Fabrication and functionalization of a pure non-noble metal catalyst showing activity and time stability for large scale applications

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Fuel cells (FC) are electrochemical devices for the generation of electricity using the reduction of oxygen (from air) on the cathode electrode side, and the oxidation of hydrogen fuel on the anode side. The resulting products of the full electrochemical reaction are the electron current and water. Polymer electrolyte membrane fuel cells (PEM-FC) are now strongly considered as a mobile energy source in the transportation sector as well as portable microelectronic devices. Besides the polymer electrolyte, one key element in the PEM-FC is the catalyst enabling the chemical reactions on both electrodes. More importantly, the oxygen reduction reaction (ORR) requires a relatively large amount of catalyst for the reaction to proceed at a rate large enough to generate the required electrical power. The catalyst used presently is platinum (Pt) in the shape of nanoparticles, a very expensive noble metal with relatively limited supply making the PEM-FC alternative uncompetitive with respect to internal combustion engines. This project uses a non-noble metal, namely iron (Fe), dispersed at the atomic level using nitrogen functionalities on a new support called graphene nanoflakes (GNF) generated in a thermal plasma reactor. This dispersion mimics the chemical organization of our blood heme structure. The interest of this new GNF support and method of fabrication is threefold: (a) the N/Fe-GNF showed for the first time a catalyst that is stable in time in the PEM-FC environment during tests of 100 hours; (b) the level of nitrogen functionalities attained which is important for the total current and power (the activity), reaches values that were never attained before, doubling the record high values attained by any other carbon support; (c) the method of fabrication using a thermal plasma reactor enables purity of the product and simplicity of a process that can easily be integrated in a large scale production of the fuel cells.