Customizing Highly Asymmetrical Coordination Microenvironment into P-Block Metal Single-Atom Sites to Boost Electrocatalytic CO2 Reduction

The coordination microenvironment modulation of single-atom catalysts (SACs) based on p-block metals holds promise for excavating their enormous potential in electrochemical CO2-to CO conversion. Guided by the instructive theoretical calculations over serial asymmetric coordination microenvironments, herein, a novel Pb SAC with highly asymmetric coordination microenvironment (Pb-N2SV) is developed. Namely, the Pb atom is coordinated with two N atoms, one S atom and one vacancy nearby. With the breaking of coordination symmetry, the obtained Pb-N2SV shows excellent ECR performance with 97.3% Faradaic efficiency of CO at -0.47 V, and long-term stability of 33 h, which exceeds the vast majority of main-group SACs. More importantly, in situ spectroscopy and density functional theory (DFT) studies unveil that the S doping in Pb SAC can significantly improve electron localization around Pb sites to facilitate *COOH intermediate adsorption, while the introduction of vacancy defect nearby the Pb sites can function as a synergistic modulation on the electronic structure for favorable *CO intermediate desorption, which jointly contributes to achieve the suitable adsorption energy for reaction intermediates to boost the ECR process. As an expandability, this approach will be widely used to construct SACs with unique coordination microenvironment for other challenging catalysis.

Automated summary

In this study, a novel Pb single-atom catalyst (SAC) with highly asymmetric coordination microenvironment was developed for electrochemical CO2-to-CO conversion. The Pb-N2SV SAC exhibited excellent performance with high Faradaic efficiency and long-term stability. The introduction of S doping and vacancy defect near the Pb sites played important roles in modulating the electronic structure and achieving suitable adsorption energy for reaction intermediates.