Synthesis of plasmonic gold nanoparticles supported on morphology-controlled TiO2 for aerobic alcohol oxidation

In the present research study, we report the synthesis of nano-sized gold (Au) particles immobilized on TiO2 support material. The morphologies of TiO2 support material was tailored and tuned to be rod, tube and microporous materials. The effect of plasmonic gold nanoparticles (NPs) deposited on different morphologies of TiO2 was studied. The prepared catalysts were characterized by various characterization techniques in order to have a detailed insight on the textural properties, morphology and electronic state of the material via UV-vis spectroscopy, N-2 physisorption analysis, Transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). We tested the controlled oxidation of benzyl alcohol to benzaldehyde using molecular oxygen at 373 K under atmospheric pressure. The results obtained from the thermal reaction conditions were compared with those performed under visible light irradiation (lambda > 420 nm) at 373 K. Among all, Au/TiO2 nanorod catalyst displayed the superior performance of 33% yield in the absence of light and 55% yield of benzaldehyde with an external quantum efficiency of 3.4% under visible light irradiation (lambda >= 420 nm) at 373 K for 4 h. The enhanced catalytic performances were attributed to the Au-LSPR phenomenon and a plausible reaction pathway has been discussed involving the generation of hot electrons during the course of reaction.