• 한국진공학회지
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• 제21권2호
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• pp.99-105
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• 2012

금 나노입자 촉매를 이용한 전기화학적 식각법에 의해 실리콘 표면에 짧은 시간의 효과적인 텍스쳐링을 통한 나노구조를 제작하여 무반사 특성을 조사하였다. 실험을 위해, 열증발증착법과 급속열처리법을 이용하여 단결정 실리콘 표면에 20 nm에서 150 nm 크기의 금 나노입자를 형성하였고, 습식식각을 위해 금 나노입자가 코팅된 실리콘을 과산화수소와 불화수소가 포함된 식각용액에 1분 동안 담가두었다. 전기화학적 습식식각을 확인하기위해, 금 나노입자가 코팅된 실리콘을 음극으로 각각 -1 V와 -2 V의 전압을 인가하여 식각깊이와 반사율 스펙트럼을 비교하였다. 태양광 스펙트럼(air mass 1.5)을 고려하여 태양가중치 반사율을 계산한 결과, 전압을 인가하지 않고 식각된 실리콘 표면의 반사율이 25.8%인 반면, -2 V의 전압을 인가하여 8.2%로 반사율을 크게 줄일 수 있었다.

• 센서학회지
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• 제21권6호
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• pp.425-428
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• 2012

This paper presents the fabrication and characterization of graphene based hydrogen sensors. Graphene was synthesized by annealing process of Ni/3C-SiC thin films. Graphene was transferred onto oxidized Si substrates for fabrication of chemiresistive type hydrogen sensors. Au electrode on the graphene shows ohmic contact and the resistance is changed with hydrogen concentration. Nanoparticle catalysts of Pd and Pt were decorated. Response factor and response (recovery) time of hydrogen sensors based on the graphene are improved with catalysts. The response factors of pure graphene, Pt and Pd doped graphenes are 0.28, 0.6 and 1.26, respectively, at 50 ppm hydrogen concentration.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.133-133
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• 2013

For both oxygen reduction (ORR) and hydrogen oxidation reactions (HOR) of proton electrolyte membrane fuel cells (PEMFCs), alloying Pt with another transition metal usually results in a higher activity relative to pure Pt, mainly due to electronic modification of Pt and bifunctional behaviour of alloy surface for ORR and HOR, respectively. However, activity and stability are closely related to the preparation of alloy nanoparticles. Preparation conditions of alloy nanoparticles have strong influence on surface composition, oxidation state, nanoparticle size, shape, and contamination, which result from a large difference in redox priority of metal precursors, intrinsic properties of metals, increasedreactivity of nanocrystallites, and interactions with constituents for the synthesis such as solvent, stabilizer, and reducing agent, etc. Carbon-supported Pt-Ni alloy nanoparticles were prepared by the borohydride reduction method in anhydrous solvent. Pt-Ru alloy nanoparticles supported on carbon black were also prepared by the similar synthetic method to that of Pt-Ni. Since electrocatalytic reactions are strongly dependent on the surface structure of metal catalysts, the atom-leveled design of the surface structure plays a significant role in a high catalytic activity and the utilization of electrocatalysts. Therefore, surface-modified electrocatalysts have attracted much attention due to their unique structure and new electronic and electrocatalytic properties. The carbon-supported Au and Pd nanoparticles were adapted as the substrate and the successive reduction process was used for depositing Pt and PtM (M=Ru, Pd, and Rh) bimetallic elements on the surface of Au and Pd nanoparticles. Distinct features of the overlayers for electrocatalytic activities including methanol oxidation, formic acid oxidation, and oxygen reduction were investigated.