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In the present study, MWCNTs were synthesized through CVD method, employing CH4 as carbon source over Co-Mo/MgO nanocatalyst at a temperature of 1000 °C and then treated by two methods. First by KOH activation (A-MWCNTs), with a weight ratio of KOH: MWCNTs = 3:1 at 900 °C in He atmosphere and second treated by H2SO4: HNO3 = 3:1 (F-MWCNTs). MWCNT samples were characterized by FE-SEM, TEM, XRD, FT-IR, BET and Raman spectroscopy. The adsorption of H2 gas was performed using volumetric method. Various parameters on adsorption of H2 including surface defects, surface areas, pore characteristics and functional groups have been investigated. Furthermore, it was found that the hydrogen adsorption of P-MWCNTs, A-MWCNTs and F-MWCNTs were 0.67, 1.24 and 0.40 wt%, respectively at room temperature (298 K) while the pressure varied from 0 to 34 bar. The results indicated a considerable rise in the H2 adsorption capacity of A-MWCNTs (85%), due possibly to the high surface area and enhanced micro-pore volume and the defects formed on the surface sites of MWCNTs by KOH activation. In this case, hydrogen molecules adsorption on the defective cavities could have a significant role through van der walls forces. Therefore, it can be concluded that KOH-modified MWCNTs is one of the most significant ways of developing the textural characteristic and improving hydrogen storage properly.

Al-doped ZnO (AZO), as one of the most promising transparent conducting oxide (TCO) materials, has now been widely utilized in thin film solar cells. In this research the optimization process of AZO thin films deposited by plasma focus device was carried out by investigation of its physical properties under different deposition conditions for its utilize as a front contact for the Cadmium Telluride (CdTe) based thin film solar cell applications. The effects of number of focus shots and angular position of substrate on the microstructure, surface morphology and photoluminescence properties of the thin films have been systematically studied. X-ray diffraction (XRD) study confirmed the polycrystalline nature of the all deposited AZO thin films. XRD analysis also revealed that crystal structure characteristics of obtained samples strongly depend on deposition conditions (number of shots and angular position). Scanning electron microscopy (SEM) and atomic force microscopy (AFM) analyses revealed the structure growth and enhancement of surface roughness, with increasing of focus shots or decreasing of angular position. From Photoluminescence (PL) emission spectra, the variations of structural defects and band gap energy for all the AZO thin films prepared under different deposition conditions were also discussed.

ZnO is one of the most promising transparent conducting oxide materials, which widely used in thin film gas sensors. In this research, the dependence of the thermal oxidation time on structural, morphological and gas sensing properties of ZnO thin films is investigated. ZnO nanostructures are synthesized by using DC magnetron sputtering for deposition of pure zinc layers on glass substrates and then thermal oxidation of deposited zinc layers to produce zinc oxide (ZnO) thin films. Obtained results from X-ray diffraction revealed that the degree of crystallinity and the average grain size of the ZnO deposited thin films enhance with increasing the thermal oxidation time. Surface topography and growth behavior of ZnO thin films have important role in optimization of gas sensing properties of these films. In this study, scanning electron microscopy and atomic force microscopy have been used to investigate the effective parameters related to the surface topography of the films. Obtained results from these analyzes revealed that the surface topography of ZnO deposited samples strongly depend on thermal oxidation time. Also the effect of thermal oxidation time on the performance of ZnO gas sensors is investigated. The results indicated that the ethanol gas sensing properties of ZnO samples improve with decreasing the size of grains.