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

Abstract

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 195nm. 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 267nm. These Cu@Zn nanostructures showed superior co-catalytic activity after impregnation on (001) faceted titanium nanosheets (surface area=72.8m2g−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=2.1×10−1h−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.