Structural Properties and Photocatalytic Activity of TiO2/Au Nanocomposites Synthesized with Glucose

A one-pot synthesis of plasmonic gold-modified TiO2 nanocomposites is reported by using glucose reduction of HAuCl4 in presence of titanium tetraisopropoxide. The resulting nanocomposites are characterized by thermal-gravimetric analyses, X-ray diffraction combined with X-ray fluorescence and photoelectron spectroscopies. A binary system of beta-TiO2 and anatase phases is obtained for low Au content while only anatase form is favored when the initial Au rate rises. This investigation also suggests the inclusion of gold in the TiO2 structure. Although the optical bandgap of the different nanocomposites remains around 3 eV, the increase of Au content induces a shift of both valence and conduction edge bands to lower energy levels. The photocatalytic activity of TiO2/Au nanocomposites is assessed through the decolorization of different cationic and anionic dyes as model compounds. Regarding rhodamine and methylene blue dyes, the sample TiO2 modified with 3.5 wt% of Au presents the best performance. The relation between the structure of the nanocomposites and their capacity to degrade pollutants is discussed. The synthesis of Au-doped TiO2 nanocomposites is carried out by a chemical codeposition method with glucose used as reducing agent of gold. Structural characterizations confirm that Au is dispersed homogeneously into the nanocomposites, inducing a progressive shift of both valence and conduction band edges. Adsorption and photodegradation performance are assessed as a function of the nature of the dye. image