Enabling Interfacial Lattice Matching by Selective Epitaxial Growth of CuS Crystals on Bi2WO6 Nanosheets for Efficient CO2 Photoreduction into Solar Fuels

Photocatalytic CO₂ reduction serves as an important technology for value-added solar fuel production, however, it is generally limited by interfacial charge transport. To address this limitation, a two-dimensional/two-dimensional (2D/2D) p-n heterojunction CuS-Bi₂WO₆ (CS-BWO) with highly connected and matched interfacial lattices was designed in this work via a two-step hydrothermal tandem synthesis strategy. The integration of CuS with BWO created a robust interface electric field and provided fast charge transfer channels due to the work function difference, as well as highly connected and matched interfacial lattices. The p-n heterojunction combination promoted the electron transfer from the Cu to Bi sites, leading to the coordination of Bi sites with high electronic density and low oxidation state. The Bi sites in the BWO nanosheets facilitated the adsorption and activation of CO₂, and the generation of high-coverage key intermediate b-CO₃ ^2-, while CuS (CS) acted as a broad light-harvesting material to provide abundant photoinduced electrons that were injected into the conduction band of BWO for CO₂ photoreduction reaction. Remarkably, the p-n heterojunction CS-BWO exhibited average CO and CH₄ yields of 33.9 and 16.4 μmol g^-1 h^-1, respectively, which were significantly higher than those of CS, BWO, and physical mixture CS-BWO samples. This work provided an innovative design strategy for developing high-activity heterojunction photocatalyst for converting CO₂ into value-added solar fuels.