Single transition metal anchored on defective boron carbide monolayer for efficient and selective CO₂ electrochemical reduction: A theoretical study

Electrochemical reduction of CO2 to produce fuels and industrial chemicals shows significant promise for reducing greenhouse gas emission and mitigation the energy crisis. The exploitation of highly efficient catalysts has long been considered an attractive yet challenging task. Herein, we systematically studied the electrocatalytic performance of a range of transition metal (TM) single atom anchored on defective BC3 monolayer, specifically those with a boron vacancy (V-B) and a carbon vacancy (V-C), named TM@V-B and TM@V-C, respectively, as single-atom catalysts (SACs) for CO2 reduction reaction (CO2RR) via density functional theory (DFT). We screened a total of 28 stable SACs by evaluating the formation energy and dissolution potential of metal atoms. Detail reaction mechanisms involved in CO2 reduction process to produce diverse C1 products were considered. Among the 28 candidates, Cu@V-B, Mo@V-B, Re@V-B, Co@V-C, and Ir@V-C displayed remarkable efficiency in reducing CO2 into HCOOH at nearly zero or extremely low limiting potentials (U-L) of -0.01 similar to 0 V. These SACs exhibit excellent electrocatalytic activity, surpassing most previously reported catalysts. Furthermore, these five SACs effectively suppressed the competing hydrogen evolution reaction, highlighting their high selectivity toward HCOOH. In addition, the volcano relationship between the triangle G(*HCOO) and U-L was established. This work may offer a promising strategy for the research and development of high-efficiency CO2RR electrocatalysts, which has potential implications for addressing environmental and energy challenges.