Achieving Efficient CO 2 Electrolysis to CO by Local Coordination Manipulation of Nickel Single-Atom Catalysts.

Selective electroreduction of CO 2 to C 1 feed gas provides an attractive avenue to store intermittent renewable energy. However, most of the CO 2 -to-CO catalysts are designed from the perspective of structural reconstruction, and it is challenging to precisely design a meaningful confining microenvironment for active sites on the support. Herein, we report a local sulfur doping method to precisely tune the electronic structure of an isolated asymmetric nickel-nitrogen-sulfur motif (Ni 1 -NSC). Our Ni 1 -NSC catalyst presents >99% faradaic efficiency for CO 2 -to-CO under a high current density of -320 mA cm -2 . In situ attenuated total reflection surface-enhanced infrared absorption spectroscopy and differential electrochemical mass spectrometry indicated that the asymmetric sites show a significantly weaker binding strength of *CO and a lower kinetic overpotential for CO 2 -to-CO. Further theoretical analysis revealed that the enhanced CO 2 reduction reaction performance of Ni 1 -NSC was mainly due to the effectively decreased intermediate activation energy.