Well-Defined Single-Atom Cobalt Catalyst for Electrocatalytic Flue Gas CO2 Reduction

Single-atom Co catalyst Co-Tpy-C with well-defined sites is synthesized by pyrolysis of a Co terpyridine (Tpy) organometallic complex. The Co-Tpy-C catalyst exhibits excellent activity for the electrochemical CO2 reduction reaction in aqueous electrolyte, with CO faradaic efficiency (FE) of over 95% from -0.7 to -1.0 V (vs RHE). By comparison, catalysts without Co or Tpy ligand added do not show any high CO FE. When simulated flue gas with 15% of CO2 is used as the source of CO2, CO FE is kept at 90.1% at -0.5 V versus RHE. During gas phase flow electrolysis using simulated flue gas, the CO partial current density is further increased to 86.4 mA cm(-2) and CO FE reached >90% at the cell voltage of 3.4 V. Experiments and density functional theory calculations indicate that uniform single-atom Co-N-4 sites mainly contribute to the high activity for CO2 reduction.