Interface Coordination Bonding-Driven Charge Transport for High-Performance Photoelectrochemical Water Splitting

Photoelectrochemical (PEC) water oxidation for hydrogen production is an appealing strategy, yet the oxygen evolution reaction (OER) at the photoanode faces bottlenecks: weak water activation and a low charge utilization rate. Here, hydrophilic SO42– groups were introduced at the CdS/SnS2 photoanode interface to construct directional interfacial coordination bonds (Sn-SO42–-Cd) that serve as interfacial charge-migration channels, thereby improving the utilization efficiency of photogenerated carriers. The optimized SO42–-SnS2/CdS photoanode exhibits a maximum photocurrent density value of 1.48 mA cm–2 at 1.23 V vs RHE, demonstrating an enhancement of about 9.25 times relative to the SnS2 photoanode. The photocurrent density value of the SO42–-SnS2/CdS-PANI photoanode may be further increased to 1.83 mA cm–2 by loading polyaniline (PANI) as a hole transport layer (HTL), resulting in an applied bias photon-to-current efficiency (ABPE) of 0.76% and prolonged photostability. From experimental findings and density functional theory (DFT) simulations, the meliorative water oxidation capacity is caused by the design of the Sn-SO42–-Cd directional interfacial coordination in SO42–-SnS2/CdS, which speeds up the photoinduced charge transfer, lowers the water-splitting energy barriers, and raises the OER dynamics. This straightforward, yet broad method offers a foundation to design directional interfacial coordination bonds for high-performance PEC water-splitting applications.