Unlocking the potential of p-block single-atom anchored on MXene electrocatalyst surface for efficient CO2 reduction

Abstract

The electrochemical reduction of CO2 into value-added products has emerged as a promising approach for mitigating CO2 emissions. In this study, 23 p-block single-atom (PSA)-anchored on Mo2CO2 catalyst for CO2 reduction has been systematically investigated using density functional theory at atomic level. Based on the binding energy and cohesive energy, the 9 PSA prefers to anchor on Mo2CO2 hollow carbon site. Side-on and end-on modes are preferred for CO2 adsorption on PSA-anchored Mo2CO2 (PSA@Mo2CO2). Projected density of states (PDOS) analysis indicates that PSA@Mo2CO2 exhibits a metallic-like electronic structure. The Bader charge analysis and charge density difference show unique behavior for Sn@Mo2CO2, with a lower Gibbs free energy change for the potential-determining step CO2 to *OCHO (0.58 eV). Sn@Mo2CO2 is located on top of the volcano plot of limiting potential versus adsorption energy. Furthermore, Sn@Mo2CO2 exhibits the best selectivity for CO2 reduction into HCOOH and suppresses the competing hydrogen evolution reaction. PDOS analysis of the *OCHO intermediate reveals that the oxygen and Sn p orbitals show moderate overlap. Ab initio molecular dynamics indicate that Sn@Mo2CO2 is stable at 300 K. This work provides an orbital-based strategy for catalyst design to enable selective CO2 reduction to HCOOH.