Photocatalytic decolorization of Gentian Violet with Na-doped (SnO2 and ZnO)

Photocatalysis is a technique used for the purification and decolorization of water. In this work, the photocatalytic decolorization of aqueous solutions of Gentian Violet has been investigated. The photocatalysts used for the study are tin dioxide (SnO2) and zinc oxide (ZnO) doped with sodium and prepared by sol-gel process. Photocatalysts were synthesised by sol-gel process and characterized by several techniques such as X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Brunauer, Emmett and Teller (BET) method and UV-vis Spectroscopy. The results of photocatalytic activity of gentian violet degradation under ultraviolet irradiation, indicated that the synthesised photocatalyst exhibit good photocatalytic performance

Structural and optoelectronic properties of SnO2 thin films doped by group-1A elements

This paper presents the results of an experimental work devoted to the synthesis and the characterization of tin dioxide (SnO2 Þ thin layers doped with group-IA elements (Li, Na and K). The materials were synthesized by the sol–gel method and deposited by dip-coating, using tin (II) chloride dihydrate as a source of tin and absolute ethyl alcohol as solvent. Thin ¯lms prepared were characterized by several techniques including X-ray di®raction (XRD), scanning electron microscopy (SEM), infrared spectroscopy (IR), visible and ultraviolet spectroscopy and complex impedance method. The results obtained show that the materials kept their tetragonal rutile structure with preferred orientation of (101), whereas doping leads to a reduction of their energy band gap. The complex impedance analysis suggests that the di®erent processes occurring at the electrode interface are modeled by an electrical circuit not a®ected by the doping

Synthesis, characterization and photocatalytic properties of alkali metals doped tin dioxide

In order to improve the photocatalytic properties of tin dioxide, crystallized powders of SnO(2) photocatalysts doped by alkali metals (Li, Na and K) were synthesized by sol-gel process. The physical properties of these materials were characterized by X-ray diffraction, nitrogen adsorption-desorption, Scanning electron microscopy and Ultraviolet-visible diffuse reflection spectroscopy. The photocatalytic tests under UV radiation conducted on four aromatic compounds (phenol, paranitrophenol, pentachlorophenol and benzoic acid) showed that tin dioxide modified by sodium possesses good photocatalytic activity; The Li-doped SnO(2) is moderately active, while modification by potassium does not improve this activity. (C) 2011 Elsevier B.V. All rights reserved

Structural, optical and electrical properties of Ni-doped Co3O4 prepared via Sol-Gel technique

<div><p>In this article, Nickel doped Cobalt oxide thin films and powders have been prepared on glass substrates using sol gel based dip coating process in order to investigate their optical, structural and electrical properties. The Ni concentration was changed from 0 to 9 wt(%).The synthesized samples were characterised by Ultraviolete visible analysis, X-ray diffraction, Fourier transform infrared spectroscopy and Complex impedance spectroscopy to depict the optical, structural, vibrational and electrical properties. Our structural results show that the obtained samples were composed of (Co3O4) polycrystalline with spinel-type preferentially oriented in the (311) plane. Our optical results show that the films have high transparency over the visible region (85% for Co3O4 and ∼ 60-75% for all doped samples). The optical band gaps were found to be (Eg1 = 1.50 eV, Eg2 = 2.20 eV) and (Eg1 = 1.42 eV, Eg2 = 2.07 eV) for the case of (pure Co3O4 and 9% Ni-doped Co3O4) respectively. The complementary phase information is provided by FT-IR spectroscopy. FT-IR spectra confirms the presence of Co2+-O and Co3+-O vibrations in the spinel lattice. The Nyquist plots suggests that the equivalent circuit of our films is an parallel circuit RpCp. It was found that the resistance Rp decreases whereas the capacity Cp increases with increasing doping levels.</p></div

Visible Light Sensitive SnO2/ZnCo2O4 Material for the Photocatalytic Removal of Organic Pollutants in Water

In this study, pure ZnCo2O4 and SnO2/ZnCo2O4 mix photocatalysts have been synthesized by the sol-gel process with three different SnO2 loading percentages (10, 20, and 30 wt %). Their photocatalytic activities were assessed on the degradation of organic pollutants in water under visible illumination. The structural, morphological, and optical properties were analyzed by X-ray diffraction (XRD), scanning electron microscopy, energy-dispersive X-ray (EDX), Fourier transform infrared (FTIR), nitrogen adsorption-desorption isotherms, X-ray photoelectron spectroscopy (XPS), and UV&ndash;Visible diffuse reflectance measurements. The results have shown that the materials are composed of a crystalline ZnCo2O4 matrix with a decrease in crystallite size with the amount of SnO2. Weakly crystalline SnO2 is also observed for loaded samples. The specific surface area is modified with the loading ratio. The evaluation of the photoactivity of the samples under visible light for the degradation of p-nitrophenol has highlighted that all materials are highly photoactive under visible light thanks to heterojunction between the two oxides. An application test has been conducted on a dye, congo red, showing the same tendencies. An optimal amount of SnO2 loading is observed for the sample containing 20 wt % of SnO2. A comparison with commercial Evonik P25 showed that the materials developed in this work have five to six times better efficiency under visible light, leading to a promising photocatalyst material

Sol-gel preparation and characterisation of SnO2 powders employed as catalyst for phenol photodegradation

Crystallized pure SnO2 powders were prepared by the sol-gel process and were used as photocatalyst for the degradation of phenol under UV light at pH 6.5 and a temperature of 20°C. The physical properties of photocatalyst were characterized by X-ray diffraction, Scanning Electron Microscopy, nitrogen adsorption-desorption and Ultraviolet-visible diffuse reflectance spectroscopy. The influences of different operating variables such as the pH, the photocatalyst loading, the initial concentration of phenol, were studied to improve the efficiency of phenol degradation

Visible-light photo-activity of alkali metal doped ZnO

In order to utilize visible light more efficiently in the field of photocatalysis, Li, Na and K-doped ZnO nanoparticles were prepared using a sol–gel method. The obtained samples were characterized by BET surface area measurements, X-ray diffraction, scanning electron microscopy and UV–vis analysis. The photocatalytic activity of the photocatalysts was evaluated for the degradation of p-nitrophenol (p-NP) under visible light irradiation. It has been observed that these photocatalysts could be a promising photocatalyst for degradation of organic molecules as compared to transition metal doped ZnO under visible light. Li-doped ZnO is the most active photocatalyst and shows high photocatalytic activity for the degradation of p-nitrophenol (p-NP). The enhanced photocatalytic activity of Li-doped ZnO is mainly due to the electron trapping by lithium metal ions, small particle size, large surface area, and high surface roughness of the photocatalysts