Fabrication of a CuS-cocatalyst-supported g-C₃N₄ nanosheet composite photocatalyst with improved performance in the photocatalytic reduction of CO₂

Carbon dioxide (CO₂) is not only a greenhouse gas but also an abundant carbon resource. By using solar energy to reduce CO₂ into high-value hydrocarbons <i>via</i> photocatalysis, we can mitigate the greenhouse effect and enable energy recycling. In this paper, a two-step calcination process was employed to thermally exfoliate graphite-phase carbon nitride (g-C₃N₄) into ultrathin nanosheets, after which the CuS co-catalyst was loaded onto the g-C₃N₄ surface using a one-step hydrothermal method. The ultrathin nanosheet structure of g-C₃N₄ can increase the specific surface area of the composite material and improve the anchoring of active components and CO₂ adsorption sites. CuS, acting as a co-catalyst, can capture photogenerated electrons from the g-C₃N₄ conduction band, thereby enhancing the separation and migration of photogenerated charges. Moreover, the interfacial charge transfer (IFCT) mechanism of CuS enhances the efficiency of separating photogenerated electrons and holes. The prepared 10CuS/g-C₃N₄ composite photocatalyst, loaded with 10 wt% CuS, has significantly improved CO₂ photoreduction performance. The highest CO yield reached 15.34 μmol g^-1. This work provides guidance for developing low-cost artificial photosynthesis to utilize CO₂ as a resource.