An in-depth understanding of chemical reactions occurring at solid-liquid interfaces is crucial for a large number of technological processes. These include heterogeneous catalysis, electrochemistry, corrosion, environmental science, development of energy sources, and others. At the same time, our knowledge about the processes which take place on the solid surfaces in a liquid medium remains incomplete. The main reason for this is that most of the conventional surface science methods are based on the use of various particles (electrons, ions, or atoms) to probe the surface. These methods work well under ultrahigh vacuum conditions. However, the use of them for the study of solid-liquid interfaces is limited due to the issues associated with the mean free path of the particles. Therefore, new experimental methods free from the above problems are needed.
Hydrogen peroxide ($H_2O_2$) is used for an effective oxidizing agent which is common in industry. On the surface of metal catalysts, $H_2O_2$ is converted into oxygen and water. In order to understand this process at the elementary level is greatly important in many industrial applications, such as, the direct synthesis of $H_2O_2$ from $H_2$ and $O_2$. Using a chemicurrent approach, we not only studied chemical reactions at solid-liquid interface but also rate of $H_2O_2$ decomposition and the corresponding chemicurrent are sensitive to concentration and pH of the reactive solution. For that matter, $H_2O_2$ decomposition catalyzed on Pt/n-Si catalysts is used. which is based on detection of hot electrons created as a result of dissociative adsorption of $H_2O_2$ molecules on platinum. This phenomenon is explained by variations of the potential barrier for an electron transfer at the Pt/solution interface caused by adsorption of $H^+$ and $OH^-$ species from the solution on the catalytic surface.
고체-액체 계면에서의 화학반응을 이해하기 위하여 전기화학, 다중성분의 촉매반응, 환경과학 등의 여러 분야에서 실험이 진행되고 있습니다. 고전 표면 과학이 전자, 이온, 원자 등의 다양한 입자를 사용하는 것에 기초를 두고 있기 때문에 고체와 액체 계면에서의 반응과정은 잘 알려져 있지 않습니다. 이러한 방식은 초고진공 상황에서는 잘 작동하지만 현실에서는 MFP(Mean Free Path) 문제로 잘 작동하지 않기 때문입니다. 따라서 과산화수소를 이용한 금속촉매에서의 분해반응을 이용하여 실험을 진행하였습니다. 과산화수소는 부산물이 물과 산소뿐인 환경 친화적 산화제로 기초수준의 많은 산업적 활용을 위해서 중요합니다. 화학적으로 발생한 전류를 이용하여 화학반응뿐만 아니라 과산화수소의 분해반응이 과산화수소 용액의 농도와 pH 에 따른 변화에 대하여 민감하다는 것을 알 수 있었습니다. 이를 확인하기 위하여 Pt/n-Si 촉매 나노 소자를 사용하였습니다.
