Electrocatalytic H2 evolution using binuclear cobalt complexes as catalysts

Abstract

We report herein on the use of two binuclear cobalt complexes with the N,N′-bis(salicylidene)-phenylmethanediamine ligand as catalysts for the H₂ evolution in DMF solution with acetic acid as proton source. Both experimental analyses (electrochemical analysis, spectroscopy analysis) and theoretical analysis (foot-of-the wave analysis) were employed. These catalysts required an overpotential of ca. 470 mV to catalyze the H₂ evolution and generated H₂ gas with a faradaic efficiency of 85–95% as calculated on the basis of after 5 hour bulk electrolysis. The kinetic investigation showed the maximal TOF value of 50 s⁻¹ on the basis of an ECEC mechanism. Two cobalt centers, standing at a long distance of 4.175 Å, operated independently during catalysis without a synergetic effect or cooperation capability.