With the depletion of fossil fuels, the development of renewable energy is becoming increasingly important. In the case of polymer electrolyte membrane fuel cells (PEMFCs), it is possible to obtain energy through electrochemical reaction. The energy efficiency of PEMFCs is very high, and there is low discharge of environmental pollutants. However, it is necessary to develop a catalyst for higher efficiency, and platinum catalysts are widely used because of their high reactivity to various electrochemical reactions. Platinum is undergoing much research to improve stability as well as activity in order to minimize its use due to high rarity and price. These include size control of platinum nanoparticles, shape control, core-shell structure, and nano-alloys. In the case of nano-alloys, the electronic and geometric structure of the platinum are changed by the alloying effect, and the catalyst characteristics can be greatly improved. In this thesis, we will focus on the study of the application of platinum nano-alloy catalysts as electrochemical catalysts by controlling the structure and improving the activity and stability.