Deciphering the work function induced local charge regulation towards activating an octamolybdate cluster-based solid for acidic water oxidation

Abstract

The advancement of highly robust and efficient electrocatalysts for the oxygen evolution reaction (OER) under acidic conditions is imperative for the sustainable production of green hydrogen. In accomplishing sustainable and sturdy electrocatalysts for oxygen evolution at low pH, the challenge is tough for non-iridium/ruthenium-based electrocatalysts. This study elaborates on the intrinsic alterations in electronic arrangements and structural disorder upon the precise activation of an octamolybdate cluster-based solid [{Cu(pz)₄}₂Mo₈O₂₆]·2H₂O through room temperature grinding with rGO (reduced graphene oxide), resulting in enhanced conductivity, stability, and activity of the electrocatalyst towards the acidic OER without employing any benchmark metal ion (Ru or Ir). Additionally, the work function of the composites was found to be low compared to that of pristine polyoxometalates (POMs), indicative of the improved conducive behavior, which is lacking in the POM structure. The catalyst displays a notably reduced overpotential of 185 mV to achieve a current density of 10 mA cm⁻², coupled with significant stability lasting 24 hours at a higher current density of 100 mA cm⁻². These findings propose the manipulation of crystalline POMs with highly conductive non-metallic elements to facilitate superior water oxidation at lower pH levels which can help in the production of green hydrogen.