Alternative method for preparation of Au/TiO2 with precise Au0/Auδ+

Abstract

AbstractBACKGROUNDAu valence for Au catalysts has been considered a vital parameter for catalytic activity towards CO oxidation. However, there is no effective method to prepare precise Au0/Auδ+ molar ratios with the same Au nanoparticles (NPs) sizes.RESULTSA series of Au/TiO2 catalysts with tuneable Au0/Auδ+ molar ratios were prepared by the combination of a biosynthesis method and a deposition–precipitation (DP) method, and characterized by XPS, TEM, DRUV‐Vis techniques. First, biosynthesized metallic Au NPs were immobilized onto TiO2 supports to obtain Au/TiO2 catalysts with different Au loadings but with the same sized Au NPs. And then positively ionized Au species were supported onto the above Au/TiO2 catalysts by a DP method. The metallic Au and positively ionized Au species could be totally supported on the support. Therefore, the Au0/Auδ+ molar ratios could be controlled exactly. Compared with Au/TiO2 catalysts with metallic and positively ionized Au species alone, the catalyst Au/TiO2‐1:1 showed the best initial catalytic activity, suggesting enhanced catalytic performance due to the coexistence of Au0 and Auδ+.CONCLUSIONThis study verifies that Au/TiO2 catalysts with accurate Au0/Auδ+ molar ratios can be prepared by a combination of biosynthesis and a DP method. © 2015 Society of Chemical Industry