N-Bridged Co-N-Ni: New bimetallic sites for promoting electrochemical CO₂reduction

The electrochemical CO2 reduction reaction (CO2RR) is of importance for reducing global CO2 emissions. Herein, we reported a highly active CO2RR catalyst, namely Co-N-Ni/NPCNSs, which is considered as an advanced single-site catalyst with Co-N-Ni bimetallic sites connected by a N bridge between Co and Ni. The N-bridged Co-N-Ni bimetallic sites were confirmed by the X-ray absorption spectroscopy. The Co-N-Ni/NPCNSs catalyst shows a higher turnover frequency of 2049 h-1 at a low overpotential of 370 mV and CO faradaic efficiency of 96.4% compared to that of Co-N/NPCNSs (1205 h-1 and 61.5%) and Ni-N/NPCNSs (404 h-1 and 45.0%) with single Co-N4 and Ni-N4 sites, respectively. In situ synchrotron radiation Fourier transform infrared spectra and DFT calculations show that N-bridged Co-N-Ni bimetallic sites promote the formation of COOH* intermediates, thus accelerating CO2RR.