초록 ▼

Methanol 과 formic acid등의 작은 유기 물질을 연료로 사용하는 연료전지의 연료전지의 산화전극으로 백금이 널리 이용된다. 그러나, 귀금속인 백금의 가격이 높기 떄문에 백금을 이용한 연료 전지의 경제적 효율성이 저하된다. 이러한 문제점을 해결하기 위하여, 외부 금속을 전극의 표면에 도포하여 백금의 전극의 촉매적 활성을 증가시키려는 연구가 활발히 진행되고 있다. 외부 금속을 이용한 전극 표면의 변형은 미달전위법과 비가역 흡착법을 통하여 성취된다. 방법의 비가역성 때문에 비가역 흡착법에 의하여 변형된 백금 전극

Methanol 과 formic acid등의 작은 유기 물질을 연료로 사용하는 연료전지의 연료전지의 산화전극으로 백금이 널리 이용된다. 그러나, 귀금속인 백금의 가격이 높기 떄문에 백금을 이용한 연료 전지의 경제적 효율성이 저하된다. 이러한 문제점을 해결하기 위하여, 외부 금속을 전극의 표면에 도포하여 백금의 전극의 촉매적 활성을 증가시키려는 연구가 활발히 진행되고 있다. 외부 금속을 이용한 전극 표면의 변형은 미달전위법과 비가역 흡착법을 통하여 성취된다. 방법의 비가역성 때문에 비가역 흡착법에 의하여 변형된 백금 전극이 더 안정하며, 백금 전극 표면에 비가역 방법에 의하여 도포된 외부금속의 역할에 관한 연구에 많은 관심이 모아지고 있다.

Abstract ▼

Platinum is exclusively employed as an anode in fuel cell using small organic molecules, like methanol and formic acid, as fuels. However, the cost of such a fuel cell is high due to the price of platinum. To reduce the cost, many researches are being conducted to .enhance the catalytic activity of

Platinum is exclusively employed as an anode in fuel cell using small organic molecules, like methanol and formic acid, as fuels. However, the cost of such a fuel cell is high due to the price of platinum. To reduce the cost, many researches are being conducted to .enhance the catalytic activity of platinum by depositing foreign metals on the surfaces of the electrodes. Modification of platinum electrode surfaces with metal adsorbates could be achieved by underpotential deposition or irreversible adsorption. Since the metallic layer depositing by the irreversible adsorption is more stable due to the irreversibiiity of the depositing method, a lot of interest is focused on the role of the foreign metal adatoms prepared with the irreversible adsorption.
In this project, investigated are the electrochemical behavior of irreversibly adsorbed Sb on Pt(111) and Pt(100) surfaces, the surface structure of irreversibly adsorbed Bi on Pt111), and the oxidation of methanol and formic acid on Pt(111) and Pt(100) electrcdes modified with Bi. A conbasting behavior of irreversibly adsorbed Sb on Pt(111) and Pt(100) was observed On Pt(100), the N1 coverage of irreversibly adsorbed oxygenous Sb was 033. Upon the reduction of the oxygenous Bi layer, addition Bi was underpotentially deposited into the oxygen vacancies formed during the reduction. The coverage of metallic Sb on Pt(100) was determined to be 0.39.
On the other hand, the reduced metallic Sb atoms on Pt(111) formed an electrochemically inactive aggregates and the saturation coverage was measured to be 0.38.
The irreversibly adsorbed Bi on Pt(111) and Pt(100) decreased the catalytic activity toward oxidation of methanol and increased the catalytic activity toward oxidation of formic acid. In methanol oxidation, Bi adatoms reduced the number of ective sites to decrease the overall oxidation rate although the formation of catalytic poison or the adsorption of the mison was inhibited. On the contrary, both of reduced and oxidized Bi adatoms b s e d the oxidation rate of formic acid. The reduced Bi adlayer enhanced the dissociative adsorption of formic acid to increase the oxidation rate, while the oxidized Bi layer increase the rate of the oxidative removal of the poison to increase the oxidation rate.
An atomic image of the saturated oxygenous Bi layer on Pt(111) was observed with in-situ STM. The surface structure of Bi was (3x3), which implies that the coverage of Bi is 0.22 and that the number of electrons involved in the redox process of the adsorbed Bi is 3. However, more experimental result. are absolutely needed to support the above statement. Any way, the in-situ atomic image obtained in this research is the very fust one in Korea.
The above results are very irnporEant in understanding the behavior of irreversibly adsorbed foreign metal adatoms and their mles in oxidation of small organic molecules. In addition, the in-situ STM technique established in this project is expected to be a novel research method to study the liquid/solid interface in atomic level.

목차 Contents

• 연구내용...5
• 가. 연구결과 요약문(국.영문)...5
• 나. 서론...7
• 다. 연구방법 및 이론...9
• 라. 결과 및 고찰...12
• 마. 결론...31
• 바. 인용문헌...32
• 논문발표목록서 및 자체평가서...35