Graduate Research Assistant
Contact Information
Baker Laboratory Ithaca, NY 14853
rgb57@cornell.edu
office:(607) 255-4164
Doped Metal Oxide Catalyst Supports for Applications
in Polymer Electrolyte Membrane Fuel Cells
Bachelor of Arts, 2007: Bellarmine University Louisville, KY
- National Science Foundation IGERT Fellowship Recipient, 2009-2011
- Valedictorian, Bellarmine University, 2007
- American Chemical Society Outstanding Chemistry Graduate, Louisville Section, 2007
- In Veritatis Amore Award for student Service and Leadership, Bellarmine University, 2007
- National Science Foundation REU, 2006
- Honorable Order of Kentuky Colonels, 2005
Project Description:
As the demand for fossil fuels increases, the call for alternative sources of energy becomes loud and clear. While many new technologies have been developed to address this call, material difficiencies and slow development have hindered their full intergration into our lives. One of the largest areas of innovation has been with fuel cells -- devices which directly convert chemical energy into electrical energy. Among the many different types of fuel cells which are described here, my primary interest lies with Polymer Electrolyte Membrane Fuel Cells (PEMFC), those which have the potential to power automobiles.
PEMFCs could potentially revolutionize the transportation industry, but many challenges must first be overcome. These challenges include fuel distribution infrastructure, improving device performance and efficiency to maximum levels, as well as lowering the cost and increasing the stability of materials. My research focuses on the last of these challenges.
Current PEMFCs use a platinum nanoparticle catalyst supported on amorphous carbon as the anode material (where the fuel is oxidized). However under the operating conditions of the fuel cell the carbon support is unstable, corroding away, and ultimately causing device failure. A good support material would be one with modest conductivity (only 1 millionth that of copper) and high stability in low pH, high positive potential environments (conditions like those in a fuel cell).
Figure 1. Pourbaix (Potential vs pH) diagram for Nb2O5. The highlighted region shows the conditions in a fuel cell and the stability of the niobium pentaoxide phase.
Environments like those in a fuel cell are highly oxidizing, so when thinking of materials that might be stable in a highly oxidizing environment, metal oxides which are in their highest oxidation state are the first to come to mind. We can describe the stability of metal oxides as a function of pH and potential using what chemists call a Pourbaix Diagram. That's just a fancy word for a graph of what the material is as we change the environment. The figure on the right shows a Pourbaix Diagram for Nb2O5. Note the red highlighted region that shows the environment like that in a fuel cell, and note that Nb2O5 doesn't change in that region.
If we look at all the metal oxides we can think of, surpisingly, only a small number are stable in this region. In fact, you can count them on one hand. They are Nb2O5, TiO2,WO3,and Ta2O5. With these oxides as my starting place, I am working on mixing them up in different ratios and adding other metals to them in small amounts to try and find one that is stable and has the required conductivity. Most metal oxides are not conducting at all, so the last part is harder than it sounds. But I am making progress and hopefully soon I'll have a new material that meets many, if not all of the requirements for a good fuel cell support.