Molecular Copper Phthalocyanine and FeOOH Modified BiVO₄ Photoanodes for Enhanced Photoelectrochemical Water Oxidation

Abstract The limited performance of BiVO₄ for photoelectrochemical (PEC) water splitting is currently restricted to limited light absorption and rapid carrier recombination. Herein, molecular copper phthalocyanine (CuPc) and FeOOH co‐integrated BiVO₄ photoanode are prepared by a simple dipping method and demonstrate significantly improved PEC water oxidation activities. The optimized BiVO₄/CuPc/FeOOH photoanode attains a photocurrent density of 3.67 mA cm⁻² at 1.23 V_RHE and maintains the PEC performance without significant decay over a long period of time. In addition, significant increase of charge separation efficiency and decrease of charge transfer resistance of the BiVO₄/CuPc/FeOOH photoanode also demonstrate that the hole–electron transfer and water oxidation reaction are promoted. It is found that CuPc has a similar structure to photosensitized chlorophyll, which can broaden the absorption range of BiVO₄ in the visible region and improve the photo‐generated carriers transfer in the semiconductor. Whereas the FeOOH layer can rapidly transfer the photo‐generated holes into the electrolyte to participate in the water oxidation reaction as oxygen evolution cocatalyst. This work provides a feasible pathway to improve the PEC water splitting performance of BiVO₄ by increasing light absorption and accelerating carrier transfer.