Platinum Nanoparticles on Plasma-Pretreated Carbon Nanotubes Prepared By Atomic Layer Deposition As Polymer Electrolyte Membrane Fuel Cell Catalysts

Abstract

Polymer electrolyte fuel cells (PEMFC) are attracting attention as the next generation power supply for electric vehicles, unmanned aerial vehicles and submarines. However, the high price of fuel cell catalysts i.e. platinum (Pt) or platinum alloys is considered a major hurdle to the development of economical fuel cell electric vehicles. Another problem with Pt catalysts is the low stability of long term operation due to separation and aggregation of the catalyst from the carbon support resulting from repeated on-off switching. Recently, atomic layer deposition (ALD) has been proposed as a technique for synthesizing metal nanoparticles. ALD is considered to be the most advanced deposition technology that can control material size and composition in the atomic scale. In addition, ALD has demonstrated large scale conformal deposition of uniform films and particles over high aspect ratio trenches and complex three dimensional contours. In this study, Pt nanoparticles were successfully deposited on carbon nanotubes (CNTs) by ALD. The key to the success of high quality ALD Pt production has been found to be a plasma pretreatment that introduces functional groups that make the CNT surface ready to initiate the ALD nucleation. ALD Pt-CNT catalysts were evaluated as cathode catalysts for PEMFC membrane-electrode-assemblies (MEAs). As a result, even though the Pt load is significantly reduced, the performance is significantly improved compared to commercial PEMFC MEAs in terms of power and stability.