Graphene - Metal Tungstate Nanocomposites for Catalytic Applications

Abstract

The research thesis entitled ‘Graphene - Metal Tungstate Nanocomposites for Catalytic Applications’ deals with the synthesis, characterization and studies on catalytic properties of some graphene - metal tungstate nanocomposites. The work describes successful synthesis of five different kinds of novel graphene-metal tungstate based nanocomposites namely, NRGO/ZnWO4/Fe3O4, NRGO/NiWO4/ZnO, NRGO/CoWO4/Fe2O3, NRGO/FeWO4/Fe3O4 and NRGO/BaWO4/g-C3N4 using facile microwave irradiation method. All the synthesized nanocomposites were carefully characterized for their elemental composition, structural, morphological and optical properties by employing appropriate techniques such as, XRD, SEM, FESEM, TEM, HRTEM, BET, XPS, DRS, Raman, FTIR, UVVis and PL spectroscopies. Thereafter, each nanocomposite was investigated for its catalytic efficiency towards, (i) The photodegradation of methylene blue dye under the visible light irradiation, (ii) The reduction of 4-Nitrophenol to 4-Aminophenol by sodium borohydride in aqueous media and (iii) The electrocatalytic hydrogen evolution reaction in alkaline media. The synthesized nanocomposites exhibit high catalytic activity due to the synergistic effects of the components of the nanocomposite materials. The reusability of the catalysts in all the above processes is also good. Therefore, the observed results suggest that these novel graphene - transition metal tungstate based ternary nanocomposites are potential candidates as multifunctional catalysts in the field of clean energy and environmental applications.