Proton-rich two-dimensional defective Bi2S3-derived nanosheets for boosting CO2 electroreduction

Abstract

Bismuth (Bi)-based catalysts have attracted great attention in electrocatalytic CO2 reduction into formate, but suffer from modest activity due to insufficient active sites and slow protonation process. Here, two-dimensional (2D) defect-rich Bi2S3 nanosheets are first achieved through chemical vapor sulfurization of Bi2O3 solids. It is found that the defects enable the stable immobilization of S heteroatoms into 2D Bi lattice. A combination of computational and experimental analyses reveal that S dopants can not only facilitate water dissociation to construct proton-rich surface, but also concentrate potassium cations to stabilize *OCHO intermediates. Further cooperating with defects, the *OCHO formation can be both kinetically and thermodynamically boosted. Remarkably, the constructed Bi2S3 nanosheets exhibit a high formate Faradaic efficiency (>90%) over a wide potential window and a high intrinsic stability over 200 h. The excellent performance in flow cell as well as promising solar-driven CO2 electrocatalysis further demonstrate the great potential for practical implementation.