Electrochemical-driven water reduction catalyzed by a water soluble cobalt(III) complex with Schiff base ligand

Abstract

A new molecular catalyst based on cobalt complex [LCoCl] (1) is formed by the reaction of N,N-dimethylethylenediamino-N,N-bis(2,4-dimethyl) phenol (H2L) with CoCl2·6H2O for electrolytic water reduction. To our knowledge 1 is by far the most active electrocatalyst for hydrogen generation from water with a turnover frequency (TOF) of 2744mol of hydrogen per mole of catalyst per hour at an overpotential of −638mV (pH 7.0). This is attributed to the ionic ligand, L2−, that coordinates strongly through two nitrogen atoms and two oxygen atoms to the cobalt center, leaving one Cl− ion in axial position and making the Cl− ion ionize in water.