• Transactions of the Korean hydrogen and new energy society
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• v.33 no.3
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• pp.202-208
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• 2022

Pt-Ni nanocatalysts were loaded on carbon black by spontaneous reduction reaction of platinum (II) acetylacetonate and nickel (II) acetylacetonate, and they were characterized by transmission electron microscopy (TEM), thermogravimetric analyzer (TGA), energy dispersive x-ray analyzer (EDS), BET surface area and fuel cell test station. The distribution of the Pt and Ni nanoparticles was observed by TEM, and the loading weight of Pt-Ni nanocatalysts on the carbon black was measured by TGA. The elemental ratio of Pt and Ni was estimated by EDS. It was found that the loading weight of Pt-Ni nanoparticles was 5.54 wt%, and the elemental ratio of Pt and Ni was 0.48:0.35. Specific surface area was measured by BET analysis instrument and I-V characteristics were estimated.

• Korean Chemical Engineering Research
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• v.48 no.3
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• pp.322-326
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• 2010

Stability of sodium borohydride solution during storage was studied. In order to enhance the $NaBH_4$ stability, NaOH and KOH were added to the $NaBH_4$ solution. The effect of concentration of the borohydride and alkaline solution, temperature and materials of storage vessels on the rate of borohydride hydrolysis was investigated. The rate of hydrogen evolution decreased as the concentration of alkaline increased due to increase of $NaBH_4$ stability in the solution. The stability of $NaBH_4$ solution decreased when the borohydride concentration raised from 10 to 15 wt% and then increased when the $NaBH_4$ concentration increased above 15 wt% due to increase in the pH of the concentrated solution. The activity coefficient of hydrolysis of $NaBH_4$ solution(NaOH 3.0 wt%, $NaBH_4$ 25 wt%) was 115.1 kJ/mol and this value was 1.5~4.0 times higher than that of hydrolysis of $NaBH_4$ solution with catalyst. The borohydride solutions in glass and stainless-steel vessel were more stable than the solution in plastic(PE) vessel.

• Membrane Journal
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• v.33 no.2
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• pp.77-86
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• 2023

In this study, pore-filled ion exchange membranes with low membrane resistance and high hydroxide ion conductivity was developed. To improve alkali durability, a porous substrate made of polytetrafluoroethylene was used, and a copolymer was prepared using monomers 2-(dimethyl amino) ethyl methacrylate (DMAEMA) and vinyl benzyl chloride (VBC) for pores. divinyl benzene (DVB) was used as the cross-linker, and ion exchange membranes were prepared for each cross-linking agent content to study the effect of the cross-linker content on DMAEMA-DVB and VBC-DMAEMA-DVB copolymers. As a result, chemical stability is improved by using a PTFE material substrate, and productivity can be increased by enabling fast photo polymerization at a low temperature by using a low-pressure UV lamp. To confirm the physical and chemical stability of the ion exchange membrane required for an anion exchange membrane fuel cell, tensile strength, and alkali resistance tests were conducted. As a result, as the cross-linking degree increased, the tensile strength increased by approximately 40 MPa, and finally, through the silver conductivity and alkali resistance tests, it was confirmed that the alkaline stability increased as the cross-linking agent increased.

• Journal of the Korean Electrochemical Society
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• v.2 no.3
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• pp.163-170
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• 1999

The effects of the operating conditions in AFC single cells have not been studied in detail. In this study, by using a one-dimensional isothermal model a computational simulation was conducted to investigate the effects of the initial electrolyte concentration and the operating gas pressure. According to the result, the optimum electrolyte concentration at the base-case was found to be within $3.0\~3.5$ M. The variation of the cell performance according to the electrolyte concentration was found to be caused mainly by the charge transfer resistances of both electrodes, Henry's constant and the liquid phase diffusivity of the dissolved gases. It was also found that an increase in operating pressure increased the reaction rates and the solubilities of the gases, which led to a considerable enhancement of the cell performance.

• Korean Journal of Materials Research
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• v.11 no.8
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• pp.703-707
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• 2001

The effects of chromium addition on the catalytic activity of Raney nickel in alkaline fuel cell (AFC) have been studied. When the catalysts are prepared from various contents of chromium, the electrochemical characteristics shows the highest mass activity of 3.588 A/g. Operating temperature and electrolyte concentration of half cell were $80^{\circ}C$ and 6N KOH, respectively. With the addition of chromium, the particle size is diminished from 12.11 $\mu\textrm{m}$ to 11.07 $\mu\textrm{m}$ and the decrease of particle size contributes to the enlargement of the specific surface area from 0.653 $\m^2$/g to 0.685$\m^2$/g. The residual aluminium contents of Raney nickel surface are considerably influenced by the particle size and chromium acts as sintering inhibitor.

• Transactions of the Korean hydrogen and new energy society
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• v.15 no.4
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• pp.324-332
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• 2004

According to the rapid depletion of the fossil fuels, the electricity and hydrogen will gradually take charge of the future energy supply. Especially, in order to control the supply and demand of electricity, energy storage medium is necessary and this could be solved by the combination of water electrolysis and fuel cell. Although electricity can be generated from such alternative energies as hydropower, nuclear, solar, and wind-power resources, alternative energy storage medium is also required since regenerative energies, solar and wind-powers, are intermittent energy resources. In this regard, hydrogen production from water electrolysis was recognized as a superb method for electricity storage. In this work, the current development and economic status of alkaline, solid polymer, and high temperature electrolysis were reviewed, and then the practical use of water electrolysis technology were discussed.

• Applied Chemistry for Engineering
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• v.3 no.4
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• pp.701-709
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• 1992

Silver particles were impregnated on carbon black with colloidal method and used as catalyst for oxygen electrode in alkaline fuel cell. With the addition of sodium dodecylbenzenesulfonate in $AgNO_3$ and $NaBH_4$solution, colloidal solution was made and confirmed with electrophoresis test. Effects of particle size on electrode performance were studied and $200{\AA}$ of silver particle size shown the highest value of mass activity. The aggromeration of silver particle was Influenced with surfactant amount, stirring time and heat treatment. Considering the increase of particle size caused of operating temperature, recommendable particle size of silver catalyst for manufacturing the electrode was $100{\AA}$. Dispersity of carbon black was investigated and reagglomeration was appeared after homogenizing 30 sec.

• Transactions of the Korean hydrogen and new energy society
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• v.20 no.4
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• pp.300-308
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• 2009

In a pursuit of the development of alternative mobile power sources with a high energy density, a planar and air-breathing PEMFCs with a new type of hydrogen cartridge which uses onsite $H_2$ generated from sodium borohydride ($NaBH_4$) hydrolysis have been investigated for use in advanced power systems. Two types of $H_2$ generation through $NaBH_4$ hydrolysis are available: (1) using organic acids such as sulphuric acid, malic acid, and sodium hydrogen carbonate in aqueous solution with solid $NaBH_4$ and (2) using solid selected catalysts such as Pt, Ru, CoB into the stabilized alkaline $NaBH_4$ solution. It might therefore be relevant at this stage to evaluate the relative competitiveness of the two methods mentioned above. The effects of flow rate of stabilized $NaBH_4$ solution, MEA (Membrane Electrode Assembly) improvement, and type and flow control of the catalytic acidic solution have been studied and the cell performances of the planar, air-breathing PEMFCs using $NaBH_4$ has been measured from aspects of power density, fuel efficiency, energy density, and fast response of cell. In our experiments, planar, air-breathing PEMFCs using $NaBH_4$ achieved to maximum power density of 128mW/$cm^2$ at 0.7V and energy efficiency of 46% and has many advantages such as low operating temperature, sustained operation at a high power density, compactness, the potential for low cost and volume, long stack life, fast star-up and suitability for discontinuous operation.

• Transactions of the Korean hydrogen and new energy society
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• v.20 no.1
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• pp.1-8
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• 2009

Hydrogen production by the reaction of aluminum alloys and NaOH solution was studied for an automotive proton exchange membrane fuel cell(PEMFC) application. In our experiment conditions($30{\sim}75^{\circ}C$, NaOH $0.5{\sim}5M$), passivation of aluminum was not occurred. Higher rate of hydrogen production was observed at the reaction with Al alloys that contain impurities. With an increase in reaction temperature, hydrogen production rate by an increase in NaOH concentration increased much. When hydrogen was fed into the anode without filtering, PEMFC cell performance decreased 35% by ionic contamination such as $Na^+$ on the membrane and electrode. Thus, filtering of produced hydrogen is necessary for PEMFC operation.

• Transactions of the Korean hydrogen and new energy society
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• v.34 no.5
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• pp.421-430
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• 2023

Fe-Ni-Pt nanocatalysts were loaded on carbon black powders which were synthesized by a spontaneous reduction reaction of iron (II) acetylacetonate, nickel (II) acetylacetonate and platinum (II) acetylacetonate. The morphology and the loading weight of Fe-Ni-Pt nanoparticles were characterized by transmission electron microscopy and thermogravimetric analyzer. The amount of Fe-Ni-Pt catalyst supported on the carbon black surface was about 6.42-9.28 wt%, and the higher the Fe content and the lower the Pt content, the higher the total amount of the metal catalyst supported. The Brunauer-Emmett-Teller Analysis (BET) specific surface area of carbon black itself without metal nanoparticles supported was 233.9 m²/g, and when metal nanoparticles were introduced, the specific surface area value was greatly reduced. This is because the metal nanocatalyst particles block the pore entrance of the carbon black, and thereby the catalytic activity of the metal catalysts generated inside the pores is reduced. From the I-V curves, as the content of the Pt nanocatalyst increased, the electrolytic properties of water increased, and the activity of the metal nanocatalyst was in the order of Pt > Ni > Fe.