Stabilization of cobalt-polyoxometalate over poly(ionic liquid) composites for efficient electrocatalytic water oxidation

Abstract

The key to unlock a renewable, clean, and energy-dense hydrogen fuel lies in designing an efficient oxygen evolving catalyst exhibiting high activity, stability, and cost-effectiveness. This report addresses an improved activity toward oxygen evolution by a composite of cobaltpolyoxometalate [Co4(H2O)2(PW9O34)2] 10− (CoPOM) and an ionic polymer, poly(vinyl butyl imidazolium) (PVIM), in highly alkaline media. PVIM provides a stable platform for CoPOM and acts as a conductive linker between CoPOM and the electrode surface, forming a concrete solid composite, which balances the multinegative charge of CoPOM synergistically. This improved stability and conductivity of CoPOM by PVIM in the PVIM−CoPOM composite performs remarkable electrocatalytic water oxidation with a very low overpotential of 0.20 V and a very high current density of 250 mA/ cm2 (at 1.75 V vs RHE) with a turnover frequency (TOF) of 52.8 s−1 in 1 M NaOH.