Synthesis, characterization and electrocatalytic activity of a novel binuclear polypyridine nickel complex

Abstract

The pursuit of highly efficient water oxidation catalysts has garnered significant attention due to the central role of the water oxidation reaction in overall water splitting. Herein, we report the synthesis, characterization, and electrocatalytic water oxidation performance of a novel binuclear nickel(II) complex, [Ni2(BPMAB)(OH2)4](ClO4)4 (1, BPMAB = 6,6′-Bis[bis(2-pyridylmethyl)aminomethyl]-2,2′-bipyridine). Single-crystal X-ray diffraction analysis reveals that complex 1 adopts an asymmetric tetragonal bipyramidal geometry, coordinated by nitrogen atoms from the BPMAB ligand and oxygen atoms from water molecules. In a neutral phosphate buffer solution, complex 1 homogeneously catalyze water oxidation to oxygen, achieving onset overpotential of 630 mV and turnover frequency (TOF) of 1.16 s-1. Electrochemical studies suggest that the water oxidation proceeds via a synergistic binuclear mechanism, resulting in a high faradaic efficiency of 96%. To the best of our knowledge, this work presents the first example of a homogeneous Ni-based water oxidation catalyst operating through a binuclear catalytic pathway.