Ligand environment engineering of nickel single atomic sites for efficient electrochemical carbon dioxide reduction reaction

Abstract

The electrochemical carbon dioxide reduction reaction (CO2RR) is considered one of the feasible options for a net reduction of CO2 emissions, especially when coupled with renewable energy resources. Many techno-economical assessments on the CO2RR have concluded that the production of syngas (CO/H2), a precursor for Fischer-Tropsch synthesis, is beneficial. Thus, cost-effective and durable catalysts are needed to selectively promote the CO2RR to produce syngas. Ni-based single-atom catalysts (Ni-SACs) have gained significant interest for the CO2RR towards syngas production. However, there is still a lack of understanding of the physicochemical properties of isolated Ni atomic sites with different ligand environments and the resultant CO2RR performance. In this study, we combined experimental measurements, in situ X-ray absorption fine structure analyses, and density functional theory calculations to study a series of Ni-SACs with controlled Ni configuration and N-coordination and revealed that Ni-Nx sites with less than 4 N coordination are the catalytically active sites for the selective CO2RR process. This study provides fundamental insights into the rational design for Ni-SACs for enhanced CO2RR activity and selectivity based on their structure-property relationship.