Bimetallic Cu(core)@Zn(shell) co-catalyst impregnated TiO2 nanosheets (001 faceted) for the selective hydrogenation of quinoline under visible light irradiation

Bimetallic nanostructures have gained immense importance owing to their enhanced co-catalytic effect in improving photocatalytic activity of TiO2 for various applications relative to monometallic ones. However, the use of bimetallic core@shell catalyst/nanocatalyst for hydrogenation of important industrial organic is not much explored relative to conventional metal catalysts. In this respect, the present study demonstrated the synthesis of core@shell (Cu@Zn) nanostructure based on their galvanic interactions. TEM analysis confirmed the formation of Cu@Zn nanoparticles with a shell thickness of 195 nm. It was observed that with increasing Cu:Zn weight ratio (1:1, 2:1, and 3:1) the average hydrodynamic size increases from 198 to 267 nm. These Cu@Zn nanostructures showed superior co-catalytic activity after impregnation on (001) faceted titanium nanosheets (surface area = 72.8 m(2)g(-1)) for the selective hydrogenation of quinoline under visible light radiations. The optimized Cu@Zn(3:1)/TiO2 photocatalyst showed enhanced conversion, selectivity, and higher rate constant (k = 2.1 x 10(-1) h(-1)) compared to Cu and Zn-TiO2 nanocomposites. The superior activity of Cu@Zn-TiO2 photocatalyst was attributed to the synergistic interaction occurring at bimetallic-TiO2 interface which effectively promotes the transfer of electron and hydride (H-) for quinoline hydrogenation. The conventional hydrogenation of quinoline required high temperature, solvents, expensive bases and involved multistep procedure. Therefore, the use of Cu@Zn-TiO2 photocatalyst might be a greener approach for the selective hydrogenation of industrial important unsaturated organic compounds under light radiations. (C) 2019 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.