Papers by Author: Rajesh J. Tayade

Abstract: Ta₂O₅, Ta₂O₅–SrO and Ta₂O₅–TiO₂ photocatalysts were prepared by hydrothermal method and characterized using X-ray diffraction (XRD), Ultraviolet-visible Diffuse Reflectance spectroscopy (UV-Vis DRS) and Thermogravimetry (TGA). In synthesized series of TiO₂-Ta₂O₅ catalysts, formation of anatase TiO₂, hexagonal Ta₂O₅ and titanium tantalates were observed. For Ta₂O₅-SrO (Ta:Sr= 1:1) formation of mixed oxide and crystallinity was observed at calcinations temperature at 1100 °C (5hr). These synthesized catalysts were used for degradation study of methylene blue. The result demonstrated that the photocatalytic activity of the mixed oxides [Ta₂O₅-TiO₂(1:1), Ta₂O₅-TiO₂(2:1), Ta₂O₅-TiO₂(1:2), Ta₂O₅-SrO (Ta:Sr= 1:1)] was higher than that of Ta₂O₅ alone.

Abstract: Anatase TiO₂ nanotubes (ATNT) was synthesised by hydrothermal method using anatase TiO₂ nanoparticles (AT) as precursor and calcined at two different temperatures (250 & 450 °C) for 2 h. The AT and synthesized ATNT photocatalysts were characterized by X-ray diffraction, transmission electron microscopy, N₂ adsorption-desorption measurements, UV-vis diffuse reflectance and Fourier Transform Infra-red spectroscopy techniques for their structural, textural and electronic properties. The photocatalytic degradation of Indigo carmine (IC) dye aqueous solution has carried out using ATNT-250 and ATNT-450 photocatalysts under UVLED irradiation. The kinetic analysis has also revealed that the degradation of IC dye solution follows first order kinetic model. The overall study demonstrates the appropriate band gap of the photocatalysts used and the suitable irradiation source which could accelerate the rate of photocatalytic degradation. The band gap of the synthesised ATNT is not much affected due to the change in morphology from nanoparticle to nanotube. The results demonstrated that the irradiation of UV-LED could be utilised for the degradation of organic dyes

Abstract: Mg_xMn_1-xFe₂O₄ (x = 0.0, 0.2, 0.4, 0.5, 0.6 0.8 and 1.0) spinel ferrite system was synthesized by the chemical co-precipitation route. Subsequent characterization of synthesized Mg-Mn ferrites was carried out by X-ray powder diffraction and transmission electron microscopy to study the structural and textural properties of photocatalysts. Porosity, surface area and equivalent surface free energy of different Mg-Mn ferrite photocatalysts were calculated. The photocatalytic activity of synthesized photocatalysts was evaluated by degradation of nitrobenzene in aqueous medium under ultraviolet light irradiation. The results demonstrated that the percentage degradation of nitrobenzene was decreased with increase in Mg concentration (x) from x = 0.0 0.5 and further increase in concentration from x = 0.6 1.0 results increase in percentage degradation of NB. This dissimilarity in the percentage degradation of NB may be due to the change in grain morphology, optical energy band gap, role played by d-electrons and porosity as a function of Mg-substitution for Mn²⁺ in the system. The percentage degradation was further confirmed by chemical oxygen demand (COD) analysis.

Abstract: Titanium dioxide (Titania; TiO₂) is one of the most widely used metal oxide semiconductor in the field of photocatalysis for removal of pollutants. It has been noted that titanium dioxide is a research friendly material as its physico-chemical and catalytic properties can be easily altered as per specific application. Since many years, researchers have tried to modify the properties of titanium dioxide by means of doping with metals and non-metals to improve its performance for photocatalytic degradation (PCD) applications. The doping of various metal ions like Ag, Ni, Co, Au, Cu, V, Ru, Fe, La, Pt, Cr, Ce, etc. in titanium dioxide have been found to be influencing the band gap, surface area, particle size, thermal property, etc. and therefore the photocatalytic activity in PCD. Moreover, photocatalytic activity of doped titanium dioxide has been observed in visible light range (i.e., at wavelength >400 nm). In this review, different synthesis route for doping of metal ions in titanium dioxide have been emphasised. The effect of metal dopant on the structural, textural and photocatalytic properties of titanium dioxide has been reviewed.

Abstract: Present work describes the synthesis of nanocrystalline TiO₂ photocatalyst using sol-gel and solution combustion methods and their characterisation by powder X-ray Diffraction, Diffuse Reflectance Spectroscopy, surface area measurement, FT-IR, FT-Raman, Thermo Gravimetric Analysis, and Transmission Electron Microscopy. Their photocatalytic activity was evaluated by the degradation of two nitro aromatic pollutants, viz. para-nitroaniline (PNA) & meta-dinitrobenzoic acid (DNBA) commonly observed in nitroaromatic plants. Performance of the synthesized catalysts was compared with commercial Degussa P25 sample. The photocatalytic degradation and total mineralization were monitored using UV/VIS spectrophotometer and total organic carbon content analysis respectively. The materials properties such as crystallinity and surface hydroxyl group on the nanocrystalline TiO₂ played crucial role for the total mineralization of the nitroaromatics.

Abstract: TiO2 derived nanotubes were prepared by hydrothermal treatment of TiO2 (anatase) powder in 10 M NaOH aqueous solution. The crystalline structure, band gap, and morphology of the TiO2 nanotubes were determined by X-ray diffraction (XRD), diffuse reflectance spectroscopy (DRS), scanning electron microscopy (SEM), Transmission Electron microscopy (TEM) and N2 adsorption (BET) at 77 K, respectively. It was observed that the surface area of the nanotubes was increased twelve times compared with TiO2 (anatase) powder. The results demonstrated that the photocatalytic activity of TiO2 nanotubes was higher than that of TiO2 (anatase) powder. The photocatalytic activity of the nanotubes was evaluated in presence of sunlight by degradation of aqueous nitrobenzene. Complete degradation of nitrobenzene was obtained in 4 hours using TiO2 nanotubes whereas 85% degradation was observed in case of TiO2 (anatase).