Photodeposition of Au Nanoclusters for Enhanced Photocatalytic Dye Degradation over TiO₂ Thin Film

Au nanoparticle (NP) decorated heterogeneous TiO2 catalysts are known to be effective in the degradation of various organic pollutants. The photocatalytic performance of such Au–TiO2 structures remarkably depends on the size, morphology, and surface coverage of the Au NPs decorating TiO2. Here we propose an effective way of preparing a highly active Au nanocluster (NC) decorated TiO2 thin film by a novel photodeposition method. By altering the solvent type as well as the illumination time, we achieved well-controlled surface coverage of TiO2 by Au NCs, which directly influences the photocatalytic performance. Here the Au NCs coverage affects both the electron store capacity and the optical absorption of the hybrid Au–TiO2 system. At low surface coverage, 19.2–29.5%, the Au NCs seem to enhance significantly the optical adsorption of TiO2 at UV wavelengths which therefore leads to a higher photocatalytic performance.