Microwave Plasma Assisted Sol-gel Technique for Synthesis of TiO2 Nanoparticles: A Recent Study

Titanium dioxide (TiO2) nanoparticles have attracted the attention of research community due to their novel functionalities as compared to the bulk material. TiO2 is an excellent photocatalyst due to its high photosensitivity, nontoxicity, high refractive index, strong oxidizing ability, high stability, wide band gap and high resistance to photochemical. TiO2 is found in nature in polymorphs crystalline form, such as stable rutile, brookite and anatase. The main objective of this study was to investigate the influence of microwave (MW) plasma treatment on TiO2 nanoparticles synthesized using sol-gel method. TiO2 nanoparticles were obtained through sol-gel method at ambient temperature. The suspension was heated at 300°C for 2 h to evaporate the organic content. The obtained nanoparticles were placed in partially vacuumized chamber for MW plasma treatment. The plasma treatment is a promising technique for oxidation of nanomaterials. Both plasma treated and untreated samples were evaluated with X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV-Visible spectroscopy for crystallite size, crystal phases, band gap energy and surface morphology. The obtained results confirmed the existence of anatase and rutile phases of TiO2 with smaller particle size within the range of 0.2-14 nm. The particles were of aggregated and trigonal shapes. The MW Plasma treatment improved the photocatalytic activity of TiO2 nanoparticles by raising their band gap energy and reducing the grain size.