• Title/Summary/Keyword: Oxide anodes

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Review on Proton Exchange Membranes for Microbial Fuel Cell Application (미생물 연료 전지 적용을 위한 양성자 교환막에 대한 검토)

  • Kim, Ji Min;Patel, Rajkumar
    • Membrane Journal
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    • v.30 no.4
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    • pp.213-227
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    • 2020
  • As unrenewable energy resources have depleted over the years, the demand for renewable energy has increased promoting research for more effective methods to produce renewable energy. The field of fuel cell development, specifically microbial fuel cells (MFCs), has developed because of the dual performance potential of the technology. MFCs convert power by facilitating electrode-reducing organisms such as bacteria (microbes) as a catalyst to produce electrical energy. MFCs use domestic and industrial wastewater as fuel to initiate the process, purifying the wastewater as a result. Proton exchange membranes (PEM) play a crucial role in MFCs as a separator between the anodes and cathodes chambers allowing only protons to effectively pass through. Nafion is the commercially used PEM for MFCs, but there are many setbacks: such as cost, production time, and less effective proton conductivity properties. In this review there will be largely two parts. Firstly, several newly developed PEM are discussed as possible replacements of Nafion. Secondly, MFC based on PEM, blended PEM and composite PEM are summarized.

Performance Evaluation of Antioxidizing Device for Protection of Car Body (자동차 차체 보호를 위한 산화방지 장치의 성능 평가)

  • Kim, Hae Sik;Yun, Yeong Jin;Ji, Jong Gi
    • Journal of the Korean Chemical Society
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    • v.46 no.5
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    • pp.444-456
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    • 2002
  • To protect the occurrence of the oxidation of car body, we developed antioxidizing device made with sacrificial anode. Because car body is made of iron and iron-alloy and oxidation potential of Mg, Al and Zn is higher than that of iron, sacrificial anodes were made with Mg, Al and Zn. Accordingly, Mg, Al and Zn are better oxidizing than car body, iron and iron-alloy can be protected from oxidizing. We have made an antioxidizing device and evaluated their anti-corrosive effect for iron piece in the solution of hydrochloric, nitric and sulfuric acid using balance, SEM and XPS. When iron pieces were connected with antioxidizing device of car body, weight loss by oxidation was remarkably reduced and surface corrosion of iron piece was protected. It was shown that the surface of iron pieces which is not con-nected to the device was changed to iron(Ⅲ) oxide, Fe$_2$O$_3$. Therefore, if this device is attached to car body, corrosion and oxidation of car body will be reduced, considerably.

Application of Hierarchically Porous Fe2O3 Nanofibers for Anode Materials of Lithium-ion Batteries (계층적 다공구조를 갖는 Fe2O3 나노섬유의 리튬 이차전지 음극소재 적용)

  • Jo, Min Su;Cho, Jung Sang
    • Korean Chemical Engineering Research
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    • v.57 no.2
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    • pp.267-273
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    • 2019
  • Hierarchically porous $Fe_2O_3$ nanofibers with meso- and macro- pores are designed and synthesized by electrospinning and subsequent heat-treatment. The macro pores are generated by selectively decomposition of polystyrene as a dispersed phase in the as-spun fibers containing $Fe(acac)_3$/polyacrylonitrile continuous phases during heat-treatment. Additionally, meso-pores formed by evaporation of infiltrated water vapor during electrospinning process interconnected the macro-pores and results in the formation of hierarchically porous $Fe_2O_3$ nanofibers. The initial discharge capacity and Coulombic efficiency of the hierarchically porous $Fe_2O_3$ nanofibers at a current density of $1.0A\;g^{-1}$ are $1190mA\;h\;g^{-1}$ and 79.2%. Additionally, the discharge capacity of the nanofibers is $792mA\;h\;g^{-1}$ after 1,000 cycles. The high structural stability and morphological benefits of the hierarchically porous $Fe_2O_3$ nanofibers resulted in superior lithium ion storage performance.

Electrochemical Decomposition Characteristics of Ammonia by the Catalytic Oxide Electrodes (촉매성 산화물 전극에 의한 암모니아의 전기 화학적 분해 특성)

  • Kim, Kwang-Wook;Kim, Young-Jun;Kim, In-Tae;Park, Gun-Ill;Lee, Eil-Hee
    • Korean Chemical Engineering Research
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    • v.43 no.1
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    • pp.9-15
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    • 2005
  • In order to know the electrochemical decomposition characteristics of ammonia to nitrogen, this work has studied several experimental variables on the electrolytic ammonia decomposition. The effects of pH and chloride ion at $IrO_2$, $RuO_2$, and Pt anodes on the electrolytic decomposition of ammonia were compared, and the existence of membrane equipped in the cell and the changes of the current density, the initial ammonia concentration and so on were investigated on the decomposition. The performances of the electrode were totally in order of $RuO_2{\approx}IrO_2>Pt$ in the both of acid and alkali conditions, and the ammonia decomposition was the highest at a current density of $80mA/cm^2$, over which it decreased, because the adsorption of ammonia on the electrode surface was hindered due to the evolution of oxygen. The ammonia decomposition increased with the concentration of chloride ion in the solution. However, the increase became much dull over 10 g/l of chloride ion. The $RuO_2$ electrode among the tested electrodes generated the most OH radicals which could oxidized the ammonium ion at pH 7.

Effect of Pressing Process on the High-Temperature Stability of Yttria-Stabilized Zirconia Ceramic Material in Molten Salt of CaCl2-CaF2-CaO (CaCl2-CaF2-CaO 용융염에서 YSZ 세라믹의 고온 안정성에 미치는 성형공정의 영향)

  • Kim, Wan-Bae;Kwon, Suk-Cheol;Cho, Soo-Haeng;Lee, Jong-Hyeon
    • Korean Journal of Materials Research
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    • v.30 no.4
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    • pp.176-183
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    • 2020
  • The high-temperature stability of YSZ specimens fabricated by die pressure and cold isostatic press (CIP) is investigated in CaCl2-CaF2-CaO molten salt at 1,150 ℃. The experimental results are as follows: green density 46.7 % and 50.9 %; sintering density 93.3 % and 99.3 % for die press and CIP, respectively. YSZ foremd by CIP exhibits higher stability than YSZ formed by die press due to denseness dependency after high-temperature stability test. YSZ shows peaks mainly attributed to CaZrO3, with a small t-ZrO2 peak, unlike the high-intensity tetragonal-ZrO2 (t-ZrO2) peak observed for the asreceived specimen. The t-ZrO2 phase of YSZ is likely stabilized by Y2O3, and the leaching of Y2O3 results in phase transformation from t-ZrO2 to m-ZrO2. CaZrO3 likely forms from the reaction between CaO and m-ZrO2. As the exposure time increases, more CaZrO3 is observed in the internal region of YSZ, which could be attributed to the inward diffusion of molten salt and outward diffusion of the stabilizer (Y2O3) through the pores. This results in greater susceptibility to phase transformation and CaZrO3 formation. To use SOM anodes for the electroreduction of various metals, YSZ stability must be improved by adjusting the high-density in the forming process.