In-situ surface reconstruction of BiVO4/CuFe2O4 photoanode for efficient and robust solar water oxidation

• Self-etching in-situ reconstruction of composite heterojunction photoanode . • Stable 4.07 mA cm −2 at 1.23 V RHE , surpassing most BiVO 4 -based systems in performance. • Synergistic reduce photon-generated carrier recombination and enhance OER kinetics. Photoelectrochemical (PEC) water splitting is a promising approach for sustainable hydrogen production, yet it faces challenges in achieving efficient charge separation and stable photoanode operation. In this work, we develop a BiVO 4 /CuFe 2 O 4 (BVO/CFO) heterojunction photoanode with in-situ surface reconstruction capabilities to enhance PEC performance and operational durability. The BVO/CFO heterojunction , formed by coupling n-type BVO with p-type CFO, effectively reduces charge recombination through an intrinsic electric field, promoting efficient charge separation. The BVO/CFO photoanode exhibits a photocurrent density of 2.77 mA cm −2 and a charge separation efficiency of 79.7 % at 1.23 V vs. RHE. After loading NiOOH co-catalysts, the photocurrent density increases to 3.72 mA cm −2 . More importantly, under PEC conditions, the surface of CFO undergoes in-situ reconstruction, forming an FeOOH layer that serves as a robust oxygen evolution reaction (OER) catalyst, enhancing water oxidation kinetics and providing protection against photocorrosion. The BVO/CFO/FeOOH photoanode, formed via this in-situ surface reconstruction process, achieves a photocurrent density of 4.07 mA cm −2 and a charge injection efficiency of 75.4 %. Our study highlights the effectiveness of integrating heterojunction engineering with adaptive surface reconstruction, offering a scalable pathway to high-performance, durable PEC systems for solar-driven hydrogen production.