Recently, clean energy sources derived from renewable energy have attracted much attention as an alternative to global climate change and petroleum-based energy source depletion. Therefore, it is essential to secure environmentally friendly clean energy sources for the survival, health and life of human beings in the future. To achieve this, one of the key technologies is the energy conversion, production, and storage using electrocatalysts. Thus, in this dissertation, the development of highly efficient and robust electrocatalysts and its application will be described.
First, in Chapter 2, we will describe multiscale Pt nanoarchitecture as electrocatalysts for polymer electrolyte membrane fuel cells (PEMFCs) that converts hydrogen energy into electrical energy. In contrast with conventional commercial catalysts such as Pt/C, multiscale Pt nanoarchitecture catalyst have no carbon corrosion phenomenon and dramatically reduce the thickness of the electrodes resulting in superior durability and mass transfer enhancement. In addition, it is possible to control the crystal plane of the catalyst surface to achieve excellent specific activity via oblique angled deposition process.
Secondly, in Chapter 3, we will describe the development of high-performance 3D Au nanoarchitectural electrocatalysts for $CO_2$ reduction systems which convert $CO_2$ to electro-fuels. Herein, we controlled the microstructure of Au nanowires to form high index plane and high density of grain boundaries. Simultaneously, by fabricating 3D Au nanoarchitectures to induce local pH gradient effect, high faradaic efficiency at low overpotential could be obtained.
Lastly, the aforementioned 3D nanoarchitecture electrocatalysts were fabricated by nanotransfer printing process. Because this process is very simple and can be mass-produced, thus, it can be applied to real industry. Furthermore, if we extend these processes to a variety of materials, it will be able to provide a new pathway for the development of highly efficient and robust electrocatalysts to various energy application fields.