Reduction potentials and UV–visible absorption edge energies of H6P2MoxW18−xO62 heteropolyacid (HPA) catalysts as a probe of oxidation catalysis for ethanol conversion reaction

Reduction potentials of H6P2MoxW18−xO62 Wells–Dawson heteropolyacid (HPA) catalysts were measured electrochemically. UV–visible spectra of H6P2MoxW18−xO62 catalysts were then obtained in order to explore the reduction potentials of the HPA catalysts. Absorption edge energies shifted to lower values and reduction potentials increased with increasing molybdenum substitution. An HPA catalyst with a high reduction potential showed a low absorption edge energy in the UV–visible spectrum. The absorption edge energies could be utilized as a correlation parameter for the reduction potentials of the H6P2MoxW18−xO62 catalysts, and furthermore, as a probe of oxidation catalysis of the HPA catalysts.