• Title/Summary/Keyword: Oxygen Evolution Catalyst

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Development of Micro-Tubular Perovskite Cathode Catalyst with Bi-Functionality on ORR/OER for Metal-Air Battery Applications

  • Jeon, Yukwon;Kwon, Ohchan;Ji, Yunseong;Jeon, Ok Sung;Lee, Chanmin;Shul, Yong-Gun
    • Korean Chemical Engineering Research
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    • v.57 no.3
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    • pp.425-431
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    • 2019
  • As rechargeable metal-air batteries will be ideal energy storage devices in the future, an active cathode electrocatalyst is required with bi-functionality on both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) during discharge and charge, respectively. Here, a class of perovskite cathode catalyst with a micro-tubular structure has been developed by controlling bi-functionality from different Ru and Ni dopant ratios. A micro-tubular structure is achieved by the activated carbon fiber (ACF) templating method, which provides uniform size and shape. At the perovskite formula of $LaCrO_3$, the dual dopant system is successfully synthesized with a perfect incorporation into the single perovskite structure. The chemical oxidation states for each Ni and Ru also confirm the partial substitution to B-site of Cr without any changes in the major perovskite structure. From the electrochemical measurements, the micro-tubular feature reveals much more efficient catalytic activity on ORR and OER, comparing to the grain catalyst with same perovskite composition. By changing the Ru and Ni ratio, the $LaCr_{0.8}Ru_{0.1}Ni_{0.1}O_3$ micro-tubular catalyst exhibits great bi-functionality, especially on ORR, with low metal loading, which is comparable to the commercial catalyst of Pt and Ir. This advanced catalytic property on the micro-tubular structure and Ru/Ni synergy effect at the perovskite material may provide a new direction for the next-generation cathode catalyst in metal-air battery system.

Enhancement of oxygen evolution reaction of NiCo LDH nanocrystals using Mo doping (Mo 도핑을 이용한 NiCo LDH 나노결정의 산소발생반응 향상)

  • Kyoungwon Cho;Jeong Ho Ryu
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.34 no.3
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    • pp.92-97
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    • 2024
  • To improve the efficiency of water splitting systems for hydrogen production, the high overvoltages of electrochemical reactions caused by catalysts in the oxygen evolution reaction (OER, Oxygen Evolution Reaction) must be reduced. Among them, LDH (Layered Double Hydroxide) compounds containing transition metal such as Ni, 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 metallic porous material, was used as a support, and NiCo LDH (Layered Double Hydroxide) nanocrystals were synthesized through a hydrothermal synthesis process. In addition, changes in the shape, crystal structure, and water decomposition characteristics of the Mo-doped NiCo LDH nanocrystal samples synthesized by doping Mo to improve OER properties were observed.

Characterization for Performance of Zn-Air Recharegeable Batteries on Different Composition in Acidic Electrolyte (산성용액에서 전해액 조성에 따른 아연공기 이차전지의 성능변화)

  • DAI, GUANXIA;LU, LIXIN;SHIM, JOONGPYO;LEE, HONG-KI
    • Transactions of the Korean hydrogen and new energy society
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    • v.32 no.5
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    • pp.401-409
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    • 2021
  • The combination of different concentrations of ZnSO4 in acidic solution as electrolyte in Zn-air batteries was investigated by Zn symmetrical cell test, half-cell and full cell tests. Using 1 M ZnSO4 + 0.05 M H2SO4 as electrolyte and MnO2 as air cathode catalyst with Zn foil anode, this combination had a satisfactory performance with balance of electrochemical activity and stability. Its electrochemical activity was matched to or even better than the PtRu catalyst in different current density. And its cycle life was improved (more than 100 cycles stable) by suppressing the growth of zinc dendrites on anode obviously. This electrolyte overcame the shortcomings of alkaline electrolyte that are easy to react with CO2 in the air, severely growth of Zn dendrites caused by uneven plating/stripping of Zn.

Effect of Gas Diffusion Layer on La0.8Sr0.2CoO3 Bifunctional Electrode for Oxygen Reduction and Evolution Reactions in an Alkaline Solution (알칼리용액에서 산소환원 및 발생반응에 대한 La0.8Sr0.2CoO3 전극의 기체확산층 영향)

  • LOPEZ, KAREEN J.;YANG, JIN-HYUN;SUN, HO-JUNG;PARK, GYUNGSE;EOM, SEUNGWOOK;RIM, HYUNG-RYUL;LEE, HONG-KI;SHIM, JOONGPYO
    • Transactions of the Korean hydrogen and new energy society
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    • v.27 no.6
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    • pp.677-684
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    • 2016
  • Various commercially available gas diffusion layers (GDLs) from different manufacturers were used to prepare an air electrode using $La_{0.8}Sr_{0.2}CoO_3$ perovskite (LSCP) as the catalyst for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in an alkaline solution. Various GDLs have different physical properties, such as porosity, conductivity, hydrophobicity, etc. The ORR and OER of the resulting cathode were electrochemically evaluated in an alkaline solution. The electrochemical properties of the resulting cathodes were slightly different when compared to the physical properties of GDLs. Pore structure and conductivity of GDLs had a prominent effect and their hydrophobicities had a minor effect on the electrochemical performances of cathodes for ORR and OER.

Characterization of NiO and Co3O4-Doped La(CoNi)O3 Perovskite Catalysts Synthesized from Excess Ni for Oxygen Reduction and Evolution Reaction in Alkaline Solution (과량의 니켈 첨가로 합성된 NiO와 Co3O4가 도핑된 La(CoNi)O3 페로브스 카이트의 알칼리용액에서 산소환원 및 발생반응 특성)

  • BO, LING;RIM, HYUNG-RYUL;LEE, HONG-KI;PARK, GYUNGSE;SHIM, JOONGPYO
    • Transactions of the Korean hydrogen and new energy society
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    • v.32 no.1
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    • pp.41-52
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    • 2021
  • NiO and Co3O4-doped porous La(CoNi)O3 perovskite oxides were prepared from excess Ni addition by a hydrothermal method using porous silica template, and characterized as bifunctional catalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) for Zn-air rechargeable batteries in alkaline solution. Excess Ni induced to form NiO and Co3O4 in La(CoNi)O3 particles. The NiO and Co3O4-doped porous La(CoNi)O3 showed high specific surface area, up to nine times of conventionally synthesized perovskite oxide, and abundant pore volume with similar structure. Extra added Ni was partially substituted for Co as B site of ABO3 perovskite structure and formed to NiO and Co3O4 which was highly dispersed in particles. Excess Ni in La(CoNi)O3 catalysts increased OER performance (259 mA/㎠ at 2.4 V) in alkaline solution, although the activities (211 mA/㎠ at 0.5 V) for ORR were not changed with the content of excess Ni. La(CoNi)O3 with excess Ni showed very stable cyclability and low capacity fading rate (0.38 & 0.07 ㎶/hour for ORR & OER) until 300 hours (~70 cycles) but more excess content of Ni in La(CoNi)O3 gave negative effect to cyclability.

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.

Photoelectrochemical Properties of Gallium Nitride (GaN) Photoelectrode Using Cobalt-phosphate (Co-pi) as Oxygen Evolution Catalyst (산소발생용 Cobalt-phosphate (Co-pi) 촉매를 이용한 Gallium Nitride (GaN) 광전극의 광전기화학적 특성)

  • Seong, Chaewon;Bae, Hyojung;Burungale, Vishal Vilas;Ha, Jun-Seok
    • Journal of the Microelectronics and Packaging Society
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    • v.27 no.2
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    • pp.33-38
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    • 2020
  • In the photoelectrochemical (PEC) water splitting, GaN is one of the most promising photoanode materials due to high stability in electrolytes and adjustable energy band position. However, the application of GaN is limited because of low efficiency. To improve solar to hydrogen conversion efficiency, we introduce a Cobalt Phosphate (Co-pi) catalyst by photo-electrodeposition. The Co-pi deposition GaN were characterized by SEM, EDS, and XPS, respectively, which illustrated that Co-pi was successfully decorated on the surface of GaN. PEC measurement showed that photocurrent density of GaN was 0.5 mA/㎠ and that of Co-pi deposited GaN was 0.75 mA/㎠. Impedance and Mott-Schottky measurements were performed, and as a result of the measurement, polarization resistance (Rp) and increased donor concentration (ND) values decreased from 50.35 Ω to 34.16 Ω were confirmed. As a result of analyzing the surface components before and after the water decomposition, it was confirmed that the Co-pi catalyst is stable because Co-pi remains even after the water decomposition. Through this, it was confirmed that Co-pi is effective as a catalyst for improving GaN efficiency, and when applied as a catalyst to other photoelectrodes, it is considered that the efficiency of the PEC system can be improved.

Research Trend in Electrocatalysts for Anion Exchange Membrane Water Electrolysis (음이온교환막 수전해 촉매기술 동향)

  • Kim, Jiyoung;Lee, Kiyoung
    • Journal of the Korean Electrochemical Society
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    • v.25 no.2
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    • pp.69-80
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    • 2022
  • The anion exchange membrane (AEM) water electrolysis for high purity hydrogen production is attracting attention as a next-generation green hydrogen production technology by using inexpensive non-noble metal-based catalysts instead of conventional precious metal catalysts used in proton exchange membrane (PEM) water electrolysis systems. However, since AEM water electrolysis technology is in the early stages of development, it is necessary to develop research on AEM, ionomers, electrode supports and catalysts, which are key elements of AEM water electrolysis. Among them, current research in the field of catalysts is being studied to apply a previously developed half-cell catalyst for alkali to the AEM system, and the applied catalyst has disadvantages of low activity and durability. Therefore, this review presented a catalyst synthesis technique that promoted oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) using a non-noble metal-based catalyst in an alkaline medium.

Developing efficient transition metal-based water splitting catalyst using rechargeable battery materials (배터리 소재를 이용한 전이금속 화합물 기반 물 분해 촉매 개발)

  • Kim, Hyunah;Kang, Kisuk
    • Ceramist
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    • v.21 no.4
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    • pp.416-426
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    • 2018
  • Water splitting is regarded as one of the most environmentally benign routes for hydrogen production. Nevertheless, the low energy efficiency to produce the hydrogen has been a critical bottleneck, which is attributable to the multi-electron and multi-step reactions during water splitting reaction. In this respect, the development of efficient, durable, and inexpensive catalysts that can promote the reaction is indispensable. Extensive searching for new catalysts has been carried out for past decades, identifying several promising catalysts. Recently, researchers have found that conventional battery materials; particularly high-voltage intercalation-based cathode materials, could exhibit remarkable performance in catalyzing the water splitting process. One of the unique capabilities in this class of materials is that the valency state of metals and the atomic arrangement of the structure can be easily tailored, based on simple intercalation chemistry. Moreover, taking advantage of the rich prior knowledge on the intercalation compounds can offer the unexplored path to identify new water splitting catalysts.

Effect of Electroplating Parameters on Oxygen Evolution Reaction Characteristics of Raney Ni-Zn-Fe Electrode (Raney Ni-Zn-Fe 전극의 산소발생 반응 특성에 미치는 도금변수의 영향)

  • CHAE, JAEBYEONG;KIM, JONGWON;BAE, KIKWANG;PARK, CHUSIK;JEONG, SEONGUK;JUNG, KWANGJIN;KIM, YOUNGHO;KANG, KYOUNGSOO
    • Transactions of the Korean hydrogen and new energy society
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    • v.31 no.1
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    • pp.23-32
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    • 2020
  • The intermittent characteristics of renewable energy complicates the process of balancing supply with demand. Electrolysis technology can provide flexibility to grid management by converting electricity to hydrogen. Alkaline electrolysis has been recognized as established technology and utilized in industry for over 100 years. However, high overpotential of oxygen evolution reaction in alkaline water electrolysis reduces the overall efficiency and therefore requires the development of anode catalyst. In this study, Raney Ni-Zn-Fe electrode was prepared by electroplating and the electrode characteristics was studied by varying electroplating parameters like electrodeposition time, current density and substrate. The prepared Raney Ni-Zn-Fe electrode was electrochemically evaluated using linear sweep voltammetry. Physical and chemical analysis were conducted by scanning electron microscope, energy dispersive spectrometer, and X-ray diffraction. The plating time did not changed the morphology and composition of the electrode surface and showed a little effect on overpotential reduction. As the plating current density increased, Fe content on the surface increased and cauliflower-like structure appeared on the electrode surface. In particular, the overpotential of the electrode, which was prepared at the plating current density of 320 mA/㎠, has showed the lowest value of 268 mV at 50 mA/㎠. There was no distinguishable overpotential difference between the type of substrate for the electrodes prepared at 80 mA/㎠.