Mechanochemical synthesis of nanocrystalline SnO2 ZnO photocatalysts (original) (raw)
Related papers
Physicochemical and Photocatalytic Investigations of Mechanochemically Treated TIO2-ZNO Composites
Materials Methods Technologies, 2014
The nanodimensional TiO 2-ZnO composites in different weight ratios 1:1; 1:2 and 2:1 were prepared by mechanochemical activation. As starting materials were used ZnO synthesized by precipitation and commercial TiO 2. The phase composition and structure of obtained mechanochemically activated nanosized TiO 2-ZnO samples were confirmed by X-ray diffraction analysis and Fourier transform infrared spectroscopy. The produced materials were examined as catalysts for degradation of Reactive Black 5 dye under UV light. The results show the relation between photocatalytic activity of prepared samples TiO 2-ZnO and stoichiometric ratio of TiO 2 and ZnO in the mixture. The rate constants of dye degradation increase as follows TiO 2-ZnO (1:2) (2.16х10-2 min-1) < TiO 2-ZnO (2:1) (2.45х10-2 min-1) < TiO 2-ZnO (1:1) (2.60х10-2 min-1).
Increasing the Photocatalytic Activity by Mechano-chemically Milling on Zn-Doped TiO 2
This paper pursed one new cost effective strategy to improve the photocatalytic activity of the sol-gel developed Zn doped TiO 2 by mechano-chemically milling in high energy planetary mill. The results showed that the photocatlytic activity was improved two times due to the increase of the surface area and the decrease in average crystallite size at the same time after using the high energy ball milling. Kubelka-Munk spectra of pristine and ball milled samples revealed a blue shift from 3.2 eV to 3.35 eV, which may be because of the presence of quantum size effects. SEM microstructural investigations revealed variations in the surface morphology with different Zn doping concentrations in the TiO 2-Xwt.% Zn nanoparticulates. EDS spectra of these samples confirmed the stoichiometric concentration of Zn. Other characterization including X-ray diffraction (XRD), BET surface and the photocatalytic decomposition were also studied and the results were in agreement with each other.
TiO2-ZnO Binary Oxide Systems: Comprehensive Characterization and Tests of Photocatalytic Activity
Materials
A series of TiO 2-ZnO binary oxide systems with various molar ratios of TiO 2 and ZnO were prepared using a sol-gel method. The influence of the molar ratio and temperature of calcination on the particle sizes, morphology, crystalline structure, surface composition, porous structure parameters, and thermal stability of the final hybrids was investigated. Additionally, to confirm the presence of characteristic surface groups of the material, Fourier transform infrared spectroscopy was applied. It was found that the crystalline structure, porous structure parameters, and thermal stability were determined by the molar ratio of TiO 2 to ZnO and the calcination process for the most part. A key element of the study was an evaluation of the photocatalytic activity of the TiO 2-ZnO hybrids with respect to the decomposition of C.I. Basic Blue 9, C.I. Basic Red 1, and C.I. Basic Violet 10 dyes. It was found that the TiO 2-ZnO material obtained with a molar ratio of TiO 2 :ZnO = 9:1 and calcined at 600 • C demonstrates high photocatalytic activity in the degradation of the three organic dyes when compared with pristine TiO 2. Moreover, an attempt was made to describe equilibrium aspects by applying the Langmuir-Hinsherlwood equation.
The Journal of …, 2001
The multiwall carbon nanotubes (MWCNTs)/titanium dioxide (P25) composite in different ratios was prepared using simple evaporation and drying process. The composite was characterized by Raman spectroscopy, X-ray diffraction (XRD), UV-visible diffuse reflectance spectroscopy, and scanning electron microscopy (SEM). The photocatalytic activity of this composite was investigated using degradation of the Bismarck brown R dye (BBR). An optimal MWCNTs/TiO 2 ratio of 0.5% (w/w) was found to achieve the maximum rate of BBR degradation. It was observed that the composite exhibits enhanced photocatalytic activity compared with TiO 2 . The enhancement in photocatalytic activity performance of the MWCNTs/P25 composite is explained in terms of recombination of photogenerated electron-hole pairs. In addition, MWCNTs act as a dispersing support to control the morphology of TiO 2 particles in the MWCNTs/TiO 2 composite.
Materials Research
This paper describes the development of TiO 2 and ZnO particles by a chemical route, using two different wet synthesis methods: polymeric precursor (PP) and sol-gel (SG). This study aimed to shed a light on how the synthesis method affects the photocatalytic activity of these oxides. Rhodamine B (RhB) degradation was used as a probe reaction to test the as-synthesized TiO 2 and ZnO photoactivity. It was observed that surface availability, which is related to the presence of synthesis residue, is the key parameter to determine photoactivity. ZnO PP and ZnO SG presented degradation of 88% to RhB. Both samples presented synthesis residue on the surface. On the other hand, TiO 2 PP presented a better performance than TiO 2 SG, once 90% of RhB was degraded, while TiO 2 SG degraded 80% of the dye. In this case, TiO 2 PP was free of synthesis residue on the surface, while TiO 2 SG presented residues.
Catalysis Today, 2019
In this work, ZnO-TiO 2 nanomaterials with various ZnO/(ZnO + TiO 2) weight ratios (0.1-0.9) were synthesized by using sol-gel and precipitation methods The influence of the ZnO weight ratio (R) and the preparation method on the structural, optical, morphological and photocatalytic properties of the prepared nanomaterials has been studied. The obtained physicochemical characterization results indicated that the crystalline structure, the morphological and the optical properties of the ZnO-TiO 2 nanomaterials are strongly influenced by the preparation method as well as the ZnO weight ratio. The results of the photocatalytic degradation of Methyl Orange (MO) in the presence of the synthesized photocatalysts and UV-A light irradiation showed the existence of two domains of ZnO weight ratio. The first is between 0.2 and 0.5 in which the ZnO-TiO 2 nanomaterials prepared by sol-gel method exhibited the lowest MO conversion values in comparison with those prepared by precipitation method. These low MO conversion values were due to the intervention of a combination of various parameters that are the particles' agglomeration, the poor crystallinity and the high E g values. The second corresponds to R ≥ 0.67 in which the sol-gel method leads to the fabrication of ZnO-TiO 2 materials with better photocatalytic efficiencies. The kinetic study showed that the Zn(Pr)-Ti-0.1 sample exhibited the best final MO conversion (99.5%) with the highest apparent rate constant value (0.01763 mn −1).
Journal of Photochemistry and Photobiology A: Chemistry, 2012
In the present work, the TiO 2 films doped with 0-0.6 at.% Gd were deposited by DC reactive magnetron sputtering and annealed in ambient air at 1273 K. The effects of Gd concentration on crystal phase formation and subsequent changes in optical and photocatalytic properties were determined. Photoluminescence (PL) spectra and their correlation with electronic structure were described. Structural studies revealed that Gd doping in the TiO 2 lattice led to a low anatase thermal stability relative to pure TiO 2 . A study based on a joint use of PL and XPS analyses showed the enhancement of oxygen vacancy concentration in the Gd-doped TiO 2 films. Photocatalytic activity was dependent on Gd doping and phase structure. A suitable amount of Gd doping (0.3-0.4 at.%) was favorable to the creation of abundant oxygen vacancies, so that the films could show an improvement in photocatalytic activity. After annealing, the photocatalytic activity of the films decreased with the increase of Gd content, due to the occurrence of the rutile phase.
Enhanced Photocatalytic Activity of TiO2/SnO2 Binary Nanocomposites
Journal of Nanomaterials
The paper presents the results of characterization and study of adsorption-photocatalytic properties of commercial and synthesized-by-hydrothermal method TiO2 and TiO2-SnO2 nanocomposites. Hydrothermal synthesis of TiO2-based nanocomposites was performed in two ways: single-stage and two-stage methods. Characterization was carried out by XRD, X-ray fluorescence method, XPS, EPR, PL, and low-temperature adsorption-desorption of nitrogen, which showed that TiO2-SnO2 nanostructured composites were obtained with tin(IV) oxide content of 10 wt.% and had acidic surface and different porous structures. Besides, modification of a commercial sample with tin(IV) oxide led to a slight decrease in the specific surface area, while modification of a synthesized-by-hydrothermal method TiO2 sample led to an increase. It was found that sorption properties of the obtained nanocomposites and pure TiO2 are better towards anionic dyes. Photocatalytic activity, on the contrary, is higher towards cationic...
Materials, 2021
The main goal of the study was the hydrothermal-assisted synthesis of TiO2-ZnO systems and their subsequent use in photoactive processes. Additionally, an important objective was to propose a method for synthesizing TiO2-ZnO systems enabling the control of crystallinity and morphology through epitaxial growth of ZnO nanowires. Based on the results of X-ray diffraction analysis, in the case of materials containing a small addition of ZnO (≥5 wt.%), no crystalline phase of wurtzite was observed, proving that a high amount of modified titanium dioxide can inhibit the crystallization of ZnO. The transmission electron microscopy (TEM) results confirmed the formation of ZnO nanowires for systems containing ≥ 5% ZnO. Moreover, for the synthesized systems, there were no significant changes in the band gap energy. One of the primary purposes of this study was to test the TiO2-ZnO system in the photodegradation process of 4-chlorophenol using low-power UV-LED lamps. The results of photo-oxida...