Electrocatalytic activity of cobalt tris(4-nitrophenyl)corrole for hydrogen evolution from water

Catalytic activities for hydrogen (H₂) evolution of cobalt 5,10,15-tris(phenyl)corrole (1) and 5,10,15-tris(4-nitrophenyl)corrole (2) (in homogeneous system was examined from acetic acid and water. In phosphate buffer solution (pH 7.0), the hydrogen evolution turnover frequency (TOF) for 1 and 2 were 62 and 150 h⁻¹ at the overpotential of −1.53 V versus Ag/AgCl. In acetic acid media, hydrogen evolution TOF for 1 and 2 were 56 and 127 h⁻¹, respectively, at an overpotential of 961 mV versus Ag/AgNO₃. In the practical electrocatalytic hydrogen evolution experiment at −1.45 V (vs. Ag/AgCl) overpotential for 1 h, the TOF were 76 and 188 h⁻¹ for 1 and 2, respectively. No observable decomposition of the catalyst could be observed after electrolysis for 72 h with a glassy carbon electrode.