Cu–Ni core–shell bimetallic cocatalyst decorated polymeric carbon nitride for highly efficient and selective methane production from photocatalytic CO2 reduction

Abstract

The development of non-noble bimetallic cocatalysts for the efficient and selective CO2 photoreduction is extremely desirable yet challenging. Herein, we rationally synthesized a series of non-noble Cu–Ni bimetallic cocatalysts by varying the Cu and Ni molar ratios, and then, we decorated these cocatalysts on polymeric carbon nitride (CN) for photocatalytic CO2 reduction. Elemental distribution maps demonstrated that the Cu–Ni-11 bimetallic cocatalyst with a Cu:Ni molar ratio of 1:1 has a perfect core–shell configuration. Notably, this Cu–Ni-11 core–shell cocatalyst-decorated CN (Cu–Ni-11@CN) exhibited remarkable CO2 photoreduction activity for selective CH4 production, outperforming bare CN, Cu@CN, Ni@CN, and Cu–Ni-13@CN and Cu–Ni-31@CN catalysts with different metal proportions. Additionally, the Cu–Ni-11@CN catalyst was remarkably stable and durable over multiple test runs. The remarkable CO2 conversion activity and stability of the developed catalyst are predominantly due to the synergistic effect of the Cu–Ni-11 core–shell cocatalyst and CN, which affords significantly improved optical absorption, CO2 adsorption, and photoexcited charge separation. Therefore, the study results elucidate the rational design and development of non-noble bimetallic cocatalysts for photocatalytic CO2 conversion.