Papers by Keyword: Doped TiO₂

Abstract: Titanium dioxide (TiO₂) has been acknowledged as a promising photocatalyst in environmental remediation including wastewater treatment. In this study, TiO₂ nanoparticles co-doped with iron (Fe) and nitrogen (N) was synthesized via sol-gel method and subsequently followed by calcination process at 300 °C, 500 °C and 700 °C for 3 hours. The prime objective of this study is to investigate an effect of different calcination temperatures in enhancing the photocatalytic activity of synthesized TiO2 which was evaluated through the degradation of methyl orange (MO) dye. The structure and properties of the prepared samples were studied by X-Ray Diffraction (XRD), Energy Dispersive X-Ray Spectroscopy (EDX), Field Emission-Scanning Electron Microscope (FE-SEM) and Ultraviolet-Visible Spectrophotometer (UV-Vis). The results obtained from XRD showed the presence of anatase phase in all samples at 300 °C and 500 °C. Further increase of calcination temperature up to 700 °C, mixed-phase of anatase and rutile formed. XRD results also suggest that the addition of impurities has a great effect on the crystallinity and particle size of TiO₂. The obvious agglomeration phenomena existed in the annealed samples with nanometer size, as observed in FESEM images. The photocatalytic performance under UV light shows that co-doped Fe, N-TiO2 at 500 °C indicated highest MO degraded of 96.5 % within 3 hours of irradiation time. From the current finding, Fe,N-TiO₂ possessed the potential to be commercialized as a photocatalyst in wastewater remediation especially in treating dye pollution.

Abstract: TiO₂ is one of the most promising photocatalysts that is widely used for environmental clean-up due to its ability to degrade organic pollutants in air or water. The purpose of this study is to enhance the photocatalytic activity of TiO₂ by absorbing energy in visible light region in order to degrade pollutants. In this study, the nanostructured Fe-TiO₂ was successfully synthesised via a combined method of sol-gel and calcination process. The calcination temperatures used varied from 400 to 800 °C. The as-prepared samples were characterized by X-ray diffraction (XRD), FESEM and UV-Vis spectroscopy (UV-Vis). XRD results show that the phases of TiO₂ are dependent on calcination temperature. It is found that both TiO₂ and Fe-TiO₂ phases were transformed from anatase to rutile as the temperatures were increased. FESEM images revealed that the particle size was agglomerated and the average grain size was about 54 to 66 nm. UV-Vis analysis indicated that the incorporation of Fe and varied calcination temperature may affect the optical properties as the absorption profile was shifted from 445 nm to 585 nm. Thus, this results show that Fe-TiO₂ is a highly potential photocatalyst to degrade pollutants under visible light irradiation.

Abstract: Developing new semiconductor materials with improved photocatalytic activity is a promising technology for the remedy of environmental pollution. Here we report on the synthesis of Yb containing TiO2 nanoparticles and their catalytic activity under visible light. Highly monodispersed, spherical TiO2 and TiO2 :Yb nanoparticles of 27- 40 nm size range were prepared through controlled hydrolysis of titanium tetrabutoxide (TTB) and characterized by X-ray diffraction (XRD), energy dispersion spectroscopy (EDS), high-resolution transmission electron microscopy (HRTEM), high angle annular dark field (HAADF), and ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS) techniques. Average size of the nanoparticles was found to decrease with the increase of Yb doping concentration. The photocatalytic activity of Yb doped TiO2 was evaluated by measuring the degradation rates of methylene blue (MB) under UV and visible lights. Doping with ytterbium ions enhanced significantly the photocatalytic activity of TiO2 nanoparticles for MB oxidation under visible light.