Molecular Nickel Thiolate Complexes for Electrochemical Reduction of CO2to C1–3Hydrocarbons

Abstract We report the unprecedented electrocatalytic activity of a series of molecular nickel thiolate complexes ( 1 – 5 ) in reducing CO 2 to C 1–3 hydrocarbons on carbon paper in pH‐neutral aqueous solutions. Ni(mpo) 2 ( 3 , mpo=2‐mercaptopyridyl‐N‐oxide), Ni(pyS) 3 − ( 4 , pyS=2‐mercaptopyridine), and Ni(mp) 2 − ( 5 , mp=2‐mercaptophenolate) were found to generate C 3 products from CO 2 for the first time in molecular complex. Compound 5 exhibits Faradaic efficiencies (FEs) of 10.6 %, 7.2 %, 8.2 % for C 1 , C 2 , C 3 hydrocarbons respectively at −1.0 V versus the reversible hydrogen electrode. Addition of CO to the system significantly promotes the FE C1–C3 to 41.1 %, suggesting that a key Ni−CO intermediate is associated with catalysis. A variety of spectroscopies have been performed to show that the structures of nickel complexes remain intact during CO 2 reduction.