Selective and efficient aerobic oxidation of benzyl alcohols using plasmonic Au-TiO2: Influence of phase transformation on photocatalytic activity

Abstract

Chemical processes using heterogeneous photocatalytic systems are widely used for the synthesis of valuable fine chemicals. To improve these chemical processes both environmental and energy aspects must be kept in mind for favorable reaction conditions, such as optimum temperature and atmospheric pressure. In this study, plasmonic Au nanoparticles (Au NP) dispersed over TiO2 photocatalyst with different phases of TiO2 (amorphous, anatase and rutile) have been synthesized by using a facile sol–gel method followed by calcination for the photocatalytic oxidation of benzyl alcohol (BnOH) to benzaldehyde (BzH) under visible light irradiation at ambient conditions. The best photocatalyst exhibits high surface area and excellent catalytic conversion efficiency (96%) for the oxidation of BnOH to BzH in less reaction time using a green solvent, acetonitrile at room temperature. The detailed optimization of reaction parameters was performed for alcohol conversion. In addition the corresponding green metrics parameters were also calculated. The photocatalyst also shows excellent stability and reusability for multiple cycles. This work suggests that the Au-TiO2 catalyst provides a novel green and sustainable approach for the selective and efficient aerobic oxidation of BnOH to BzH under visible light irradiation. Furthermore, the impact of different phases of TiO2 on the photocatalytic activity has also been discussed.