Michigan State University (East Lansing, MI) researchers have found a method for making a carbon-metal-nitrogen oxygen reducing cathode catalyst. According to inventors MSU Chemical Engineering Professor Scott A Calabrese Barton, Kothandaraman Ramanujam and Vijayadurga Nallathambi, the method includes mixing a carbon source with a transitional metal precursor to form a metal precursor loaded carbon substrate; adding a nitrogen precursor compound to the metal precursor loaded carbon substrate to form a carbon-metal-nitrogen precursor. Those steps are followed by pyrolyzing the carbon-metal-nitrogen precursor in a closed vessel to form an oxygen reducing cathode catalyst.
The carbon-metal-nitrogen catalyst requires no precious metal such as platinum (Pt), and also provides benefits such as controlled deposition of catalytically active nitrogenous compounds that can increase the catalytic activity of the catalyst when compared to gaseous deposition of nitrogen to the surface of the carbon support. The catalyst is detailed in U.S. Patent Application 20100048380.
There is an increasing interest to replace platinum (Pt) based electro-catalysts with cost-effective non-noble catalysts for the oxygen reduction reaction ("ORR") in low-temperature fuel cells, such as Polymer Electrolyte Fuel Cells (PEFCs) and Direct Methanol Fuel Cells ("DMFCs") etc. Non-noble metal catalysts based on iron (Fe) and cobalt (Co) ions are among the possible candidates for replacement of Pt based catalyst metals for ORR. These catalysts are active towards ORR and exhibit selectivity towards ORR in the presence of a fuel, thereby increasing the volumetric energy density of a DMFC.
The Michigan State researchers created a method to control the anchoring of a nitrogen containing compound on a high surface area carbon surface, which actively contributes to the catalytic activity of the cathode catalyst over preexisting methods of depositing nitrogen, thereby effectively increasing the catalytic activity per unit mass of catalytic material on a substrate. The cathode catalyst material produced lowers the cost for producing the catalyst material and follows a simple synthesis method compared to platinum/carbon catalysts and other non-precious metal catalysts conventionally used in fuel cell designs. The nano-carbon catalyst supports can include carbon nanotubes, carbon nanofibers, carbon nanowires, carbon nanohorns and carbon nanorings.