LAUSR

In the present work, we have synthesized noble bimetallic nanoparticles (Au-Pd NPs) on carbon based support and integrated with titania to obtain Au-Pd/C/TiO2 and Au-Pd/rGO/TiO2 nanocomposites using an ecofriendly hydrothermal method. Here, 1:1 (w/w) Au-Pd bimetallic composition was dispersed on (a) high surface area (3000 m2g-1) activated carbon (Au-Pd/C), prepared from locally available plant source (in Assam, India), and (b) reduced graphene oxide (rGO) (Au-Pd/rGO); subsequently, they were integrated with TiO2. Shift observed in Raman spectroscopy demonstrates the electronic integration of bimetal with titania. The photocatalytic activity of the above materials for hydrogen evolution reaction (HER) was studied under one sun conditions using methanol as a sacrificial agent in powder form. The photocatalysts were also employed to prepare thin film by drop-casting method. Au-Pd/rGO/TiO2 exhibits 43 times higher hydrogen (H2) yield with thin film (21.50 mmol h-1g-1) compared to powder form (0.50 mmol h-1g-1). On the other hand, Au-Pd/C/TiO2 shows 13 times higher hydrogen (H2) yield with thin film (6.42 mmol h-1g-1) compared to powder form (0.48 mmol h-1g-1). While powder form of both catalysts show comparable activity, Au-Pd/rGO/TiO2 thin film shows 3.4 times higher activity than that of Au-Pd/C/TiO2. This can be ascribed to (a) an effective separation of photogenerated electron-hole pairs at the interface of Au-Pd/rGO/TiO2, and (b) the better field effect due to plasmon resonance of bimetal in thin film form. The catalytic influence of carbon based support is highly pronounced due to synergistic binding interaction of bimetallic nanoparticles. Further, large amount of hydrogen evolution in film form with both catalysts (Au-Pd/C/TiO2 and Au-Pd/rGO/TiO2) reiterates that charge utilization should be better compared to powder catalysts.