Boosting Solar Water Splitting via Spatial Carrier Separation on Bismuth Vanadate Photoanodes

Utilizing solar energy to drive the photoelectrochemical splitting of water is an attractive strategy for sustainable hydrogen production in the pursuit of carbon neutrality, where the efficient separation and extraction of photogenerated charge carriers are crucial for achieving excellent solar-to-hydrogen conversion efficiency. Herein, we report a rationally designed sandwich-structured BiVO₄-based photoanode that enables spatially directed charge separation, resulting in substantially improved photoelectrochemical (PEC) water-splitting performance. More specifically, under the simulated AM 1.5G solar irradiation (100 mW·cm^-2), the functionally layered Pt/BiVO₄/NiFe photoanode yielded a photocurrent density of 4.06 mA·cm^-2 under a bias of 1.23 V_RHE, corresponding to an enhancement of 3.47 times compared to the pristine BiVO₄. Systematic experimental analyses reveal that the underlying metallic Pt layer facilitates efficient electron extraction from the semiconductor, while the surface-deposited NiFe catalyst promotes the rapid hole injection into the electrolyte. This synergistic charge management strategy enables effective spatial separation of photogenerated carriers, leading to a markedly improved PEC performance. These findings underscore the pivotal role of functional interlayers in directing charge transport and establish a practical framework for the development of advanced photoelectrodes toward efficient solar fuel production.