A review of electrospun metal oxide semiconductor-based photocatalysts

Summary

In recent years, photocatalytic materials with a nanofiber-like morphology have garnered a surge of academic attention due to their distinctive properties, including an expansive specific surface area, a considerable high aspect ratio, a pronounced resistance to agglomeration, superior electron survivability, and robust surface activity. Consequently, the synthesis of photocatalytic nanofiber materials through various methodologies has drawn considerable attention. The electrospinning technique has been established as a prevalent method for fabricating nanofiber-structured materials, owing to its advantageous properties, including the ability for mass production and the assurance of high continuity. This review focuses on metal oxide semiconductor-based materials, which are crucial components of photocatalysts. We summarize several recent studies that explore morphology modulation, surface modification, element doping, and composite construction using uniaxial and coaxial electrospinning techniques. Finally, we present potential approaches for constructing high-activity photocatalytic systems through electrospinning technique.

Graphical abstract

Catalysis; Materials science; Energy materials

Introduction

Historically, the earliest catalysts consisted of three-dimensional bulk materials or particle-like structures, typically composed of metals, oxides, or other active substances in a solid state. Although these materials demonstrated certain catalytic capabilities, they were inherently limited by their large particle size and restricted surface area, constraining their catalytic activity and selectivity.¹ To overcome these issues, research has increasingly focused on modulating catalyst morphology—by reducing particle size, developing two-dimensional sheets, and creating one-dimensional nanostructures like nanofibers.^2,3,4 One-dimensional nanofibers and nanowires, with their high surface area-to-volume ratios arising from their extreme extensiveness in one dimension and thinness in the other two dimensions, have shown remarkable potential in improving catalyst performance by enhancing selectivity, reducing side reactions, and promoting efficient electron transport.⁵ Consequently, the synthesis of photocatalytic nanofiber materials has attracted considerable attention due to their unique properties, including extensive specific surface area, high aspect ratios, significant resistance to agglomeration, enhanced electron survivability, and robust surface activity, and related works have thus been widely researched to facilitate the exploration of diverse methodologies aimed at optimizing their production.⁶

Among the various techniques for preparing one-dimensional nanofibers, such as templating, sol-gel, and self-assembly, electrospinning stands out due to its unique advantages, including the ability to modulate the specific surface area of the material, feasibility for mass production, and simplicity of the apparatus, which requires only a syringe, a receiver, and a high-voltage power supply, as shown in Figure 1.^7,8

Figure 1.

Schematic diagram of the electrospinning device

The electrospinning technique does not require complex equipment or substantial expense, yet it facilitates the rapid generation of nanofibers within a short time frame, simultaneously ensuring that the fibers exhibit an exceptionally high surface area-to-volume ratio, thus guaranteeing its practicability and scalability. Electrospinning is rapidly differentiating from the single-fluid electrospinning to bi-fluid coaxial and side-by-side electrospinning, and to tri-fluid coaxial, Janus, and their combined electrospinning processes.^{9,10,11,12,13,14} Meanwhile, electrospinning is also frequently combined with other traditional techniques such as electrospraying and solvent casting for expanding its capability of creating nanofibers.^15,16,17 However, the most popular electrospinning processes are uniaxial and coaxial processes, as shown in Figure 2, which have been broadly employed for producing metal oxide semiconductor-based photocatalysts. Relatively speaking, uniaxial electrospinning is limited in producing more complex structures when compared with the coaxial electrospinning. When compared with uniaxial electrostatic spinning, the most notable distinction is that the coaxial needle comprises two parts. One part of the apparatus is loaded with the shell liquid, whereas the other part is loaded with the core liquid. On the other hand, to construct photocatalytic systems with enhanced activities, many modulation strategies have been developed, such as surface modification, element doping, and composite construction. By coaxial spinning or adding additional components into the spinning solution, the above-mentioned modulations can be easily realized through an in situ process.¹⁸

Figure 2.

(A and B) Comparison of single-axis and coaxial needles

Based on the above investigation, this review provides a systematic survey and summary of current research on the preparation of highly active photocatalytic systems using electrospinning technology, focusing primarily on enlarging the specific surface area of the materials by modulating their morphology, modifying some functional groups or metal particles on their surface, doping some elements in their structure, and introducing other semiconductor materials to construct composites. At last, we propose a promising strategy for constructing photocatalytic systems with enhanced charge separation properties and catalytic performance through coaxial electrospinning technology.

Morphology modulation

The specific surface area of bulky, large-sized materials is inherently limited, as depicted in Figure 3A, resulting in fewer surface-active sites and reduced contact with reactants. To address this issue, nanofibers produced via electrospinning, as shown in Figure 3B, have been widely researched for their ability to increase the specific surface area.¹⁹ By adjusting parameters such as solution viscosity, voltage, and flow rate, it is possible to create materials with varying pore sizes. Among these techniques, coaxial electrospinning (illustrated in Figure 3C) produces hollow or core-shell fibers, which further enhance performance by increasing surface area and facilitating efficient carrier migration.^20,21 This structure improves charge separation and reduces electron-hole recombination due to shortened migration pathways. Additionally, hollow porous nanofibers, shown in Figure 3D, provide even greater advantages with their porous structure, introducing additional channels and active sites.²² This configuration promotes reactant diffusion, enhances charge carrier separation, and suppresses electron-hole recombination, resulting in significantly improved photocatalytic efficiency.

Figure 3.

Comparison of the different morphology, including nanoparticle from common preparation methods (A), nanofiber (B), hollow nanofiber (C) and hollow mesoporous nanofiber (D) from electrospinning method.

A number of studies have employed uniaxial electrostatic spinning to fabricate fibrous photocatalysts with a high specific surface area. For example, Juncai Lu et al.²³ prepared ZnWO₄ nanofibers using uniaxial electrospinning, achieving a specific surface area of 110 m² g⁻¹, which was significantly higher than the 75 m² g⁻¹ of irregular ZnWO₄ nanoparticles prepared by the same method. This increase in surface area, attributed to the electrospinning process, also led to a higher density of defects and active sites, enhancing the material’s catalytic efficiency. As a result, the ZnWO₄ nanofibers degraded 70% of RhB (10 mg/L) within 45 min, compared with 70 min required by the nanoparticles. The enhanced surface area and accelerated charge separation due to electrospinning are also crucial for improving hydrogen production technologies.

Ling Wang et al.²⁴ synthesized MgTiO₃ nanofibers with a specific surface area of 22.62 m² g⁻¹, about 3.5 times greater than that of MgTiO₃ particles (6.3 m² g⁻¹) prepared via sol-gel and calcination. The high aspect ratio of the nanofibers enhanced light absorption and facilitated rapid migration of photogenerated charge carriers, reducing electron-hole recombination and improving charge transport. This led to a hydrogen production rate of 0.33 mmol g⁻¹·h⁻¹, four times higher than that of MgTiO₃ particles. The porous structure between nanofibers further enhanced reactant conversion and hydrogen production efficiency.

Shama Perween et al.²⁵ produced ZnTiO₃ nanopowders via uniaxial electrospinning, starting with calcination to form ZnTiO₃ powder, followed by sol formation with a surfactant, and finally electrospinning. The specific surface area of the electrospun ZnTiO₃ (24.47 m² g⁻¹) was significantly higher than that of the sol-gel-prepared sample (1.05 m² g⁻¹). The increased surface area and nanoporous structure, formed by removing organic components during synthesis, contributed to a 1.7-fold improvement in the phenol degradation rate under visible light, showcasing superior photocatalytic performance.

Some studies have utilized coaxial electrospinning to create hollow fiber structures, aiming to further enhance the material’s specific surface area. For instance, Juran Kim et al.²⁶ utilized coaxial electrospinning to fabricate TiO₂ hollow nanofibers, where the transition from solid to hollow structures was controlled by varying the core solution flow rate. When the flow rate was set to zero, the resulting solid fibers had a specific surface area of 16.01 m² g⁻¹, comparable to fibers produced by uniaxial spinning. However, as the core solution flow increased, the fibers transformed into hollow nanofibers, achieving a maximum surface area of 51.28 m² g⁻¹. This hollow architecture, characterized by a larger internal cavity, significantly increased the material’s surface active sites, thereby enhancing its adsorption capacity and catalytic performance. The unique layered structure also facilitated greater exposure of catalytic sites to reactants, allowing for more efficient diffusion and interaction. As a result, the NO removal rate within 60 min reached 66.2%, more than double the 31.2% achieved by the solid fibers. This improvement is largely due to the increased surface area and improved electron transport across the hollow structure, which enhances the availability of reactive species at the active sites.

Shudan Li et al.²⁷ employed a similar coaxial electrospinning method, using air as the core material to produce hollow, mesoporous LaFeO₃ nanofibers with a belt-like structure. The hollow fibers, with their high porosity, differed markedly from the densely packed uniaxial fibers typically formed after calcination. The hollow structure not only provided a larger surface area but also improved light utilization by enhancing the penetration and scattering of light within the fiber matrix, increasing the efficiency of photocatalytic reactions. Moreover, the belt-like structure of the nanofibers facilitated greater contact between the catalyst and the reaction substrate, improving mass transfer. The smaller crystalline domains further contributed to the reduction of photogenerated electron-hole recombination by shortening the distance electrons and holes must travel to reach the surface, thus optimizing the photocatalytic activity. These structural advantages resulted in a methylene blue (MB) degradation efficiency of 59.79% within 2 h, demonstrating the efficacy of hollow, mesoporous fibers in enhancing both light absorption and catalytic performance.

Both uniaxial electrostatic spinning and coaxial electrostatic spinning are feasible methods in regulating the morphology of materials, thereby enhancing their specific surface area. Herein, a summary of some related works is presented as shown in Table 1, including the related spinning conditions, carrier polymers used, and catalytic efficiency.

Table 1.

Morphological modulation using electrostatic spinning

Photocatalyst	Spinning conditions	Solvents	Carrier polymers	Photocatalytic testing	Test conditions	Activity results	Reference
ZnWO4	Voltage 15 kV Distance (to needle tip) 15 cm	DI	PVP	Degrading RhB	RhB solution at 10 mg/L	70% within 45 min	Lu et al.23
MgTiO3	Voltage 12 kV Distance 12 cm	CH3COOH, CH3OH	PVP	Hydrogen production	300-W Xe lamp	0.33 mmol g−1·h−1	Wang et al.24
ZnTiO3	Voltage 10 kV Distance 12 cm	CH3COOH	PVA	Degrading C6H6O	Visible light (output power 100 W)	70% within 1 h	Perween et al.25
TiO2	Voltage 15 kV Distance 12 cm	DMF, CH3COOH, C2H5OH	PVP	Degrading RhB	200-W Xe light RhB solution at 20 mg/L	99% within 90 min	Kim et al.26
LaFeO3	Pushing speed 0.4 mL h−1 Distance 12 cm	CH3COOH, C2H5OH	PVP	Degrading MB	125-W Xe light MB solution at 5 mg/L	59.8% within 120 min	Li et al.27
BiVO4	Voltage 16 kV Distance 14 cm	DMF, CH3COOH, C2H5OH	PVP	Redox Cr(VI)	Cr(VI) solution concentration 10 mg/L	95.3% within 80 min	Lv et al.28
ZnO	Voltage 17 kV Distance 11 cm	DMF	PAN	Degrading MB	MB solution concentration 15 μM	99% within 60 min	Pantò et al.29
WO3	Voltage 28 kV Distance 15 cm	DMF, C2H5OH	PVP	Degrading C6H6O	C6H6O solution at 20 mg/L	2.87 mg L−1·h−1	Tong et al.30

DI, deionized water; PVP, polyvinyl pyrrolidone; PVA, polyvinyl alcohol; PAN, polyacrylonitrile; DMF, dimethyl formamide.

Surface modification

Surface modification of groups, molecules, or metal particles is a widely used method for enhancing charge separation, light absorption, or redox capacity of photocatalysts.³¹ As illustrated in Figure 4, introducing raw materials into the spinning solution is a feasible method for surface modification.^32,33 Besides, in the postmodification method, the fiber-like structure of the catalyst prevents agglomeration, which is also beneficial for subsequent modifications.

Figure 4.

(A and B) Material surface modification methods

Several studies have demonstrated the critical role of electrospinning in tailoring photocatalytic materials by facilitating the incorporation and precise distribution of modifying agents during synthesis. For instance, Chunqie Han and colleagues³⁴ synthesized Ag/Ga₂O₃ photocatalysts using electrospinning, introducing Ag nanoparticles via in situ surface modification. Although the specific surface area decreased from 19.6 m²/g (pure Ga₂O₃) to 14.3 m²/g (Ag/Ga₂O₃), the photocatalytic hydrogen production increased 6-fold. This improvement was driven by the structural benefits from electrospinning, which ensured uniform Ag nanoparticle distribution, enhancing charge separation and reducing electron-hole recombination. Additionally, the plasmonic effects of Ag nanoparticles expanded light absorption into the visible spectrum, compensating for the reduced surface area and boosting photocatalytic activity.

Similarly, Ye Shengjun et al.³⁵ used electrospinning to incorporate multi-walled carbon nanotubes (MWCNTs) into BiVO4 nanofibers. The MWCNTs formed a conductive network that enhanced electron mobility and minimized recombination. Although surface area data were not provided, the structural changes reduced the band gap from 2.35 to 2.16 eV, leading to improved visible light absorption and a 2-fold increase in the photocatalytic degradation of oxytetracycline.

Seonyoung Jo and colleagues³⁶ applied electrospinning to create TiO₂ nanofibers modified with perovskite quantum dots (PQDs). The resulting mesoporous structure increased the interaction surface with water, improving hydrophilicity. The uniform distribution of PQDs broadened the light absorption spectrum and improved charge separation, resulting in over 90% degradation of rhodamine B in 1 h, far outperforming commercial TiO₂ (P25).

Several studies have effectively demonstrated the advantages of coaxial electrospinning in enhancing the photocatalytic properties of materials by encapsulating functional modifiers within the outer or inner layers of host nanofibers, as illustrated in Figure 5. For instance, Labeesh Kumar et al.³⁷ used coaxial electrospinning to fabricate hollow Au@TiO₂ porous nanofibers with gold nanoparticles encapsulated inside. The porous and hollow structure, created by electrospinning, allowed the catalytic sites (Au nanoparticles) to remain highly active while being protected by the TiO₂ shell. Even though the surface area after calcination did not increase dramatically, the hollow structure ensured that the majority of catalytic sites remained accessible, leading to excellent catalytic efficiency and recyclability for the reduction of 4-nitrophenol and Congo red dye.

Figure 5.

Surface modification structure of coaxial spinning material

Similarly, Xiangqian Guo et al.³⁸ used coaxial electrospinning to synthesize Cu-loaded SrTiO₃ nanofibers aimed at enhancing the photocatalytic reduction of CO₂ to CH₃OH. The electrospinning technique facilitated a uniform distribution of Cu across the nanofibers, improving charge separation and electron transfer from SrTiO₃ to Cu. Despite the surface area remaining around 10 m²/g, one-dimensional structure and surface modification with Cu significantly enhanced the photocatalytic efficiency. The methanol yield peaked at 8.08 μmol/g/h when 8% Cu was incorporated, highlighting how electrospinning improved charge dynamics and stability, compensating for the relatively low surface area.

Ruyi Xie et al.³⁹ employed coaxial electrospinning to fabricate flexible CQDs-Bi₂₀TiO₃₂/PAN nanofiber membranes. The CQDs-Bi₂₀TiO₃₂ were uniformly anchored to the nanofiber surfaces, while the PAN fibers provided flexibility. Although the surface area increased only modestly (from 7.53 m²/g to 11.18 m²/g), the hierarchical structure of the electrospun fibers, with both macro- and mesoporous features, boosted photocatalytic activity, enabling effective degradation of the herbicide isoproturon under visible light. The robust structure also enhanced the catalyst’s recyclability and durability, critical for environmental remediation applications.

Electrospinning plays a very important role in the surface modification of materials. Both uniaxial and coaxial electrospinning can prepare materials simply and quickly, greatly improving the efficiency of material synthesis. In particular, coaxial electrospinning technology can precisely encapsulate the surface of materials. To summarize the application of electrospinning in surface modification, we have compiled some research and listed it in Table 2.

Table 2.

Surface modification using electrostatic spinning

Photocatalyst	Spinning conditions	Solvents	Carrier polymers	Photocatalytic testing	Test conditions	Activity results	Reference
Ag/Ga2O3	Voltage +19, −6 kV	C2H5OH	PVP	Hydrogen production	300-W Xe light	65.7 mmol within 2 h	Han et al.34
MWCNT/BiVO4	Voltage 15–20 kV Distance 10–15 cm	C2H5OH	PVP	Degrading OTC	500-W Xe light OTC solution at 10 mg/L	88.8% within 60 min	Ye et al.35
PQDs-modified TiO2	Voltage 13 kV Distance 12 cm	C2H5OH	PVP	Degrading RhB	RhB solution at 20 ppm	97.9% within 2 h	Jo et al.36
Au/TiO2	Voltage 25 kV Distance 20 cm	DMF	PVP	Borohydride reduction of 4-NP	4-NP solution at 0.2 mM	99% within 20 min	Kumar et al.37
Cu-loaded SrTiO3	Voltage +18, −3 kV Distance 15 cm	DMF	PVP	Redox CO2	300-W Xe light	8.08 μmol g−1·h−1	Guo et al.38
CQDs-Bi20TiO32/PAN	Voltage 20 kV Distance 20 cm	DMAc	PAN	Degrading isoproturon	500-W Xe light Isoproturon solution at 15 mg/L	90.4% within 3 h	Xie et al.39
Bi/BixTiO-TiOyz2/CNFs	Voltage 25 kV Distance 15 cm	CH3COOH, C2H5OH, DMF	PAN	Degrading RhB	300-W Xe light RhB solution at 10 mg/L	97% within 30 min	Yao et al.40
Cu0/S-doped TiO2	Voltage 18 kV Distance 15 cm	CH3COOH, C2H5OH	PVP	Hydrogen production	Magnetic stirring under sunlight	91% within 90 min	Yousef et al.41
Fe2O3-TiO2	Voltage 15 kV Distance 15 cm	DMF, CH3COOH, C2H5O	PVP	Degrading CR	Congo red aqueous solution at 10 mg/L	78.8% within 90 min	Sheikh et al.42

OTC, oxytetracycline; DMAc, N,N-dimethylacetamide; CR, congo red.

Element doping

Modulating the structure of the materials through doping element is also a feasible approach for improving their photocatalytic activities as the dopants can introduce some good properties, including promoting charge separation, providing activity cites, and extending light absorption.^43,44

Several studies have demonstrated the successful in situ doping of nanofibers by introducing a doping source into the spinning solution, followed by electrostatic spinning to create doped nanostructures with enhanced photocatalytic properties.⁴⁵ The use of electrospinning, whether uniaxial or coaxial, allows for precise control over the incorporation of dopants, leading to improved material properties such as increased surface area, extended light absorption, and enhanced charge carrier dynamics. For instance, Shaoju Jian et al.⁴⁶ fabricated La-doped ZnO nanofibers using electrospinning, achieving 94.31% degradation efficiency for rhodamine B under visible light. La doping introduced oxygen vacancies, improving charge separation and extending the material’s light absorption into the visible spectrum. The high surface area and porosity of the electrospun nanofibers enhanced pollutant interaction, reducing recombination and boosting overall photocatalytic performance.

Yan Chen et al.⁴⁷ synthesized (N,F)-co-doped TiO_2-δ nanofibers via electrospinning, achieving a specific surface area of 24.27 m²/g, nearly three times that of commercial TiO₂. The electrospinning technique allowed the formation of mesoporous nanofibers, enhancing both light absorption and charge separation. Nitrogen and fluorine doping introduced oxygen vacancies, crucial for extending light absorption into the visible spectrum and improving electron-hole separation, thus preventing recombination. This led to significant improvements in photocatalytic efficiency, with degradation rates of 27.2% for rhodamine B, 40.9% for methylene blue, and 31% for Cr(VI) within 60 min, far outperforming commercial TiO₂.

Wei Qi et al.⁴⁸ developed Zr/Ag co-doped TiO₂ nanofibers through electrospinning, creating a core-shell structure that optimized photocatalytic performance. Zr stabilized the anatase phase of TiO₂, while Ag nanoparticles provided plasmonic effects, extending light absorption into the visible range. The synergistic heterojunction between Zr and Ag further improved charge carrier mobility and electron-hole separation. This resulted in a 12-fold increase in the degradation rate constant for Congo red dye compared with undoped TiO₂.

Some studies have indicated that introducing dopants into the core or shell layer while constructing a heterojunction structure using coaxial electrospinning is a viable strategy to enhance the performance of the product. Sangmo Kang et al.⁴⁹ used this technique to fabricate Ag⁺-doped rGO/TiO₂ core-shell nanofibers, which exhibited a 25-fold increase in the photocatalytic reduction of CO₂ to CH₄ compared with undoped TiO₂ nanofibers. This enhancement was due to Ag nanoparticles acting as electron traps, minimizing recombination, while the rGO layer facilitated rapid electron transport thanks to its high conductivity. The core-shell structure also provided a larger surface area for photon absorption and improved interaction with the reactants.

In a notable study by Zi Zhu et al.,⁵⁰ Ce-doped TiO₂/graphite/g-C₃N₄ heterojunctions were synthesized using a tri-coaxial electrospinning technique. This method allowed for the uniform incorporation of Ce into the TiO₂ matrix, resulting in a hybrid material with superior photocatalytic hydrogen evolution rates. The coaxial electrospinning process played a critical role in achieving the precise doping required for the efficient separation of photogenerated charge carriers, as well as optimizing the interaction between TiO₂, Ce, and the other components in the heterojunction. The polarization effect of the graphite layer further strengthened the internal electric field, enhancing charge transfer and suppressing recombination. The Ce-doped TiO₂ nanofibers prepared by electrospinning exhibited a remarkable hydrogen production rate, four times higher than that of undoped TiO₂, demonstrating the potential of this technique in producing high-performance photocatalytic materials.

The doping of different materials plays an important role in improving the photocatalytic performance, and a summary of related works by electrostatic spinning methods is presented in Table 3.

Table 3.

Doping using electrostatic spinning

Photocatalyst	Spinning conditions	Solvents	Carrier polymers	Photocatalytic testing	Test conditions	Activity results	Reference
La-doped ZnO	Voltage 15 kV Distance 20 cm	DMF	PAN	Degrading RhB	350-W Xe light RhB solution at 10 mg/L	94.31% within 510 min	Jian et al.46
(N,F) co-doped TiO2-δ	Voltage 18 kV	DMF	PAN	Degrading MB	5-W LED light	40.9% within 60 min	Chen et al.47
Zr/Ag co-doped (TiO2)	Voltage 15 kV Distance 12 cm	C2H5OH	PVP	Degrading CR	300-W Xe light CR solution at 30 mg/L	99.3% within 120 min	Qi et al.48
Ag/TiO2	Voltage 15 kV Distance 8 cm	DMF, CH3COOH	PVP	Redox CO2	500-W Xe light	4.301 μmol g−1 in 7 h	Kang et al.49
Ce-doped TiO₂/graphite/g-C₃N₄	–	DMF, C2H5OH	PVP	Hydrogen -production	300-W Xe light	3.05 mmol g−1·h−1	Zhu et al.50
Sr-doped Bi4O5Br2/Bi2MoO6	Voltage 20 kV Distance 18 cm	DMF	PAN	Degrading 4-CP	300-W visible LED light 4-CP solution at 10 mg/L	98.7% within 80 min	Pan et al.51
Fe-doped LaMnO3	Voltage +12, −2 kV Distance 15 cm	DMF	PVP	Hydrogen production	300-W Xe light	767.71 μmol g−1·h−1	Zhan et al.52
Sc-doped Bi3TiNbO9	Voltage 20 kV Distance 15 cm	C2H5OH, CH3COOH	PVP	Degrading RhB	RhB solution at 20 mg/L	98.55% within 120 min	Song et al.53
C-ZnO	Voltage 15 kV Distance 15 cm	DMF	PAN	Degrading caffeine	300-W solar light Caffeine solution at 30 ppm	80.4% within 120 min	Gadisa et al.54
Bi0.9Gd0.07La0.03FeO3	Voltage 15 kV Distance 15 cm	DMF	PVP	Degrading MB	300-W Xe light MB solution at 20 mg/L	89% within 90 min	Mani et al.55
Ag/Fe-HAP@CA	Voltage 18 kV Distance 15 cm	CH3COCH3	CA	Degrading MB	MB solution at 10 mg/L	Over 90% within 2 h	Shalan et al.56
Fe-doped TiO2	Voltage 20 kV Distance 20 cm	C2H5OH	PVP	Degrading MB	500-W Xe light MB solution at 20 mg/L	38.3% within 90 min	Na et al.57
Sn4+-doped BiFeO3	Voltage 17 kV Distance 14 cm	DMF	PAN	O2 evolution	300-W Xe light	516.4 mmol g−1·h−1	Ren et al.58
Fe-doped ZnO	Voltage 17.5 kV Distance 10 cm	DW	PVA	Degrading MB	50-W Xe light MB solution at 10 mg/L	Above 80% for 6 h	Liu et al.59
Ta-doped TiO2	Voltage 13 kV	DI, C2H5OH	PVP	Degrading MB	12-W UV lamp MB solution at 20 μM	Above 90% for 4 h	Singh et al.60
N-doped In2O3	Voltage 10 kV Distance 10 cm	DMF	PVP	Degrading RhB	150-W Xe light RhB solution at 10 mg/L	97% within 180 min	Lu et al.61

LED, light-emitting diode.

Composite construction

Semiconductor photocatalysts with a wide band gap often face the challenge of limited light absorption, whereas those with a narrow band gap are prone to significant charge recombination. Constructing composite system is a feasible method for solving these problems.⁶² Electrospinning technology can facilitate an in situ combination by simply mixing the raw materials into the spinning solution and can even produce a one-dimensional core-shell structure through coaxial spinning, which enhances the interaction between the composite materials, and thus has been widely researched.^63,64

Several studies have employed uniaxial electrospinning techniques to construct composite systems by modifying the spinning solution composition, highlighting the versatility of this method in enhancing photocatalytic performance. Yinyin Ai et al.^64,65 prepared a ZnIn₂Se₄/TiO₂ composite via electrospinning, featuring a Z-scheme heterojunction with ZnIn₂Se₄ nanoparticles tightly bonded to TiO₂ nanofibers through Ti-Se interfacial bonds. This strong interface, formed through uniaxial electrospinning, enhances the internal electric field, promoting efficient charge transfer and reducing electron-hole recombination. As a result, the composite achieved a photocatalytic hydrogen evolution rate of 0.11 mmol/g/h, three times higher than bare TiO₂. The Ti-Se bond and internal electric field make this structure particularly effective for hydrogen production and other catalytic applications. Beyond increasing surface area, electrospinning plays a crucial role in optimizing electron transport pathways, improving overall photocatalytic performance.

Similarly, QingHao Li and colleagues synthesized CS/TiO₂/g-C₃N₄ composite nanofibers via electrospinning,⁶⁶ achieving a Cr(VI) removal rate of over 90% under visible light, a 50% improvement over pure CS. The synergy between g-C₃N₄ and TiO₂ broadened light absorption and enhanced charge separation, key factors that improved the material’s photocatalytic performance. The composite also maintained high stability and activity over multiple cycles, demonstrating the durability imparted by the electrospinning process, making it suitable for real-world applications.

Lu Wang et al.⁶⁷ used electrospinning to create g-C₃N₄/Nb₂O₅ composite nanofibers, resulting in a specific surface area of 36.18 m² g⁻¹, 1.2 times higher than that of Nb₂O₅ alone. The heterojunction between g-C₃N₄ and Nb₂O₅ effectively reduced the band gap, extending light absorption into the visible spectrum and leading to an RhB degradation efficiency of 98.1% in two hours—nearly double that of Nb₂O₅ nanofibers. The increased surface area, combined with enhanced charge separation, underscores how electrospinning facilitates the creation of highly efficient catalytic materials by improving both structural and electronic properties.

In certain studies, composite fibers with core-shell structures have been constructed using coaxial spinning technology, in which the precursors of the materials are separately placed in the outer shell and inner core, as shown in the Figure 6. For instance, Yang Yaoyao et al.⁶⁸ prepared AgCl/ZnO-loaded nanofibrous membranes using coaxial electrospinning. The core-shell structure provided by the coaxial technique allowed for the separation of AgCl in the core and ZnO in the shell, enhancing the material’s stability and active site exposure. This architecture facilitated efficient electron-hole separation and charge transport, resulting in a photocatalytic degradation efficiency of 98% for MB within 70 min, with over 95% efficiency retained across five cycles. The structural control offered by coaxial electrospinning was key in improving both the photocatalytic performance and long-term stability of the nanofibers.

Figure 6.

Coaxial electrostatically core-shell-structured nanofiber

Similarly, Mao Yihang et al.⁶⁹ developed g-C₃N₄/PAN/PANI@LaFeO₃ core-shell nanofibrous membranes using coaxial electrospinning, where the core-shell design played a critical role in enhancing the photocatalytic properties. The LaFeO₃ was deposited in the outer shell, whereas g-C₃N₄ and PAN/PANI were distributed in the core, forming a Z-scheme heterojunction. This configuration promoted efficient charge separation, extended light absorption, and increased pollutant interaction with the active sites. As a result, the membranes achieved high pollutant removal rates, including 97.0% for MB, 94.3% for methyl violet, and 87.6% for ciprofloxacin. The structured design not only boosted photocatalytic efficiency but also ensured strong mechanical integrity and reusability.

In another example, Bin Jiang et al.⁷⁰ used coaxial electrospinning to synthesize SnO₂@PW12@TiO₂ core-shell nanofibers, forming a complex three-layer structure. The SnO₂ core, PW12 middle layer, and TiO₂ outer shell were strategically designed to create a Z-scheme heterojunction between the layers, which enhanced charge separation and suppressed recombination. This multilayer structure increased the interaction between the active layers and maximized light absorption, leading to a 73.8% degradation of tetracycline within 30 min, compared with 44.8% for SnO₂@TiO₂ fibers without the PW12 layer. The enhanced photocatalytic performance was largely attributed to the efficient charge transfer pathways enabled by the core-shell architecture, highlighting the structural advantages coaxial electrospinning provides.

Electrostatic spinning is typically employed for the rapid fabrication of composite structures comprising diverse materials, as well as the synthesis of core-shell multilayered composite nanofibers. To facilitate rapid access to multilayered composites, we present a synopsis of composite precursor preparation methods and their catalytic activity in Table 4.

Table 4.

Compounding with electrostatic spinning

Photocatalyst	Spinning conditions	Solvents	Carrier polymers	Photocatalytic testing	Test conditions	Activity results	Reference
ZnIn₂Se₄/TiO₂	Voltage +15, −5 kV Distance 20 cm	CH3COOH, C2H5OH	PVP	Hydrogen production	–	0.11 mmol g−1·h−1	–
CS/g-C3N4/TiO2	Voltage 15 kV Pushing speed 5 mL h−1	CH3COOH	PEO	Redox Cr(VI)	800-W Xe light Cr(VI) solution 100 mg/L	90% within 4 h	Li et al.66
g-C3N4/Nb2O5	Voltage 18 kV Distance 20 cm	DMF	PVP	Degrading RhB	–	98.1% within 120 min	Wang et al.67
AgCl/ZnO	Voltage 10 kV Distance 15 cm	C2H5OH, DI	PVP	Degrading MB	300-W Xe lamp	99.70% within 35 min	Yang et al.68
g-C3N4/PAN/PANI@LaFeO3	Voltage 18 kV Distance 15 cm	DMF	PAN	Degrading MB	500-W Xe lamp MB solution at 20 mg/L	97% within 75 min	Mao et al.69
m-Hal@Ag3PO4/PAN	Voltage +18, −2 kV Distance 15 cm	DMF	PAN	Degrading ciprofloxacin	500-W Xe light Ciprofloxacin solution at 15 mg/L	99.98% within 200 min	Ma et al.71
SnO2@PW12@TiO2	–	CH3COOH, C2H5OH, DMF	PVP	Degrading TC	300-W Xe light TC solution at 20 mg/L	73.8% within 30 min	Jiang et al.70
NaYF4/Yb/Tm/TiO2	–	C2H5OH, CH3COOH	PVP	Degrading RhB	RhB solution at 0.01 mmol/L	99.12% within 2 h	Guo et al.72
TiO2/WO3	Voltage 15 kV Distance 8 cm Pushing speed 1 mL h−1	CH3COOH, C2H5OH	PVP	Degrading MO	UV and visible light MO solution was 4 × 10−5 M	21.6% within 240 min	Odhiambo et al.73
Fe2O3/TiO2	Voltage 15 kV Distance 15 cm	CH3COOH, C2H5OH	PVP	Degrading RhB	RhB solution 5 mg/L	99% within 90 min	Liu et al.74
CoFe2O4/BiOI	Voltage 12 kV Pushing speed 5 μL min−1	DMF, C2H5OH	PVP	Degrading RhB	150- to 300-W Xe light RhB solution 10 mg/L	97.2% within 90 min	Chang et al.75
PAN/Bi2MoO6/Ti3C2	Voltage 20 kV Pushing speed 0.01 mm/s	DMF	PAN	Degrading tetracycline	300-W Xe light TC solution 15 mg/L	90.3% within 4 h	Zhang et al.76
TiO2/WO3/C/N	Voltage 20 kV Pushing speed 1 mL h−1	CH3COOH, C2H5OH	PVP	Degrading MB	MB solution 12.6 mg/L	39.4% within 4 h	Odhiambo et al.77
Au/CeO2	Voltage 20 kV Pushing speed 0.5 mL h−1	DMF	PVP	Degrading PhCHO	UV light	83.3% within 5 h	Li et al.78
g-C3N4/K0.5Na0.5NbO3	Voltage 18 kV	C2H5OH	PVP	Hydrogen production	300-W Xe light	96.3 μmol g−1·h−1	Zhang et al.79
CuBi2O4/Bi2O3	Voltage 18 kV Distance 12 cm	DMF	PVP	Degrading MO	–	99.2% within 130 min	Yang et al.80
ZnIn2S4/Ag2MoO4	Voltage 15 kV Distance 15 cm	DMF, C2H5OH, CH3COOH	–	Degrading ENR	300-W Xe light ENR solution at 20 mg/L	100% within 120 min	Li et al.81
ZnFe2O4/Ag/AgBr	Voltage 17–19 kV	DMF	PVP	Degrading RhB	RhB solution at 100 mg/L	86.3% within 100 min	Sabzehmeidani et al.82
SiO2/Ga2O3	Voltage 15 kV Distance 20 cm	DMF	PAN	Degrading RhB	RhB solution 10 mg/L	98% within 30 min	Du et al.83
BN/Ce2O3/TiO2	Voltage 1.25 kV/cm Pushing speed 1 mL h−1	C2H5OH	PVP	Hydrogen production	500-W halogen lamp	850 μmol g−1·h−1	Ghorbanloo et al.84
W2N/C/TiO-n	Voltage 13 kV Distance 20 cm	DMF	PAN	Hydrogen production	300-W Xe light	3.11 μmol g−1·h−1	Gong et al.85
ZnO-In2S3	Voltage 14 kV Distance 14 cm	DI	PVA	Hydrogen production	5-W blue LED	539.5 μmol g−1·h−1·L−1	Chang et al.86
ZnO/Ti3C2	Voltage 14 kV Distance 14 cm	DMF	PVDF	Degrading CR	50-W LED light CR solution concentration 20 μM	96% within 210 min	Sahu and Dhar Purkayastha87
Ni(DMG)2/TiO2	Voltage 10 kV Distance 15 cm	DMF	PAN, PVP	Degrading MB	MB solution at 10 mg/L	97% within 60 min	Lv et al.88
InVO4/CeVO4	Voltage 20 kV Distance 20 cm	C2H5OH	PVP	Degrading TC	800-W Xe light TC solution at 20 mg/L	100% within 90 min	Ding et al.89
WO2.72/Fe3O4	Voltage 15 kV Distance 15 cm	C2H5OH	PVA	Redox Cr(VI)	500-W Xe light	100% within 3 h	Motora et al.90
WO3/CdWO4	Voltage 20 kV Distance 15 cm	DMF, C2H5OH	PVP	Degrading TC	500-W Xe light TC solution at 10 mg/L	81.6% within 90 min	Rong et al.91
PVDF/CdS/TiO2	Voltage 9.32 kV Distance 15 cm	DMF, CH3COCH3	PVDF	Redox Cr(VI)	350-W Xe light	96.6% within 40 min	Li et al.92
RGO/TiO2/PANCMA	Voltage 14 kV Distance 30 cm	DMF	PANCMA	Degrading MG	MG solution at 100 ng/L	90.6% within 62 min	Du et al.93
RbxWO3@Fe3O4	Voltage 15 kV Distance 15 cm	MC, DMF	PET	Redox Cr(VI)	Cr(VI) solution at 50 mg/L	100% within 90 min	Naseem et al.94
TiO2(A-R)/ZnTiO3	Voltage 18 kV Distance 18 cm	DMF	PVP	Hydrogen production	–	887.7 μmol g−1·h−1	Yerli Soylu et al.95
ZnO/ZnFe2O4/Pt	Voltage 17 kV Pushing speed 0.5 mL h−1	DMF	PVP	Degrading CIP	300-W Xe light CIP solution at 10 mg/L	92% within 2 h	Sobahi et al.96
TiO2-SiO2-Al2O3-ZrO2-CaO-CeO2	Voltage 20 kV Distance 13 cm	DMF	PAN	Degrading MB	MB solution at 20 mg/L	90.7% within 120 min	Yerli Soylu et al.95
BiOI/SiO2	Voltage 9 kV Pushing speed 10 μL/min	DI	PVA	Degrading RhB	RhB solution 10 mg/L	68% within 3 h	Liu et al.97
CeO2/CuS	Voltage 18–19 kV Pushing speed 0.05 mL/min	DMF, C2H5OH	PVP	Degrading MB	Striped blue LEDs MB solution 3 mg/L	96.38% within 50 min	Sabzehmeidani et al.98
ZnO/Ag	Voltage 28 kV Pushing speed 1.5 mL/h	DMF	PVP	Degrading MO	100-W UV lamp MB solution 10 mg/L	92% within 15 min	Li et al.99
SrTiO3/TiO2	Voltage 15 kV Distance 15 cm	DMF and CH3COOH	PVP	Degrading MO	25-W UV-C mercury lamp MO solution at 15 mg/L	93% within 40 min	Zhao et al.100
ZnO/γ-Bi2MoO6	Voltage 20 kV Needle diameter 0.8 mm	DI and C2H5OH	PVP	Degrading MB	500-W Xe lamp	95.6% within 4 h	Wang et al.101
TiO2@Ag@Cu2O	Voltage 18 kV Needle Pushing speed 1.5 mL/h	DMF	PAN	Degrading MB	600-W Xe lamp MB solution at 10 mg/L	99% within 2.5 h	Li et al.102
Bi2MoO6/S-C3N4/PAN	Voltage 15 kV Pushing speed 0.5 mm/h	C2H6O2, C2H5OH	PAN	Degrading 4-NP	An LED lamp (10-W, λ ≥ 400 nm)	83% within 3 h	Chen et al.103
g-C3N4/AuNPs/PVDF	Voltage 20 kV Push speed 1.5 mL/h.	DI	PVDF	Degrading MB	Two COB LEDs	98% within 3 h	Saha et al.104
g-C3N4/BiOI	Voltage 10 kV Distance 16 cm	DMF	PAN	Degrading RhB	Visible light irradiation (λ > 400 nm)	98% within 90 min	Zhou et al.105
GO/MIL-101(Fe)/PANCMA	Voltage 11 kV Distance 30 cm	DMF	PAN	Degrading RhB	16-W UV lamp	93.7% within 20 min	Huang et al.106
BaTiO3-TiO2	Voltage 18kV Distance 15 cm	C2H5OH, CH3COOH	PVP	Degrading RhB	300-W high pressure mercury lamp	99.8% within 1 h	Liu et al.107
Co3O4@CeO2	Voltage 20 ± 0.5 kV	C2H5OH, CH3COOH, DMF	PAN	Degrading levofloxacin	Levofloxacin concentration at 20 ppm	93.8% within 14 min	Wang et al.108
CuS QDs/BiVO4@Y2O2S	Voltage 21 kV Distance 18 cm	DMF	PVP	Degrading RhB	300-W Xe lamp RhB solution at 10 mg/L	87.4% within 2 h	Guo et al.109
MoS2/PANI/PAN@BiFeO3	Voltage 17 kV Distance 15 cm	DMF	PAN, PANI	Degrading MO	MO solution 15 mg/L	99.9% within 60 min	Lin et al.110
Tm@ND@TiO2/mSC	–	DMF	PAN/PEG	Degrading MO	MO solution 40 mg/L	94% within 60 min	Su et al.111
CoMn2O4/HACNFs	Voltage 13 kV Distance 8 cm	DMF	PMMA, PAN	Degrading RhB	RhB concentration at 50 μM	84.8% within 200 min	Kang et al.112

COB, chip-on-board; MO, methyl orange; ENR, enrofloxacin; PEO, polyethylene oxide; MC, methylene chloride; CIP, ciprofloxacin; PVDF, polyvinylidene fluoride; PEG, polyethylene glycol; PMMA, polymethyl methacrylate; PANCMA, poly(acrylonitrile-co-maleic acid); MG, malachite green.

Summary and outlook

In recent years, electrospinning technology has found widespread application in the preparation of nanofiber-structured photocatalysts.¹¹³ This review provides a comprehensive summary of the current application and development status of electrospinning technology in the preparation and modification of photocatalysts. Despite significant efforts, the industrial application of photocatalysis technology remains distant due to inadequate efficiency exhibited by current photocatalysts.⁵ Constructing a multiple heterojunction compound model represents a potential strategy for designing highly active photocatalysts by enhancing charge separation properties.¹¹⁴ However, the current methods, primarily wet-chemical and in situ growth, do not allow for precise arrangement of the components according to the model. In contrast, coaxial electrospinning technology is a suitable method for effectively constructing a multilayer system due to its ability to arrange materials in layers along the concentric axis. Therefore, the construction of a multicomponent composite system using coaxial electrospinning technology holds great significance for studying a multicomponent photocatalytic system model.

Moreover, electrospinning offers significant potential for large-scale production, particularly in fabricating complex nanostructures such as hollow, core-shell, and mesoporous fibers. These advanced architectures provide enhanced surface area and improved access to active catalytic sites, optimizing interactions between photocatalytic components and boosting reaction efficiency.¹¹⁵ By facilitating better light absorption and charge transport pathways, electrospun nanofibers reduce electron-hole recombination, a key limitation in many photocatalytic systems. Understanding the process-structure-performance relationship—factors such as polymer composition, solution viscosity, applied voltage, and spinning speed—allows for fine-tuning fiber morphology, porosity, and crystallinity, all of which directly impact performance.¹¹⁶ As electrospinning techniques evolve, they offer a scalable, cost-effective solution for producing high-performance photocatalysts, particularly in metal oxide semiconductor systems.¹¹⁷ This approach not only enables industrial-scale production but also paves the way for advanced materials designed for environmental remediation, solar energy harvesting, and other energy applications.

Acknowledgments

We are grateful for financial support from the National Natural Science Foundation of China (22002074), Natural Science Foundation of Shandong Province (ZR2022ME010), and Youth Innovation Team Program in Colleges of Shandong Province (2023KJ144).

Author contributions

Investigation and writing – original draft, F.G.; writing – review & editing, L.H., L.F., B.H., J.N., X.Z., S.C., and B.L.; supervision, X.Z. and S.C.

Declaration of interests

The authors declare no competing interests.