Papers by Keyword: SnO₂

Abstract: This article presents the elaboration of tin oxide (SnO₂) thin films on glass substrates by spray pyrolysis technique. Our interest is on the investigation of Effect solution concentration on the structural, optical and morphological properties of the films. Structural analysis by X-ray diffraction showed that the deposited films are polycrystalline in nature with a tetragonal structure having a preferential orientation along with (1 1 0) plane. SEM micrograph proved the existence of small cracks on the film surface, EDS confirmed the composition percentage ratio of Sn and O₂ and no trace of impurities could be detected. The spectrophotometer UV-Visible confirms that it is possible to get good transparent SnO₂ films with a transmission of 80 to 90% in the visible. The values of optical band gaps vary between 3.6 and 4.0 eV depending on the spraying solution concentration.

Abstract: This research studied the preparation of titanium dioxide (TiO₂) composite films with the incorporation of tin oxide and reduced graphene oxide (SnO₂-RGO) for uses as photoanodes in dye-sensitized solar cells (DSSCs). The experimental procedure started with the synthesis of graphene oxide by Hummer's method, followed by the preparation of SnO₂-RGO composite materials by hydrothermal process. The resultant SnO₂-RGO was sequentially mixed with TiO₂ to prepare the composite films by doctor-blade method. The results indicated that the addition of graphene oxide into SnO₂ could reduce the band gap, avoid the agglomeration, and improve the dispersion of tin oxide particles (SnO₂). According to the efficiency tests of the obtained photoanodes, a small amount of RGO could significantly affect the DSSC’s performance. Without RGO, TiO₂-SnO₂ photoanodes exhibited very poor performance. This could be due to low dye-adsorption capability and low electron transfer ability. The addition of excess amount of RGO in photoanode could, however, lead to negative effects such as charge trapping and lower solar cell efficiency.

Abstract: Graphene-Tin Oxide (G-SnO₂) nanocomposites in different morphology were synthesized using tin (II) chloride (SnCl₂) and graphene Oxide (GO) via hydrothermal process in the presence of hydrazine and ammonia by adding surfactant for 12 hours in a teflon autoclave at 100oC reaction temperature. Poly (vinyl prolidon) (PVP) and poly (ethylene glycol) (PEG) were used as nonionic surfactants while hexadecyl trimethyl ammonium bromide (CTAB) and sodium dodecyl sulfonate (SDS) were utilized as cationic and anionic surfactants, respectively. The synthesized nanocomposites were characterized by XRD, FESEM, C-TEM and FT-IR. The gas sensing properties of the obtained samples to the vapors of various Volatile Organic Compounds (VOC), such as Ethanol, Methanol, Chloroform, Toluene and Acetone were also investigated at room temperature. The prepared G-SnO₂ nanocomposites exhibited high detection performances for ethanol, chloroform and methanol. The nanocomposites could be used as sensor material for VOC gases.

Abstract: A series of experiments is made to produce silica, mixing with tin dioxide (SnO₂), and characterizing for application of waveguide device. Silica xerogels (SX) are prepared from raw materials derived from rice husks ash (RHA), which abundant in South East Sulawesi. The synthesis conditions have been optimized to obtain the ash of rice husks with the maximum silica content. SnO₂ are prepared from a commercial powder. The ceramic waveguide materials are produced by mixing SX and SnO₂ with various composition. The mixtures are molded to form the rectangular shape of 20 mm, 40 mm, and 5 mm in size. The samples will be sintered at different level of temperatures (from 300°C to 1200°C) by using microwave heating system as well as electric furnace. The microstructural of sintered samples were characterized on the basis of the experimental data obtained using densification measurement method (Archimedes method), crystallization (X-ray diffraction, XRD), microstructure (Scanning electron microscope, SEM). Optical and related properties such as the functional groups, structure, and absoption were characterized by using FTIR, Infrared and Raman Spectroscopy and absorption (UVVis). The permittivity and permeability will be calculated from S-parameters determined by using Vector Network Analyzer (VNA). Characterization results are presented in this paper and the others are will be published in another separated papers. Furthermore, the relationship between properties with SnO₂ content and sintering temperature is also studied.

Abstract: To elaborate the effect of CeO₂ nanoparticles on the sensing properties of SnO₂, CeO₂-functionalized SnO₂ wire-in-tube nanofibers (WITN) was prepared by electrospinning and subsequently impregnating treatment. The gas sensing studies revealed that the CeO₂ loaded SnO₂ WITN exhibited enhanced sensitivity to ethanol compared to the pristine SnO₂. With increasing amount of CeO₂, the response of nanocomposites increases firstly and then decreases. And the response of nanocomposites to ethanol reach maximum when the concentration of impregnated Ce (NO₃)₃·6H₂O is 0.03 mol·L^-1. To detail the sensing mechanism, the X-ray photoelectron spectroscopy was firstly employed to detect the variation in oxygen species corresponding to different amounts of CeO₂, but no obviously changes in oxygen species was detected. Subsequently, it was found that the initial resistance of CeO₂@SnO₂ WITN was higher than pristine SnO₂, which could be beneficial to the improvement of sensing properties. More importantly, oxygen vacancy (mainly offered by CeO₂ nanoparticles) was proved to be positively correlated to their gas-sensing performance. In this work, the electronic sensitization mechanism based on CeO₂ loaded SnO₂ was detailed, which could help for the better understanding the sensitization effect of rare earth element on semiconductor oxides.

Abstract: The addition of certain co-solvents to the hydrothermal synthesis starting solution can greatly alter morphology and enhance different morphology dependent properties of the synthesized material. While ethanol is the most common co-solvent used for the synthesis of various SnO₂ nano/microstructures by hydro/solvothermal process, it is not clear how the use of some other alcoholic co-solvents (for example, methanol or isopropanol) affect morphology and properties of SnO₂, especially if synthesis is done under similar conditions as in the case of ethanol co-solvent. In the present study, we investigated how the use of various alcoholic co-solvents (methanol, ethanol, 2-propanol, ethylene glycol and glycerol) affects crystal structure, morphology and specific surface area of the hydrothermally synthesized SnO₂. Additionally, sensitivity towards 100 ppm ethanol of the synthesized materials was tested. The formation of nanoparticles, rod-cluster structures and spherical SnO₂ structures were observed depending on the alcoholic co-solvent used. The highest sensitivity (~22 at 250 °C) showed the material that was synthesized in the presence of ethanol co-solvent.

Abstract: SnO₂-TiO₂/zeolite Y composites were prepared by the impregnation of tin chloride and tetrabutyl titanate solution with zeolite Y and subsequent calcination at 500. SnO₂-TiO₂ heterostructures coated on zeolite Y is ascertained by X-ray diffraction, high-resolution transmission electron microscopy and UV-vis diffuse reflectance spectra characterization. The photocatalytic studies suggested that the SnO₂-TiO₂/zeolite Y showed enhanced photocatalytic efficiency of photodegradation of methyl orange compared with TiO₂/ zeolite Y and SnO₂/zeolite Y under UV light irradiation.

Abstract: Pure SnO₂ and Pt doped SnO₂ (0≤Pt≤10wt.%) ceramics have been successfully fabricated in the form of pellet by sintering at 1000 °C for 3 h. The resistance of the samples in air and in reducing gases (200 ppm H₂ and 200 ppm CO) was determined by measuring current – voltage (I-V) characteristics via two-probe method between 150 to 450 °C. All samples show a decrease in resistance with an increase in temperature both in air and in gases. However, the values of resistance in gases are lower compared when the same samples were in air, due to gas molecules reactions with surface oxygen species which affect potential barrier to decrease and causes resistance to reduce. The resistance of the doped samples also increased by 279 - 1226% with an increase in Pt doping in SnO₂, due to Pt surface states density.

Abstract: SnO₂/CNT nanocomposites were synthesized via microwave-assisted process using SnCl₄·5H₂O as a starting precursor and UV-treated multi-wall carbon nanotubes (MWCNTs) as scaffolds. The concentration of SnCl₄ was varied in the range of 0.01-0.05 M. Effect of precursor concentration on their physical properties and micro structural morphology were investigated by X-ray diffraction (XRD) and scanning electron microscope (SEM). XRD results indicate that the as-synthesized composites are the mixture of two separated phases including SnO₂ and MWCNT. SEM images indicate that the surfaces of MWCNT are thoroughly covered with SnO₂ nanoparticles. Comparative gas sensing result reveals that the prepared hybrid SnO₂/MWCNT composites exhibit much higher sensing sensitivity and recovery property in detecting alcohol gas at room temperature than the bare SnO₂.

Abstract: In this report it is being discussed approaches for designing the SnO₂ and In₂O₃ ozone sensors based on the film parameters optimization. It was considered the influence of the conditions of the SnO₂ and In₂O₃ films deposition by spray pyrolysis method and the parameters of those films on operating characteristics of ozone sensors. Main factors, controlling operating characteristics of thin film ozone sensors were determined. Recommendations to process of the SnO₂ and In₂O₃ films deposition, promoting an attainment of optimal operating gas sensing properties, were formulated.