▎ 摘　　要

Green synthesis of multifunctional metal oxide nanoparticles and its composites are widely evaluated for their efficacy in environmental and biomedical applications. In this study, green synthesized nickel oxide nanoparticles (NiO-NPs) using Tribulus terrestris extract were anchored on graphene oxide nanosheets (GO) to obtained nickel oxide -graphene oxide composite (GO-NiO). Further, morphological and physiochemical characterization using X-ray diffraction, RAMAN, FTIR, FESEM, TEM, EDS and XPS revealed incorporation of NiO on GO. UV-Vis spectroscopy analysis suggested a decrease in band gap, which is favourable for photo catalysis and fiber optic gas sensing applications. Consequently, the synthesised GO-NiO nanocomposites displayed substantial response towards photo catalysis of rhodamine B. In addition, room temperature Ethanol gas sensing activity was found to be increased due to the synergistic effect of graphene oxide, which acts as an elastic conductive channel facilitating better charge transport and more favourable ionic diffusion. Moreover, GO-NiO showed an elevated anticancer response compared to NiO against Human renal cell carcinoma cell line (ACHN) as well as Human Tongue Squamous Carcinoma Cell Line (HSC-3). In brief, GO-NiO is a promising multifunctional composite for environmental and biomedical applications.