http://ir.haramaya.edu.et//hru/handle/123456789/224 Wed, 15 Apr 2026 19:38:52 GMT 2026-04-15T19:38:52Z http://ir.haramaya.edu.et//hru/handle/123456789/478 SYNTHESIS AND CHARACTERIZATION OF COPPER OXIDE NANOPARTICLES USING PRECIPITATION METHOD hunde keneni, Amenu; tandon, U. S. Major Advisor (Prof.) Preparation and properties of CuO nanoparticles as an important p-type semiconductor via a simple precipitation method at different reaction temperatures: 300 0C, 400 0C and 600 0C using copper sulphate and sodium hydroxide as a starting material have been reported. In addition, we investigated the influence of the temperature through synthesizing the nanosized CuO. Results indicated that size and band gap of samples had great dependence on the temperature. The crystallite size and crystallization increased with increasing the temperature, but band gap decreased. The band gap of samples was estimated to be in the range of 3.69–4.28 eV that is larger than the reported value for the bulk CuO (1.85 eV). This study provides a simple method for the preparation of nanosized CuO with a better surface uniformity and a narrow size distribution. Samples were characterized by XRD, and UV-Vis techniques. 39 Mon, 01 Apr 2019 00:00:00 GMT http://ir.haramaya.edu.et//hru/handle/123456789/478 2019-04-01T00:00:00Z http://ir.haramaya.edu.et//hru/handle/123456789/1225 Cu2O/ZnO/Ag3PO4TERNARY OXIDE NANOCOMPOSITE: SYNTHESIS, CHARACTERIZATION AND OPTOELECTRONIC PROPERTIES. lemma, Tadesse; taddesse, Abi Major Advisor Dr; goro, Girma Co Advisor Dr In this work, a nanoparticle of pure ZnO and heterostructures of Cu2O/ZnO, Ag3PO4/ZnO and Cu2O/ZnO/Ag3PO4with different ratios of precursor salts were prepared by simple precipitation method. Modern characterization instruments such as X-ray diffractometer (XRD), UV-Vis spectroscopy, Spectro fluorophotometerandBrunauer–Emmett–Teller(BET) were used to characterize the synthesized powders. Crystal sizes of all the prepared powders were examined using XRD. The average crystal size of the prepared powders was calculated based upon the intense peak, using the DubyeScherrer equation. The BET method was used to analyze the surface area of the prepared powders. Based on BET and XRD results, Cu2O/ZnO/Ag3PO4with metal ratio of (15:70:15) was selected among ternary nanocomposites for further characterization. UV- Vis spectroscopy was employed to estimate band gap energies of prepared powders. The room temperature Spectro fluorophotometer was used to measure the optical emissions from the synthesized powders as electrons return to the ground state. The result shows that the emission intensity of Cu2O/ZnO/Ag3PO4 is smaller than ZnO, Cu2O/ZnO and Ag3PO4/ZnO, which indicates that the electron hole recombination rate in the ternary nanocomposite is less than that of a pure nanoparticle and binary nanocomposite. In general, the nanocomposite semiconductor have better absorption in visible region than the pure/single nanoparticle. Therefore, the heterojunctions of three semiconductor are better for optical device application in visible light region 52 Tue, 01 Aug 2017 00:00:00 GMT http://ir.haramaya.edu.et//hru/handle/123456789/1225 2017-08-01T00:00:00Z http://ir.haramaya.edu.et//hru/handle/123456789/1318 SYNTHESIS OF SILVER NANOPARTICLES USING BACTERIAL AND FUNGAL REDUCTION METHODS AND ANALYTICAL EVALUATION OF THEIR PHYSICAL AND ANTIMICROBIAL CHARACTERISTICS habte wollamo, Tizazu; tandon, U.S. (Prof.); Kebede, Ameha Co Advisor (PhD); adgo, Abebaw Co Advisor (PhD) Nanoparticles (NPs) have been steadily interesting in Physics, Chemistry, Biology, Biomedicine, etc. In this thesis work, green synthesis of silver nanoparticles by the fungal and bacterial method was investigated. Two different concentrations of AgNO3 viz. 10mM and 1mM were used as precursors, whereas cell- free supernatants from A. niger and E. coli were prepared and used as source of enzyme for the reduction and stabilization of nanoparticles. The crude enzyme was produced by A. niger, using Solid State Fermentation (SSF). The medium used for the fermentation contained wheat bran as the growth substrate and was incubated at 29 ± 1ºC for five days. Whereas for enzyme production by E. coli, Luria Bertani (LB) medium was used and it was incubated at 37 ± 1 ºC overnight. The culture for the growth of A. niger was filtered by muslin cloth and centrifuged at 12000 rpm for 20 min and the filtrate was used as source of crude enzyme for the synthesis of Ag NPs as well as for characterization. Similarly, the E. coli culture was first filtered by Millipore filter paper followed by centrifugation of the supernatant at 12000 rpm for 20 min. Visual indication of the synthesis of silver nanoparticles was obtained when the color of supernatant plus the precursor changed from yellow to orange for E. coli and from light brown to dark brown for A. niger. The characterization of the synthesized Ag NPs as well as the supernatants obtained from E. coli and A. niger were done using UV-Vis absorption spectroscopy to confirm the formation of silver nanoparticles. The UV- Vis absorption peak for Ag NPs synthesized by E. coli was seen around 416nm; whereas, the UV-Vis peak for Ag NPs synthesized by A. niger appeared around 425nm. The next characterization of the synthesized silver nanoparticle was done by Fourier Transform Infrared spectroscopy (FTIR), which was used to reveal the functional groups accompanying the synthesized NPs. Finally the antimicrobial activity of the synthesized silver nanoparticles was tested against three gram negative and two gram positive bacteria by disc diffusion method. Extracellular crude extracts obtained from both microbes did not show any antibacterial effect on the tested pathogens. However, all the four kinds of Ag NPs synthesized by both species exhibited antibacterial effect. The Ag NPs showed stronger antibacterial activities on gram positive bacteria than on gram negative bacteria. The results also indicated that a larger value of ZOI was produced for the Ag NPs synthesized at the lowest concentration (1mM) of the precursor AgNO3 used for the synthesis of Ag NPs. 64 Sat, 01 Oct 2016 00:00:00 GMT http://ir.haramaya.edu.et//hru/handle/123456789/1318 2016-10-01T00:00:00Z http://ir.haramaya.edu.et//hru/handle/123456789/1490 SYNTHESIS AND CHARACTERIZATION OF TIO2 NANOPARTICLES AND ITS BAND GAP ENERGY ESTIMATION gadisa hika, Edosa; Tandon, U.S. Major Advisor (Prof.) Nanocrystalline semiconductor metal oxides have achieved a great importance in our industrial world today. They may be defined as metal oxides with crystal size between 1 and 100 nm. TiO2 nanosized particles have attracted significant interest of materials scientists and physicists due to their special properties and have attained a great importance in several technological applications such as photocatalysis, sensors, solar cells and memory devices. The objective of the project is to undertake synthesis and characterization of TiO2 nanoparticles and its band gap estimation. In this paper TiO2 nanoparticles were synthesized by sol-gel method using TiCl4 solution added in deionized water in ice bath under fume hood followed by the addition of ethanol with vigorous stirring for 30 min at room temperature. A drop wise of ammonium hydroxide (NH4OH) was added and stirred vigorously, then settled for 12 hrs and washed with distilled water. The gel solution was obtained and then got dried using oven at 200oC for 4 hours. Then, the dried gel was calcined at 4000C using furnace for 2 hours. Finally, TiO2 nanopowder was obtained. The characterization of particles was carried out by SEM and UV-Vis spectroscope techniques. Spongy like shape and small size of the sample was detected from diameter indicated by SEM image and UV-vis spectroscopy, which shows the wavelength of the synthesized nanoparticle at maximum absorbance is equal to ~376nm. Then the energy band gap of the synthesis nanoparticle TiO2 was estimated from this value of wavelength and is equal to~3.3ev. 48 Fri, 01 May 2015 00:00:00 GMT http://ir.haramaya.edu.et//hru/handle/123456789/1490 2015-05-01T00:00:00Z