Achieving Efficient CO₂ Electrolysis to CO by Local Coordination Manipulation of Nickel Single-Atom Catalysts

Selective electroreduction of CO2 to C-1 feedgas provides an attractive avenue to store intermittent renewableenergy. However, most of the CO2-to-CO catalysts are designedfrom the perspective of structural reconstruction, and it is challengingto precisely design a meaningful confining microenvironment for activesites on the support. Herein, we report a local sulfur doping methodto precisely tune the electronic structure of an isolated asymmetricnickel-nitrogen-sulfur motif (Ni-1-NSC). OurNi(1)-NSC catalyst presents >99% faradaic efficiency forCO(2)-to-CO under a high current density of -320 mAcm(-2). In situ attenuated totalreflection surface-enhanced infrared absorption spectroscopy and differentialelectrochemical mass spectrometry indicated that the asymmetric sitesshow a significantly weaker binding strength of *CO and a lower kineticoverpotential for CO2-to-CO. Further theoretical analysisrevealed that the enhanced CO2 reduction reaction performanceof Ni-1-NSC was mainly due to the effectively decreasedintermediate activation energy.