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

Abstract

AbstractWe report the unprecedented electrocatalytic activity of a series of molecular nickel thiolate complexes (1–5) in reducing CO2to C1–3hydrocarbons 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 C3products from CO2for the first time in molecular complex. Compound5exhibits Faradaic efficiencies (FEs) of 10.6 %, 7.2 %, 8.2 % for C1, C2, C3hydrocarbons respectively at −1.0 V versus the reversible hydrogen electrode. Addition of CO to the system significantly promotes the FEC1–C3to 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 CO2reduction.