He has been studying the structure and functions of novel material phases and electron transfer reactions at solid/liquid interfaces for more than 35 years. His main contribution is investigation on construction, structure, observation, and functions of atomically/molecularly ordered interphases such as electrochemical atomic layer epitaxy of metal and self-assembled monolayer. He has demonstrated that functional phases constructed by processes at solid/liquid interfaces are highly ordered and show very high performance comparable to those constructed by much more complicated and expensive vacuum processes. He developed many in situ techniques to study interfacial processes in solution in atomic/molecular resolution. He led this field internationally by not only publishing many influential papers and presenting many invited lectures but also organizing many international meetings and symposia and acting as committee members of international societies and editor and editorial member of international journals as shown below.