Carbon Supported Pt Nanocatalysts Decorated with Titanium Oxide By Coaxial Pulse Arc Plasma Deposition

Fuel cells are power sources converting chemical energy into electrical energy through electrochemical reactions occurring on catalyst surfaces, in general, on Pt or Pt alloy surfaces. Hydrogen is mostly and widely used as the fuel, but other fuels such as methanol, ethanol and formic acid are investigated as alternatives because of their higher energy density as well as easy transport in our society. Among these alternative systems, direct methanol fuel cells (DMFCs) have been developed and considered for applications in electronics because of their high theoretical energy density, simple systems and ease of handling. In contrast to these merits even over the hydrogen-based systems, the complicated and slow electrooxidation reactions of methanol have hampered their commercialization. In this light, a variety of electrocatalysts for methanol oxidation reactions have been synthesized and evaluated in order to enhance the sluggish reactions, in other words, to reduce a fuel cell stack cost by decreasing the amount of Pt usage (e.g., alloying with other metals, making Pt monolayer on other metals, making composites with other substances to have synergy effects, and controlling the shapes to utilize more active surface structures). The carbon supported Pt nanoparticles (Pt/C) have been recognized as the most reasonable starting point for each fundamental research, though alloys are widely used in the research and commercial products for achieving better performance. Pt and its alloys have the best activities in methanol oxidation reactions (MOR) and oxygen reduction reactions (ORR), and, in order to utilize Pt surface effectively, Pt/C catalysts have been generally prepared, e.g. , by an i mpregnation method involving a wet - chemical reduction ( i.e. , impregnation of the carbon supports with solutions containing the metal salts to be deposited). This method is quite simple and is easy for large-scale production. Very recently, we have proposed a new approach for preparation of Pt/C catalysts by arc plasma deposition (APD) method, where Pt nanoparticles can be deposited on carbon in vacuum and has been applied for various fields other than fuel cell catalyst. Herein, we focus on a preparation of new MOR and ORR catalysts by using our coaxial pulse APD method, where two different metal sources (Pt and Ti) can be deposited on carbon support through vacuum processes. The morphology of the obtained sample was characterized by the scanning electron microscope