Electrocatalytic Hydrogen Evolution of Transition Metal (Fe, Co and Cu)–Corrole Complexes Bearing an Imidazole Group.

The study of the hydrogen evolution reaction (HER) by non-noble transition metals is of great significance for the production of hydrogen energy. In this work, a new 5,15-bis-(pentafluorophenyl)-10-[4-(1H-imidazole) phenyl]-corrole and its metal complexes (metal = Co, Cu, Fe) were synthesized and used for electrocatalyzed HER in DMF organic solvent and aqueous media. The prepared cobalt corrole showed the best catalytic performance in both media. Its turnover frequency (TOF) and catalytic efficiency (C.E) could reach 265 s⁻¹ and 1.04 when TsOH was used as the proton source in a DMF solvent. In aqueous media, its TOF could also reach 405 h⁻¹. The catalytic HER may go through an EECEC or ECEC (E: electron transfer, C: chemical step) pathway for these catalysts, depending on the acidity and concentration of the proton source. The present work successfully demonstrates that imidazole at a meso-phenyl group may improve the electrocatalytic HER activity of transition metal corroles. [ABSTRACT FROM AUTHOR]