Stabilization of Cobalt-Polyoxometalate over Poly(ionic liquid) Composites for Efficient Electrocatalytic Water Oxidation

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 cobalt-polyoxometalate
[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.