Photochemical environment effect on V ₂ O ₅ ‐Fe ₂ O ₃ heterostructures for efficient water splitting under visible light

Abstract

Summary To enhance eco‐friendly energy generation from photoelectrochemical water splitting, the photoanode should be immersed in a photochemical environment for a long time. Here, V2O5 surfaces modified with Fe2O3 nanoparticles were synthesized using a simple method, and the stability of the synthesized photoanodes in a 0.1 M Na2SO3 electrolyte was investigated. The heterostructure was subjected to dark and light conditions, and their effect on the optical properties and kinetic behavior of the photoanode was analyzed. The V2O5‐Fe2O3 heterostructures showed better light absorption than the pristine V2O5 and Fe2O3 structures. At 0 h immersion, the maximum photocurrent density was 0.25 mAcm−2 for the V2O5‐Fe2O3 photoanodes, which was 8‐fold and 5‐fold that of the V2O5 and Fe2O3 photoanodes, respectively, in the 0.1 M Na2SO3 electrolyte. Furthermore, the V2O5‐Fe2O3 photoanode exhibited the lowest charge‐transfer resistance (3.75 Ω) and Tafel slope (68.1 mV·dec−1). After immersion for 96 h in the 0.1 M Na2SO3 electrolyte, the V2O5‐Fe2O3 photoanode showed a significant decrease in photocurrent density, which could be owing to the shrinkage of active sites in the photoanode and increased charge‐transfer resistance, exchange current density, limiting current density, and Tafel slope. Thus, the photochemical environment has a critical role in the photo‐induced currents of the photoanode under illumination conditions.