Surface Sulfurization of Cubic Cu₂O to Form Cu₂S Nanostructure-Decorated Catalysts for Light-Enhanced...

Developing highly efficient bifunctional catalysts for electrocatalysis and photocatalysis suffers from sluggish charge transfer and poor photo-to-electric conversion rate. Herein, micro-sized Cu₂O cubes were initially prepared for subsequent transformation into Cu₂O@Cu₂S core-shell structures by a slight surface sulfurization. The formation of nanostructured Cu₂S thin layer at Cu₂O surface can endow an immediate charge separation and migration under light irradiation, leading to high surface photovoltages (SPV, 18-30 mV). As a result, the as-prepared Cu₂O@Cu₂S catalysts exhibited reduced overpotentials (η, only 86 mV is required for the optimized sample to achieve a current density of 10 mA cm^-2) for H₂ evolution with good cycling stability in electrocatalytic water splitting. Meanwhile, a high methane (CH₄) production rate of 30.3 μmol h^-1 g^-1 can be delivered from the optimized Cu₂O@Cu₂S sample when used for photocatalytic CO₂ reduction. This work has provided a strategy to prepare bifunctional catalysts with improved photoelectric properties for photo/electrocatalytic applications.