Exclusive Ni–N4 Sites Realize Near-Unity CO Selectivity for Electrochemical CO2 Reduction

Electrochemical reduction of carbon dioxide (CO2) to value-added carbon products is a promising approach to reduce CO2 levels and mitigate the energy crisis. However, poor product selectivity is still a major obstacle to the development of CO2 reduction. Here we demonstrate exclusive Ni–N4 sites through a topo-chemical transformation strategy, bringing unprecedentedly high activity and selectivity for CO2 reduction. Topo-chemical transformation by carbon layer coating successfully ensures preservation of the Ni–N4 structure to a maximum extent and avoids the agglomeration of Ni atoms to particles, providing abundant active sites for the catalytic reaction. The Ni–N4 structure exhibits excellent activity for electrochemical reduction of CO2 with particularly high selectivity, achieving high faradaic efficiency over 90% for CO in the potential range from −0.5 to −0.9 V and gives a maximum faradaic efficiency of 99% at −0.81 V with a current density of 28.6 mA cm–2. We anticipate exclusive catalytic sites will shed new light on the design of high-efficiency electrocatalysts for CO2 reduction.