Hollow Nanocoils to Enhance Water Splitting, an Essential Process for the Hydrogen-Based Economy

Professor Kim Young-keun’s group from the Department of Materials Science and Engineering, College of Engineering at Korea University, and Professor Nam Ki-tae’s group from the Department of Materials Science and Engineering at Seoul National University, conducted a joint research project and have developed a hollow nanocoil composite that can increase the efficiency of existing water splitting catalysts.

The results of the study were published online on September 24 in Small, an international nanotechnology journal, featuring on the cover of the issue.
- Title of Paper : Inorganic Hollow Nanocoils Fabricated by Controlled Interfacial Reaction and Their Electrocatalytic Properties
- Author : 김영근 (교수) (교신저자/고려대학교), 남기태 (교수) (교신저자/서울대학교), 문준환 (제1저자, 고려대학교), 이무영 (제1저자, 서울대학교), 박범철 박사 (공동저자, 고려대학교), 전유상 박사 (공동저자, 고려대학교), 김승현 (공동저자, 고려대학교), 김태순 (공동저자, 고려대학교), 고민준 (공동저자, 고려대학교), 조강희 (공동저자, 서울대학교)

Electricity-driven environment-friendly energy conversion reaction which produces hydrogen and oxygen, which are clean energy sources. It is considered a process that will be essential to the hydrogen-based economy of the future. Photosynthesis is a representative water splitting reaction found in nature, and through it water oxidation is carried out through the use of a cluster based on manganese and calcium. Inspired by the manganese-calcium cluster, a manganese-based electrocatalyst was developed to replace the noble metal catalysts. Due to its high overpotential, studies have been steadily conducted to identify a breakthrough that can improve the performance of this technique.

In order to maximize the number of active sites at which the electrocatalyst can make contact with water molecules, the research team focused on the spiral nanocoil, which has the largest possible surface area in a 3-dimensional structure. After synthesizing nanocoils through electroplating, the research team synthesized 3D transition metal-based single-component and multicomponent inorganic hollow nanocoils on the basis of the differences in their electrochemical pathways and their material diffusion rates. The team developed the world’s first nanocomposite that was prepared by attaching oxide manganese nanoparticles to a manganese-based hollow nanocoil, thereby significantly increasing its surface area and its number of active sites compared with the performance of previously reported manganese-based catalysts.
*Active site refers to the site of a catalyst at which the reaction with water is substantially facilitated by collision with a reactant. As the collision between a catalyst and a reactant occurs more actively, the activation energy is decreased and the reaction rate is increased.
 
The research team explained the significance of the study, saying “The novel nanostructure in which nanoparticles are attached to spiral nanocoils suggested a new catalyst design methodology that enables one to efficiently increase the performance of electrocatalysts in a simple manner. The nanostructure can be applied to various other areas in the fields of energy, environment and biotechnology, where the large surface area of the hollow nanocoil structure and active site control are necessary.”
 
The study was supported by the Mid-Career Research Program and the Creative Materials Discovery Program of the Korea Ministry of Science and ICT (MSIT).