A Novel Polyoxovanadate-Based Metal-Organic Framework as an Efficient Electrocatalyst for Oxygen Evolution

Abstract

The shift to renewable energy is driven by environmental degradation and the energy crisis. Water electrolysis, key for energy storage, faces challenges due to the high cost and inefficiency of current oxygen evolution reaction (OER) catalysts. This study reports the synthesis of a novel polyoxovanadate-based metal-organic framework, [Co(bix)1.5(mim)][V2O6] (denoted as Co-V-MOF, where bix = 1,4-bis(imidazol-1-ylmethyl)benzene and mim = 1-methylimidazole), under hydrothermal conditions. Co-V-MOF features a three-dimensional framework in which the inorganic layers of {V8Co2} are interconnected by bix bridges. Remarkably, Co-V-MOF demonstrates outstanding performance as an electrocatalyst for OER, exhibiting superior catalytic activity with an overpotential of 350 mV at 10 mA·cm−2 in 1 M KOH, outperforming the benchmark RuO2 catalyst. The material's exceptional electrochemical stability and fast electron transfer rate, as evidenced by its small Tafel slope and electrochemical impedance, position it as a promising candidate for sustainable electrocatalysis. This work underscores the potential of POV-MOFs in advancing renewable energy technologies. Furthermore, magnetic investigations have evinced the emergence of antiferromagnetic interactions within Co2+ centres.

Keywords: Polyoxovanadate, Metal-organic frameworks, Oxygen evolution reaction, Electrocatalysis