Informatics Publishing Limited

Abstract

Objectives: In this study, pure and cobalt doped ZnO nanoparticles are synthesized by simple solution method and doping effect of cobalt on the optical properties ZnO nanoparticles is studied at room temperature to enhance the optical properties by varying the electrons of appropriate concentration. Methods: Synthesis of ZnO nanoparticles was achieved by the simple and effective solution method using zinc nitrate tetra hydrate and cobalt nitrate tetra hydrate.  The defects and impurities were investigated by Fourier transform infrared spectroscopy. Findings: The FTIR spectrum shows the characteristics peak of ZnO at 490 cm^-1. In cobalt doping ZnO nanoparticles, the entire peak transmittance % got quenched. Together these results identified the impurities which exist near ZnO surface. No other peak was not observed in the spectra confirms that final products is ZnO nanoparticles. we measured the absorption spectra  for pure and cobalt doped ZnO nanoparticles to study the effect of  doping concentration of cobalt on the absorption of ZnO, After being doped with Co, the absorption peaks shifted towards longer wavelength region from 358 nm to 372nm. Band gap for Co doped ZnO nanoparticles are found to be between 3.28–3.05 eV range. This is due to the increase in particle size that results the less quantum confinement within the nanoparticles. Applications: Zinc Oxide semiconductor material is applied to many applications like solar cells, transparent electrode, transducer, and laser diodes due to its enhanced optical properties by doping transition materials.

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Objectives: To fabricate the electro chemical; super capacitors by one step controllable redox deposition method for coating manganese oxide onto the surface of a graphite cylindrical electrode. The purpose of this investigation is to employ manganese oxide as the electrode material along with a grahite electrode due to its low cost, environmental benignity and excellent capacitive performance in aqueous electrolytes. Manganese oxide is a material very attractive for its availability, low cost and non polluting effects compared to ruthenium oxide.Methods:  The sample is prepared by the immersion technique by varying the immersion time of the graphite electrode with analytical grade Potassium permanganate, Sulphuric acid, Hydrochloric acid and Acetone as precursor sources. Double distilled water was used throughout the experiment. Epoxy resin was used to give the insulating coating for the graphite rod to make a graphite electrode.Statistical analysis : The energy dispersive X-ray analysis revealed the ratio oxygen, manganese and carbon present in the sample. The morphology of the manganese oxide coating on the graphite electrode was examined using scanning electron microscope. Cyclic voltammograms, and chronopotentiometric charge-discharge analysis were taken. Findings: The cyclic voltammograms of the manganese oxide coated graphite electrode shows that its operational stability is high. The chronopotentiometric charge-discharge curves demonstrate high electrochemical reversibility and good stability. Scanning electron microscope  results shows that the agglomeration of particles is not seen much. The observed spherical particles are between 220 and 415 nm in diameter.Applications: The most effective and practical technologies for electrochemical energy conversion and storage are batteries, fuel cells, and electrochemical supercapacitors (ES). In recent years, ES have attracted significant attention, mainly due to their high power density, long life cycle, and bridging function for the power and energy gap between traditional dielectric capacitors (which have high power output) and batteries and fuel cells.

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