Pulse Electrodeposited Au–WO₃ Catalyst from a Water–Ionic Liquid Microemulsion for Photoaccelerated Methanol Electrooxidation

For improving the separation efficiency of photogenerated carriers and electrocatalytic activity, we have used visible light-responsive tungsten oxide (WO₃) as a support for a plasmonic gold nanoparticle (Au NP) cocatalyst. It has been fabricated by a two-step optimized pulse electrodeposition method in aqueous and water-in-ionic liquid microemulsion media. By taking advantage of interfacial heterojunctions and the synergistic effect, the plasmonic Au NP electrocatalyst on WO₃-coated fluorine-doped tin oxide as a photoanode has shown enhanced electrocatalytic current density as well as a negative shift in the onset potential under light irradiation for methanol electrooxidation. The pulse electrodeposited Au–WO₃ nanocatalyst under light irradiation displays ∼3.85 times enhancement in electrocatalytic activity than without light irradiation, and it has been attributed to the simultaneous enhancement in electron–hole (e–/h⁺) pair separation of WO₃ and Au NP surface plasmon resonance absorption. The mechanism of enhanced electrocatalytic performance of Au–WO₃ has also been proposed under light illumination.