Efficient photocatalytic CO2 reduction to CH4 via electric field-regulated d-band center on Ga2S3/CuS S-type heterojunction interface structures

Photocatalytic CO2 reduction is an excellent method for the resource utilization of CO2. However, challenges such as inferior product yields and poor selectivity still exist. In this investigation, a novel composite catalyst of S-type heterojunction Ga2S3/CuS was formulated and synthesized using a facile two-step hydrothermal method. The CH4 product yield of 30 wt% Ga2S3/CuS reached 18.8 μmol·g−1·h−1. The reaction pathways were investigated through in-situ DRIFTS and DFT calculations, revealing the internal built-in electric field at the S-type heterojunction induces migration of the Cu atomic d-band center towards the Fermi energy level. The elevation of the Cu d orbital energy levels enables electron contributions from the dxz orbital to facilitate the formation of π* bonds with CO2, thereby promoting the adsorption of both CO2 and intermediate species to produce CH4. This study emphasizes the influence of the intrinsic electric field at the interface on product yield and selectivity.