Nearly 100% Charge Transfer in BiVO 4 via Conjugated Organic–Inorganic Interface Engineering for Photoelectrochemical Water Splitting

Photoelectrochemical water splitting is regarded as a promising strategy for the direct conversion of solar energy into hydrogen energy. However, detrimental bulk charge transport and surface trap‐state‐mediated carrier recombination result in low efficiency. Herein, we propose a dual hole transport layer strategy by combining a covalent organic polymer (CHN) framework and an inorganic NiO x layer to enhance the PEC performance of BiVO 4 photoanode. The dual hole transport layers not only reinforce the built‐in electric field but also reduce the surface‐state‐mediated charge recombination. The resulting BiVO 4 /CHN/NiO x /NiFeO x photoanode delivers a high photocurrent density of 4.45 mA/cm 2 at 1.23 V versus RHE and excellent stability for continuous 24 h illumination. Overall, this work provides a versatile platform for interface engineering modulation of BiVO 4 photoanodes, and sheds light on the mechanism of organic–inorganic hole transport layers for boosting PEC performance.