A p-n WO₃/SnSe₂ Heterojunction for Efficient Photo-assisted Electrocatalysis of the Oxygen Evolution Reaction

Water splitting is important to the conversion and storage of renewable energy, but slow kinetics of the oxygen evolution reaction (OER) greatly limits its utility. Here, under visible light illumination, the p-n WO₃/SnSe₂ (WS) heterojunction significantly activates OER catalysis of CoFe-layered double hydroxide (CF)/carbon nanotubes (CNTs). Specifically, the catalyst achieves an overpotential of 224 mV at 10 mA cm⁻² and a small Tafel slope of 47 mV dec⁻¹, superior to RuO₂ and most previously reported transition metal-based OER catalysts. The p-n WS heterojunction shows strong light absorption to produce photogenerated carriers. The photogenerated holes are trapped by CF to suppresses the charge recombination and facilitate charge transfer, which accelerates OER kinetics and boost the activity for the OER. This work highlights the possibility of using heterojunctions to activate OER catalysis and advances the design of energy-efficient catalysts for water oxidation systems using solar energy.