Exfoliated 2D layered and nonlayered metal phosphorous trichalcogenides nanosheets as promising electrocatalysts for CO2 reduction

Two-dimensional (2D) materials catalysts provide an atomic-scale view on a fascinating arena for understanding the mechanism of electrocatalytic carbon dioxide reduction (CO₂ ECR). Here, we successfully exfoliated both layered and nonlayered ultra-thin metal phosphorous trichalcogenides (MPCh₃) nanosheets via wet grinding exfoliation (WGE), and systematically investigated the mechanism of MPCh₃ as catalysts for CO₂ ECR. Unlike the layered CoPS₃ and NiPS₃ nanosheets, the active Sn atoms tend to be exposed on the surfaces of nonlayered SnPS₃ nanosheets. Correspondingly, the nonlayered SnPS₃ nanosheets exhibit clearly improved catalytic activity, showing formic acid selectivity up to 31.6 % with −7.51 mA cm⁻² at −0.65 V vs. RHE. The enhanced catalytic performance can be attributed to the formation of HCOO* via the first proton-electron pair addition on the SnPS₃ surface. These results provide a new avenue to understand the novel CO₂ ECR mechanism of Sn-based and MPCh₃-based catalysts.