Electrocatalytic hydrogen evolution by cobalt triaryl corroles with appended ester and carboxyl on the 10-phenyl group

Abstract

Two A2B cobalt triaryl corroles bearing ester (1) or carboxylic acid group (2) at the 10-para-phenyl group were prepared and used as homogeneous electrocatalysts for hydrogen evolution reaction (HER) with acetic acid and water as proton sources. CV results revealed the HER underwent two routes with [CoIII–H]– (EECC pathway) and [CoII–H]2– (ECEC pathway) as the intermediates at low acetic acid concentration. While the HER mainly went through the ECEC route at high acetic acid concentration. The HER turnover frequencies of 1 and 2 in neutral aqueous media were 291.8 and 190.6 h−1, respectively, at an overpotential of 838 mV. Unexpectedly, 1 exhibited significantly better HER activity than 2, showing the factors controlling electrocatalytic HER activity of cobalt corrole are complicated.