Recent advance and prospectives of electrocatalysts based on transition metal selenides for efficient water splitting

Fabrication of transition metal selenides and their applications in energy storage

Study of optical properties of thermally evaporated ZnSe thin films annealed at different pulsed laser powers

In this work, synthesis of nickel oxide (NiO) using nickel acetate as a starting material by sol–gel method and then deposited as collide on glass slides to form thin layers of NiO by spin-coating technique with high photo-catalytic activity using as self cleaning coating. These films of NiO were annealed at different temperature 450 °C, 550 °C. The structural, morphological, spectral and optical properties of prepared NiO thin films were measured by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), Ultraviolet spectroscopy (UV-visible) respectively. These results; it was shown that the crystallinity of NiO films evolves gradually as the temperature of the annealing films increases. Depended on the (SEM) and (AFM) result in the average grain size is a range of (15–30) nm. The films achieved a higher optical transparency of thin films synthesis it was annealing at 550 °C temperature. Finally, photo-catalytic test were studies by using potassium permanganate (KMnO4) as a model of pollutant with two methods for achieved the effect of annealing temperature of NiO thin films on the photo-catalytic test and effect the grain size and weight of NiO nanopowder for photo-degradation percentage under exposure to UV-Visible source irradiation.

Photocatalytic Activity of Nickel Oxide

Thermally evaporated zinc-cadmium selenide (CdxZn1-xSe) thin films with different Cd-concentration (0.0 ≤ x ≤ 1.0 ,  at%) have been prepared. The deposition process of films was controlled where the vacuum was fixed at ≈10−5 Pa, the film thickness at 7500 A, and the rate of deposition at ≈100 A/s. These prepared films have been annealed under vacuum at 500⁰C for 2-hrs. X-ray diffraction, XRD study confirmed the crystallinity nature of annealed CdxZn1-xSe films with a face-centered cubic structure, which is transformed into a hexagonal structure with increasing the cadmium. Energy-dispersive X-ray analysis shows that there is good consistency between the detected and selected element ratios. Scherrer, Williamson-Hall, Size-Strain plot, and Halder-Wagner methods were used to examine the crystallite size and microstrain using XRD peak-broadening analysis. According to the Williamson-Hall method the crystallite size increased from 14.70 nm to 31.30 nm and microstrain decreased from 14.19×10−3 to 7.29×10−3. The Cd-addition leads to improving the film crystallinity and reducing the crystal imperfections.

Comparative microstructural studies using different methods: Effect of Cd-addition on crystallography, microstructural properties, and crystal imperfections of annealed nano-structural thin CdxZn1-xSe films

Synthesis of thermally evaporated ZnSe thin film at room temperature

Texture of the nano-crystalline AlN thin films and the growth conditions in DC magnetron sputtering

In this work, the morphological transformation and band gap modulation of ZnO by Aluminum doping has been investigated. Pure ZnO and Aluminum doped Zinc oxide (Al:ZnO) nanostructure have been fabricated using hydrothermal method on the seed layer coated FTO substrates. The prepared samples were investigated with such analytical techniques as Raman spectroscopy, Field Emission scanning electron microscope (FESEM), Photoluminescence (PL) and spectrophotometer. Raman spectra revealed E2 (high) and E1 (low) vibrational modes for pure ZnO. However, a successive shift in E2 (high) mode towards higher wavenumbers has been observed by placing ZnO with different concentration of Aluminum nitrate nano-hydrate solution (0.1 mM, 0.2 mM and 0.3 mM) confirming the sequential Al incorporation in the ZnO nanostructure. SEM results show the morphological transformation from a typical hexagonal ZnO nano-wire to petal shaped nano-rods with the increase of Al concentration. The optical properties have been investigated using the photoluminescence (PL) and optical transmission. In the PL spectra, pure ZnO nanostructure has UV peak with higher intensity compared to the visible peak. However, the addition of Al in the ZnO causes enhanced emission in the visible region compared to the UV emission. The addition of Al in ZnO nanostructure also modifies the optical band gap of ZnO from 3.2 to 3.15 eV.

The role of Al doping on ZnO nanowire evolution and optical band gap tuning

The key to energy conversion and storage for supercapacitors is the development of easy-to-prepare electrode materials with high capacity performance. We have synthesized a series of nanocomposites based on copper oxide (CuO) and titanium dioxide (TiO2), symbolized as CuO/TiO2 with varying wt% Firstly, the current research uses a low-cost wet chemical method for high-performance asymmetric supercapacitor (ASC) ratios of CuO. Nanocomposites formation and morphological evaluations were confirmed via a series of characterization techniques, e.g., SEM, XRD, Raman, and XPS certified the highly crystalline nature and purity of the samples. The electrochemical properties were tested using the conventional three and two-electrode system that exhibited an excellent energy storage performance even at a low current of 1 A g−1. The TiO2-30 % CuO electrode had a greater specific capacitance of 553 F g−1 than pure CuO (226 F g−1) and TiO2 (115 F g−1) at the constant discharge current density of 1 A g−1. Moreover, an ASC was assembled by utilizing a TiO2-30 % CuO electrode and activated carbon (AC) as positive and negative electrodes respectively. The TiO2-30 % CuO//AC ASC delivered a high energy density of 34 Wh kg−1 at 800 W kg−1 and retained 18 Wh kg−1 when the specific power increased to 4800 W kg−1 at 1 A g−1. Our ASC exhibited excellent stability of 96 % retention after 10,000 cycles with superb rate capability at a wide voltage frame of 1.6 V. According to density functional theory calculations, CuO/TiO2 improved the material's electrical conductivity and electrochemical performance. The data suggested that the CuO/TiO2 nanocomposites, with optimum concentration of CuO, could be used as a good supercapacitor electrode material in the future. 

U. Aziz

Papers

Synthesis of thermally evaporated ZnSe thin film at room temperature

Texture of the nano-crystalline AlN thin films and the growth conditions in DC magnetron sputtering

The role of Al doping on ZnO nanowire evolution and optical band gap tuning

A new CuO/TiO2 nanocomposite: An emerging and high energy efficient electrode material for aqueous asymmetric supercapacitors

Structural and optical properties of Zn1−xNixTe thin films prepared by electron beam evaporation technique