Ligand Environment Engineering of Nickel Single Atomic Sites for Efficient Electrochemical Carbon Dioxide Reduction Reaction

Abstract

Electrochemical carbon dioxide reduction reaction (CO2RR) is considered one of the feasible options for a net reduction of CO2 emission, especially when coupled with renewable energy resources. Many techno-economical assessments on 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 CO2RR to syngas conversion. 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 catalytic active sites for the selective CO2RR process. This study provides fundamental insights into the rational design for Ni-SACs toward the enhanced CO2RR activity and selectivity based on their structure-property relationship.