A Keggin Polyoxometalate Shows Water Oxidation Activity at Neutral pH: POM@ZIF-8, an Efficient and Robust Electrocatalyst

Abstract

Keggin-type polyoxometalate anions [XM12O40]n− are versatile, as their applications in interdisciplinary areas show. The Keggin anion [CoW12O40]6− turns into an efficient and robust electrocatalyst upon its confinement in the well-defined void space of ZIF-8, a metal–organic framework (MOF). [H6CoW12O40]@ZIF-8 is so stable to water oxidation that it retains its initial activity even after 1000 catalytic cycles. The catalyst has a turnover frequency (TOF) of 10.8 mol O2(mol Co)−1 s−1, one of the highest TOFs for electrocatalytic oxygen evolution at neutral pH. Controlled experiments rule out the chances of formation and participation of CoOx in this electrocatalyic water oxidation.