A metal-supported single-atom catalytic site enables carbon dioxide hydrogenation

Nitrogen-doped graphene-supported single atoms convert CO2 to CO, but fail to provide further hydrogenation to methane - a finding attributable to the weak adsorption of CO intermediates. To regulate the adsorption energy, here we investigate the metal-supported single atoms to enable CO2 hydrogenation. We find a copper-supported iron-single-atom catalyst producing a high-rate methane. Density functional theory calculations and in-situ Raman spectroscopy show that the iron atoms attract surrounding intermediates and carry out hydrogenation to generate methane. The catalyst is realized by assembling iron phthalocyanine on the copper surface, followed by in-situ formation of single iron atoms during electrocatalysis, identified using operando X-ray absorption spectroscopy. The copper-supported iron-single-atom catalyst exhibits a CO2-to-methane Faradaic efficiency of 64% and a partial current density of 128 mA cm-2, while the nitrogen-doped graphene-supported one produces only CO. The activity is 32 times higher than a pristine copper under the same conditions of electrolyte and bias.The authors acknowledge funding support from Natural Gas Innovation Fund, the Natural Sciences and Engineering Research Council (NSERC) of Canada, and Natural Resources Canada Clean Growth Program, and Ontario Research Fund − Research Excellence program. All DFT computations were performed on the Niagara supercomputer at the SciNet HPC Consortium. SciNet is funded by the Canada Foundation for Innovation, the Government of Ontario, Ontario Research Fund Research Excellence Program, and the University of Toronto. The authors thank T. Wu and G. Sterbinsky for technical support at the 9BM beamline of the Advanced Photon Source (Lemont, IL). This research used resources of the Advanced Photon Source, an Office of Science User Facility operated for the US Department of Energy (DOE) Office of Science by Argonne National Laboratory and was supported by the US DOE under Contract no. DE-AC02-06CH11357, and the Canadian Light Source and its funding partners. The authors thank Y. Hu, Q. Xiao, M. Shakouri at the 06B1-1 (SXRMB) beamline, and T. Regier and J. Dynes at the 11ID-1 (SGM) at the Canadian Light Source for their technical support. The authors also thank the help from Material and Chemical Laboratories, Industrial Technology Research Institute (ITRI), Taiwan, for STEM/EELS observation and FIB sample preparation. Dr. Mu Tung Chang and Dr. Ren-Fong Cai are responsible for acquiring HADDF STEM atomic image as well as the EELS spectrum analysis. Dr. Shih-Yi Liu and Ms. Mei Lun Wu are responsible to prepare plane-view TEM sample and sample pretreatment before FIB. S.-F.H. acknowledges support from Postdoctoral Research Abroad Program, Ministry of Science and Technology, Taiwan (Contract No. MOST 108-2917-I-564-016, MOST 110-2113-M-009-007-MY2 and MOST 110-2628-M-A49-002) and from the Yushan Young Scholar Program, Ministry of Education, Taiwan