SYNTHESIS, CHARACTERIZATION OF DOPED METAL OXIDE NANOPARTICLES AND THEIR APPLICATIONS

Abstract

The work in this dissertation is focused on the synthesis of doped metal oxide nanoparticles. Different doped metal oxide nanoparticles have been synthesized and the doped metal oxide nanoparticles were characterized using various analytical techniques. The physical and chemical properties of the host materials drastically change due to doping. The change in optical and magnetic properties due to doping were studied and the doped metal oxide nanoparticles were explored for different applications. The dissertation deals with three different doped metal oxide nanoparticles. The copper doped zinc oxide nanoparticles were synthesized using solid state method with different dopant concentration. Various characterization techniques i.e. XRD, DRS for optical properties, FE-SEM and TEM for morphology, FTIR and EDX analysis were carried out to study the properties of doped metal oxide nanoparticles. The XRD patterns show as the concentration of dopant increases, phase separation occurs due to presence of copper oxide in the copper doped zinc oxide nanoparticles. The optical properties of the materials and the band gap of the doped samples were calculated using Tauc plots. The morphological studies of pure and doped metal oxide nanoparticles were studied and change in morphology occurs on going from pure to doped metal oxide nanoparticles. Pure ZnO shows rod like morphology and copper doped zinc oxide nanoparticles shows spherical morphology. The elemental composition of the prepared samples was evaluated using energy dispersive X-ray analysis. The copper doped zinc oxide nanoparticles were explored for catalytic reduction of 4-nitropheol and the samples exhibited good catalytic behavior towards reduction of 4-nitrophenol to 4-aminophenol. The iron doped titanium dioxide nanoparticles were synthesized using a novel thermal decomposition method. Various characterization techniques were used to characterize the doped metal oxide nanoparticles. The XRD results indicate that as the concentration of iron is increased change in phase from anatase to rutile is observed and α-Fe2O3 is also formed. The microscopy studies show that there is change in morphology in iron doped titanium dioxide nanoparticles from rod-like pure TiO2 nanoparticles into spherical morphology in iron doped TiO2 nanoparticles. The elemental composition of the prepared samples was evaluated using energy dispersive X-ray iii analysis. The iron doped TiO2 nanoparticles were explored for peroxidase-like activity. The doped samples show good catalytic activity towards peroxidase-like activity. Manganese doped tin oxide nanoparticles were synthesized by homogeneous precipitation method. Various characterization techniques were used to study the properties of the doped metal oxide nanoparticles. The XRD patterns of manganese doped tin oxide nanoparticles show no additional peaks or phase separation. The optical properties of manganese doped tin oxide nanoparticles were studied and the band gap of the doped samples were evaluated using Tauc plots and a reduction in band gap was observed in Mn2+ doped SnO2 nanoparticles. The microscopy techniques show that there is no change in morphology in the doped metal oxide nanoparticles. The magnetic properties of pure and doped SnO2 nanoparticles were studied using SQUID at 300 K and 5K. At 300 K, the pure and doped samples exhibit diamagnetic behavior and at 5 K, the pure and doped samples exhibit paramagnetic and weak ferromagnetic behavior.