Interface Engineering of Ultrathin Bimetallic Metal–Organic Layers on α ‐SnWO ₄ Nanoplate Photoanode for Remarkable Visible‐Light‐Driven Photocurrent in Water Splitting

In this study, a facile bottom‐up interface‐directed strategy was developed to graft ultrathin 2D CoFe bimetallic organic layers (MOLs) onto SnWO 4 nanoplates to enhance visible‐light‐driven water splitting. Several studies reveal that CoFe‐MOLs play a multifunctional role in improving the photoelectrochemical (PEC) performance of the hybrid photoanode by enhancing light‐harvesting capability, internal quantum efficiency, and charge‐separation dynamics. Electronic reconstruction at the CoFe‐MOLs/SnWO 4 interface suppresses the formation of SnO 2 surface defects that act as photocarrier recombination centers. The CoFe‐MOLs also induce a substantial built‐in photovoltage and type‐II‐like interfacial band alignment, facilitating efficient charge separation and transport. Interface engineering enables the hybrid photoanode to achieve a surface charge‐separation efficiency exceeding 94% at 1.23 V versus the reversible hydrogen electrode (RHE), along with a remarkable photocurrent density of 1.21 mA.cm −2 and an applied‐bias photon‐to‐current efficiency of 0.22%. The presence of bimetallic Co–Fe sites acts as dual catalytic centers, serving as hole traps and active OER sites, thereby reducing the water oxidation overpotential and accelerating reaction kinetics. This work presents an innovative interface‐engineering strategy for facial grafting ultrathin bimetallic organic layers onto semiconductor photoanodes to enable visible‐light‐driven water splitting.