Synthesis of Au-decorated V₂O₅@ZnO heteronanostructures and enhanced plasmonic photocatalytic activity

A ternary plasmonic photocatalyst consisting of Au-decorated V₂O₅@ZnO heteronanorods was successfully fabricated by an innovative four-step process: thermal evaporation of ZnO powders, CVD of intermediate on ZnO, solution deposition of Au NPs, and final thermal oxidization. SEM, TEM, EDX, XPS, and XRD analyses revealed that the interior cores and exterior shells of the as-prepared heteronanorods were single-crystal wurtzite-type ZnO and polycrystalline orthorhombic V₂O₅, respectively, with a large quantity of Au NPs inlaid in the V₂O₅shell. The optical properties of the ternary photocatalyst were investigated in detail and compared with those of bare ZnO and V₂O₅@ZnO. UV-vis absorption spectra of ZnO, V₂O₅@ZnO, and Au-decorated V₂O₅@ZnO showed gradually enhanced absorption in the visible region. In addition, gradually decreased emission intensity was also observed in the photoluminescence (PL) spectra, revealing enhanced charge separation efficiency. Because of these excellent qualities, the photocatalytic behavior of the ternary photocatalyst was studied in the photodegradation of methylene blue under UV-vis irradiation, which showed an enhanced photodegradation rate nearly 7 times higher than that of bare ZnO and nearly 3 times higher than that of V₂O₅@ZnO, mainly owing to the enlarged light absorption region, the effective electron-hole separation at the V₂O₅-ZnO and V₂O₅-Au interfaces, and strong localization of plasmonic near-field effects.