• Title/Summary/Keyword: chemical oxide

Search Result 3,475, Processing Time 0.037 seconds

Nickel Oxide Nano-Flake Films Synthesized by Chemical Bath Deposition for Electrochemical Capacitors (CBD(Chemical Bath Deposition) 법으로 제조된 전기화학식 캐패시터용 NiO 나노박편 필름)

  • Kim, Young-Ha;Park, Soo-Jin
    • 한국신재생에너지학회:학술대회논문집
    • /
    • 2010.06a
    • /
    • pp.163.2-163.2
    • /
    • 2010
  • In this work, nano-flake shaped nickel oxide (NiO) films were synthesized by chemical bath deposition technique for electrochemical capacitors. The deposition was carried out for 1 and 2 h at room temperature using nickel foam as the substrate and the current collector. The structure and morphology of prepared NiO film were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). And, electrochemical properties were characterized by cyclic voltammetry, galvanostatic charge-discharge, and AC impedence measurement. It was found that the NiO film was constructed by many interconnected NiO nano-flakes which arranged vertically to the substrate, forming a net-like structure with large pores. The open macropores may facilitate the electrolyte penetration and ion migration, resulted in the utilization of nickel oxide due to the increased surface area for electrochemical reactions. Furthermore, it was found that the deposition onto nickel foam as substrate and curent collector led to decrease of the ion transfer resistance so that its specific capacitance of a NiO film had high value than NiO nano flake powder.

  • PDF

Pyro-Electrochemical Reduction of a Mixture of Rare Earth Oxides and NiO in LiCl molten Salt (LiCl 용융염에서 NiO를 혼합한 희토류 산화물의 파이로 전해환원 특성)

  • Lee, Min-Woo;Jeong, Sang Mun
    • Korean Chemical Engineering Research
    • /
    • v.55 no.3
    • /
    • pp.379-384
    • /
    • 2017
  • An electrochemical reduction of a mixture of NiO and rare earth oxides has been conducted to increase the reduction degree of rare earth oxides. Cyclic voltammetry (CV) measurement was carried out to determine the electrochemical reduction behavior of the mixed oxide in molten LiCl medium. Constant voltage electrolysis was performed with various supplied charges to understand the mechanism of electrochemical reduction of the mixed oxide as a working electrode. After completion of the electrochemical reduction, crystal structure of the reaction intermediates was characterized by using an X-ray diffraction method. The results clearly demonstrate that the rare earth oxide was converted to RE-Ni intermetallics via co-reduction with NiO.

Thermodynamic Calculations on the Chemical Behavior of SrO During Electrolytic Oxide Reduction

  • Jeon, Min Ku;Kim, Sung-Wook;Lee, Sang-Kwon;Choi, Eun-Young
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
    • /
    • v.18 no.3
    • /
    • pp.415-420
    • /
    • 2020
  • Strontium is known as a salt-soluble element during the electrolytic oxide reduction (EOR) process. The chemical behavior of SrO during EOR was investigated via thermodynamic calculations to provide quantitative data on the chemical status of Sr. To achieve this, thermodynamic calculations were conducted using HSC chemistry software for various EOR conditions. It was revealed that SrO reacts with LiCl salt to produce SrCl2, even in the presence of Li2O, and that the ratio of SrCl2 depends on the initial concentration of Li2O dissolved in LiCl. It was found that SrO reacts with Li to produce Sr during EOR and that the reduced Sr reacts with LiCl salt to produce SrCl2. As a result, the proportions of metallic forms were lower in Sr than in La and Nd under various EOR conditions. The thermodynamic calculations indicated that the three chemical forms of SrO, SrCl2, and Sr co-exist in the EOR system under an equilibrium with Li, Li2O, and LiCl.

The Photodegradation Effect of Organic Dye for Metal Oxide (Cr2O3, MgO and V2O3) Treated CNT/TiO2 Composites

  • Chen, Ming-Liang;Bae, Jang-Soon;Yoon, Hee-Seung;Lim, Chang-Sung;Oh, Won-Chun
    • Bulletin of the Korean Chemical Society
    • /
    • v.32 no.3
    • /
    • pp.815-820
    • /
    • 2011
  • Three kinds of organometallic compounds (chromium acetylacetonate, magnesium acetate and vanadyl acetylacetonate) were used as transition metal precursor, titanium n-butoxide and multi-walled carbon nanotube as titanium and carbon precursor to prepare metal oxide-CNT/$TiO^2$ composites. The surface properties and morphology of metal oxide-CNT/$TiO^2$ composites were by Brauer-Emett-Teller (BET) surface area measurement, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and energy dispersive X-ray (EDX) analysis. The photocatalytic activity of prepared metal oxide-CNT/$TiO^2$ composites was determined by the degradation effect of methylene blue in an aqueous solution under irradiation of visible light.

Electrochemical Property of the Composite Electrode with Graphene Balls and Graphene Oxide for Supercapacitor (슈퍼커패시터용 그래핀볼 - 그래핀옥사이드 복합전극의 전기화학적 특성)

  • Jeong, Woo-Jun;Oh, Ye-Chan;Kim, Sang-Ho
    • Journal of Surface Science and Engineering
    • /
    • v.53 no.5
    • /
    • pp.213-218
    • /
    • 2020
  • Composite material of the graphene ball (GB) inserted graphene oxide (GO) sheet for a supercapacitor electrode was studied. Chemical vapor deposition (CVD) process used to make GBs on the silicon oxide nanoparticles. The GBs mixed into the GO sheets to make GOGB and reduced it to create a reduced GOGB(RGOGB) composite. The RGOGB composite electrode had a large surface area and improved electrochemical properties. Specific capacitance of the RGBGO composite electrode was higher over 20 times than a pure GO and GOGB electrode in cyclic voltammetry(CV) tests, and the Z' and Z" impedance measured by an electrochemical impedance spectrometry(EIS) also low. So, the RGBGO composite electrode would use effectively to expand a performance of supercapacitor.

Effects of Metal Anion Complexes in Electrolyte on the Properties of Anodic Oxide Films on ADC12 Al Alloy

  • Yoo, Hyeonseok;Lee, Chulho;Oh, Kiseok;Choi, Jinsub
    • Journal of Surface Science and Engineering
    • /
    • v.49 no.2
    • /
    • pp.130-134
    • /
    • 2016
  • The anodization of ADC12 aluminum alloy was investigated in the metal anionic acid media. Anodic oxide films containing foreign elements were formed on ADC12 Al alloy by anodization in the anion complex solution. Furthermore, the rough surface and cracks were considerably smoothened by the deposit of metal anions. When the size of metal anion was small, relatively large amount of metal anions was loaded in anodic films. Existence of $MoO_3$, $TiO_2$ and MgO was confirmed by XPS. According to the results of Tafel analysis, Mo oxide represented the most noble anti-corrosion potential due to $MoS_2$ formation. Corrosion current densities were generally higher than that of pristine anodic oxide without anion complexes.

Integration of Graphene Oxide Into PAN Nanofibers with Improved Physical Property (Graphene Oxide를 활용한 PAN 나노섬유 제조 및 물리적 특성 향상)

  • Lee, Jeonghun;Yun, Jaehan;Byun, Hongsik
    • Membrane Journal
    • /
    • v.27 no.3
    • /
    • pp.255-262
    • /
    • 2017
  • In this study, systematic integration of graphene oxide (GO) into polyacrylonitrile (PAN) nanofibers was accomplished by electrospinning to examine their mechanical properties. Exfoliated GO was initially prepared by the modified Hummer's method, and the surface of the GO was modified with an organic surfactant (e.g., cetyltrimetylammonium chloride) to improve its stability and dispersity. The overall mechanical property of the nanofiber composite membranes was highly improved. Particularly, the composite membranes with the modified GO exhibited much improved mechanical property, presumably due to the increased stability and dispersity of GO during electrospinning.

Spectroscopic and Morphological Investigation of Copper Oxide Thin Films Prepared by Magnetron Sputtering at Various Oxygen Ratios

  • Park, Ju-Yun;Lim, Kyoung-A;Ramsier, Rex D.;Kang, Yong-Cheol
    • Bulletin of the Korean Chemical Society
    • /
    • v.32 no.9
    • /
    • pp.3395-3399
    • /
    • 2011
  • Copper oxide thin films were synthesized by reactive radio frequency magnetron sputtering at different oxygen gas ratios. The chemical and physical properties of the thin films were investigated by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray diffraction (XRD). XPS results revealed that the dominant oxidation states of Cu were $Cu^0$ and $Cu^+$ at 0% oxygen ratio. When the oxygen ratios increased above 5%, Cu was oxidized as CuO as detected by X-ray induced Auger electron spectroscopy and the $Cu(OH)_2$ phase was confirmed independent of the oxygen ratio. The valence band maxima were $1.19{\pm}0.09$ eV and an increase in the density of states was confirmed after formation of CuO. The thickness and roughness of copper oxide thin films decreased with increasing oxygen ratio. The crystallinity of the copper oxide films changed from cubic Cu through cubic $Cu_2O$ to monoclinic CuO with mean crystallite sizes of 8.8 nm (Cu) and 16.9 nm (CuO) at the 10% oxygen ratio level.

A Study on Energy Band Change and Stability in Photoelectrolysis by Use of Titanium Oxide Films on Ti-Bi Alloy (Ti-Bi 합금 위에 형성된 산화티타늄 피막의 광 전기분해시 에너지밴드와 안정성에 관한 연구)

  • Park, Seong-Yong;Cho, Byung-Won;Yun, Kyung-Suk
    • Journal of Hydrogen and New Energy
    • /
    • v.5 no.1
    • /
    • pp.41-49
    • /
    • 1994
  • Ti-Bi alloy was prepared by arc melting of appropriate amounts of titanium and bismuth powder. The photocurrent($I_{ph}$) of Ti-Bi oxide electrode was increased with the increase of Bi content, up to 10wt%. The maximum $I_{ph}$ showed $7.6mA/cm^2$ at V=0.5V vs. SCE. The band gap energy of Ti-Bi oxide electrode was observed to 3.0~2.87eV. Surface barrier($V_s$) of Ti-10Bi oxide electrode showed maximum value(1.08V) but didn't exceed 1.23V, then it was impossible to run $H_2$ generation without any other energy sources other than the light. Ti-Bi oxide electrode was found to be quite stable under alkaline solution and showed no signs of photodecomposition.

  • PDF

A Study on Characterization and Modeling of Shallow Trench Isolation in Oxide Chemical Mechanical Polishing

  • Kim, Sang-Yong;Chung, Hun-Sang
    • Transactions on Electrical and Electronic Materials
    • /
    • v.2 no.3
    • /
    • pp.24-27
    • /
    • 2001
  • The end point of oxide chemical mechanical polishing (CMP) have determined by polishing time calculated from removal rate and target thickness of oxide. This study is about control of oxide removal amounts on the shallow trench isolation (STI) patterned wafers using removal rate and thickness of blanket (non-patterned) wafers. At first, it was investigated the removal properties of PETEOS blanket wafers, and then it was compared with the removal properties and the planarization (step height) as a function of polishing time of the specific STI patterned wafers. We found that there is a relationship between the oxide removal amounts of blanket and patterned wafers. We analyzed this relationship, and the post CMP thickness of patterned wafers could be controlled by removal rate and removal target thickness of blanket wafers. As the result of correlation analysis, we confirmed that there was the strong correlation between patterned and blanket wafer (correlation factor: 0.7109). So, we could confirm the repeatability as applying for STI CMP process from the obtained linear formula. As the result of repeatability test, the differences of calculated polishing time and actual polishing time was about 3.48 seconds. If this time is converted into the thickness, then it is from 104 $\AA$ to 167 $\AA$. It is possible to be ignored because process margin is about 1800 $\AA$.

  • PDF