Gu, JunHsu, Chia-ShuoBai, LichenChen, Hao MingHu, Xile2019-06-262019-12-142019-06-262019-06-1410.1126/science.aaw7515https://infoscience.epfl.ch/handle/20.500.14299/158536WOS:000471306700046Currently, the most active electrocatalysts for the conversion of CO2 to CO are gold-based nanomaterials, whereas non-precious metal catalysts have shown low to modest activity. Here, we report a catalyst of dispersed single-atom iron sites that produces CO at an overpotential as low as 80 millivolts. Partial current density reaches 94 milliamperes per square centimeter at an overpotential of 340 millivolts. Operando x-ray absorption spectroscopy revealed the active sites to be discrete Fe3+ ions, coordinated to pyrrolic nitrogen (N) atoms of the N-doped carbon support, that maintain their +3 oxidation state during electrocatalysis, probably through electronic coupling to the conductive carbon support. Electrochemical data suggest that the Fe3+ sites derive their superior activity from faster CO2 adsorption and weaker CO absorption than that of conventional Fe2+ sites.Multidisciplinary SciencesScience & Technology - Other Topicselectrochemical reductionselective conversionelectrodesoxidationcarbonirontext::journal::journal article::research article