Papers by Keyword: Metal Oxide

Abstract: This document describes the technology of manufacturing metal oxide films ZnO, SnO₂, Zn₂SnO₄ from aqueous solutions of the corresponding salts by spray pyrolysis. The modes and conditions of deposition of metal oxide films on hot (420 °C) glass substrates are given. The electrical parameters of the films were measured by the van der Pau method and by the Hall effect, the surface resistance was in the range from 140 to 85⋅10³ Ohm/. The band gap was determined by light absorption spectra and was within 3.2...3.5 eV. For all metal oxides, the n-type conductivity was determined using the thermosonde and the Hall effect.

Abstract: Results of scientific researches in the field of creation of self-adhesive radiation shielding materials on the basis of polymers are presented in this article. It is stated, that radiation shielding coverings on the basis of ethylene propylene rubber are more preferable than coverings on the basis of BSR and SBS. Materials on the basis of ethylene propylene rubber possess high hardness at scaling from metal (more than 600 N/m) and hardness at breakoff from concrete (more than 0,1 MPa), have a high linear absorption coefficient.

Abstract: The use of thin films in optoelectronic and photovoltaic devices is aimed at improving the physical properties of the substrate material. The modification of the surface of the silicon substrate is thus one of the greatest challenges in research on photovoltaic materials, in order to achieve even greater efficiency or better adapt their properties depending on the application. The technologies of applying layers vary depending on the effect to be obtained and the material from which the layer is formed. In practice, the most common method is chemical vapor deposition and physical vapor deposition, and the most commonly applied optical materials are SiO₂, TiO₂ and Si₃N₄.This paper presents the results of investigations on morphology and optical properties of the prepared aluminium oxide thin films. Thin films were prepared with use of sol-gel spin coating method. Surface morphology studies were carried out using an atomic force microscope. To characterize the surface of the thin films, 3D images and histograms of the frequency of individual inequalities were made. In order to characterize the optical properties of Al₂O₃ thin films, the reflectance and light transmission tests were performed using a spectrophotometer. Optical constants were determined using a spectroscopic ellipsometer. Results and their analysis show that the sol-gel method allows the deposition of homogenous thin films of Al₂O₃ with the desired geometric characteristics and good optical properties. Uniform, continuous thin layers with a roughness not exceeding a few nanometres were deposited. Their deposition enabled to reduce the reflection of light from the polished substrate below 15% in a wide range (425-800nm) while maintaining high transparencies (over 90%). The obtained results causes that mentioned thin films are good potential material for optics, optoelectronics and photovoltaics.

Abstract: Metal oxides are widely used as components in photovoltaic cells such as transparent conducting front electrodes or electron-transport layers, while only few metal oxides have been used as light absorbers. In this study, cuprous oxide was modified by anchoring TSCuPc dye molecules via potentiostatic electrodeposition approach. Fourier Transform Infrared Spectroscopy results display the different vibration peaks for S=O bond and C-N present in the TSCuPc modified Cu₂O deposits signifying the attachment of TSCuPc on Cu₂O. The highest absorbance peaks of Cu₂O and TSCuPc at approximately 420 nm and 650 nm respectively was observed when 20uM of TSCuPc was added in the electrodeposition solution. Scanning Electron Microscopy reveals the formation of Cu₂O film and formation of secondary submicron size structures with the addition of TSCuPc. The surface morphology of the secondary structures changes as the concentration TSCuPc increases. With the aforementioned results, it was verified that TSCuPc can be anchored to Cu₂O via electrochemical route which could pave way in developing materials with high absorption in visible light applicable for optoelectronic devices.

Abstract: One of the great challenges facing the society today is replacing fossil fuels by renewable energy sources. Hydrogen from non-carbon sources is considered one of the viable potentials to help alleviate reliance upon fossil fuels for energy and addressing the environmental problems. Photoelectrochemical water splitting was brought to attention since the pioneering work in 1972. Since then, numerous metal oxide photocatalysts have been investigated to enhance the overall water splitting performance. Up to now, Bismuth vanadate, BiVO₄ has emerged as the most promising photocatalyst in the construction of photoelectrochemical cell utilizing sunlight and water, the most abundant resources on earth. In this review, the principles, critical factors influencing the efficient BiVO₄-based photoanode properties such as the crystal and electronic properties are discussed. Subsequently, the methods synthesis and research efforts adopted to develop efficient and active BiVO₄ photoanode are presented.

Abstract: Super capacitor, as a new type of power storage device, has been applied to various fields. This paper divides composite electrode materials of super capacitor into three main types. For each type, this paper analyses its performance, advantages and prospect. At last, a conclusion is drawn that it is a tendency to apply composite electrode materials to use for better performance capacitors.

Abstract: Developing an environmentally friendly and high-quality of fuel from vegetable oil (triglycerides) have attracted a great attention among the researches. Deoxygenation reaction using Ca-based catalyst is a potentially promising element for removing an oxygen species from organic compounds and converting the molecule to hydrocarbon. Addition of transition metal in the catalysis synthesis studies not only could enhance the properties of the catalyst but also could tune the selectivity toward desired product. Cooperation of mesoporous support such as silica alumina (SA) exhibit unique and excellent properties (high surface area, high porosity) which simultaneously could increase the catalyst activity. In the present studies, a set of bifunctional acid-base supported on the highly mesoporous SA doped with Ca and Ni were synthesized. The Ca (NO)₃ and Ni (NO)₃ were impregnated on the mesoporous SA support and were calcined at 500 °C for 2 h in order to activate the synthesized catalyst. The physicochemical properties of the catalyst were characterized by X-Ray fluorescence spectroscopy (XRF), X-Ray diffraction spectroscopy (XRD), temperature programme desorption carbon dioxide (TPD-CO₂) and temperature programme desorption ammonia (TPD-NH₃) and scanning electron microscopy (SEM).

Abstract: We have reviewed humidity sensors based on the Zinc oxide (ZnO) humidity sensor. There are only a few papers reviewing on the ZnO humidity sensor. The characteristics, structures, advantages, and fabrication methods of ZnO have been studied to understand the suitability of the ZnO to be applied at different kind of condition such as for extreme environment, low level humidity detection, and very high humidity level circumstances. The electrical and physical properties of ZnO humidity sensors such as sensitivity, response time, stability, uniformity, and crystallinity have also been discussed in this review. ZnO nanostructures have been widely used for humidity sensors because of its’ good stability, high sensitivity for humidity-sensing, low cost, and has a wide band gap. Sol-gel preparation method is commonly used to for ZnO humidity sensor fabrication since it can produce a film with high uniformity, simple process and low cost. Keywords: Humidity Sensor, Metal Oxide, Semiconducting Type, Ceramic Type, Humidity-Sensing, Band Gap, Sol-Gel Preparation Method.

Abstract: We have reviewed humidity sensors based on the Zinc oxide (ZnO) humidity sensor. There are only a few papers reviewing on the ZnO humidity sensor. The characteristics, structures, advantages, and fabrication methods of ZnO have been studied to understand the suitability of the ZnO to be applied at different kind of condition such as for extreme environment, low level humidity detection, and very high humidity level circumstances. The electrical and physical properties of ZnO humidity sensors such as sensitivity, response time, stability, uniformity, and crystallinity have also been discussed in this review. ZnO nanostructures have been widely used for humidity sensors because of its’ good stability, high sensitivity for humidity-sensing, low cost, and has a wide band gap. Sol-gel preparation method is commonly used to for ZnO humidity sensor fabrication since it can produce a film with high uniformity, simple process and low cost. Keywords: Humidity Sensor, Metal Oxide, Semiconducting Type, Ceramic Type, Humidity-Sensing, Band Gap, Sol-Gel Preparation Method.

Abstract: The effects of calcination temperature on the microstructures and photocatalytic activity of sol-gel synthesized TiO₂, WO₃, SnO₂ and ZnO metal oxides were investigated. The synergistic effect of the phase structure, surface area, and crystallinity of the photocatalysts after calcination and on the photocatalytic activity was investigated. 1,2-dichlorobenzene (DCB) was used as a model contaminant in this study. The highest photocatalytic activity was obtained using TiO₂ calcined at 900oC with large particle size, could be ascribed to the enhancement by the presence of defect site. Similarly, WO₃ calcined at 900oC exhibited the best photocatalytic activity in the series of calcination temperature ranging from 400-1000oC. SnO₂ calcined at 800oC showed the best photocatalytic activity while ZnO was found to give the lowest percent of DCB degradation. In this study, sudden increase in the surface area at higher temperature was correlated with the enhancement in the photocatalytic activity of each catalyst.