Fundamental Understanding of Photon- and Phonon-Powered Catalysis

Abstract

Photon- and phonon-powered catalysis have emerged as a cornerstone of sustainable chemical synthesis, operating through diverse mechanisms that span the solar spectrum. This review provides a unified mechanistic overview of the three primary regimes of light-matter interaction in catalysis, focusing on their fundamental principles and latest achievements. This review first examines how high-energy photons generate charge carriers to drive solar fuel production. It then evaluates photothermal catalysis, where broad-spectrum light is converted into heat and excited carriers to power methane reforming and carbon dioxide hydrogenation. Finally, this review explores how infrared radiation can selectively vibrate specific molecular bonds for precise and stable chemical synthesis. This approach, known as thermal radiative catalysis, enables precise bond activation and high stability during alkane dehydrogenation. By bridging these three mechanisms, this review offers a clear guide for designing new catalytic systems that fully utilize the energy available from both light and heat.

1. Introduction

The quest for sustainable chemical synthesis has driven the development of photon- and phonon-powered catalysis as a promising alternative to conventional thermocatalytic processes. Since the discovery of the Honda–Fujishima effect in 1972, light-powered catalysis has primarily evolved around the electronic excitation regime. Photocatalysis utilizes high-energy ultraviolet and visible (UV–vis) photons to generate electron–hole pairs in semiconductors. , These charge carriers provide the redox power needed for major achievements in water splitting and CO₂ reduction, − while there is a large amount of energy in the infrared region that is also available for catalysis.

To use more of the solar spectrum, researchers have developed photothermal catalysis. This approach relies on the coupling and conversion between photon–electron–phonon. Photons are harvested to excite hot carriers, electrons promote the adsorption and activation of reactants, while phonons accumulate to elevate local temperature, thereby accelerating reaction kinetics. Recent achievements in this field have enabled breakthroughs in high-temperature dry reforming of methane (DRM) and CO₂ hydrogenation. − By leveraging the localized hot spots generated on the surface of plasmonic, photothermal catalysis provides a robust pathway for utilizing the entire solar spectrum to drive reactions that would otherwise require significant fossil fuel-derived energy.

Beyond bulk heating, the vibrational excitation of molecules in the infrared region is an emerging frontier. Infrared photons possess energies that spectrally overlap with the vibrational absorption band (e.g., C–H and CO bonds absorption band). This allows for precise and selective bond activation, a mechanism exemplified by the recent paradigm of thermal radiative catalysis. By harvesting the intrinsic thermal radiation emitted from reactors through gaseous mediators such as CO₂ and H₂O, this strategy achieves superior yields and exceptional long-term stability in high-temperature alkane dehydrogenation. , This vibrational regime offers a unique way to control chemical pathways at the molecular level.

This review aims to establish a mechanistic framework for understanding photon- and phonon-powered catalysis by critically examining photocatalysis, photothermal catalysis, and thermal radiative catalysis (Figure ). Here, photon- and phonon-powered catalysis is discussed in a broad mechanistic sense, referring to catalytic processes in which electromagnetic radiation, either supplied externally or generated internally, participates as a key energy carrier in reactant activation. From this perspective, thermal radiative catalysis is included as a thermally powered but radiation-facilitated catalytic regime because internally generated MIR photons provide an additional pathway for molecular activation. By examining these three types of photon- and phonon-powered catalysis, this review shows how light interacts with matter in different ways and provides a guide for designing next-generation catalytic systems that use the full energy of light and heat. This unified understanding helps the chemical industry move toward a more efficient and sustainable future.

1.

Schematic representation of photon- and phonon-powered catalysis.

2. Photocatalysis

The development of photon- and phonon-powered catalysis has been historically synonymous with the generation and utilization of charge carriers in semiconductors. This regime, dominated by ultraviolet and visible photons, operates on the principle that light energy (hν) exceeding the semiconductor bandgap (E_g) can promote electrons from the valence band (VB) to the conduction band (CB), creating electron–hole pairs (Figure A). , These photogenerated charge carriers serve as the primary driving force for redox reactions, enabling chemical transformations that are unfavorable or slow under dark conditions. This section evaluates the fundamental mechanism of the electronic paradigm while highlighting the landmark achievements in solar fuel production.

2.

(A) Schematic representation of the typical photocatalytic process. Reproduced with permission from ref . Copyright 2019 John Wiley and Sons. (B) Time-scale dynamics of charge carrier generation, transport, and surface reactions in photocatalysis. (C) Time courses of the water-splitting reaction on a Cr₂O₃/Ru-modified SrTiO₃: La, Rh/Au/BiVO₄: Mo sheet under simulated sunlight. Reproduced with permission from ref . Copyright 2016 Springer Nature. (D) Temperature-dependent STH efficiency of the Rh/Cr₂O₃/Co₃O₄–InGaN/GaN NWs. (E) Stability test of the Rh/Cr₂O₃/Co₃O₄–InGaN/GaN NWs. Reproduced with permission from ref . Copyright 2023 Springer Nature. (F) Energy band position diagram of FeO _x -ns and FeO _x -nsl. (G) Comparison of photocatalytic activity for the first hour of catalysts. (H) Electron-based selectivity and product-based selectivity of catalysts. Reproduced with permission from ref . Copyright 2026 American Chemical Society.

2.1. Fundamental Mechanism

The photocatalytic process under UV–vis irradiation can be understood as a sequential chain of charge generation, separation, migration, and surface reaction. When an incident photon possesses energy that exceeds the bandgap, it promotes an electron from the valence band to the conduction band, which generates an electron–hole pair on an ultrafast femtosecond time scale. , This electronic excitation initiates a competition between charge utilization and nonradiative energy loss. Within a few picoseconds, photogenerated carriers typically lose their excess kinetic energy to the lattice through phonon emission or undergo rapid bulk recombination, which is often considered the primary loss for overall quantum efficiency. To drive reactions, these charge carriers must successfully migrate to the catalyst surface before they recombine. Oxidation occurs when holes extract electrons from molecules on the surface; reduction happens when electrons are transferred to reactants. Because these surface charge transfer events usually take place on nanosecond to microsecond time scales, they must outcompete the much faster recombination processes for the reaction to be successful (Figure B). The efficiency of photocatalysis is strongly governed by the structure–function relationship of the semiconductor and its surface active sites. Researchers improve photocatalytic performance by controlling material crystallinity and adding cocatalysts. − These strategies help separate charges and extend the lifetime of the reactive species.

2.2. Applications

The electronic excitation regime has enabled a decade of transformative progress in harnessing solar energy for chemical synthesis. By using the high redox power of photogenerated carriers, researchers have reached major milestones that offer both scientific value and practical benefits for the chemical industry. Key examples include water splitting, pollutant degradation, − and CO₂ hydrogenation. − In photocatalysis, the practical catalytic effect is commonly evaluated by quantum efficiency, product selectivity, and long-term stability. These metrics directly reflect how efficiently photogenerated charge carriers are converted into chemical products.

2.2.1. Water Splitting

One of the most celebrated achievements in this regime is the realization of overall water splitting, which produces clean hydrogen fuel. Recent breakthroughs have seen the development of semiconductor systems and Z-scheme heterojunctions that can achieve high solar-to-hydrogen (STH) conversion efficiencies. For instance, the engineering of high-quality crystalline materials such as gallium-doped zinc oxide or aluminum-doped strontium titanate has demonstrated the ability to catalyze the simultaneous evolution of H₂ and O₂ under visible light (Figure C). , These systems offer a practical way to store solar energy as chemical energy. A landmark achievement was reported by Zhou and coworkers, where an STH efficiency of 9.2% was realized using an InGaN/GaN nanowire photocatalyst under concentrated solar illumination (Figure D–E). This represents a significant milestone for photocatalytic systems that operate without external power, because it addresses the rapid recombination of carriers. This progress shows that better materials and reaction settings can bring these systems closer to practical use.

2.2.2. CO₂ Hydrogenation

Photocatalysis has also made remarkable progress in the conversion of greenhouse gases to sustainable fuels and feedstocks. By tuning the conduction band positions and surface active sites of catalysts, it is now possible to selectively reduce CO₂ to a variety of products, including carbon monoxide, methane, methanol, and multicarbon products. Recent research has focused on the use of single-atom catalysts and surface-engineered metal oxides to enhance multielectron transfer processes. These advancements have enabled high-selectivity CO₂ conversion under ambient conditions, which is a critical requirement for a future circular carbon economy.

Cheng et al. recently reported a breakthrough in making multicarbon fuels from CO₂ using unique amorphous FeO _x nanosheets. This catalyst uses structural and electronic synergy to improve performance. The amorphous framework provides many disordered sites that improve molecule adsorption. At the same time, the mesoporous structure shortens the distance that charges must travel to reach the surface. Furthermore, the integration of laser-induced oxygen vacancies was found to increase the Fe²⁺/Fe³⁺ ratio, establishing a tandem catalytic pathway whereby Fe³⁺ sites facilitate CO₂ activation and Fe²⁺ sites effectively stabilize *OCCO intermediates to promote C–C coupling. This design led to an efficiency of 1.60% at 520 nm and a high ethane selectivity of 94% (Figure F–H). This example illustrates that photocatalytic performance should be assessed not only by conversion efficiency but also by product selectivity, because charge-transfer pathways and surface intermediate stabilization strongly determine the final product distribution.

2.2.3. Organic Synthesis

Beyond energy conversion, photocatalysis has also changed the field of organic synthesis. By utilizing mild visible light and photoredox catalysts, chemists can generate highly reactive radical intermediates that enable challenging transformations, such as C–H activation and cross-coupling. This approach allows for the construction of complex molecular architectures with high efficiency and reduced reliance on toxic reagents. Driving these reactions with photons instead of high heat provides great precision. For instance, the implementation of photocatalytic sequential electron/proton transfer has enabled the direct generation of high-energy nitrogen-centered radicals from free N–H bonds, allowing for the site-selective functionalization of unactivated C­(sp³)–H centers in pharmaceuticals and natural products. Additionally, controlling the speed of charge carriers in nickel catalysis has fixed common issues in C–N cross-coupling. This allows for the successful reaction of difficult molecules while keeping the catalyst stable.

In summary, photocatalysis is a powerful way to drive chemical reactions by using light. It has enabled important progress in the production of solar fuels and the synthesis of precise organic molecules under mild conditions. However, this approach uses only high-energy photons, which leaves a large part of infrared unused. Challenges such as material stability and energy loss through carrier recombination also limit overall efficiency. − These factors provide a strong motivation to explore photothermal catalysis discussed in the following sections.

3. Photothermal Catalysis

The solar spectrum at the Earth’s surface contains only approximately 5% UV light and 45% visible light, with the remaining roughly 50% residing in the infrared region (Figure A). The need to use more of the solar spectrum has led to the development of photothermal catalysis. Photothermal catalysis captures light from ultraviolet to infrared wavelengths to synergistically drive both photochemical and thermochemical processes. As shown in the energy diagram, the thermochemical effect converts light into heat to raise the energy level of the reactants. Simultaneously, the photochemical effect lowers the activation energy barrier by creating excited states (Figure B).

3.

(A) Spectral irradiance of solar spectrum. (B) Photothermal pathway reduces the activation energy barrier in catalytic reactions. Reproduced with permission from ref . Copyright 2025 Royal Society of Chemistry. (C) Photothermal DRM performance for Ni@TS-1. (D) Stability test for Ni@TS-1 in a flow reactor with light irradiation for 300 h. Reproduced with permission from ref . Copyright 2025 Elsevier. (E) Schematic of the nanoscale greenhouse effect in Ni@p-SiO₂. (F) Estimated T_local of different catalysts under different illuminations. (G) CO₂ conversion rate of different Ni catalysts for photothermal hydrogenation of CO₂ under different intensities of light. Reproduced with permission from ref . Copyright 2021 Springer Nature. (H) Methanol rate of black indium and (I) the corresponding Arrhenius plot. Reproduced with permission under Creative Commons License (CC BY 4.0) from ref . Copyright 2022 Springer Nature.

3.1. Fundamental Mechanism

As described in photocatalysis, high-energy photons generate charge carriers that reduce the activation barrier of a reaction. These photogenerated carriers also influence the electronic environment on the catalyst surface. This process may modify the surface acidity and basicity to enhance the adsorption and activation of reactant molecules. For example, the accumulation of electrons can create more basic sites that improve the binding of acidic molecules such as CO₂. ,

The conversion of full-spectrum light into thermal energy follows direct and indirect pathways, depending on the catalyst structure. The direct pathway involves the absorption of light, where light energy is transformed immediately into lattice heat. Indirect conversion occurs in two main ways. In metallic nanostructures, plasmonically localized heating is triggered when incident light causes conduction electrons to oscillate together. This energy quickly turns into heat through electron–phonon scattering within the metal lattice. In semiconductor catalysts, heat is generated when charge carriers lose their energy through nonradiative relaxation and recombination. This includes both high-energy carriers dropping back to lower energy levels and electron–hole pairs recombining. These events release energy into the lattice as heat, which causes a temperature increase that speeds up reaction kinetics. These mechanisms enable transformative applications in synthesis, allowing the use of the entire solar spectrum for sustainable chemistry.

3.2. Applications

Photothermal catalysis has demonstrated remarkable success in driving reactions that typically require high temperatures, effectively using solar energy to replace fossil-fuel-derived heat. For photothermal catalysis, the catalytic effect is usually reflected by rate or conversion enhancement under irradiation compared to dark thermal controls, changes in apparent activation energy, improved selectivity, and stability under continuous light irradiation. These metrics are essential for evaluating whether light provides only heat or also introduces additional photoinduced effects.

3.2.1. Dry Reforming of Methane

Photothermal catalysis has led to major breakthroughs in the DRM. This process converts methane and carbon dioxide into syngas. While this reaction normally requires very high heat, light energy can make the process more efficient at lower temperatures. Improving the electronic properties of catalysts is one successful approach for this reaction. Zhang et al. showed that doping nickel with yttrium can significantly boost the performance. Yttrium transfers electrons to the nickel to keep it in a metallic state. This helps the catalyst activate methane more easily and doubles the production rate of the carbon monoxide. Wang et al. designed a catalyst by placing nickel particles inside a TS-1 zeolite matrix. The zeolite framework acts as a thermal block that prevents heat from escaping. This method achieved a conversion rate that was 300% higher than that of traditional thermodynamic limits (Figure C). The light also helped to block the unwanted side reactions. This resulted in a high-quality syngas mixture with a near-ideal hydrogen-to-carbon monoxide ratio that remained stable for 300 h (Figure D). The enhanced conversion rate and long-term stability demonstrate how photothermal heat management can be translated into practical catalytic improvements in high-temperature reforming reactions.

3.2.2. CO₂ Hydrogenation

Photothermal systems have achieved high conversion rates for CO₂ methanation and reverse water–gas shift (RWGS) reactions. ,− Guo et al. utilized narrow-band gap CuInS₂ thin films to demonstrate the efficacy of NIR-driven CO₂ hydrogenation. The catalyst effectively converts NIR photons into heat, leading to a significantly higher reaction rate than that achieved under UV–visible light alone. Inspired by the greenhouse effect, Cai et al. developed a supra-photothermal Ni@p-SiO₂ catalyst where a nickel core serves as the light absorber and a nanoporous silica shell traps IR radiation (Figure E). This unique structure acts as a radiative barrier that reduces thermal energy loss and raises the local temperature of the Ni particles significantly above that of nonencapsulated catalysts (Figure F). This intense localized heating provides the necessary energy to drive high-rate CO₂ conversion with an improved selectivity (Figure G). This work demonstrates that engineering a microgreenhouse environment at the catalyst level can maximize the utilization of full-spectrum light for solar-fuel synthesis.

Photothermal catalysis often shows a synergy between the light and heat effects. A clear example of this is seen in the synthesis of methanol over black indium oxide. Kinetic studies using Arrhenius plots are used to separate these two contributions. At lower temperatures, the activation energy for methanol synthesis remains similar under both light and dark conditions. This suggests that the reaction follows the same mechanism and that light primarily acts as a heat source. However, at higher temperatures, a distinct change occurred. While the energy barrier drops under dark conditions due to a shift in the reaction pathway, it decreases even further when light is applied (Figure H–I). This reduction happens because light helps reaction intermediates to move more easily between active surface sites. These kinetic results provide strong evidence of a photochemical process that works together with heat to improve the reaction performance.

In summary, photothermal catalysis offers a robust way to harness the full solar spectrum by integrating photochemical and photothermal effects. The photochemical contribution involves high-energy photons exciting charge carriers for direct redox reactions and surface basicity modulation, which facilitate molecular adsorption and activation. Meanwhile, the photothermal effect originates from broad-spectrum absorption that dissipates into phonons for bulk heating. This approach powers energy-intensive reactions such as methane reforming and CO₂ reduction under much milder conditions. Recent breakthroughs show that managing light and heat together can break thermodynamic limits and keep catalysts stable for long-term use. Despite these advances, several challenges remain in the field of photothermal catalysis. The local temperature of active sites is difficult to determine accurately, and the contributions of hot carriers, surface electronic modulation, and local heating are often intertwined. Standardized activity metrics are also needed because performance depends strongly on light intensity, catalyst loading, and heat dissipation. In addition, catalyst stability under intense irradiation and temperature gradients should be carefully evaluated.

4. Thermal Radiative Catalysis

The IR region provides a distinct mechanism through the direct resonant excitation of molecular vibrations. Infrared photons have energies that match the vibrational frequencies of specific chemical bonds. Vibrational excitation targets specific molecular modes. This selective action weakens intended chemical bonds and reduces the energy required for the reaction. On the basis of these physical insights, our group recently proposed and demonstrated thermal radiative catalysis (TRC) as a novel catalytic strategy. , This approach uses the thermal radiation emitted by the reactors to promote chemical reactions.

4.1. Fundamental Mechanism

The core principle of thermal radiative catalysis is the resonance between incident photons and specific vibration modes of molecules. When a molecule absorbs an IR photon, it transitions from the ground vibrational state to an excited state. This population of excited vibrational states alters the potential energy surface of the molecule, effectively elongating specific bonds and reducing the energy required for their dissociation. In traditional liquid/gas-phase chemistry, this concept was explored using high-intensity, tunable IR lasers to achieve “mode-selective chemistry”. , Seminal work by Crim and others demonstrated that exciting specific C–H or O–H stretches could enhance reaction rates by orders of magnitude compared to thermal equilibrium conditions. , However, these laser-driven approaches were limited by the high cost, low power, and narrow bandwidth of available sources, making them impractical for large-scale catalysis.

TRC differs from conventional photocatalysis and photothermal catalysis because its radiation is generated internally from a high-temperature reactor rather than supplied by an external light source. Therefore, heat remains the primary energy input in TRC. Nevertheless, the reactor-emitted MIR radiation can act as an additional driving force when it spectrally overlaps with molecular vibrational absorption bands. The use of intrinsic thermal radiation instead of external lasers is a major breakthrough. This shift provides a constant and low-cost light source for chemical reactions. It makes the vibrational activation mechanism practical for large-scale industrial use. According to Planck’s law, any object at a temperature T emits blackbody radiation with a spectral distribution peaking at λ_max ≈ 2898/T (μm·K). For a typical catalytic reactor operating at 500–800 °C (773–1073 K), the peak emission falls squarely in the MIR region, perfectly overlapping with the vibrational fingerprints of many key reactants and mediators. This suggests that the heat already applied to drive thermocatalysis inherently generates a flux of IR photons capable of driving vibrational excitation. By utilizing the heat already present in the reactor, this method significantly improves energy efficiency.

4.2. Applications

A key innovation of TRC is the use of gaseous catalystsmolecules with large IR absorption cross sections that act as “thermal radiation antennas” to harvest thermal radiation and transfer energy to reactants via inelastic collisions. Unlike solid catalysts, these mediators do not suffer from coking, sintering, or leaching, offering exceptional stability. Two main gaseous catalysts (CO₂ and H₂O) have been used to demonstrate this strategy. In TRC, the catalytic contribution of thermal radiation is commonly evaluated by comparing radiative systems with radiation-shielded or mediator-free controls. Key performance indicators include conversion, product yield, product selectivity, and long-term stability. These comparisons are important for establishing whether reactor-emitted MIR radiation contributes to reaction enhancement beyond conventional thermal effects.

4.2.1. CO₂-Catalyzed Ethane Dehydrogenation

In this system, CO₂ acts as the vibrational energy harvester. The asymmetric stretching mode of CO₂ matches the thermal emission spectrum of a reactor at 600 °C. When CO₂ absorbs these photons, it enters an excited vibrational state. These excited molecules then collide with ethane (C₂H₆) to weaken its C–H bonds and help remove hydrogen atoms (Figure A, B). Experiments were conducted in a quartz tube to allow radiation and a steel tube to block it. The introduction of CO₂ under radiation led to a 120% increase in C₂H₄ yield compared to the shielded control (Figure C). C₂H₄ selectivity remained very high at 99.26%. This result indicates that vibrational excitation specifically targets C–H bonds and prevents unwanted C–C cracking. Removing the steel tube lowered the activation barrier by 14 kJ/mol (Figure D). This proves that CO₂ works as a catalyst through thermal radiation. Computer simulations also revealed that excited CO₂ reduces the energy threshold for bond breaking by more than 1 eV. This increases the reaction probability by over 10 orders of magnitude (Figure E).

4.

(A) Schematic diagram of carbon dioxide enabling thermal radiative catalytic ethane dehydrogenation. (B) Theoretical blackbody radiation intensity spectra and the major IR absorption of different molecules. (C) Rate of C₂H₄ in C₂H₆/Ar and C₂H₆/CO₂ systems. (D) Arrhenius plot of C₂H₆/CO₂ and C₂H₆/Ar systems. (E) Potential energy surface of CO₂ + H + C₂H₅ with vibrational quantum number v₁ = v₂ = 0 and v₁ = v₂ = 2. Reproduced with permission from ref . Copyright 2023 Elsevier. (F) Schematic diagram of catalytic propane conversion with water molecules. (G) Catalytic performance for different systems. (H) The 3D structure of the in situ synchrotron radiation photoionization mass spectrometry. (I) The relative abundance of methyl radical, ethyl radical, and propyl radicals in the cases of C₃H₈ and C₃H₈/H₂O. (J) The proposed reaction pathway. Reproduced with permission from ref . Copyright 2025 John Wiley and Sons.

4.2.2. H₂O-Catalyzed Propane Dehydrogenation

Similarly, water vapor (H₂O) serves as an efficient mediator for propane (C₃H₈) dehydrogenation (Figure F). Thermal radiation excites the vibrational modes of water to generate reactive hydroxyl radicals (OH∗). These radicals abstract hydrogen atoms from propane more efficiently than heat alone. This process shifts the reaction pathway from difficult C–C bond scission to more favorable C–H bond cleavage. Using trace amounts of water under radiation achieved a propane conversion of 51.14% and an olefin yield of 37.93% (Figure G). This performance significantly outperformed systems without radiation or without water. The system was highly stable and worked for more than 2000 h without deactivation. This is a major advantage over solid catalysts that often fail within hours due to carbon buildup. Kinetic studies and isotopic labeling using D₂O and C₃D₈ confirmed that O–H and C–H bond breaking are the key steps. In situ synchrotron PI-MS results also showed fewer methyl and ethyl radicals but more propyl radicals (Figure H–J). This evidence confirms the shift in the reaction mechanism.

In summary, thermal radiative catalysis offers a highly selective pathway for chemical synthesis. This approach turns the internal thermal radiation of a reactor into precise catalytic power. By using gaseous mediators instead of solid catalysts, this method avoids common issues, such as deactivation and carbon deposition. Recent studies of carbon dioxide and water show that this strategy can significantly lower reaction barriers and improve product yields. This paradigm provides a practical way to harness thermal radiation for energy-efficient industrial processes. Although TRC provides a promising route to utilizing reactor-emitted thermal radiation, it is still an emerging field. Its key challenges include the limited selectivity of broadband MIR radiation, the difficulty of quantifying vibrational excitation under working conditions, and the strong influence of reactor geometry and radiation transport. In addition, its applicability beyond alkane dehydrogenation remains to be explored.

5. Summary and Outlook

This review summarizes three representative catalytic regimes of photon- and phonon-powered catalysis by analyzing light-matter interactions across the light spectrum. To better connect these mechanistic regimes with their practical catalytic consequences, we further compare their energy sources, representative reactions, quantifiable performance metrics, advantages, and remaining challenges, as shown in Table . Photocatalysis uses high-energy photons to create charge carriers for redox reactions in solar fuel production. Photothermal catalysis integrates heat generation with electronic excitation to accelerate the kinetics and lower reaction barriers. Thermal radiative catalysis utilizes infrared radiation to excite specific molecular vibrations for precise and stable bond activation. This framework shows that photon- and phonon-powered catalysis is a versatile approach, where each mechanism targets a specific electronic state or chemical bond within a molecule. These strategies together allow for a more efficient and controlled approach to the chemical synthesis.

1. Comparison of Photocatalysis, Photothermal Catalysis, and Thermal Radiative Catalysis.

Catalytic regime	Photocatalysis	Photothermal catalysis	Thermal radiative catalysis
Energy carriers	Photon	Photon and phonon	Photon and phonon
Typical catalysts	Heterojunctions	Plasmonic metals; semiconductors	IR-active gaseous molecules
Representative reactions	Water splitting; CO2 reduction	CO2 hydrogenation; dry reforming of methane	Alkane dehydrogenation
Quantifiable metric	Quantum efficiency	Rate and conversion	Yield and conversion
Advantages	Mild conditions; direct solar-to-chemical conversion	Broad spectral utilization; accelerated thermal reactions	Intrinsic radiation utilization; avoids catalyst deactivation
Challenges	Charge recombination	Local-temperature measurement; stability under irradiation	Broadband radiation, quantitative radiation intensity

Despite the important progress, several challenges remain. For photocatalysis, improving charge separation, suppressing recombination, and enhancing the long-term stability remain central tasks. For photothermal catalysis, accurately determining the real temperature of active sites is still difficult, and distinguishing photochemical effects from local heating requires rigorous control experiments. For TRC, the broadband nature of reactor-emitted MIR radiation limits strict mode selectivity, and the quantitative contribution of vibrational excitation remains unclear. Reactor geometry, gas composition, wall emissivity, and radiation transport should be considered when evaluating the TRC performance.

Future progress will depend on the successful coupling of these different mechanisms into integrated systems. Researchers can focus on the synergy between photons and phonons. For example, localized heat can speed up the movement of intermediates, while excited electronic states drive precise bond-forming steps. The reactor design must also evolve to manage both light absorption and internal thermal radiation effectively. In addition, the rational design of spectrally selective radiative thermal emitters represents an important future direction for TRCs. Future progress will require the integration of advanced characterization, kinetic analysis, and theoretical modeling. In situ and operando spectroscopic techniques will be important for disentangling electronic, thermal, and vibrational contributions in real-time. Advanced theoretical tools will be essential to track how energy flows across different molecular states in real time. By bridging electronic, thermal, and vibrational effects, the next generation of catalytic systems will reach higher levels of efficiency and selectivity. This transition toward spectrum-aware catalysis offers a practical way to achieve sustainable chemical synthesis and a carbon-neutral future.

The manuscript was written through contributions of all authors. All authors have given approval to the final version of the manuscript. CRediT: J.W. data curation, visualization, writingoriginal draft, writingreview and editing; L.W. conceptualization, supervision, visualization, writingreview and editing.

The authors declare no competing financial interest.

Published as part of ACS Nanoscience Au special issue “2026 Rising Stars in Nanoscience”.