Gold nanoparticles modified ZnO nanorods with improved photocatalytic activity

Well-aligned ZnO nanorods (NRs) were grown on indium–tin-oxide (ITO) slide by the hydrothermal method and used as templates for preparing ZnO/Au composite nanoarrays. The optical and morphological properties of ZnO/Au composites under various HAuCl4 concentrations were explored via UV–vis absorption spectroscopy, photoluminescence (PL) and scanning electron microscopy (SEM). The density and size of gold nanoparticles (Au NPs) on ZnO NRs can be controlled by adjusting the concentration of HAuCl4. The optimal ZnO/Au composites display complete photocatalytic degradation of methyl blue (MB) within 60 min, which is superior to that with pure ZnO NRs prepared by the same method. The reason of better photocatalytic performance is that Au NPs act as electron traps and it prevents the rapid recombination of electrons and holes, resulting in the improvement of photocatalytic efficiency. The photocatalytic performance of ZnO/Au composites is mainly controlled by the density of Au NPs formed on ZnO NRs. The application in rapid photodegradation of MB shows the potential of ZnO/Au composite as a convenient catalyst for the environmental purification of organic pollutants.

Graphical abstractIn this work, we provided a convenient method to construct ZnO/Au hybrid nanostructures by directly growing Au NPs on aligned ZnO nanorods (NRs) arrays without adding any linking molecules. The optimized ZnO/Au composites display complete photocatalytic degradation MB within 60 min, which is superior to pure ZnO NRs prepared by the same method.Figure optionsDownload full-size imageDownload high-quality image (117 K)Download as PowerPoint slideHighlights► ZnO/Au NRs as photocatalyst for degradation of methyl blue dye. ► Optimized ZnO/Au NRs display better photocatalytic activity than pure ZnO NRs. ► Photocatalytic activity is affected by density and size of Au NPs on ZnO NRs. ► Density and size of Au NPs can be controlled by altering HAuCl4 concentration.