(273f) The Role of Phosphorus in Nitrogen-Doped Graphite Oxygen Reduction Catalysts in PEM Fuel Cells

The fuels cells have the potential to transform the energy utilization and distribution sector. Proton exchange membrane fuel cells, including the direct methanol fuel cells depend on the reduction of oxygen in the fuel cell cathode. Currently, the cost and availability of platinum or platinum alloy catalysts used to accelerate the sluggish oxygen reduction reaction prohibit fuel cells from mass production. Inexpensive materials comprised of nitrogen-doped graphitic carbon have been shown to have high oxygen reduction activity. Our recent work has shown significant enhancement in oxygen reduction activity through the incorporation of phosphorous into nitrogen-doped carbon catalysts. The incorporation of multiple heteroatom types into the graphite structure could allow for tailoring of these unique catalyst materials. . The nanostructure of these materials are examined with transmission electron microscopy (TEM). The surface and subsurface material composition are determined from X-ray photoelectron spectroscopy (XPS). Many bulk and surface characterization techniques, including X-ray absorption spectroscopy, Mössbauer spectroscopy, Raman spectroscopy and temperature-programmed oxidation coupled with mass spectrometry (MS) are employed to understand the structural and molecular characteristics of these materials. The reaction kinetics and behavior are examined through a variety of electrochemical methods. The findings from these characterization and kinetic studies as well as synthesis techniques, including methods of phosphorus incorporation will be discussed.