Graphite-Based Non Precious Metal Catalyst for Oxygen Reduction Reaction

Abstract

The high cost of Pt-based catalysts for the anode and cathode has greatly limited the distribution and the commercialization of polymer electrolyte fuel cells (PEFCs). Non-precious metal catalysts (NPMCs) have shown high activity and low hydrogen peroxide yields [1, 2], and are a possible alternative to Pt-based catalysts for oxygen reduction reaction (ORR) in the PEFC cathode. In this work, we explore the development of graphite-based catalysts for fuel cell applications. The desired mechanical and chemical stability of graphite could improve durability of NPMC systems. However, implementation of graphite as a catalyst precursor presents new challenges as it is chemically inert. Given the fact that NPMCs are composed of carbon, nitrogen, and transition metals, a systematic approach will be presented to incorporate transition metal and nitrogen precursors into graphite structures. Graphite as a starting material will be treated with high temperature and pressure to intercalate transition metals and/or nitrogen compounds. The formation of active sites will be induced by the increase of defects in the material by harsh acid treatments and by microwaved synthesis. Structural, chemical, and morphological information will be presented via X-ray (XRD and XPS) techniques along with electron microscopy (SEM, TEM). The electrochemical activity for the ORR using RRDE for these graphite-based catalysts will be presented in both alkaline and acidic media. Our preliminary results indicate an improvement of the catalytic activity upon addition of defects, metal and nitrogen compounds.