Bimetallic core@shell nanostructures of galvanic metals for improved catalysis

Abstract

The work reported in this thesis involved the synthesis of bimetallic core-shell (Pd@Ni, Cu@Zn, and Pd@Au) nanostructures via galvanic displacement reaction. The incorporation of one metal over another not only improved the functionality, stability, and dispersibility but also reduced the consumption of expensive material. Furthermore, titanium dioxide is a promising, effective material and found numerous applications in the area of catalysis/photocatalysis. This work also reported the viable procedures to synthesize different shaped titanium dioxide like mesoporous TiO2, (001) faceted titania nanosheets and nanospheres which showed higher photocatalytic performance than commercially available titanium dioxide (P25). The conventional hydrogenation of different unsaturated organic compounds is usually carried out under harsh reaction conditions viz., the use of H2 under high pressure, high temperature and involving the use of different metal hydrides i.e. NaBH4, LiAlH4. In order to avoid the use of these explosives, high-cost and tedious reaction conditions, the metal-TiO2 catalyzed hydrogen transfer under light radiation is a promising alternative technique for the selective hydrogenation reactions. Here, it has been demonstrated that the spectral response and photocatalytic efficiency of titanium dioxide in solar or visible light can be improved by impregnating bimetallic nanostructures. Bimetallic Pd@Ni-TiO2, Cu@Zn-TiO2, and Pd@Au-TiO2 nanocomposites displayed superior catalytic activity for the selective hydrogenation of benzaldehyde, quinoline, and cinnamaldehyde respectively under light radiation. Hence, bimetallic-TiO2 is a promising catalyst for the selective hydrogenation of different challenging molecules and other industry-relevant compounds that work in an effective, simple, and greener way.