Layer-by-Layer Cathodic Deposition of Ni/Ni(OH)2 Particles on Steel Gauze Electrode for High-Performance Supercapacitor Application

Layer-by-layer of Ni/Ni(OH)2 particles were deposited on Steel Gauze (SG) electrode via cathodic electrodeposition. The system with two electrodes was selected for electrodeposition in the galvanostatic condition. Electrodeposition of the first layer of Nickel was conducted in the electrochemical cell with an SG substrate as a cathode. This electrode was fixed between two parallel graphite anodes and electrodeposition was performed from a mixture of NiCl2, NH4Cl, NaCl solution. Electrodeposition of the second layer of Ni(OH)2 on the Ni layer which has been formed in the first step, was carried out in the same way from a solution containing Ni(NO3)2. TG, XRD and SEM techniques were used for the characterization of the prepared SG/Ni/Ni(OH)2 electrode. The prepared SG/Ni/Ni(OH)2 electrode was analyzed by electrochemical techniques such as Cyclic Voltammetry (CV), galvanostatic charge–discharge and Electrochemical Impedance Spectroscopy (EIS). The SG/Ni/Ni(OH)2 electrode demonstrated high specific capacity (1308 C g−1 at the scan rate of 5 mV s−1) and excellent cycling ability (8.9% capacity decay at the current density of 50 A g−1 after 1000 cycle).

Surface Characteristics of Ti/IrO2 Anode Material and its Electrocatalytic Properties for Polycyclic Aromatic Hydrocarbons (PAHs) Degradation in Aqueous Solution

In this study, electrochemical degradation of 16 priority PAHs was examined using Ti/IrO2 anode. Iridium dioxide (IrO2) was coated by thermal decomposition of appropriate precursor solution on surface of titanium plate. Surface morphology of coated surface was observed by FESEM and XRD analysis. All electrochemical experiments were conducted using synthetic solution of PAHs in a batch cell under galvanostatic condition. GC-MS was used to quantify PAHs concentration. Electrochemical oxidation results reveal significant degradation of PAHs at Ti/IrO2 surface. Total PAHs removal was about 97 % at all studied initial pH values 3, 6 and 9 in the presence of electrolyte. Crystalline surface of Ti/IrO2 anode exhibited good electrocatalytic properties towards PAHs degradation.

Electrolytic Coloring of Anodized Aluminum by Copper

It is important to generate aluminum oxide layer on the surface of aluminum in order to enhance the adhesion of the dye molecules in coloring aluminum industry. One of the major advantages of aluminum is the formation of a resistant oxide layer naturally, but the thickness of this layer is not high enough and it should be damaged due to lack of mechanical strength. However, the thickness of oxide layer can be increased through anodizing; this process improves its abrasion and corrosion resistance as well as its mechanical properties. In the present study, specimens of pure aluminum were anodized under galvanostatic condition in sulfuric acid electrolyte and porous nanostructured aluminum oxide layer was formed. Porosity of the anodized layer was controlled by optimizing the working conditions such as electrolyte concentration, anodizing time and current density. Finally, the specimens were electrolytically colored by applying alternating current to copper (Cu) solutions. Colored coatings were created at constant voltage and different coloring duration. The results indicated that the shade of different metal ions can be optimized by controlling the coloring parameters, the longer time of coloring results in the darker colors. The samples were examined by X-Ray Diffraction (XRD) spectroscopy and Scanning Electron Microscopy (SEM) and electrochemical test.

STRUCTURE AND MORPHOLOGICAL STUDIES OF CdSe NANOCRYSTALS

Nanocrystalline thin films of CdSe have been synthesized from an acidic solution containing CdSO 4 and SeO 2 by a cathodic electrodeposition technique under galvanostatic condition. The crystal structure and morphology have been investigated by Grazing angle X-Ray Diffraction (GXRD), Transmission Electron Microscopy (TEM) and optical microscopic measurement. The X-Ray and TEM diffraction patterns of the deposit reveal a bimodal size distribution with the presence of cubic (zinc blende) phase in the deposit. The particle sizes have been estimated from GXRD measurement found to be 4 nm to 6 nm, comparable to that obtained from TEM analysis. A Branched Fractal Pattern (BFP) in CdSe nanocrystals has been observed by optical microscopy, suggesting a diffusion-limited aggregation growth mechanism with fractal dimension 1.69 ± 0.04.