전기화학적 석출을 통해 ITO 표면에 형성한 덴드라이트 백금 구조의 전기화학적 촉매 활성

최수희,최강희,김종원,Choi, Suhee,Choi, Kang-Hee,Kim, Jongwon 한국전기화학회 2014 한국전기화학회지 Vol.17 No.4

전기화학적 석출 방법을 이용하여 indium tin oxide 표면에 백금 나노구조를 형성하고 총 석출전하량을 조절하여 형성되는 나노구조의 변화에 따른 전기화학적 메탄올 산화 반응과 산소 환원반응에 대한 촉매 활성의 변화를 관찰하였다. 석출 전하량의 변화에 따라 생성되는 백금 나노구조체 표면의 특성을 주사 전자 현미경, 전기화학적 표면적 측정, X-선 회절법, 일산화탄소 벗김분석을 통해 규명하고 전기화학적 촉매 활성과의 연계성을 조사하였다. 전기화학적 촉매 활성은 형성된 백금 나노구조에 따라 달라지는데, 석출 전하량 $0.45C\;cm^{-2}$에 해당하는 백금 나노구조에서 가장 우수한 촉매 활성이 관찰되었다. 전하량에 따른 표면적의 변화보다 형성된 구조적 특이성과 결정면이 촉매 활성에 많은 영향을 미쳤다. 세밀한 백금 나노구조의 변화에 따른 전기화학적 촉매 활성 변화에 관한 본 연구결과는 보다 우수한 촉매 시스템을 고안하는 연구에 도움이 될 것이다.

전기화학 열전지의 연구 개발 동향

강준식,김경구,이호춘,Kang, Junsik,Kim, Kyunggu,Lee, Hochun 한국전기화학회 2019 한국전기화학회지 Vol.22 No.3

중저온 (<$200^{\circ}C$) 폐열은 중요한 청정 에너지원이다. 폐열 활용 방안 중 가장 대표적인 것은 열전기술이나, 최근 전기화학 열전지가 열전소자의 대안으로 주목받고 있다. 전기화학 열전지의 기전력은 산화/환원 전극 전위의 온도 의존성에 의해 발생하며, 출력 특성은 전기화학 반응에 수반되는 동역학과 물질 이동 과전압에 의해 결정된다. 전기화학 열전지는 열전소자보다 비용 및 설계 유연성이 장점이지만, 열전소자에 비해 낮은 열-전기 변환 효율로 인해 응용 범위가 제한되어왔다. 하지만 최근 새로운 전해질과 전극을 적용하여 전기화학 열전지의 성능을 크게 향상할 수 있음이 보고되고 있다. 이 총설은 전기화학 열전지용 산화/환원쌍, 수계/비수계 전해질과 첨가제, 전극 물질 및 전지 설계 측면에서 최근 연구 동향을 소개한다.

다가 음이온성 탄소 양자점 이온 화합물 기반 전해질을 이용한 전기변색 성능 향상

임홍철 한국전기화학회 2025 한국전기화학회지 Vol.28 No.3

전해질은 이차전지, 슈퍼커패시터, 연료전지 및 전기변색소자 등 다양한 전기화학 응용 분야에서핵심적인 역할을 한다. 따라서 높은 이온 전도도, 우수한 전기화학적 안정성, 그리고 환경 친화성을 동시에 갖춘 새로운 전해질의 개발은 효율적인 전기화학 시스템을 구현하는 데 필수적이다. 본 연구에서는 다가 음이온성 탄소 양자점과 K+ 양이온을 기반으로 하는 새로운 유형의 이온화합물(K-C dot)을 합성하고 이를 전기변색 시스템에 전해질로서 적용하였다. 나노 크기의 탄소양자점 음이온은 카운터 이온인 K+ 양이온과의 정전기적 인력 및 π-양이온 상호작용을 통해 안정적인 이온 화합물을 형성한다. K-C dot은 상용 전해질인 KCl 대비 프러시안 블루(PB) 박막의 전기변색 특성에서 우수한 성능을 보였다. PB 박막은 101.5 cm2 C–1의 높은 착색 효율과0.92의 우수한 광학 밀도 변화를 나타냈으며, 1,000회의 색 전환 사이클 이후에도 초기 광학 투과도 대비 약 96%의 안정성을 유지하였다. 본 연구 결과는 전기화학 시스템용 전해질 설계에대한 새로운 통찰력을 제공하며, 에너지 저장 및 변환 소자에 적용 가능한 전해질 개발에 기여할 것으로 기대된다. Electrolytes play a pivotal role across various electrochemical applications, including secondary batteries, supercapacitors, fuel cells, and electrochromic devices. Consequently, the development of novel electrolytes that simultaneously offer high ionic conductivity, excellent electrochemical stability, and environmental compatibility is essential for the realization of nextgeneration electrochemical systems. In this study, we synthesized a new type of ionic complex, K-C dot, based on polyanionic carbon dots and their counterion, K+ cations. We then applied this K-C dot as an electrolyte in an electrochromic system. Nanoscale carbon quantum dots form stable ionic complexes through electrostatic attraction and π-cation interactions with K+ cations. The K-C dot exhibits superior performance in the electrochromic properties of Prussian blue (PB) thin films compared to the conventional electrolyte, KCl. The PB thin film demonstrated a high coloration efficiency of 101.5 cm2 C–1 and an excellent optical density change of 0.92. Furthermore, it maintained approximately 96% stability relative to its initial optical transmittance after 1,000 color switching cycles. Our research contributes new insights into the strategic design of electrolytes for electrochemical systems, with direct implications for the future development of electrolytes in both electrochromic devices and various energy storage and conversion technologies.

Supercapacitor용 이온성 액체 전해질의 전기화학적 특성

김상길,황갑진,김재철,유철휘,Kim, Sang-Gil,Hwang, Gab-Jin,Kim, Jae-Chul,Ryu, Cheol-Hwi 한국전기화학회 2011 한국전기화학회지 Vol.14 No.4

Supercapacitor has been studied actively as one of the most promising electrochemical energy storage system for a wide range of applications. To increase the energy density of supercapacitor, the introduction of ionic liquids is required. In this study, two types of EMI-$BF_4$ based on quaternary imidazolium salt were prepared with quaternary reaction and anion exchange. The structural characterization and thermal stability were analyzed by nuclear magnetic resonance($^1H$-NMR) and thermogravimetric analysis(TGA), respectively. Thermal stability of the EMI-$BF_4$ using TGA confirmed that, after heat treatment, the decomposition temperature of EMI-$BF_4$ was increased. Supercapacitors were fabricated with synthesized and commercial ionic liquids, and charge/discharge characteristics were also investigated. The capacity of supercapacitor, for synthesized and commercial EMI-$BF_4$ were determined to be 0.067 F and 0.073 F respectively, by means of charge/discharge test.

BF₃LiMA를 단량체로 하는 고체 고분자전해질 합성과 전기화학적 특성

김경찬,류상욱,Kim, Kyung-Chan,Ryu, Sang-Woog 한국전기화학회 2011 한국전기화학회지 Vol.14 No.4

Solid polymer electrolytes using $BF_3LiMA$ as monomer were synthesized by usual one step radical polymerization in THF solvent. The effect of $BF_3LiMA$ concentration on ionic conductivity and electrochemical stability was investigated by AC impedance measurement and linear sweep voltammetry. As a result, the highest ionic conductivity reached $7.71{\times}10^{-6}S\;cm^{-1}$ at $25^{\circ}C$ was obtained in 12.9 wt% of $BF_3LiMA$ content. Further increase or decrease of $BF_3LiMA$ content result to decrease the ionic conductivity due to the brittle matrix properties in former case and the insufficient number of charge carrier in the latter case. Furthermore, since the counter-anion was immobilized in the self-doped solid polymer electrolytes, high electrochemical stability up to 6.0 V was observed even in $60^{\circ}C$.

중간온도형 고체산화물 연료전지의 양극재료로서 $Gd_{0.8}Ca_{0.2}Co_{1-x}Fe_xO_3$의 전기화학특성

류지헌,장종현,이희영,오승모,Ryu Ji-H.,Jang Jong-H.,Lee Hee-Y.,Oh Seung-M. 한국전기화학회 1998 한국전기화학회지 Vol.1 No.1

For the purpose of finding new cathode materials for medium-temperature $(700\~800^{\circ}C)$ solid oxide fuel cells, $Gd_{0.8}Ca_{0.2}Co_{1-x}Fe_xO_3,\;(x=0.0\~0.5)$ are prepared, and their thermal stability and conductivity characteristics are investigated. Also, the cathodic activities are measured after the cathode layer being attached on CGO (cerium-gadolinium oxide) electrolyte disk. The X-ray analyses indicate that the materials prepared by calcining the citrate-gels at $800^{\circ}C$ have the orthorhombic perovskite structure without discernible impurities. The thermal stability of the undoped Co perovskite is so poor that it is decomposed to the individual binary oxide even at $1300^{\circ}C$. But the partially Fe-doped cobaltates exhibit a better thermal stability to retain their structural integrity up to $1400^{\circ}C$. The observation whereby both the undoped and Fe-doped cobaltates melt at ca. $1300^{\circ}C$ leads us to perform the electrode adhesion at <$1300^{\circ}C$. The cathodic activity of $Gd_{0.8}Ca_{0.2}Co_{1-x}Fe_xO_3,\;(x=0.0\~0.5)$, electrodes is superior to $La_{0.9}Sr_{0.1}MnO_3$, among the samples of $x=0.0\~0.5$, the x=0.2 cathode shows the best activity for the oxygen reduction reaction. It is likely that the Fe-doping provides a better thermal stability to the materials but in turn imparts an inferior cathodic activity, such that the optimum trade-off is made at x=0.2 between the two factors. The total electrical conductivity and ion conductivity of $Gd_{0.8}Ca_{0.2}Co_{1-x}Fe_xO_3$, are measured to be 51 S/cm and $6.0\times10^{-4}S/cm\;at\;800^{\circ}C$, respectively. The conductivity values illustrate that the materials are a mixed conductor and the reaction sites can be expanded to the overall electrode surface, thereby providing a better cathodic activity than $La_{0.9}Sr_{0.1}MnO_3$.

캐소드 루테늄 촉매의 전기화학적 환원 처리가 고분자 전해질 연료전지 성능에 미치는 영향

최종호,Choi, Jong-Ho 한국전기화학회 2011 한국전기화학회지 Vol.14 No.2

Ru black was used for cathode catalyst in polymer electrolyte membrane fuel cell which showed low performance at the initial test. However, it was observed that the performance of Ru black cathode was dramatically enhanced after certain kind of experiment compared with initial one. It might be due to an electrochemical treatment in which a voltage was applied to the Ru cathode for constant period time. When a constant potential of 0.1 V was applied to Ru cathode for 30 min, the fuel cell performance of Ru cathode showed the best results. In order to investigate the effect of electrochemical treatment on the performance enhancement, the characteristics of electrochemically treated Ru black was compared with that of Ru black which was reduced under $H_2$ atmosphere. From XRD results, it was turned out that Ru black was not completely converted to metallic Ru by electrochemical treatment, but it is sufficient to be one of reasons for the performance enhancement. According to the results of CO stripping voltammetry, it was observed that some Ru was removed from Ru electrode by electrochemical treatment which might have a bad effect on the fuel cell performance. The removal of some Ru from as-received Ru black by electrochemical treatment is also another reason for the enhancement of fuel cell performance.

니켈(II)-거대고리 착물과 폴리 우레탄으로 변성한 이중 전극에서 에피네피린의 전기화학적 정량

조형화,권수경,이상학,배준웅,Cho, Hyung-Hwa,Kweon, Soo-Geong,Lee, Sang-Hag,Bae, Zun-Ung 한국전기화학회 2007 한국전기화학회지 Vol.10 No.3

본 연구는 뇨 속에 있는 에피네피린을 선택적으로 정량하기 위한 새로운 전기화학적 센서를 제작하고 그 특성을 연구한 것이다. 전극의 제작은 유리질 탄소전극에 촉매능이 있는 니켈(II)거대고리 착물을 전착시킨 후, 그 위에 생체적합성이 좋으며 음의 하전을 띤 polyuretane benzyl L-glutamate(PUBLG)로 막을 입힌 이중 폴리머 전극이다. 이 전극은 뇨 속에 있는 많은 방해물질에 대하여 좋은 선택성을 보였으며, 우수한 장기 안정성을 보였다. 최적 실험조건하에서 이 전극을 이용한 에피네피린의 정량범위는 $8.0\;{\times}\;10^{-7}\;M$에서 $2.0\;{\times}\;10^{-4}\;M$이고, 검출한계는 $1.0\;{\times}\;10^{-7}\;M$이다. 완충용액으로 5 배 희석한 뇨 시료에서 에피네피린의 회수율은 6 회 측정에서 $101.5({\pm}3.2)%$ 이었다. A new electrochemical sensor to selectively determine epinephrine was developed and its analytical characteristics has been investigated. A glassy carbon electrode was modified with Ni(II)-macrocyclic complex which has electrocatalytic effect. It was further modified with physiologically suitable and negatively charged polyuretane benzyl L-glutamate(PUBLG). The present electrode showed long term stability and it could be applied to the selective determination of epinephrine in urine sample with various coexisting compounds. Under the optimum experimental conditions the linear range was $8.0\;{\times}\;10^{-7}\;-\;2.0\;{\times}\;10^{-4}\;M$ and the limit of detection was $1.0\;{\times}\;10^{-7}\;M$. The recovery of epinephrine in urine sample diluted 5 times with buffer solution was $101.5({\pm}3.2)%$ for 6 measurements.

전기여과에 의한 거대이온성 분자체 분리현상연구

박영규,Park Young-Gyu 한국전기화학회 1998 한국전기화학회지 Vol.1 No.1

Theoretical model has been derived in the electrophoretic separation system where an electric potential is applied to the system in the axial direction. The effect of electrophoretic convection in the polymeric media is significantly contributed to separate large ionic-molecules because the conformation of large ionic-molecule quickly orients in the field direction. The dependence of the transport in the polymeric media upon field intensity and molecular size aids in understanding the transport of large ionic-molecule in the system, since the convective velocity of large ionic-molecule is accelerated inside a porous material. The separation of two different large ionic-molecules is predicted with a value of $(Pe_t/Pe_g)$ of individual large ionic-molecule using an operator and the reptation theories.

PC 비율에 따른 $LiPF_6/PC+EC+DEC$ 전해액의 물리적 특성 및 탄소분극과의 초기 전기화학적 특성

도칠훈,문성인,윤문수,Doh Chil-Hoon,Moon Seong-In,Yun Mun-Soo 한국전기화학회 2000 한국전기화학회지 Vol.3 No.4

The exfoliation of graphite (layer) was progressed due to the irreversible insertion of PC molecules between graphene layers, when propylene carbonate (PC) solvent was used as the organic solvents. The problem could be mitigated by the replacement of PC by ethylene carbonate (EC). But, the freezing point of EC-based electrolyte increased due to the high freezing point of $EC(36.2^{\circ}C)$. Therefore, EC+PC mixed electrolyte is expected as a good organic electrolyte for lithium ion battery. The EC-based organic electrolyte containing PC within pertinent quantity can be expected to have high molar conductivity and reduced exfoliation of graphite layer. The dielectric constant and molar conductivity of $LiPF_6/PC+EC+DEC$ electrolyte was investigated with a variation in the PC content. The electrochemical properties of carbon electrode in the electrolyte were also investigated. Molar conductivity and dielectric constant increased linearly by increasing the PC volume fraction in the electrolyte. The results of charge-discharge test for carbon/electrolyte/Li cell indicated that the initial irreversible specific capacity(IIC) of MCMB-6-28s and MPCF3000 decreased by the addition of $0.83 vol\%$ of PC, but increased with PC content over than $0.83 vol\%$. In the case of MPCF3000 and PCG100 having less than $10 vol\%$ PC, IIC was lower than 50 mAh/g. The discharge specific capacities varied with carbon material, but did not vary with PC content in the electrolyte.