Titania Gold Composite: Effect of Illumination on Size of Gold Nanoparticles with Consequent Implication on Photocatalytic Water Splitting

This work deals with the study of photodeposition (PD) of gold nanoparticles (AuNPs) on TiO2 by using different illumination sources, Medium pressure Mercury lamp (ML), Solar Simulator equipped with AM 1.5 (SL) and Tungsten lamp (WL). Different particle size of AuNPs on TiO2 were obtained by photodeposition method under different illumination sources, which clearly proves the influence of light source on the synthesis of Au–TiO2. The plasmonic activity of Au–TiO2 photocatalyst for water splitting reaction was observed to be strongly influenced by the particle size of Au as well as illumination source. Amongst the three different illumination sources used, smallest particle size for AuNP–TiO2 were observed under ML followed by SL and WL, as revealed by TEM analysis. Different illumination sources were also investigated to evaluate the activity of Au–TiO2 samples thus prepared under different illumination conditions. The order of hydrogen evolution rate (HER) observed for Au–TiO2 with different source of illuminations is ML > SL > WL. The highest HER of 1709 μmol/h was observed for Au–TiO2, which was synthesized and evaluated under ML irradiation. This may be explained on the basis of reduced catalytic activity and photothermal effect of Au nanoparticles with increasing particle size.