Metal and metal oxide decorated graphene for gas sensing and electronic applications

Abstract

The aim of this thesis is to study the hybrids of metal/metal oxide nanoparticles for the development of nanomaterials based efficient sensors. Herein, we have first prepared graphene oxide by employing improved Hummer s method and then reduced it using green chemistry methods such as reduction with plant extracts and with microwaves exposure/treatment. The conventional reduction methods involved treatment with highly hazardous chemicals like hydrazine hydrate, sodium borohydride, lithium based compounds etc. Traditional methods of GO reduction using chemical reagents like hydrazine hydrate induce health hazards. In turn, ZnO-rGO, SnO2-rGO, Au-rGO nanohybrids were prepared. The nanohybrids combine the extraordinary properties of graphene and metal/metal oxide nanoparticles. Various characterization techniques like X-ray diffraction, UV Visible spectroscopy, Fourier transformed infrared spectroscopy, field emission scanning electron microscopy (FESEM), transmission electron microscopy and Raman spectroscopy techniques were employed to examine GO, rGO and their hybrids with nanoparticles. Investigation of the surface morphology displayed the dense loading of nanoparticles on graphene sheets. Optoelectronic responses of the samples were measured in dark and under ultraviolet light at room temperature. The sensitivity values were 1.91 for ZnO-rGO, 4.37 for SnO2-rGO and 1.5 for Au-rGO respectively. The main goal of this study was to synergize the photosensitive characteristics of ZnO-rGO, SnO2-rGO and Au-rGO nanohybrid films on PET substrates. The suggested method might result in the development of highly sensitive flexible light detectors. Further, we have also studied the nanohybrids for efficient sensing of H2/NO2/CO gases.