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

Abstract

Electrochemical reduction of carbon dioxide (CO2) to value-added carbon products is a promising approach to reduce the CO2 level and mitigate energy crisis. However, poor product selectivity is still a major obstacle to the development of CO2 reduction. Here we demonstrated 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 Ni-N4 structure to maximum extent and avoids the agglomeration of Ni atoms to particles, providing abundant active sites for the catalytic reaction. 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 give 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 electrocatalyst for CO2 reduction.