• Journal of Electrochemical Science and Technology
• /
• 제15권1호
• /
• pp.152-160
• /
• 2024

In this study, ZnCo₂O₄ nanoparticles were synthesized via the coprecipitation method using different annealing temperatures from 200℃ to 800℃. By varying the treatment temperature, the morphology changed from amorphous to tetragonal, and finally to polygonal particles. As temperature increased, the sizes of the nanoparticles also changed from 5 nm at 200℃ to approximately 500 nm at 800℃. The fabricated material was used to modify the working electrode of a screen-printed carbon electrode (SPE), which was subsequently used to survey the detection performance of the antibiotic, chloramphenicol (CAP). The electrochemical results revealed that the material exhibits a good response to CAP. Further, the sample that annealed at 600℃ displayed the best performance, with a linear range of 1-300 μM, and a limit of detection (LOD) of 0.15 μM. The sensor modified with ZnCo₂O₄ also exhibited the potential for utilitarian application when the recovery in a real sample was above 97%.

• 한국재료학회지
• /
• 제31권5호
• /
• pp.272-277
• /
• 2021

Owing to its low cost, easy fabrication process, and good ionic properties, aqueous supercapacitors are under strong consideration as next-generation energy storage devices. However, the limitation of the current collector is its poor electrochemical stability, leading to low energy storage performance. Therefore, a reasonable design of the current collector and the acidic electrolyte is a necessary, as well as interfacial engineering to enhance the electrochemical performance. In the present study, graphite foil, with excellent electrochemical stability and good electrical properties, is suggested as a current collector of aqueous supercapacitors. This strategy results in excellent electrochemical performance, including a high specific capacitance of 215 F g^-1 at a current density of 0.1 A g^-1, a superior high-rate performance (104 F g^-1 at a current density of 20.0 A g^-1), and a remarkable cycling stability of 98 % at a current density of 10.0 A g^-1 after 9,000 cycles. The superior energy storage performance is mainly ascribed to the improved ionic diffusion ability during cycling.

• 전기화학회지
• /
• 제14권2호
• /
• pp.110-116
• /
• 2011

Ru black을 고분자 전해질 연료전지용 cathode 촉매로 사용했을 때 초기에는 연료전지 성능이 낮게 나타났으나, 일련의 실험을 거치는 동안 연료전지 성능이 점차 증가되는 것이 관찰되었다. 이는 Ru black의 전기화학적 환원으로 인한 것으로 판단되는대, Ru black 촉매에 외부에서 가해지는 전압과 그 전압을 가하는 시간을 변화시켜 본 결과 0.1V를 30분 이상 가하게 되면 Ru black의 성능 향상이 극대화 되었다. 성능 향상 원인을 확인해 보기 위해 수소 분위기 하에서 환원된 Ru black과 XRD patterns을 비교한 결과, Ru black 촉매가 전기화학적 환원처리를 통해 완전히 metallic Ru으로 전환되었다고 판단하기는 어려웠다. 또한 Ru black을 이용해 전기화학적 환원 처리 전후의 CO stripping voltammetry를 비교해 본 결과, Ru black 중에 일부는 metallic Ru으로 환원되었지만, 일부의 Ru이 반대편 전극으로 제거됨을 확인할 수 있었다. 이 과정 중에 제거된 Ru이 연료전지 성능에 나쁜 영향을 미칠 수 있을 것이라 생각된다. 따라서, 본 연구에서 제시된 Ru black의 전기화학적 처리 과정을 통해서 일부의 Ru은 반대쪽 전극으로 제거되고, 산화된 상태로 존재하는 일부의 Ru이 metallic Ru으로 변화됨으로서 연료전지 성능이 향상된 것으로 사료된다.

• Korean Chemical Engineering Research
• /
• 제59권2호
• /
• pp.159-164
• /
• 2021

부착형(attachable) 타입의 웨어러블 디바이스 적용을 위한 패브릭(fabric)이나 텍스처(textiles) 타입의 고성능 전극 소재 개발에 대한 필요성이 부각되고 있다. 본 연구에서는 유연 전극 소재로 탄소나노튜브 섬유(CNT fibers)를 응용하고자, CNT fibers의 전기화학적 특성과 이를 적용한 비효소적 글루코스 센싱 성능을 확인하였다. CNT fibers의 표면 구조는 주사전자 현미경(SEM)을 이용하여 분석하였으며, 전기화학적 특성 및 센싱 성능 분석은 시간대전류법와 순환전압 전류법, 전기화학 임피던스 분석법을 이용하여 수행되었다. CNT fibers 전극은 낮은 capacitive current와 산화-환원 화학종과 전극 계면 간의 효율적인 direct electron transfer에 의한 우수한 electrochemical activity 등 향상된 전기화학적 특성으로 인해 높은 감도와 넓은 선형 농도 범위, 그리고 낮은 검출 한계 등 우수한 센싱 특성을 보였다. 따라서, 본 연구는 CNT fibers 기반의 고성능 유연 전극 소재 개발을 위한 기초 연구로 활용될 수 있을 것으로 기대된다.

• Journal of Electrochemical Science and Technology
• /
• 제6권3호
• /
• pp.75-80
• /
• 2015

We introduce a new synthesis method to prepare small TiO₂ nanoparticles with a narrow particle size distribution, which is achieved by electron beam (E-beam) irradiation. The effects of E-beam irradiation on the synthesis of TiO₂ nanoparticles and the electrochemical performance of TiO₂ nanoparticles as alternative anode materials for Li-ion batteries are investigated. The TiO₂ nanoparticles induced by E-beam irradiation present better cycling performance and rate capability than the TiO₂ nanoparticles synthesized by normal hydrolysis reaction. The better electrochemical performance is attributed to small particle size and narrow particle size distribution, resulting in the large surface area that provides innumerable reaction sites and short diffusion length for Li⁺ through TiO₂ nanoparticles.

• Journal of Electrochemical Science and Technology
• /
• 제13권3호
• /
• pp.398-406
• /
• 2022

To satisfy the growing demand for high-performance batteries, diverse novel anode materials with high specific capacities have been developed to replace commercial graphite. Among them, cobalt hydroxides have received considerable attention as promising anode materials for lithium-ion batteries as they exhibit a high reversible capacity owing to the additional reaction of LiOH, followed by conversion reaction. In this study, we introduced graphene in the fabrication of Co(OH)₂-based anode materials to further improve electrochemical performance. The resultant Co(OH)₂/graphene composite exhibited a larger reversible capacity of ~1090 mAh g^-1, compared with ~705 mAh g^-1 for bare Co(OH)₂. Synchrotron-based analyses were conducted to explore the beneficial effects of graphene on the composite material. The experimental results demonstrate that introducing graphene into Co(OH)₂ facilitates both the conversion and reaction of the LiOH phase and provides additional lithium storage sites. In addition to insights into how the electrochemical performance of composite materials can be improved, this study also provides an effective strategy for designing composite materials.

• 전기화학회지
• /
• 제12권1호
• /
• pp.68-74
• /
• 2009

본 연구에서는 탄소성형 분리판의 물리화학적, 전기화학적 특성을 분석하여 수소 및 개미산연료 전지의 성능에 미치는 영향을 알아보았다. 기존 기계가공 탄소분리판과 탄소복합소재 탄소성형 분리판의 접촉저항, 부식특성, 소수성을 비교 평가하였다. 특히, 현재 연구개발 중인 탄소복합소재 성형분리판의 경우 계면접촉저항이 기계가공 분리판보다 1.5배 높게 나타났으며, 내식성 실험에서는 산에 취약하여 분리판 표면이 거칠어지고 결정성이 감소하였다. 연료전지의 성능은 분리판의 계면접촉저항에 크게 영향을 받았으며, 계면저항이 적은 기계가공 분리판이 수소 및 개미산 연료 전지에서 높은 성능을 나타냈다.

• 전기화학회지
• /
• 제21권1호
• /
• pp.12-20
• /
• 2018

To solve low cycle efficiency of the zinc anode in Zn-air batteries by corrosion, this study examined the effects of Al as a cathodic protection additive to Zn. The Al-mixed Zn anodes were produced by mixing Zn and Al powder (1, 2, and 3 wt. %). To compare the effects of the Al additive, Si was selected under the same conditions. The morphology and elemental composition of the additives in the Zn were characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, and inductively coupled plasma - mass spectrometry. The anti-corrosion effects of the Al and Si-mixed Zn anodes were examined by linear polarization. Cyclic voltammetry and charge-discharge tests were conducted to evaluate the electrochemical performance of the Al and Si-mixed Zn anodes. As a result, the Al-mixed Zn anodes showed highest corrosion resistance and cycling performance. Among these, the 2 wt.% Al-mixed Zn anodes exhibited best electrochemical performance.

• Journal of Electrochemical Science and Technology
• /
• 제7권2호
• /
• pp.139-145
• /
• 2016

The electrochemical performance of carbon-coated LiMn₂O₄ nanoparticles was reported. The polydopamine layer was introduced as a new organic carbon source. The carbon layer was homogeneously coated onto the surface of the LiMn₂O₄ nanoparticles because the polymerization process from the dopamine solution (in a buffer solution, pH 8.5) easily and uniformly formed a polydopamine layer. The phase integrity of LiMn₂O₄ deteriorated during the carbon-coating process due to oxygen loss, although the main structure was maintained. The carbon-coated sample led to improved rate capability because of the effect of the conductive carbon layer. Moreover, the carbon coating also enhanced the cyclic performance. This indicates that the carbon layer may suppress unwanted side reactions with the electrolytes and compensate for the low electronic conductivity of the pristine LiMn₂O₄.

• Journal of Electrochemical Science and Technology
• /
• 제9권1호
• /
• pp.1-8
• /
• 2018

The effect of mixing ratio on the corrosion protection of carbon steel coated by a film composed of poly(vinylidene) fluoride (PVDF) and poly(methyl methacrylate) (PMMA) was examined using electrochemical impedance spectroscopy. Surface crystallization behavior and thermal properties of the PVDF/PMMA coated carbon steel were evaluated using polarized optical microscopy and differential scanning calorimetry, respectively. A Maltese cross-pattern spherulite crystal was observed in the PVDF/PMMA coating film, which became more apparent with increasing PVDF content. The highest corrosion protection performance was achieved with 60 wt.% PVDF-coated carbon steel, and delamination and corrosion reactions were observed for 20 wt.% PVDF-coated carbon steel. Further, corrosion protection performance with an amorphous/crystal mixture (PVDF/PMMA, 60/40 (w/w)) was better than those observed in the amorphous domain and the perfect-crystal domain of the PVDF/PMMA blended coating system.