crystal surface. This vertical orientation effectively drives and segregates opposing charge carriers to opposite terminal facets across the bulk [95]. By creating a strong orthogonal potential gradient, this configuration suppresses bulk recombination more effectively than its in‐plane counterpart.

In addition to inherent structural adjustments, surface modification and interface engineering through heterostructures provide new dimensions for performance optimization. BiFeO₃@TpPa‐1‐COF, a core–shell Z‐type piezoelectric photocatalyst constructed by covalently bonding a covalent organic framework (COF) with the piezoelectric material BiFeO₃, exhibits highly tunable properties. It achieved a high hydrogen production rate (1416.4 μmol·h⁻¹·g⁻¹) and oxygen evolution rate during hydrolysis [96]. The ZnO@COF composite, designed with a Z‐type heterostructure, stimulates the electron transfer from COF to ZnO through the interface electric field, breaking the edge shielding effect of ZnO in the metallic state and enhancing its polarization [97]. The modification of metal oxides improves the interface charge dynamics, further boosting the piezoelectric catalytic efficiency.

In summary, the polarization enhancement driven by lattice distortion, the band modulation induced by defects and dopants, and the construction of heterojunction interface electric fields collectively determine the charge carrier separation efficiency and the generation rate of active sites in piezoelectric catalytic materials (as illustrated in Figure 6). The synergy between piezoelectric catalysis and other AOPs arises from the regulation of charge dynamics and the reduction of carrier recombination.

FIGURE 6.

Strategies for improving the performance of piezocatalysts and piezophotocatalysts. (a) Vacancy defects. (b) Doping. (c) Crystal facet regulation. (d) Heterostructure construction. (e) Cocatalyst Loading. (f) Piezoelectric polarity regulation. (g) Morphological regulation. Reproduced with permission [88]. Copyright 2024, American Chemical Society. Reproduced with permission [95, 96, 98]. Copyright 2022, Wiley‐VCH GmbH. Reproduced with permission [89]. Copyright 2025, American Chemical Society. Reproduced with permission [83]. Copyright 2024, Wiley‐VCH GmbH. Reproduced with permission [91]. Copyright 2025, Wiley‐VCH GmbH.

3.3. Development of Novel Piezocatalytic Materials

3.3.1. 2D Piezoelectric Materials

With the rapid development of nanomaterials and interface engineering, the increasing demand for efficient utilization of low‐intensity, low‐frequency mechanical energy has driven piezoelectric catalysis research to shift from traditional bulk ceramics to low‐dimensional materials and porous structures. Through structural optimization, these materials show significant improvements in stress transfer efficiency, piezoelectric potential generation, and charge carrier separation, overcoming the inherent limitations of traditional bulk piezoelectric systems.

2D piezoelectric materials, with their atomic thickness, layered structure, and high surface area, provide a new structural foundation for efficient mechanical stress transfer and rapid polarization potential development. Transition metal dichalcogenides (TMDs) have garnered widespread attention due to their tunable polarization direction (as illustrated in Figure 7), which allows significant piezoelectric potential generation under weak mechanical disturbances [99]. MoS₂, as a representative 2D piezoelectric material, exhibits unique layer‐dependent piezoelectric properties. By applying strain, the intersubband transition energy and oscillator strength in the terahertz frequency range can be precisely controlled, enabling tunable potential wells and barriers. This provides new freedom for the design of nanoscale optoelectronic devices and atomic‐scale terahertz light sources [90]. This research shows that 2D phase engineering can significantly reduce the dependence of piezoelectric catalysis on external energy input, offering a practical approach for converting low‐grade mechanical energy available in the environment.

FIGURE 7.

Evolution and research trends of 2D material‐based piezotronics. (a) ZnO‐based piezotronics. (b) Flexible piezoelectric substrate material. Reproduced with permission [103]. Copyright 2024, Elsevier Ltd. (c) Piezoelectric property of MoS₂. Reproduced with permission [100]. Copyright 2025, Elsevier B.V. and Science Press. (d) Advanced 2D materials and broad applications. Reproduced with permission [92]. Copyright 2020, Elsevier B.V. Reproduced with permission [102]. Copyright 2026, Springer Nature. (e) 2D materials integrate into 3D mode. Reproduced with permission [91]. Copyright 2025, Wiley‐VCH GmbH.

The interface and electronic structure tuning can further enhance the piezocatalytic performance of 2D systems. By loading metal species like Cu to modify the morphology of MoS₂, the sulfur vacancy at the MoS₂ edge can be precisely controlled to reduce the unsaturated coordination, thereby improving product selectivity [100]. Additionally, other 2D layered semiconductors exhibit good piezoelectric photocatalytic or piezocatalytic behaviors due to their anisotropic electric fields and abundant surface active sites. BiOI nanomaterials, with an asymmetric hierarchical porous structure, can form multiple stress concentration zones under mechanical disturbance, promoting more uniform polarization and higher ROS generation, which is crucial for the mineralization of deep pollutants [101]. The inherent flexibility of 2D materials allows them to combine with polymers or conductive substrates to form hybrid multifunctional systems. The independent conductive layers of the bilayer ANF/MXene‐PEDOT:PSS film [102] impart excellent conductivity and electromagnetic shielding properties to the material. The composite film’s outstanding Joule heating and photothermal conversion abilities highlight the critical role of conductive paths and interface charge management in complex piezocatalytic environments.

3.3.2. Hierarchical Porous and Nanostructured Piezoelectric Materials

Another important direction parallel to the development of 2D systems is the design of 1D nanofibrous networks and hierarchical porous piezoelectric materials. These materials significantly enhance local stress concentration effects by introducing a high surface area and internal porous structure. Additionally, they shorten the carrier migration path, effectively improving piezocatalytic activity.

Studies have shown that electrospun fibers, such as PVDF/CNF@ZnO (E‐PVDF/CZ) [103] and BaTiO₃/PVDF [104] nanocomposite films, leverage their 1D nanostructure and interconnected webs to provide a high specific surface area and promote the formation of the polar β‐phase. This unique architecture effectively combines the high piezoelectricity of inorganic fillers with the flexibility of polymers.

These materials exhibit excellent piezoelectric performance under mechanical stress. The team of Chris Bowen in the United Kingdom discovered that introducing directionally aligned pores in lead‐free piezoelectric ceramics (BCZT) enhanced oxidation during the sintering process, reducing oxygen vacancy concentrations. Additionally, the porous structure caused an asymmetric distribution of dipoles, creating an internal bias electric field that promotes material polarization [105]. The mechanism of polarization enhancement induced by structural changes provides important insights for the design of flexible piezocatalytic systems. Meanwhile, MOF‐derived porous heterogeneous structures, such as NH₂‐MIL‐101(Fe)@CNF [106] and MIL‐100(Fe) [107], exhibit unique advantages in piezocatalysis due to their regular pores and tunable band structures. The porous framework not only offers ample contact interfaces for reactants but also enables cooperative transport of electrons and ions in multidimensional channels, effectively reducing carrier recombination and amplifying piezoelectric response. As more flexible, porous polymer‐based materials show long‐term potential in natural environments, piezocatalytic materials are evolving from high‐performance experimental materials to sustainable, self‐powered functional materials. However, the stability of 2D and porous piezoelectric materials is still limited by interlayer slippage, pore wall collapse, and surface oxidation. Future research should combine interface chemistry control and band engineering to achieve controlled interlayer charge channel construction and enhance structural toughness, thereby advancing the practical application of new piezocatalytic systems in self‐powered environmental remediation and green energy conversion.

4. Applications and Comparisons of Piezocatalysis

4.1. Environmental Remediation

Piezocatalysis offers a compelling alternative to photocatalysis, particularly in environments where light is absent or attenuated. For example, ultrathin Bi₁₁VO₁₉ nanosheets [108] exhibit a degradation efficiency for Rhodamine B that is 10 times higher than that of bulk BiVO₄, a feat attributed to their superior lattice distortion and high surface‐to‐volume ratio. This remarkable performance is attributed to lattice distortion and the ultrathin nanosheet morphology. The enhanced piezoelectric response adjusts the electronic band structure, shifting the conduction band upward, which improves electron reduction capability and carrier mobility. Additionally, the high surface area of the material increases active sites, promoting dye adsorption. However, most inorganic ferroelectric systems require high‐frequency ultrasound and specific water environments, limiting their practical application in water treatment. Liu et al. achieved high degradation of the dye KN‐R in an acidic environment (pH = 3) on the narrow‐gap semiconductor Bi₂Fe₄O₉ through piezoelectric–photocatalytic synergistic effects [109].

Piezocatalytic technology plays a key role in environmental remediation, particularly in the degradation and mineralization of organic pollutants, including dyes, pharmaceuticals, and persistent organic pollutants. Materials such as BaTiO₃, NaNbO₃, and BiFeO₃ have shown excellent performance in the degradation of dyes, antibiotics, and persistent organic pollutants. Studies have shown that the piezoelectric effect driven by mechanical energy generates transient potentials at the solid–liquid interface, promoting electron–hole pair separation and generating various ROS, such as ·OH, ·O₂ ⁻ and ¹O₂, enabling nonlight‐dependent pollutant oxidation and degradation [110]. BaTiO₃ modified by oxygen vacancy engineering achieved rapid removal of amoxicillin under aerated conditions, with ·O₂ ⁻ and ¹O₂ as the main active species, highlighting the significant role of gas oxygen content in determining ROS generation pathways [55].

For pharmaceuticals and antibiotics, piezocatalysis demonstrates higher energy efficiency and environmental adaptability compared to traditional photocatalysis. PANI/β‐PVDF spheres, for instance, achieved near‐complete degradation of levofloxacin using water flow, consuming only 6.6% of the energy required by traditional systems [111]. In composite systems, Fe‐doped Bi₂WO₆ with g‐C₃N₄/NH₂‐MIL‐101(Fe) Z‐type heterostructures can simultaneously generate and activate H₂O₂ in situ. Through piezoelectric‐Fenton dual‐effect synergy, these systems significantly improve the degradation rates of antibiotics and dyes [112]. In these systems, metal ion doping not only lowers the electron transport barrier but also promotes continuous radical generation, leading to a significant increase in the mineralization rate of complex pharmaceuticals such as ciprofloxacin and carbamazepine.

Experimental conditions significantly influence the reaction pathway and activity of piezocatalysis, with pH directly determining surface charge states and ROS species. Under neutral or weakly alkaline conditions, the generation rate of ·O₂ ^– is higher, while acidic environments favor ·OH dominated oxidation pathways [112]. Reaction pressure and mechanical input form also play a critical role in efficiency. Huang et al. studied a 1T/3R‐MoS₂ [113] system triggered by low air pressure, which achieved simultaneous removal of dye and Cr(VI) under only 0.1 MPa. The built‐in electric field strength and interlayer sliding energy combined to form a high‐density polarization region, significantly enhancing electron migration rates. Temperature and humidity also affect the reaction kinetics; moderate humidity facilitates interface polarization conduction, but excessive water molecule coverage weakens the electric field strength [110].

Overall, the mechanism of piezocatalytic degradation of organic pollutants (as illustrated in Figure 8a) is attributed to the redox reaction chain triggered by the conversion of mechanical energy into interfacial potential. Its efficiency is influenced by the material’s polarization strength, band structure, and external reaction conditions. Unlike photocatalysis (as illustrated in Figure 8b), which relies on external light sources, piezocatalysis can effectively harness weak mechanical energy from the environment, such as fluid flow, water waves, or low‐frequency vibrations, enabling rapid pollutant removal under low energy consumption. This demonstrates its potential for sustainable water environmental remediation.

FIGURE 8.

Mechanism diagram. (a) Piezoelectric degradation of organic pollutants. (b) Piezoelectric photocatalysis. Reproduced with permission [64]. Copyright 2026, Elsevier.

4.2. Energy Conversion and Storage

In the realm of renewable energy, piezocatalysis facilitates the direct conversion of mechanical energy into chemical fuels. Dai et al. systematically summarized the band theory, charge shielding theory, and displacement current theory for piezoelectric water splitting, emphasizing the irreplaceable role of the piezoelectric field in lowering reaction energy barriers and promoting charge separation [114]. However, the hydrogen production efficiency of single piezoelectric systems is still limited by reaction kinetics and the number of active sites. As a result, multienergy coupling strategies have gradually become mainstream. By combining piezocatalysis with photocatalysis or thermocatalysis, the overall energy conversion efficiency is significantly improved, enhancing the application potential of piezocatalysis in integrated energy systems.

Research on ferroelectric materials has confirmed the feasibility of mechanically driven water splitting. By constructing CaBi₂Nb₂O₉ (CBN) nanosheets [115], researchers have exposed specific active crystal planes, such as (020) and (200), that enhance the built‐in electric field during ultrasonic stimulation and overcome the inherent limitations of graphite‐phase carbon nitride (g‐C₃N₄). Studies have shown that the kinetic limitations of traditional photocatalysts can be overcome by combining asymmetric structures with strong piezoelectric polarization responses. The intrinsic piezoelectric field and interfacial electric field not only significantly lower the energy barrier for O₂ reduction to *OOH but also coordinate proton transport and electron supply, promoting rapid PCET reactions and the generation of H₂O₂. Yang’s team achieved hydrogen production on centrosymmetric SrTiO₃ nanoparticles [116] using strain gradient‐induced polarization techniques. These studies expand the range of materials for converting mechanical energy into chemical fuels, demonstrating that piezocatalysis can be a component of hybrid energy conversion schemes and further broadening its potential energy applications.

In composite systems, the introduction of heterojunctions has enhanced mechanical energy conversion efficiency. Fe‐doped Bi₂WO₆ [56] and WO₃/MIL‐100(Fe) [117] have improved interfacial charge migration through dual light‐piezoelectric driving, overcoming the high electron–hole recombination rate typically observed in traditional photocatalysis. These systems demonstrate high energy conversion efficiency under low light intensity and mechanical energy. Pd‐metal‐modified MoS₂ layered systems [118] utilize Pd—S bonds to achieve directional interlayer charge transfer, doubling the hydrogen production rate compared to the unmodified sample. The tunable band structure and flexible strain response of these 2D piezoelectric materials enable stable hydrogen production under low‐frequency mechanical disturbances, such as wind or liquid flow, opening up new possibilities for converting natural mechanical energy into zero‐external‐input energy.

The coupling of piezocatalysis with other renewable energy sources has also attracted significant attention. Cai et al. designed an MXene/Bi₂WO₆ [119] composite film that integrates solar photothermal energy and fluid mechanical energy, enabling distributed self‐powered antibiotic wastewater treatment and simultaneous hydrogen generation. This system leverages the high conductivity and light absorption properties of MXene, allowing photogenerated and piezogenerated electrons to cooperate in reactions, significantly enhancing energy utilization. Additionally, flexible PANI/β‐PVDF [58] and porous PVDF/Fe₂O₃/CNF membranes [120] can produce hydrogen under fluid vibration for extended periods. Their energy conversion efficiency is several times higher than that of ultrasonic systems, demonstrating the low‐carbon and sustainable advantages of mechanically driven systems.

To circumvent the kinetic bottlenecks of single‐component systems, multifield coupling (e.g., piezophotocatalysis) has become a dominant research frontier. Although significant progress has been made in material design and energy utilization in piezocatalytic hydrogen production systems, the quantification of energy conversion efficiency still needs improvement. Future efforts must focus on ensuring the consistency of polarization responses across varying frequencies and scaling these laboratory‐scale successes into distributed energy harvesting applications.

4.3. Comparison Between Piezocatalysis and Tribocatalysis

With the rapid advancement in mechanical‐to‐chemical energy conversion, clearly delineating the physical boundaries between different catalytic mechanisms is crucial for the rational design of highly active catalysts. Both piezocatalysis and mechanically driven contact‐electrocatalysis (CEC) harness ambient mechanical energy to generate ROS and drive catalytic reactions. However, they exhibit fundamental differences in their core operating mechanisms and material prerequisites. The interfacial electron transfer mechanism of CEC does not rely on the bulk noncentrosymmetric crystal structure of a material. Instead, it is a surface phenomenon that is entirely governed by the physicochemical properties at the two‐phase interface [121]. When this interface undergoes periodic contact and separation under external mechanical stimuli, the atomic‐level electron clouds overlap. This overlap triggers the “electron‐cloud‐potential‐well” effect, which drives the direct transfer of electrons across the interface [122].

For instance, as a typical inorganic oxide, tetragonal BaTiO₃ possesses a noncentrosymmetric crystal structure. Its catalytic activity originates from the strong internal piezoelectric field, which facilitates the spatial separation and surface enrichment of charge carriers. In contrast, polytetrafluoroethylene (PTFE) is a highly stable and chemically inert polymer. By leveraging the strong electron‐withdrawing ability of the fluorine atoms on its side chains, PTFE demonstrates exceptional interfacial electrification and electron‐accepting performance [123]. During periodic frictional contact at the phase boundary, PTFE efficiently captures electrons directly from surrounding H₂O molecules via localized electron cloud overlap, which subsequently triggers the high‐yield generation of ROS.

Currently, high‐power ultrasonication serves as the predominant mechanical energy source for piezocatalysis. The high‐frequency acoustic radiation induces the formation, growth, and violent implosion of microscopic cavitation bubbles within the liquid medium [53]. On one hand, the transient, localized high‐pressure microjets that are generated by cavitation implosions provide the necessary external stress to induce the lattice deformation of the catalyst. On the other hand, the localized, instantaneous ultrahigh temperatures and extreme pressures that are caused by the cavitation collapse directly lead to the sonochemical pyrolysis of water molecules, which intrinsically generates free radicals such as ·OH. Consequently, while high‐energy ultrasound activates piezocatalysis, it inevitably introduces a concurrent sonochemical process. The coexistence of these dual effects significantly complicates the experimental effort to isolate and identify the true catalytic contribution of the intrinsic piezoelectric polarization [124].

To accurately distinguish the intrinsic piezocatalytic effect of a material from sonochemical pyrolysis, a multidimensional control strategy must be established throughout the experimental process. First, a control material with an identical chemical structure but a centrosymmetric crystal structure can be introduced [114]. A quantitative comparison between the piezocatalyst and this control under the same acoustic field allows researchers to precisely evaluate the baseline contribution of pure sonochemical cavitation to the total radical yield. Furthermore, the selective use of hydrophilic and hydrophobic radical scavengers to track the spatial distribution of ROS helps distinguish the surface‐bound piezocatalytic pathway from bulk sonochemical reactions. Temperature‐dependent kinetic analysis can also serve as an auxiliary diagnostic tool. The pure sonochemical pyrolysis process exhibits a gradual and monotonic trend in response to macroscopic temperature changes. In contrast, the charge migration and surface adsorption behaviors driven by the intrinsic piezoelectric effect display a much more pronounced and complex local temperature kinetic response.

To overcome the limitations of the cavitation effect, current research is shifting toward the application of low‐frequency and low‐intensity ambient mechanical energy. Through the structural design of flexible catalysts, piezoelectric nanoparticles are anchored within electrospun polymer membranes, or free‐floating macroscopic spheres, PANI/β‐PVDF, are fabricated [58]. These flexible structures can maximize fluid‐induced bending or torsional strains under low‐frequency flow conditions. This mechanical flexibility enables them to generate sufficient transient piezoelectric potentials solely by utilizing ambient kinetic energy. Consequently, this drives surface redox reactions and completely circumvents the energy‐intensive cavitation mechanism.

5. Characterization Methods and Control Strategies of Piezoelectric Catalysis

5.1. Characterization Methods

The primary objective of piezocatalytic characterization is not only to confirm the structural properties of piezoelectric materials but, more importantly, to establish quantitative correlations among mechanical deformation, polarization behavior, charge carrier dynamics, and catalytic activity [68]. Compared with conventional catalytic systems, piezocatalytic materials require additional characterization of their electromechanical coupling behavior under dynamic mechanical stimulation [125, 126]. Therefore, characterization strategies in piezocatalysis should focus on elucidating the structure–piezopotential–activity relationship rather than merely describing morphology or composition.

Conventional structural characterization techniques remain essential for identifying the crystal structure, morphology, and surface chemistry of piezocatalytic materials. As illustrated in Figure 9, X‐ray diffraction (XRD) is commonly employed to verify the formation of noncentrosymmetric piezoelectric phases and to analyze lattice distortion, crystallinity, and defect evolution [103, 104, 105]. Electron microscopy techniques, including scanning electron microscopy (SEM) and transmission electron microscopy (TEM), are widely used to investigate morphology, dimensional characteristics, interfacial structures, and defect distributions in nanosheets, nanowires, porous architectures, and heterojunction systems [106, 107]. Surface‐sensitive spectroscopic techniques, such as X‐ray photoelectron spectroscopy (XPS), Raman spectroscopy, and Fourier‐transform infrared spectroscopy (FTIR), are further applied to characterize elemental valence states, oxygen vacancies, sulfur vacancies, functional groups, and local bonding environments that strongly influence polarization behavior and interfacial charge‐transfer processes [108].

FIGURE 9.

Common means of representation. (a) XRD patterns and partially enlarged XRD patterns. XRD patterns of (b) the pristine BTO and BTO‐RhSA. (c,d) SEM images of BWO before and after CTAB modification. (e) A new peak appeared in the XPS Mo‐3d spectrum of MoS₂, confirming the formation of unsaturated Mo sites near sulfur vacancies. (f) The Raman spectra of MoS₂ indicate that an increase in sulfur vacancies leads to a weakening of the Mo—S bond. (g) The EPR spectrum of MoS₂ shows that the signal intensity of sulfur vacancies increases with annealing time. Reproduced with permission [127, 128, 129]. Copyright 2026, The Authors; Copyright 2026, The Authors; Copyright 2025, The Authors.

However, conventional material characterization alone is insufficient to verify genuine piezocatalytic activity. Therefore, direct characterization of piezoelectric responses and dynamic polarization behavior is essential. Piezoresponse force microscopy (PFM) has become one of the most important techniques for nanoscale piezoelectric characterization [56]. By monitoring the amplitude and phase responses under an alternating electric field, PFM enables the visualization of local piezoelectric domains, polarization‐switching behavior, and electromechanical coupling strength [96, 130]. In particular, phase‐reversal behavior under an applied bias provides important evidence for reversible polarization characteristics in ferroelectric piezoelectric systems [39].

Macroscopic piezoelectric current and piezoelectric potential measurements are widely used to evaluate the electrical output generated under periodic mechanical stimulation such as ultrasonic vibration, fluid flow, or cyclic compression [96, 131]. Dynamic current responses can directly reflect the efficiency of mechanical‐to‐electrical energy conversion and provide indirect evidence for charge carrier separation during piezocatalytic processes [111]. Nevertheless, special caution must be exercised because triboelectric charge generation and electrostatic interference may also contribute to measured electrical signals in mechanically agitated systems [132].

Recent advances increasingly emphasize in situ and operando characterization techniques capable of probing dynamic interfacial processes under realistic catalytic conditions. Kelvin probe force microscopy (KPFM) enables surface potential mapping and provides valuable information regarding local piezopotential distribution and transient band bending behavior [111, 133]. In situ atomic force microscopy (AFM) and piezoresponse mapping in liquid environments offer opportunities to directly observe dynamic polarization evolution under external mechanical stimulation [134]. Furthermore, synchrotron‐based X‐ray spectroscopy and operando Raman spectroscopy can reveal real‐time changes in local electronic structure, defect states, and interfacial bonding during catalytic reactions [108].

Characterization of catalytic reaction pathways and reactive intermediates is equally important for understanding piezocatalytic mechanisms [113]. Electrochemical impedance spectroscopy (EIS) is commonly employed to evaluate interfacial charge‐transfer resistance and carrier separation efficiency. Radical trapping experiments combined with electron paramagnetic resonance (EPR) spectroscopy are widely used to identify ROS such as ·OH, ·O₂ ^–, and ¹O₂ [114, 115]. However, in ultrasound‐driven systems, it remains necessary to distinguish ROS generated from intrinsic piezoelectric polarization from those induced by acoustic cavitation or sonochemical effects. Therefore, rigorous control experiments using nonpiezoelectric materials, cavitation‐free low‐frequency mechanical excitation, and catalyst‐free systems are essential for clarifying genuine piezocatalytic pathways.

Another important issue involves the interpretation of ferroelectric hysteresis loops in piezoelectric materials. In some reported systems, apparent polarization hysteresis may originate from leakage currents, dielectric breakdown, or charge injection rather than genuine ferroelectric switching [135]. Therefore, reliable identification of ferroelectric behavior requires combined analysis using PFM phase imaging, leakage current correction, polarization retention testing, and frequency‐dependent hysteresis measurements [136]. Establishing a standardized characterization protocol for piezocatalytic reactions, such as the characterization methods recommended for measuring the properties of applicable materials as shown in Table 1, is crucial for improving reproducibility and mechanistic reliability across different studies.

TABLE 1.

Recommended characterization methods for measuring the corresponding applicable material properties.

Characterization method	Measured property	Applicable materials
Piezoelectric coefficient measurement (d33 meter)	Macroscopic piezoelectric coefficient (d33)	Bulk ceramics, dense films, poled polymers
Laser interferometry	Electric‐field‐induced displacement and piezoelectric coefficient	Thin films, ceramics, single crystals
PFM amplitude imaging	Local piezoelectric response amplitude	Nanomaterials, thin films, 2D materials
PFM phase imaging	Polarization orientation and domain structure	Ferroelectric piezoelectric materials
Switching spectroscopy PFM (SS‐PFM)	Local polarization switching	Ferroelectric materials
Polarization‐electric field (P‐E) hysteresis loop	Ferroelectric polarization reversal	Ferroelectric piezoelectric materials
Positive‐up‐negative‐down (PUND) measurement	True switchable polarization	Ferroelectric materials
KPFM	Surface potential distribution	Piezoelectric semiconductors, heterojunctions
Dynamic piezocurrent measurement	Current generated under mechanical stimulation	Most piezoelectric materials
Dynamic piezopotential measurement	Voltage generated under mechanical excitation	Most piezoelectric materials
EIS	Charge‐transfer behavior	Piezocatalysts
EPR	Reactive oxygen species generation	Piezocatalytic systems
In situ AFM under mechanical stimulation	Dynamic deformation and surface response	Thin films and nanostructures
Synchrotron‐based X‐ray techniques	Electronic structure evolution	Complex piezocatalytic systems

5.2. Regulation Strategy

The regulation strategies of piezocatalytic systems fundamentally aim to maximize the efficiency of mechanical energy conversion into usable chemical energy through optimization of polarization generation, charge separation, interfacial charge transfer, and surface reaction kinetics. Current regulation approaches can generally be divided into internal structural engineering, external operating condition optimization, and multifield coupling strategies.

Internal structural engineering primarily focuses on enhancing the intrinsic polarization response and regulating charge carrier dynamics at the material level. Defect engineering, including the introduction of oxygen vacancies and sulfur vacancies, has emerged as an effective strategy for tuning the local electronic structure, polarization asymmetry, and reactant adsorption behavior [116, 117]. An appropriate defect concentration can serve as charge‐trapping centers, facilitating charge carrier separation, whereas excessive defect accumulation may induce charge recombination and piezopotential screening effects [137]. Similarly, heteroatom doping can simultaneously modulate lattice distortion, band structure, dielectric properties, and piezoelectric coefficients, thereby optimizing piezopotential generation and enhancing catalytic performance.

Morphology and dimensional control also exert a significant influence on piezocatalytic performance. Low‐dimensional structures, such as nanosheets, nanowires, hollow architectures, and porous frameworks, exhibit enhanced strain‐transfer efficiency and shortened charge carrier migration distances, thereby enabling more effective polarization‐induced charge separation [118, 119]. In particular, ultrathin 2D materials can effectively suppress bulk charge recombination and promote dynamic surface charge redistribution under mechanical deformation [138]. However, excessive miniaturization may introduce depolarization fields and charge‐screening effects, thereby compromising the stability of polarization when the material dimensions fall below a critical threshold [16].

Heterostructure engineering represents another important strategy for improving interfacial charge dynamics. By constructing semiconductor heterojunctions, Schottky junctions, or Z‐scheme systems, internal electric fields can be synergistically coupled with piezoelectric polarization fields, thereby promoting directional charge carrier migration and suppressing electron–hole recombination [139,  140]. Beyond band alignment effects, interfacial strain and local symmetry breaking at heterointerfaces may further modulate the intrinsic piezoelectric coefficients and polarization behavior. In addition, surface cocatalysts and conductive components can accelerate surface redox reactions by reducing activation barriers and facilitating interfacial electron transfer [141].

Verification of heterostructure‐induced modulation of piezoelectric properties remains challenging because changes in catalytic activity may originate from electronic band alignment rather than genuine enhancement of piezoelectric response. Therefore, direct characterization of piezoelectric behavior is necessary. PFM can be employed to compare local piezoresponse amplitudes and phase distributions before and after heterostructure construction, thereby revealing possible changes in polarization behavior and domain structures [130]. Quantitative measurements of piezoelectric coefficients using laser interferometry or d33 meters can further evaluate whether interface engineering enhances electromechanical coupling strength. In addition, KPFM enables visualization of interfacial potential distributions and piezopotential evolution, providing direct evidence for polarization modulation induced by interfacial strain and local symmetry breaking [133]. Combining these techniques with finite‐element simulations and first‐principles calculations can provide a more comprehensive understanding of heterostructure‐mediated piezoelectric enhancement.

Optimization of external operating conditions is equally important for achieving high piezocatalytic performance in practical applications. Mechanical stimulation parameters, including frequency, amplitude, pressure, and excitation mode, directly determine stress‐transfer efficiency and polarization intensity. Although increasing ultrasonic power generally enhances catalytic activity, excessive acoustic cavitation may lead to bubble‐shielding effects, catalyst fragmentation, or the generation of nonpiezoelectric radicals [142, 143]. Therefore, matching the excitation frequency with the intrinsic mechanical resonance frequency of the piezoelectric material can provide more efficient energy transfer than simply increasing external power input.

Reaction environment conditions, such as pH, dissolved oxygen concentration, humidity, and temperature, can also significantly influence interfacial reaction pathways [144]. The solution pH regulates the surface charge state of the catalyst and the adsorption behavior of reactants, thereby affecting the selectivity of ROS generation and the associated oxidation pathways. Dissolved oxygen typically acts as an electron acceptor for the formation of ·O₂ ^–, whereas oxygen exclusion may be required in reduction‐dominated reactions, such as hydrogen evolution [145]. Variations in temperature not only affect reaction kinetics but may also induce pyroelectric effects in polar materials, thereby enabling synergistic thermo‐piezocatalytic processes [26].

Current research efforts are increasingly focused on coupling piezocatalysis with other energy fields to achieve synergistic effects that exceed the sum of the individual contributions. Among these approaches, photopiezocatalytic synergistic systems have been the most extensively investigated. Under light irradiation, semiconductor catalysts generate photogenerated electron–hole pairs, while the internal electric field induced by the piezoelectric effect acts as a “pump” that greatly promotes the spatial separation of these charge carriers and drives their participation in surface reactions. By integrating piezoelectric materials, such as BaTiO₃, with photocatalytic materials, including TiO₂ and g‐C₃N₄, degradation and hydrogen‐production performances under simultaneous light and ultrasonic stimulation can substantially exceed those achieved by the individual processes alone [146, 147]. In addition, coupling piezocatalysis with thermocatalysis, electrocatalysis, tribocatalysis, and advanced oxidation processes has further expanded the functionality and adaptability of piezocatalytic systems. Consequently, future regulation and optimization strategies should shift toward dynamic interfacial engineering and intelligent multienergy coupling systems capable of efficiently harvesting low‐frequency and stochastic mechanical energy under realistic environmental conditions.

6. Current Challenges and Future Research Directions in Piezoelectric Catalysis

6.1. Problems and Challenges

Despite rapid advances in recent years, piezocatalysis remains at an early stage of development, and numerous fundamental and engineering challenges continue to hinder its practical implementation. One of the most critical issues lies in the incomplete understanding of the intrinsic catalytic mechanism and the difficulty in quantitatively correlating mechanical excitation, polarization evolution, charge carrier dynamics, and catalytic activity.

A major mechanistic challenge involves distinguishing genuine piezocatalytic effects from other mechanically induced physicochemical phenomena. In many ultrasound‐driven systems, acoustic cavitation can independently generate reactive radicals through sonochemical pathways, while friction‐induced triboelectric charge generation may also contribute to catalytic activity in slurry systems or mechanically agitated reactors. Consequently, the observed catalytic performance in some reported systems may originate from coupled piezoelectric, sonochemical, and triboelectric effects rather than purely intrinsic piezocatalysis [44, 148]. The absence of standardized control experiments and quantitative evaluation criteria has therefore resulted in considerable mechanistic ambiguity across the current literature.

Another important challenge concerns the dynamic nature of piezoelectric polarization under oscillatory mechanical stimulation. Unlike static electric fields in conventional electrocatalytic systems, piezopotential continuously evolves with time‐dependent mechanical deformation [43]. The transient band bending behavior, periodic interfacial charge redistribution, and dynamic adsorption energetics during cyclic stress remain poorly understood. Furthermore, the lifetimes of mechanically induced charge carriers are typically extremely short, and rapid recombination significantly limits catalytic efficiency. Although heterojunction construction and defect engineering can partially improve charge separation, the lack of operando characterization and quantitative kinetic models continues to restrict mechanistic understanding.

Material stability and structural durability also pose significant challenges to the long‐term practical implementation of piezocatalytic systems. Under prolonged cyclic stresses, such as ultrasonic vibration or mechanical stirring, microcracks and dislocations may gradually develop within piezoelectric materials, resulting in the deterioration of polarization performance. In catalytic environments, particularly aqueous systems, materials may additionally undergo chemical corrosion or photocorrosion, further shortening their service lifetime. To enhance catalytic activity, piezocatalysts are often engineered into nanostructured forms. However, owing to their high surface energy and continuous mechanical agitation, these nanostructures are prone to agglomeration, which reduces the number of accessible active sites and consequently diminishes piezocatalytic efficiency. Furthermore, organic piezoelectric materials, such as PVDF‐based systems, may experience β‐phase degradation, fatigue‐induced depolarization, and structural deterioration under harsh chemical or ultrasonic conditions.

To improve long‐term stability, several strategies have been proposed. Composite construction with mechanically robust inorganic piezoelectric components can effectively suppress structural degradation and polarization attenuation in organic piezoelectric materials. Surface encapsulation and protective coatings may reduce chemical corrosion and defluorination under harsh environments. Cross‐linking strategies and polymer‐chain engineering can enhance mechanical strength and preserve β‐phase content during repeated mechanical stimulation. In addition, immobilized catalyst architectures and flexible substrate‐supported systems may reduce mechanical fatigue associated with particle collision and ultrasonic fragmentation. Future studies should also emphasize long‐term cycling tests and operando characterization to evaluate structural and piezoelectric stability under realistic working conditions.

In addition, many high‐performance piezoelectric materials, including certain lead‐containing perovskites and materials with complex hierarchical architectures, face challenges associated with environmental concerns and high fabrication costs [149]. Therefore, the development of lead‐free, low‐cost, and highly efficient piezoelectric materials that are compatible with large‐scale synthesis remains a prerequisite for the commercialization of piezocatalytic technologies.

From the perspective of practical applications, the discrepancy between laboratory conditions and realistic environmental mechanical energy sources remains particularly significant. Most current studies rely on high‐frequency ultrasonic excitation under highly controlled laboratory conditions, whereas naturally available mechanical energy sources, including water flow, wind fluctuation, vibration, and human motion, are typically broadband, low‐frequency, random, and spatially heterogeneous. Efficient harvesting and utilization of such irregular mechanical energy remain highly challenging. Moreover, stress transfer efficiency within reactors is often nonuniform, especially in slurry systems where catalyst particles may experience uneven mechanical stimulation.

Reactor engineering and process scalability also remain underdeveloped. In powder‐based slurry systems, catalyst recovery and reuse are difficult, while particle aggregation and sedimentation reduce effective interfacial contact [150, 151]. Continuous‐flow operation introduces additional complexities associated with hydrodynamic transport, stress distribution, and catalyst immobilization. Furthermore, there currently exists no universally accepted method for evaluating mechanical‐to‐chemical energy conversion efficiency in piezocatalytic systems. Variations in ultrasonic power density, frequency, reactor geometry, and excitation mode across different studies make direct comparison of catalytic performance extremely difficult.

6.2. Future Research Directions

The design and development of novel material systems serve as the cornerstone for the advancement of piezocatalysis, with the key focus being to move beyond reliance on traditional lead‐based materials and achieve function‐oriented design. By exploring biocompatible and environmentally friendly lead‐free piezoelectric materials, and through strategies such as the intentional introduction of oxygen vacancies or doping with heterogeneous atoms [152, 153, 154], it is possible to enhance the material’s piezoelectric properties while simultaneously modulating its band structure. This allows the piezoelectric‐induced band bending to be more conducive to specific catalytic reactions.

The deep integration of theoretical simulations with in situ characterization provides theoretical prescreening for the design of efficient materials. DFT calculations can be employed to compute the electronic structure and surface adsorption energies of materials under various strains. Combined with phase‐field simulations and finite element analysis, the potential distribution on catalyst particles under actual stress conditions can be simulated at a macroscopic scale. Furthermore, developing and applying techniques such as AFM for in situ observation of surface potential changes in liquid environments and utilizing synchrotron radiation X‐ray techniques to track real‐time changes in the atomic structure and electronic states of catalysts under mechanical force, are crucial for verifying theoretical models and revealing the key aspects of the actual reaction process.

To translate laboratory achievements into practical productivity, engineering considerations must be addressed. This involves investigating the variation patterns of physical fields (force field, electric field, and flow field) during the scale‐up of piezocatalytic units from milligram to kilogram levels and establishing reliable scale‐up design criteria. Regarding the simulation of real‐world environments, efforts can be made to design energy harvesters capable of efficiently capturing low‐frequency, random mechanical energy from nature (such as wave energy, wind energy, and fluid kinetic energy) [155] and integrating them with piezocatalytic reactors. The catalytic efficiency under different mechanical excitation modes (impact, sliding, and vibration) should be studied. This also entails moving from the laboratory’s batch processing mode using beakers and ultrasound toward continuous‐flow reactor designs. Through microfluidics or packed bed designs, issues related to difficult catalyst recovery and low mass transfer efficiency can be addressed [156], enabling the realization of continuous and automated catalytic processes.

7. Conclusion

Piezocatalysis, as an emerging interdisciplinary field, is progressively moving from the exploration of fundamental physical effects toward the core of chemistry and materials science. By converting mechanical energy that is ubiquitous yet often overlooked in the environment, such as vibration, water flow, or even weak pulses, into usable chemical energy, piezocatalysis offers a distinctive pathway for green chemistry. In recent years, researchers have made significant progress in the design and modification of piezoelectric materials, thereby continuously expanding the application scenarios of piezocatalysis. Piezocatalysis is demonstrating its multifaceted potential in environmental remediation, energy conversion, and other high‐value fields. Concurrently, with advancements in characterization techniques and the introduction of multifield coupling regulation strategies, the understanding of microscopic mechanisms, such as charge separation and surface reactions during the piezocatalytic process, is becoming increasingly profound.

Of course, this field is still in its infancy. The long‐term stability of materials, catalytic efficiency in complex environments, and the precise elucidation of the quantitative relationship between the piezoelectric effect and chemical reactions remain practical challenges for researchers. Future development may lie not only in searching for materials with better performance but also in breaking down disciplinary barriers to organically integrate piezocatalysis with other catalytic modalities such as photo‐, thermal‐, and electrocatalysis. Through the interplay and validation of theory and experiment, more universal catalytic models can be constructed. It is foreseeable that with the continuous advancement of nanofabrication techniques, in situ characterization methods, and theoretical simulation capabilities, piezocatalysis is expected to move from the laboratory toward broader practical applications. In this process, deep interdisciplinary integration and persistent inquiry into fundamental scientific questions will be key to driving this field toward maturity.

Funding

This study was supported by the National Natural Science Foundation of China (Grant No. 52570088).

Conflicts of Interest

The authors declare no conflicts of interest.

Biographies

Yue Zhang is a PhD candidate in chemistry at the School of Science, Tianjin University. Her current research mainly focuses on the degradation of pollutants in water. Her work aims to elucidate underlying reaction mechanisms by integrating theoretical calculations with experimental findings.

Yifan Chi is a PhD candidate in the Department of Chemistry, School of Science, Tianjin University. Her research focuses on water pollution control, with a specialization in the rational design and fabrication of functional materials.

Yi Li received her PhD from Shandong University. She joined the School of Science at Tianjin University in 2007. She became an associate professor in 2009 and a professor in 2017. Prof. Li’s main research interests include water pollution control and resource utilization, advanced oxidation processes water treatment technology, and the application of functional nanomaterials in environmental pollution control.

Zhang Yue, Chi Yifan, Li Tingting, Cao Chunhe, Liu Yuepeng, Li Yi, Harnessing Mechanical Energy for Catalysis: Mechanisms, Materials, and Applications of the Emerging Piezocatalysis Frontier, ChemPlusChem 2026, 91, e70200. 10.1002/cplu.70200

Data Availability Statement

Data sharing is not applicable to this article as no datasets were generated or analyzed during the current study.