Novel microporous organic-inorganic hybrid metal phosphonates as electrocatalysts towards water oxidation reaction

In recent years, the development of electrochemical water oxidation requires an efficacious heterogeneous electrocatalyst to improve the high catalytic activity. Herein, newly designed three transition metal-based phosphonate materials i.e., cobalt phosphonate (CoEDA), nickel phosphonate (NiEDA), and nickel-cobalt phosphonate (NiCoEDA), were synthesized using etidronic acid (1-Hydroxyethane 1,1-diphosphonic acid) as the organophosphorus source under hydrothermal reaction condition at pH 6.5. Among these materials, CoEDA exhibits a high surface area with a proper microporous channel, one of the key parameters for showing excellent electrocatalytic activity towards oxygen evolution reaction (OER) with a lower overpotential (318 mV) and Tafel slope (70.1 mV dec−1). The superior catalytic activity towards OER can be correlated with the presence of the organic-inorganic hybrid material containing Co-O-P bond and the formation of highly electroactive cobalt oxyhydroxide (CoOOH) species onto the pore wall of the microporous channel. Besides, as-synthesized CoEDA catalyst displays outstanding catalytic stability for 25 h with a change in current density of only 6%.