Insight into coupled Ni-Co dual-metal atom catalysts for efficient synergistic electrochemical CO2 reduction

The development of highly active, selective, and stable electrocatalysts can facilitate the effective implementation of electrocatalytic CO2 conversion into fuels or chemicals for mitigating the energy crisis and climate problems. Therefore, it is necessary to achieve the goal through reasonable material design based on the actuality of the operational active site at the molecular scale. Inspired by the stimulating synergistic effect of coupled heteronuclear metal atoms, a novel Ni-Co atomic pairs configuration (denoted as NiN3©CoN3-NC) active site was theoretically screened out for improving electrochemical CO2 reduction reaction (CO2RR). The structure of NiN3©CoN3-NC was finely regulated by adjusting Zn content in the precursors Zn/Co/Ni-zeolite imidazolate frameworks (Zn/Co/Ni-ZIFs) and pyrolysis temperature. The structural features of NiN3©CoN3-NC were systematically confirmed by aberration-corrected HAADF-STEM coupled with 3D atom-overlapping Gaussian-function fitting mapping, XAFS, and XRD. The results of theoretical calculations reveal that the synergistic effect of Ni-Co atomic pairs can effectively promote the *COOH intermediate formation and thus the overall CO2RR kinetic was improved, and also restrained the competitive hydrogen evolution reaction. Due to the attributes of Ni-Co atomic pairs configuration, the developed NiN3©CoN3-NC with superior catalytic activity, selectivity, and durability, with a high turnover frequency of 2265 h−1 at −1.1 V (vs. RHE) and maximum Faradaic efficiency of 97.7% for CO production. This work demonstrates the great potential of DACs as highly efficient catalysts for CO2RR, provides a useful strategy to design heteronuclear DACs, exploits the synergistic effect of multiple metal sites to facilitate complex CO2RR catalytic reactions, and inspires more efforts to develop the potential of DACs in various fields.