Improving catalysts for fuel cells

On Tuesday, September 13, Dr. Svitlana Pylypenko gave a presentation entitled “Improving Catalyst-Support Interactions in Direct Methanol Fuel Cells.”

Pylypenko, a postgraduate from the University of New Mexico, has been at the Colorado School of Mines for just under two years and has been working with the National Renewable Energy Laboratory on creating more efficient fuel cells. Her research involves “improving the catalytic activity and durability” in methanol fuel cells.

Direct methanol fuel cells work by inducing a two part reaction between methanol and oxygen, yielding CO2 and H20, just as from the combustion of methanol. However, rather than converting the chemical energy of the bonds into thermal energy, fuel cells convert the chemical energy directly into electrical energy.

Pylypenko stated that the problems of current fuel cells are poor utilization and stability. Currently fuel cells involve low precious metal utilization, “which is costly,” according to Pylpenko.

She showed that, in a fuel cell that uses platinum as a catalyst, the addition of ruthenium helps with efficiency. As the methanol oxide, carbon monoxide is formed, which attaches to the platinum sites. This reduces the surface area available to catalyze the methanol. Adding another catalyst, such as ruthenium, to oxidize water to produce hydroxide can increase the efficiency because the hydroxide reacts with the carbon monoxide to produce carbon dioxide and elemental hydrogen.

The concern as Pylypenko stated, however, is that “[ruthenium] is not as stable as we would like it to be.” Nitrogen doping has been proposed to increase the stability of the ruthenium. The role of nitrogen doping is to assist with platinum binding in the catalytic process.

Pylpenko found in her research that low levels of nitrogen doping lead to negative effects on stability. However, high levels of nitrogen doping, though, led to positive effects on stability. She summarized that Nitrogen Doping can be very useful in making fuel cells more efficient.

Pylypenko concluded by stating one hypothetical application of her research is that “[Companies] use a ton of catalyst, thus this may lower prices.” Lowering prices on fuel cells would increase the value of these fuel cells to the consumer, possibly resulting in a higher adoption.

Her research involves “improving the catalytic activity and durability.” This is necessary because the reaction within the cathode and anode of a fuel cell leads to the deterioration of the catalyst and thus a less efficient battery.