Carbon Nano-Onions Synthesized By Laser Pyrolysis As Catalyst Support in Proton Exchange Membrane Fuel Cells

Abstract

Proton exchange membrane fuel cells (PEMFC) typically utilize nanostructured carbon (such as carbon black, carbon nanotubes, graphene and porous carbon) as the support material for catalysts. The durability and electrical conductivity of the material are important contributors to the fuel cell performance, as well as the structural design to maximize the triple phase boundary between the fuel, the catalyst and the electrolyte membrane. In view of engineering the structure and composition of the carbon catalyst support, a versatile manufacturing method with flexibility in size, shape, structure, and properties (such as electrical conductivity) of the carbon material would open up a chance to investigate an expansive composition matrix for potential improvements of the cell performance. In addition, for potential commercialization, processes that are clean and high-throughput are desired. Laser pyrolysis of hydrocarbons has been established as a widely adopted gas phase production of carbon nanoparticles. In particular, multilayered particles with concentric graphitic shells, commonly called carbon nano-onions, are of interest as the size, shape and the number of graphitic shells are easily tuned by adjusting the experimental parameters. In this work, we present a CO2 laser induced pyrolysis of gaseous hydrocarbons (such as acetylene and ethylene) that generates various types of carbon nanoparticles, and demonstrate that these carbon nano-onions have superior durability and electrical conductivity to commonly used commercial carbon materials such as Vulcan XC-72. Platinum-decorated carbon nano-onions have been used to fabricate PEMFCs and they are shown to have comparable performance to conventional cells, and the accelerated stress test reveals that the durability of the cells have improved.