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 [Co 4 (H 2 O) 2 (PW 9 O 34 ) 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/ cm 2 (at 1.75 V vs RHE) with a turnover frequency (TOF) of 52.8 s −1 in 1 M NaOH.

Polyoxometalates: Tailoring metal oxides in molecular dimension toward energy applications

“…Polyoxometalate itself can act as photosensitizer for oxygen production under light irradiation . A very low overpotential at 0.20 V and turnover frequency at 52.8 seconds −1 for water oxidation is achieved by [Co 4 (H 2 O) 2 (PW 9 O 34 ) 2 ] 10− stabilized via ionic polymer . The [Co 9 (H 2 O) 6 (OH) 3 (HPO 4 ) 2 (PW 9 O 34 ) 3 ] 16− ‐based polyoxometalate cluster achieves good electrocatalytic water oxidation properties, while [(PW 9 O 34 ) 2 Co 4 (H 2 O) 2 ] 10− in a porphyrinic metal‐organic framework is employed for water oxidation .…”

“…202,203 A very low overpotential at 0.20 V and turnover frequency at 52.8 seconds −1 for water oxidation is achieved by [Co 4 (H 2 O) 2 (PW 9 O 34 ) 2 ] 10− stabilized via ionic polymer. 204 The [Co 9 (H 2 O) 6 (OH) 3 40 has been employed to reduce the oxygen with the proximity of silver nanoparticles and graphene. 211 In addition, a number of studies have been devoted to applying the polyoxotungstates for photodegrading organic pollutions owing to their excellent photocatalytic properties.…”

Electrochemical properties of the [SiW10O36(M2O2Kemmegne‐Mbouguen1, Floquet2, Cadot3 2021Comptes Rendus. Chimie4000View full textAdd to dashboardCite

“…In particular, with a tremendously diverse variety of POMs capable of storing a high number of electrons and displaying proton transfer capabilities, this class of compounds behaves as very efficient electrocatalysts for reactions of environmental interest such as CO 2 reduction [20][21][22], proton reduction into hydrogen [23][24][25], oxygen evolution reaction [26][27][28][29], or detection of environmental pollutants like nitrogen oxides [30][31][32][33][34][35], bromates [35][36][37][38], or iodates [35,37,[39][40][41].…”

Amphiphilic poly(ionic liquid)/Wells–Dawson‐type phosphovanadomolybdate ionic composites as efficient and recyclable catalysts for the direct hydroxylation of benzene with H2O2

“…An example is tuning the hydrophobicity and hydrophilicity of PILs to fulfill the phase separation of the phases. A series of PIL‐based POM composites or hybrids were prepared by introducing various POM anions, which were used as green heterogeneous catalysts with high catalytic activity and selectivity for chemical reactions such as olefin epoxidation with H 2 O 2 , electrocatalytic water oxidation, selective oxidation of sulfides, etc. Starting from SO 3 H‐functionalized acidic ionic liquid monomer via controllable polymerization, microporous, mesoporous, macroporous and hierarchically nanoporous PILs were prepared with strong acid strength, and used as efficient solid acids in various acid‐catalyzed reactions …”