Oxygen vacancy modulated interface chemistry: identifying iron(iv) in heterogeneous Fenton reaction

WO_3−x switched the reaction of Fe^II with H₂O₂ from the formation of Fe^III towards the direct generation of Fe^IV. Fe^IV was reduced to Fe^III/Fe^II by electrons localized in the t_2g orbitals of WO_3−x, which favored the generation of ˙O₂⁻, ˙OH, and ¹O₂.