High-performance Photoanodes Research Articles

Commercial-scale reproducible GaN nanowires with 6.4% solar to hydrogen conversion efficiency in photoelectrochemical water splitting

In this article, we demonstrate how commercial-scale reproducible GaN nanowires (GNWs) passivated with metal oxide overlayers and assisted by an efficient co-catalyst with a visible absorption wavelength can be used as a high-performance photoanode for photoelectrochemical (PEC) water splitting to produce solar-driven hydrogen. The facile growth of GNWs using a vapor-liquid-solid method by metal-organic chemical vapor deposition (MOCVD) raises the density of the NWs, increasing the active area for the water splitting reaction and facilitating charge transport. The passivation of surface defects through overlayers and being aided by a co-catalyst with a photo absorption range in the visible region greatly increases the photocurrent density up to 4.6 mA/cm2 under 1 sun illumination at zero applied biasing versus the reference electrode. The measured solar to hydrogen conversion efficiency of 6.4% is among the highest documented values for GNWs-based photoanodes grown using MOCVD.

BiVO4 Photoanodes Modified with Synergetic Effects between Heterojunction Functionalized FeCoOx and Plasma Au Nanoparticles

The design and development of high-performance photoanodes are the key to efficient photoelectrochemical (PEC) water splitting. Based on the carrier transfer characteristics and localized surface plasmon resonance effect of noble metals, gold nanoparticles (AuNPs) have been used to improve the performance of photoanodes. In this study, a novel efficient composite BiVO4/Au/FeCoOx photoanode is constructed, and the quantitative analysis of its performance is systematically conducted. The results reveal that the co-modification of AuNPs and FeCoOx plays a synergetic role in enhancing the absorption of ultraviolet and visible light of BiVO4, which is mainly attributed to the localized surface plasmon resonance effect induced by AuNPs and the extended light absorption edge position induced by the BiVO4/FeCoOx heterojunction. The BiVO4/Au/FeCoOx photoanode exhibits a high photocurrent density of 4.11 mA cm−2 at 1.23 V versus RHE at room temperature under AM 1.5 G illumination, which corresponds to a 299% increase compared to a pristine BiVO4 photoanode. These results provide practical support for the design and preparation of PEC photoanodes decorated with AuNPs and FeCoOx.

Engineering BiVO4 and Oxygen Evolution Cocatalyst Interfaces with Rapid Hole Extraction for Photoelectrochemical Water Splitting

Tailoring the oxygen evolution cocatalyst (OEC)/BiVO4 interfaces with a hole transfer layer (HTL) is expected to suppress the interfacial charge recombination, thus achieving highly efficient photoelectrochemical (PEC) water splitting. Herein, Co3O4 nanoparticles are inserted between the NiOOH OEC and BiVO4 as an HTL for the design of NiOOH/Co3O4/BiVO4 photoanodes. A champion photoanode achieves a photocurrent density of 6.4 mA cm–2 at 1.23 V versus the reversible hydrogen electrode (RHE) under AM 1.5 G illumination (100 mW cm–2). Stable PEC water splitting is realized for up to 90 h. Being highly dispersed at the surfaces of BiVO4, the p-type Co3O4 nanoparticles form p–n junctions with BiVO4, thus providing an extra driving force for the extraction of the photogenerated holes from BiVO4 to the NiOOH OEC, which efficiently suppresses charge recombination at the BiVO4/NiOOH interfaces and accelerates the surface water oxidation kinetics. A charge separation efficiency of 95.6% and a surface charge transfer efficiency of 97.7% are achieved at 1.23 V vs RHE. The strategy is applicable to other OEC (e.g., MnOx and FeOOH)/BiVO4 photoanodes. This work may inspire the rational design of high-performance photoanodes for feasible solar energy conversion.

TiO2/g-C3N4 photoanode prepared with polydopamine inspiration for photocatalytic fuel cells towards simultaneous wastewater treatment and electricity generation

Photocatalytic fuel cell is a promising wastewater treatment technology, which can degrade pollutants and generate electricity simultaneously. However, the development of high-performance photoanode remains a challenge for photocatalytic fuel cells. Inspired by the bionic material of polydopamine, we propose to apply polydopamine to prepare the TiO2/g-C3N4 photoanode for enhancing the adsorption of protonated g-C3N4 nanosheets onto TiO2 via electrostatic interaction, which greatly promotes charge transfer and inhibits electron-hole recombination. Moreover, the polydopamine particles can be converted into plenty of pores during the calcination process, which enhances light scattering and mass transfer. Consequently, the TiO2/g-C3N4 photoanode prepared with polydopamine inspiration exhibits superior photoelectrochemical activity than the TiO2/g-C3N4 photoanode prepared without using polydopamine and the pristine TiO2 photoanode, presenting an improvement in the maximal power density by 8.7 % and 70.4 %, respectively. In addition, the effect of the adsorption time of the protonated g-C3N4 nanosheets is also studied. It is shown that an excessive amount of the protonated g-C3N4 nanosheets by increasing the adsorption time leads to more serious recombination and thereby decreases the photoanode performance. This study provides a novel and efficient way to prepare composite photoanode for photoelectrochemical applications.

A comprehensive machine learning strategy for designing high-performance photoanode catalysts

Machine learning models are used to capture intricate relationships among BiVO4 photoanodes, cocatalysts, and electrolytes. Model interpretability is then performed to provide some heuristic rules to guide cocatalyst selection for BiVO4 photoanodes.

Surface dependent photoelectrochemical water-splitting performance of zinc tin oxide films

The process of splitting water into hydrogen (H2) and oxygen (O2) gases via the photoelectrochemical (PEC) cell route has recently been emerged as a promising approach, which requires the development of novel and high performance photoanode materials with good stability. Zinc-tin oxide (ZTO) is a promising photoanode material for PEC cell application because of its high chemical stability. Herein, ZTO films were deposited using the commercial co-sputtering process at various substrate temperatures (Tsub). At 200 °C of Tsub, the ZTO films changed from amorphous to crystalline nature. The ZTO films had the band gap in the range of 3.40–3.70 eV and resistivity in the range of 0.69–0.10 Ω·cm. The high photocurrent of 0.22 mA/cm2 was achieved for the ZTO films sputtered at a Tsub of 100 °C and thickness of 1000 nm due to the high surface roughness of 7.55 nm. The electrochemical impedance spectroscopy (EIS) result of ZTO film with 1000 nm thickness showed smallest semicircle, indicating lowest charge transfer resistance. Moreover, a detailed explanation of the effects of the Tsub on the properties of films and the performance of photoanode has been presented.

Si-Ti interaction in unique morphology of fibrous silica titania photoanode for enhanced photoelectrochemical water splitting

Extensive efforts toward titania (TiO2) modification have been developed in order to overcome the shortcomings as an efficient photoanode for photoelectrochemical (PEC) water splitting. Herein, a unique morphology possessed fibrous silica titania (FST) fabricated by microemulsion method was used for the first time as a photoanode. The FST was characterized by XRD, Raman, N2 adsorption–desorption, FESEM, TEM, FTIR, XPS, UV–vis/DRS, and PL. The results confirmed the creation of a bicontinuous concentric lamellar structure of FST with a high surface area. The inclusions of Ti in the silica matrix induced the Si-Ti interaction and narrowed the band gap. The FST photoanode exhibited a superior photocurrent density of 13.79 mA/cm2 with 16.9 % solar-to-hydrogen (STH) efficiency, which is 2.5 times higher compared to commercial TiO2 which performed at 5.51 mA/cm2 with 6.8 % STH. Significantly, the conduction band of FST lies closer to the reduction potential of hydrogen compared to TiO2, leading to the fast charge transfer and allowing spontaneous production of H2. The fabrication of FST provided new insight into developing high-performance photoanode for enhanced PEC water splitting.

Synergistic effects of nano-structured WO3-Se heterojunction decorated by organic Nafion layer on improving photoelectrochemical performance

Exploration of high-performance photoanodes is considered as an essential challenge in photoelectrochemical (PEC) water splitting due to the complex four-electron reaction in water oxidation. Herein, the nano-structured WO3-Se heterojunction decorated by organic Nafion layer is designed. The optimized WO3-Se200-0.05Nafion photoanode shows a remarkable photocurrent of 1.40 mA cm−2 at 1.23 V versus reversible hydrogen electrode, which is 2.5-fold higher than that of pure WO3 nanosheets (WO3 NS) photoelectrode. Remarkably, the photocurrent increments of WO3-Se200-0.05Nafion is larger than the increment sum of WO3-Se200 and WO3-0.05Nafion, which affirming the synergistic effect of Se nanospheres and Nafion layer. The improved PEC performances are attributed to the quick charge separation and transfer, the increased electric conductivity, and the excellent kinetics of oxygen evolution, which is derived from the strong interaction among WO3, Se and Nafion. Meanwhile, the better visible-light harvesting from Se nanospheres as photosensitizer and the induction of transparent Nafion as a passivation layer can explain this synergy. It hopes this heterostructure design with organic Nafion decoration can inspire to exploit outstanding performance photoanodes for PEC water splitting.

Surface active oxygen engineering of photoanodes to boost photoelectrochemical water and alcohol oxidation coupled with hydrogen production

Photoelectrochemical conversion of solar energy into fuels (or chemicals) is in urgent need of efficient photoanodes to drive its practical applications. Nevertheless, the development of high performance photoanode usually suffers from slow charge transfer and sluggish surface catalytic kinetics. Here, we report a surface active oxygen engineering strategy through the modification and activation of NiCo layered double hydroxide (NiCo-LDH), where the activated NiCo-LDH (NiCo-LDH-Act) captures the photogenerated holes and acts as cocatalyst for surface oxidation reactions. The as-developed BiVO4/NiCo-LDH-Act achieves more than 3-fold higher photocurrent density than that of pristine BiVO4. Experimental integrated with theoretical studies further testify the bifunctional of NiCo-LDH-Act for hole transport and catalytic reactions. Moreover, the adsorbed ·OH originated from active oxygen enables efficient oxidation of glycerol to attain 1,3-dihydroxyacetone (DHA) with a productivity of 20.5 μmol cm–2 h–1 at 1.4 V vs. RHE with simultaneously producing hydrogen at the cathode.

Electronegative Cl− modified BiVO4 photoanode synergized with nickel hydroxide cocatalyst for high-performance photoelectrochemical water splitting

BiVO4 is a promising photoanode material for converting solar energy into hydrogen fuel, but its practical applicability is primarily constrained by severe surface charge recombination and slow water oxidation processes. Here, the modification of BiVO4 surface by Cl− with appropriate electronegativity greatly promoted the photoelectric water oxidation activity. The Cl-BiVO4 electrode exhibited a photocurrent of 2.55 mA cm−2, at 1.23 V vs RHE. The research shows that the surface anion polarization of BiVO4 is helpful for trapping photogenerated holes and prolonging the electron lifetimes. Then, the cocatalyst Ni(OH)2 is anchored on Cl-BiVO4 by a simple impregnation method, and a high-performance photoanode Ni(OH)2/Cl-BiVO4 is successfully constructed. The photocurrent density of the composite photoanode is 4.33 mA cm−2 (1.23 V vs RHE), which is approximately 3.0 times that of pure BiVO4 (1.44 mA cm−2). Moreover, the initial potential is negatively shifted, and the ABPE, IPCE and charge separation efficiency are also significantly improved. This research presents a simple and effective strategy for producing low-cost, high-performance solar water decomposition catalysts.

Defect Engineering and Surface Polarization of TiO2 Nanorod Arrays toward Efficient Photoelectrochemical Oxygen Evolution

The relatively low photo-conversion efficiencies of semiconductors greatly restrict their real-world practices toward photoelectrochemical water splitting. In this work, we demonstrate the fabrication of TiO2-x nanorod arrays enriched with oxygen defects and surface-polarized hydroxyl groups by a facile surface reduction method. The oxygen defects located in the bulk/surface of TiO2-x enable fast charge transport and act as catalytically active sites to accelerate the water oxidation kinetics. Meanwhile, the hydroxyl groups could establish a surface electric field by polarization, for efficient charge separation. The as-optimized TiO2-x nanorod photoanode achieves a high photocurrent density of 2.62 mA cm−2 without any cocatalyst loading at 1.23 VRHE under 100 mW cm−2, which is almost double that of the bare TiO2 counterpart. Notably, the surface charge separation and injection efficiency of the TiO2-x photoanode reach as high as 80% and 97% at 1.23 VRHE, respectively, and the maximum incident photon-to-current efficiency reaches 90% at 400 nm. This work provides a new surface treatment strategy for the development of high-performance photoanodes in photoelectrochemical water splitting.

Design and Fabrication of High Performance Photoanode of Fe2(MoO4)3/RGO Hybrid Composites for Triiodide Reduction in Dye-Sensitized Solar Cells

Here in, synthesis of Fe2(MoO4)3/reduced graphene oxide (RGO) nanocomposite was prepared by simple hydrothermal approach and used as high efficient dye sensitized solar cells (DSSCs). The decoration of RGO into the Fe2(MoO4)3 was proved by various physic-chemical studies such as XRD, SEM, TEM, Raman, UV, PL and BET analysis. The individual spherical shaped nanoparticles of Fe2(MoO4)3 with sizes in the range of 25–35 nm was uniformly decorated on the surface of RGO nanosheets. Due to the synergic effect between the Fe2(MoO4)3 and RGO the light absorption property is significantly improved as well the high surface area (112.5 m2/g) and pore size (38.7 nm) was achieved than compared with bare Fe2(MoO4)3 (88.5 m2/g and 17.8 nm). The Fe2(MoO4)3/RGO hybrid photoanode establish to display an outstanding catalytic activity toward the reduction of triiodide to iodide in a dye-sensitized solar cell (DSSC) and can provide a solar cell efficiency of 9.6 ± 0.001%, which is superior to a Pt-based DSSC (6.1 ± 0.002%). The better electro-catalytic ability of Fe2(MoO4)3/RGO electrode is obtained by a synergistic effect that resulted in the high specific surface area and intrinsic reactivity of the materials.

W:BiVO4-WO3-V2O5 heterostructures increase light absorption and charge transport in photoanodes for water splitting

Efficient light absorption and charge separation and transfer are the main obstacles that still need to be addressed to increase the performance of photoanodes for the water oxidation reaction. Here, we show that the combination of W:BiVO4, WO3, and V2O5 can simultaneously improve light absorption and the separation and transport of electrons and holes in the photoanode and consequently its photoelectrochemical performance for the water oxidation reaction. The high photoelectrochemical activity of the photoanode is due to the different bandgap energies of W:BiVO4 (2.44 eV), WO3 (2.90 eV), and V2O5 (2.27 eV), which provide higher absorption of visible light and improved charge transport in the heterojunction: V2O5 facilitates the transport of holes while WO3 increases electron mobility. As a result, the W:BiVO4-WO3-V2O5 photoanode produces a photocurrent density as high as 8.2 mA cm−2 at 1.23 V vs. RHE in sodium sulfate electrolyte (pH 6.96). By modifying the surface of the W:BiVO4-WO3-V2O5 photoanode with an electrocatalyst for water oxidation, the photocurrent can reach 12.1 mA cm−2. Thus, the multiple ternary heterojunctions of W:BiVO4-WO3-V2O5 proved an efficient strategy for producing high-performance photoanodes for photoelectrochemical applications.

A new strategy: fermi level control to realize 3D pyramidal NiCo-LDH/ReS2/n-PSi as a high-performance photoanode for the oxygen evolution reaction

ReS2 nanosheets have been grown on n-type Si substrate as photoanode for OER. By introducing pyramid Si and NiCo-LDH co-catalyst, the photocurrent of NiCo-LDH/ReS2/n-PSi was boosted from 0,31 mA cm−2 of ReS2/n-Si to 1.74 mA cm−2.

Bismuth sulfide decorated TiO2 arrays heterojunction assembly for enhanced photoelectrochemical performance

Hetero-junction photo-anode exhibits unique optical and electrical properties which are depended on their composition, morphology and structure. In this work, TiO2/Bi2S3 heterojunction photoanode was successfully prepared. Firstly, the TiO2 nanorod arrays were prepared by hydrothermal method under different reaction time, and then the Bi2S3 has been deposited with successive ionic layer adsorption and reaction method (SILAR). The array length and radius nanorods of TiO2 have important influence on their photoelectric properties. The deposition time was optimized according to the photoelectric performance. The Bi2S3 nanomaterials on TiO2 nanoarrays is not obvious. The existence of Bi2S3 on TiO2 was confirmed by XPS and HRTEM. This is mainly due to the fact of that Bi2S3 prepared by SILAR method is very small and relatively dispersed. The photoelectric properties of TiO2/Bi2S3 photoanode can be enhanced by increasing the reaction concentration. The photoelectric response of TiO2/Bi2S3 shows firstly increase and then decreases with the increasing of cationic solution concentration. When the reaction concentration is 10 mmol/L, the photocurrent density reached the maximum (0.060 mA/cm2). It is anticipated that the present work can provide a simple and rapid preparation technology for the development and use of high-performance photoanode composites based on titanium dioxide.

Molybdenum doped bilayer photoanode nanotubes for enhanced photoelectrochemical water splitting

Conversion of solar energy into hydrogen energy via photoelectrochemical (PEC) water splitting is one of the most promising approaches for generation of clean and sustainable hydrogen energy in order to address the alarming global energy crisis and environmental problems. To achieve superior PEC performance and solar to hydrogen efficiency (STH), identification, synthesis, and development of efficient photoelectrocatalysts with suitable band gap and optoelectronic properties along with high PEC activity and durability is highly imperative. With the aim of improving the performance of our previously reported bilayer photoanode of WO3 and Nb and N co-doped SnO2 nanotubes i.e. WO3-(Sn0.95Nb0.05)O2:N NTs, herein, we report a simple and efficient strategy of molybdenum (Mo) doping into the WO3 lattice to tailor the optoelectronic properties such as band gap, charge transfer resistance, and carrier density, etc. The Mo doped bilayer i.e. (W0.98Mo0.02)O3-(Sn0.95Nb0.05)O2:N revealed a higher light absorption ability with reduced band gap (1.88 eV) in comparison to that of the undoped bilayer (1.94 eV). In addition, Mo incorporation offered improvements in charge carrier density, photocurrent density, with reduction in charge transfer resistance, contributing to a STH (∼3.12%), an applied bias photon-to-current efficiency (ABPE ∼ 8% at 0.4 V), including a carrier density (Nd ∼ 7.26 × 1022 cm−3) superior to that of the undoped bilayer photoanode (STH ∼2%, ABPE ∼ 5.76%, and Nd ∼5.11 × 1022 cm−3, respectively). The substitution of Mo6+ for W6+ in the monoclinic lattice, forming the W–O–Mo bonds altered the band structure, realizing further enchantments in the PEC reaction and charge transfer kinetics. Additionally, doped bilayer photoanode revealed excellent long term PEC stability under illumination, suggesting its robustness for PEC water splitting. The present work herein provides a simple and effective Mo doping approach for generation of high performance photoanodes for PEC water splitting.

Unveiling the influence of SmFeO3-TiO2 nanocomposites as high performance photoanodes of dye-sensitized solar cells

Dye-sensitized solar cells (DSSCs) with boosted performances were obtained with a tri-layered photoanode structure containing compact, mesoporous plus light scattering TiO2 films. Furthermore, synthesis of SmFeO3 inorganic perovskite nanocrystalline material was accomplished via the sol-gel process which was then used to prepare diverse (0–2.5%) SmFeO3/TiO2 nanocomposite films as photoanodes of DSSCs. All materials including TiO2, SmFeO3 and SmFeO3/TiO2 nanocomposites were characterized using different analysis methods, i.e. SEM images, XRD, EDS, photoluminescence (PL), DRS, FT-IR, UV–Vis spectra as well as dye adsorption. Besides, influence of SmFeO3 nanostructure was unveiled on the performances of fabricated DSSCs. The bandgap values of the TiO2, SmFeO3 were 3.25, 1.75 eV but they were altered in the range of 1.75–3.10 eV for the (0.25–2.5%) SmFeO3 + TiO2 nanocomposites. The photocurrent density–voltage diagrams were attained to measure DSSCs’ performances. It was shown that the champion device contained 0.5% SmFeO3 + TiO2 composite photoelectrode which indicated PCE = 7.06%, JSC = 17.37 mA.cm−2, VOC = 0.77 V, FF = 0.53. As a result, the 0.5% SmFeO3 + TiO2 nanocomposite enhanced the PCE by 2.66 folds (∼60%) compared to that of reference solar cell composed of pure TiO2 with champion PCE = 4.40%, JSC = 12.75 mA.cm−2, VOC = 0.64 V, FF = 0.53. According to electrochemical impedance spectroscopy (EIS) data, among diverse devices, (0.5% SmFeO3 + TiO2) photoelectrode exhibited the lowest RCT2 value of 5.27 Ω.cm−2. In fact, SmFeO3 incorporation into the TiO2 photoanode highly boosted the JSC values of DSSCs compared to that of the device containing pure TiO2 which confirmed addition of SmFeO3 led to greatly enhanced charge transport within the DSSC through declining charge recombination. Therefore, SmFeO3 could be considered as an effective nanostructured perovskite material to fabricate high-performance DSSC devices.

CoNiFe-LDHs decorated Ta3N5 nanotube array photoanode for remarkably enhanced photoelectrochemical glycerol conversion coupled with hydrogen generation

Solar-driven photoelectrochemical (PEC) technology has been widely recognized as a green and sustainable approach to produce fossil-fuel-alternative energy sources, whereas currently its feasibility is still a great challenge due to the lack of high-performance photoanodes. Herein, two-dimensional trimetallic CoNiFe-layered double hydroxides (CoNiFe-LDHs) nanosheets were uniformly anchored on one-dimensional Ta 3 N 5 nanotube arrays used as a novel integrated photoanode. Serving as a hole collector, CoNiFe-LDHs can accelerate hole extraction from photo-excited Ta 3 N 5 towards surface water oxidation reaction (WOR), thus promoting the separation of electron-hole pairs and ultimately markedly improving PEC water-splitting performance. Moreover, the trimetallic CoNiFe-LDHs were more effective in boosting the PEC performance than the three sets of bimetallic LDHs. By further replacing WOR with glycerol oxidation reaction (GOR), the composite photoanode achieved a ten-fold enhancement of solar energy conversion efficiency reaching 0.56% with nearly 100% Faradaic efficiency for concurrent generation of formate and hydrogen. Importantly, the stability of Ta 3 N 5 was dramatically enhanced due to the synergy of CoNiFe-LDHs loading and anodic GOR. The significantly enhanced PEC properties can be mainly attributed to the increased surface active sites, promoted hole extraction and utilization, and particularly the improved charge separation efficiency. This work provides a reference for the fabrication of high-performance Ta 3 N 5 -based photoanodes towards efficient and stable PEC hydrogen generation and the green conversion of biomass derivatives into valuable chemicals. • 2D CoNiFe-LDHs NSs were uniformly anchored on 1D Ta 3 N 5 NAs as an integrated photoanode. • CoNiFe-LDHs loading remarkably enhanced the solar-driven PEC water-splitting performance of Ta 3 N 5 . • Highly efficient and stable PEC H 2 production was achieved due to surface modification and anodic glycerol oxidation. • The enhanced PEC properties originate from increased active sites, promoted hole extraction, faster charge separation.

Decorating Pt nanoparticles on oxygen vacancies incorporated hematite photoanode for enhanced water oxidation

Pt-treatment and oxygen vacancies incorporation as effective strategies had been extensively used to improve the photoelectrochemical (PEC) water splitting performance of hematite. Herein, by coupling Pt-decoration and oxygen vacancies incorporation through a facile solution route, an efficient hematite photoanode for PEC water splitting was fabricated. PEC measurements indicated that the photocurrent density was increased from 0.80 mA/cm2 at 1.23 V versus RHE for the pristine Fe2O3 film to 1.15 mA/cm2 at 1.23 V versus RHE for the co-modified sample. Based on various characterizations, this improvement could be attributed to the cumulative effect of Pt-decoration and oxygen vacancies incorporation, in which the incorporation of oxygen vacancies could increase the donor density and consequently promote the charge transport in the bulk hematite, while the excellent electrical conductivity of Pt was beneficial for facilitating the charge transfer across hematite/electrolyte interface. This study provides a feasible approach for the development of high-performance hematite photoanodes.

Solar energy storage by a microfluidic all-vanadium photoelectrochemical flow cell with self-doped TiO2 photoanode

All-vanadium photoelectrochemical flow cell, which combines the vanadium redox flow battery and the photoelectrochemical flow cell, is a promising technology to store solar energy in reversible redox pairs. The development of a high-performance photoanode is vital to promote the storage of solar energy. In this work, we developed a self-doped TiO2 photoanode and applied it to a microfluidic all-vanadium photoelectrochemical flow cell (μVPFC). The self-doped TiO2 photoanode was simply prepared by annealing the TiO2 photoanode with NaBH4 in the nitrogen atmosphere, by which the self-dopant led to the formation of a disordered layer on the surface and created a mid-band. As a result, the light absorption region was extended and the electron-hole pair separation efficiency was enhanced, promoting the capability of the μVPFC with the self-doped TiO2 photoanode. The superiority of the self-doped TiO2 photoanode was confirmed by its excellent photoelectrochemical performance and vanadium ion conversion rate. The μVPFC with the self-doped TiO2 photoanode yielded an average photocurrent density as high as 0.064 mA·cm−2 in 6-h operation, which was much higher than the reported TiO2 and Ti2O3 photoanodes and presented the improvements by approximately 167% and 60%, respectively. In addition, intensifying the intensity of light and concentration of vanadium ion enabled the performance of the μVPFC with the self-doped TiO2 photoanode to be promoted.