• Title/Summary/Keyword: Electrochemical catalyst

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Technology Trends in Stainless Steel for Water Splitting Application (스테인레스 강의 수전해 전극 응용기술 동향)

  • Kim, Moonsu;Ha, Jaeyun;Kim, Yong-Tae;Choi, Jinsub
    • Journal of the Korean Electrochemical Society
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    • v.24 no.2
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    • pp.13-27
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    • 2021
  • Stainless steel, which includes Ni and Cr with Fe balance, is most often applied for a wide range of applications such as structure and equipment material. It is not only suitable for use in these applications due to its good corrosion resistance, but also can be applied to catalyst, supporting material, and current collector due to intrinsic properties of Ni and Fe contained in stainless steel. Therefore, in recent years, a lots of surface treatment methods have been studied to activate stainless steel, developing application of water splitting system. In this review paper, the research on the surface treatment technology of stainless steel for water splitting is summarized. It is expected to be able to propose the diverse surface treatment approaches of stainless steel for application to low-cost and highly efficient water splitting electrode.

Effect of Ramping Rate on the Durability of Proton Exchange Membrane Water Electrolysis During Dynamic Operation Using Triangular Voltage Cycling

  • Hye Young Jung;Yong Seok Jun;Kwan-Young Lee;Hyun S. Park;Sung Ki Cho;Jong Hyun Jang
    • Journal of Electrochemical Science and Technology
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    • v.15 no.2
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    • pp.253-260
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    • 2024
  • Proton exchange membrane water electrolysis (PEMWE) is an efficient method for utilizing renewable energy sources such as wind and solar powers to produce green hydrogen. For PEMWE powered by renewable energy sources, its durability is a crucial factor in its performance since irregular and fluctuating characteristics of renewable energy sources, especially for wind power, can deteriorate the stability of PEMWE. Triangular voltage cycle is well able to simulate fluctuating wind power, but its effect on the durability has not been investigated extensively. In this study, the performance degradation of the PEMWE cell operated with the triangular voltage cycling was investigated at different ramping rates. The measured current responses during the cycling gradually decreased for both ramping rates, and I-V curve measurements before and after the cycling confirmed the degradation of the performances of PEMWE. For both measurements, the degradation rate was larger for 300 mV s-1 than 30 mV s-1, and they were determined as 0.36 and 1.26 mV h-1 (at the current density of 2 A cm-2) at the ramping rates of 30 and 300 mV s-1, respectively. The comparison with other studies on triangular voltage cycling also indicate that an increase in the ramping rate accelerates the deterioration of the PEMWE performance. X-ray photoelectron spectroscopy and transmission electron microscopy results showed that the Ir catalyst was oxidized and did not dissolve during the voltage cycling. This study suggests that the ramping rate of the triangular voltage cycling is an important factor for the evaluation of the durability of PEMWE cells.

A Study on Glucose Sensing Measured by Catalyst Containing Multiple Layers of Glucose Oxidase and Gold Nano Rod (글루코스산화효소와 금나노로드 입자의 다층막으로 구성된 촉매를 이용하여 측정한 글루코스 센싱에 대한 연구)

  • Chung, Yong-Jin;Hyun, Kyuhwan;Han, Sang Won;Min, Ji Hong;Chun, Seung-Kyu;Koh, Won-Gun;Kwon, Yongchai
    • Transactions of the Korean hydrogen and new energy society
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    • v.26 no.2
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    • pp.179-183
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    • 2015
  • In this study, we propose a catalyst structure including enzyme and metal nano rod for glucose sensing. In the catalyst structure, glucose oxidase (GOx) and gold nano rod (GNR) are alternatingly immobilized on the surface of carbon nanotube (CNT), while poly(ethyleneimine) (PEI) is inserted in between the GOx and GNR to fortify their bonding and give them opposite polarization ($[GOx/GNR]_nPEI/CNT$). To investigate the impact of $[GOx/GNR]_nPEI/CNT$ on glucose sensing, some electrochemical measurements are carried out. Initially, their optimal layer is determined by using cyclic voltammogram and as a result of that, it is proved that $[GOx/GNR/PEI]_2/CNT$ is the best layer. Its glucose sensitivity is $13.315{\mu}AmM^{-1}cm^{-2}$. When it comes to the redox reaction mechanism of flavin adenine dinucleotide (FAD) within $[GOx/GNR/PEI]_2/CNT$, (i) oxygen plays a mediator role in moving electrons and protons generated by glucose oxidation reaction to those for the reduction reaction of FAD and (ii) glucose does not affect the redox reaction of FAD. It is also recognized that the $[GOx/GNR/PEI]_3/CNT$ is limited to the surface reaction and the reaction is quasi-reversible.

Low-iridium Doped Single-crystalline Hydrogenated Titanates (H2Ti3O7) with Large Exposed {100} Facets for Enhanced Oxygen Evolution Reaction under Acidic Conditions ({100} 단결정 수소화 티타네이트(H2Ti3O7)를 활용한 저함량 Irridium 수전해 양극 촉매 개발)

  • Sun Young Jung;HyukSu Han
    • Journal of the Microelectronics and Packaging Society
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    • v.30 no.1
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    • pp.79-89
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    • 2023
  • Development of efficient and stable electrocatalysts for oxygen evolution reaction (OER) under acidic conditions is desirable goal for commercializing proton exchange membrane (PEM) water electroyzer. Herein, we report iridium-doped hydrogenated titanate (Ir-HTO) nanobelts as a promising catalyst with a low-Ir content for the acidic OER. Addition of low-Ir (~ 3.36 at%) into the single-crystalline HTO nanobelts with large exposed {100} facets significantly boost catalytic activity and stability for OER under acidic conditions. The Ir-HTO outperforms the commenrcial benchmark IrO2 catalyst; an overpotential for delivering 10 mA cm-2 current density was reduced to about 25% for the Ir-HTO. Moreover, the catalytic performance of Ir-HTO is positioned as the most efficient electrocatalyst for the acidic OER. An improved intrinsic catalytic activity and stability are also confirmed for the Ir-HTO through in-depth electrochemical characterizations. Therefore, our results suggest that low-Ir doped single-crystalline HTO nanobelts can be a promising catalyst for efficient and durable OER under acidic conditions.

Effects of Mo co-doping into Fe doped β-Ni(OH)2 microcrystals for oxygen evolution reactions (Fe-doped β-Ni(OH)2의 산소발생반응 증가를 위한 Mo의 동시도핑효과)

  • Je Hong Park;Si Beom Yu;Tae Kwang An;Byeong Jun Kim;Jeong Ho Ryu
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.34 no.1
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    • pp.30-35
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    • 2024
  • In order to improve the efficiency of the water splitting system for hydrogen production, the high overvoltage in the electrochemical reaction caused by the catalyst in the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) must be reduced. Among them, transition metal-based compounds are attracting attention as catalyst materials that can replace precious metals such as platinum that are currently used. In this study, nickel foam, an inexpensive metal porous material, was used as a support, and Fe-doped β-Ni(OH)2 microcrystals were synthesized through a hydrothermal synthesis process. In addition, in order to improve OER properties, changes in the shape, crystal structure, and water splitting characteristics of Fe-Mo co-doped β-Ni(OH)2 microcrystals synthesized by co-doping with Mo were observed. The changes in the shape, crystal structure, and applicability as a catalyst for water splitting were examined.

A Study on the Electrochemical Properties of SPEEK/PWA/Silica Composite Membranes (SPEEK/PWA/Silica 복합막의 전기화학적 특성에 관한 연구)

  • Oh, Sae-Joong
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.14 no.5
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    • pp.2529-2535
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    • 2013
  • Sol-gel method was utilized to prepare SPEEK/PWA electrolyte composite membranes. TEOS was used as a precursor and phosphotungstic acid(PWA) as a catalyst for the sol-gel reaction. It was observed through FE-SEM analysis that the PWA and silica nanoparticles were uniformly dispersed into the polymer matrix. The water uptake of SPEEK/PWA/silica composite membranes was less affected by TEOS concentration at higher TEOS contents, while the water uptake decreased as TEOS concentration increased at lower TEOS contents. The proton conductivity of the composite membranes showed similar trend as the water uptake of the composite membranes. The methanol permeability of SPEEK/PWA/silica composite membranes decreased as TEOS concentration increased.

A comparative study on the characteristics of the dye-sensitized solar cell with different methods of manufacturing the counter electrode (상대전극 제작 방식에 따른 염료감응형 태양전지 특성 비교 연구)

  • Son, Min-Kyu;Seo, Hyun-Woong;Shin, In-Young;Kim, Jin-Kyoung;Hong, Ji-Tae;Chae, Won-Yong;Kim, Hee-Je
    • Proceedings of the KIEE Conference
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    • 2009.07a
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    • pp.1338_1339
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    • 2009
  • Dye-sensitized solar cell (DSC) consists of photo electrode, counter electrode and electrolyte. Photo electrode has titanium oxide layer with dye molecule to create electrons. And counter electrode is made of one layer that has catalytic ability for redox system such as the iodide/triiodide couple. Most DSC researchers use platinum as catalyst on counter electrode because platinum has good catalytic ability and conductivity. Platinum is doped on fluorine-doped tin oxide glass with different methods such as sputtering method, electrochemical method and so on. In this paper, we deposit platinum on counter electrode glass with two methods. One is the radio frequency (RF) sputtering method and the other is the chemical method with heating treatment. Finally, we compare the photovoltaic characteristics of DSCs that are assembled using two different counter electrodes.

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Electrochemical Properties of Pd Nanocrystals by Shape Control (나노 형상 조절에 의한 Pd의 전기화학적 특성)

  • Lee, Young-Woo;Han, Sang-Beom;Lee, Jong-Min;Kim, Jy-Yeon;Ko, A-Ra;Park, Kyung-Won
    • 한국신재생에너지학회:학술대회논문집
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    • 2009.06a
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    • pp.386-388
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    • 2009
  • 차세대 에너지로 연료전지가 각광을 받고 있는 현재, 세계 각국에서는 연료전지의 상용화를 위해 노력하고 있다. 그러나 촉매분야에서 백금계 촉매의 사용량의 문제에 따른 매장량 한계점과 귀금속이라는 문제점이 존재하기 때문에 이에 대하여 대책강구가 필요한 시점이다. 이에 백금 촉매의 활성을 증대하고자 나노 크기의 제어 연구가 진행되고 있다. 또한, 촉매의 구조적인 면에 따라 촉매의 활성이 달라지는 점을 착안하여 백금계의 나노 형상 조절 연구와 백금계 촉매를 대체할 비백금계의 촉매 개발 연구가 활발히 진행되어지고 있다. 이에 본 연구는 백금계 촉매 중 Pd을 polyol process에 의한 나노 형상 조절을 통하여 단위 질량당(or 단위 부피당) 촉매의 활성을 높이고자 하였다. Polyol process에서는 환원제, 계면활성제, 온도, 시간, 기타 첨가제에 따라 나노 형상이 다르게 조절되는데, 이에 계면활성제로 PVP를 사용하고, 반응속도 및 형상조절을 위해 다양한 첨가제를 이용하여 polygonal Pd NPs을 형성하였다. 본 나노 형상 조절에서는 첨가제와 온도가 가장 큰 영향을 미치는 요인으로 착안하여 그에 따른 polygoanl Pd NPs의 사이즈 조절을 통해 전기화학 특성이 차이의 연구에 중점을 두었다. 이에 따라 나노 형상 조절이 된 Pd촉매를 이용하여 상용화된 촉매(Pd/C(XC-72R))에 비하여 전기화학적인 특성의 차이와 Pd 촉매의 촉매적 특성의 효과를 보고자 한다.

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NiFeOx co-catalyzed BiVO4 photoanode for improved photoelectrochemical water splitting

  • Kim, Jin Hyun;Kang, Hyun Joon;Magesh, Ganesan;Lee, Jae Sung
    • Rapid Communication in Photoscience
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    • v.3 no.2
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    • pp.35-37
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    • 2014
  • PEC (photoelectrochemical) water splitting for $O_2/H_2$ production is one of the promising but difficult way to utilize solar energy. Among photocatalytic materials for PEC water oxidation, $BiVO_4$ (Eg = 2.4 eV) has been recently intensively studied since it has various advantageous properties. But its maximum efficiency has not been realized owing to kinetic factors - slow water oxidation at surface & insufficient stability. These problems can be simultaneously solved by application of oxygen evolution catalyst (OEC) such as $CoO_x$, Co-Pi, $IrO_x$ etc. Herein we report the first successful application of $NiFeO_x$ OEC on $BiVO_4$, showing good performance compared to other effective OEC applied on $BiVO_4$ under basic conditions. The enhanced activity of OEC loaded $BiVO_4$ has been supported by the surface charge separation efficiency and electrochemical impedance studies.

Developement of a PEFC electrodes under the high temperature and low humidified conditions (고온/저 가습 운전을 위한 고분자 전해질 연료전지용 전극 개발)

  • Ryu, Sung-Kwan;Choi, Young-Woo;Park, Jin-Soo;Yim, Sung-Dae;Yang, Tae-Hyun;Kim, Han-Sung;Kim, Chang-Soo
    • 한국신재생에너지학회:학술대회논문집
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    • 2009.11a
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    • pp.149-149
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    • 2009
  • Generally, Nafion ionomer is used in the polymer electrolyte fuel cell (PEFC) electrodes to achieve high power density. At the high temperature operation of PEFC, however, ionic conductivity of Nafion remarkably decreased due to the evaporation of water in Nafion polymer. Recently, many researchers have focused on using the Ionic Liquids(ILs) instead of water in Nafion polymer. ILs have intrinsic properties such as good electrochemical stability, high ionic conductivity, and non-flammability. Especially, ILs play a crucial role in proton conduction by the Grottuss mechanism and act as water in water-free Nafion polymer. However, it was found that the ILs was leached out of the polymer matrix easily. In this study, we prepared membrane electrode assemblies with various contents of ILs. The effect of ILs in the electrode of each designed was investigated by a cyclic voltammetry measurement and the cell performance obtained through a single cell test using H2/Air gases. Electrodes with different contents of ILs in catalyst layer were examined at high temperature and low humidified condition.

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