Electrocatalytic Hydrogen Evolution by Binuclear Metal (M=Co, Fe, Mn) Xanthine Bridged Bis-corrole

Three binuclear metal (M=Co, Fe, Mn) xanthine bridged bis-corrole complexes were synthesized and investigated as electrocatalysts for the hydrogen evolution reaction (HER). All the prepared metal bis-corrole catalysts exhibited good HER performance when using acetic acid (AcOH), trifluoroacetic acid (TFA) and p-toluenesulfonic acid (TsOH) as proton sources. The catalytic HER activities followed an order of Co bis-corrole (1)> Fe bis-corrole (2)> Mn bis-corrole (3) and complex 1 exhibited a significantly lower overpotential at −270 mV (in TsOH). Furthermore, complex 1 may go EECC and EECEC pathways in organic solvents (E: electron transfer step, C: proton coupling) and exhibit an HER activity with a turnover frequency (TOF) of 85 h⁻¹ and a Faraday efficiency of 94% when using water as proton source.