|Polarization curves for H2 oxidation on different catalysts in the presence of 2% CO at room temperature. The new Pt/titanium tungsten oxide catalyst is in blue. Credit: ACS, Wang et al. Click to enlarge.|
A team at Cornell University has developed a new highly stable and CO-tolerant platinum/titanium tungsten oxide anode (Pt/Ti0.7W0.3O2) electrocatalyst for PEM fuel cells. A paper on their work was published online 12 July in the Journal of the American Chemical Society.
Among the challenges facing the commercialization of fuel cells for automotive and portable electronics applications is the development of inexpensive, durable and efficient catalysts for hydrogen oxidation. Platinum is currently the catalyst of choice, but is easily “poisoned” by low levels of CO (10 ppm), resulting in a significant degradation in performance.
Other research has shown that platinized metal oxides—especially those of tungsten—exhibit increased CO tolerance. However, tungsten suffers from low electronic conductivity.
To address that issue, the Cornell team, led by Dr. Hector Abruña, turned to titania (TiO2), which been used as a catalyst support in fuel cells duel to its stability, even though its own electronic conductivity is much lower than that of conventional carbon supports. The conductivity of titania, the team noted, can be improved by aleovalent cation substitution.
The Cornell team synthesized nanoparticles of Pt supported on conducting Ti0.7W0.3O2.
Initial tests indicated that Pt/Ti0.7W0.3O2 is more stable than Pt/C and PtRu/C catalysts. After 500 cycles, the loss in the integrated Coulombic charge of the CV for the new catalyst was only 5%, while it was more than 30% in the case of a commercial E-TEK PtRu/C catalyst.
The new material also exhibited high activity for H2 oxidation as well as a higher CO tolerance than Pt/C and PtRu/C catalysts.
This work was supported by the US Department of Energy (DOE) and by the Energy Materials Center at Cornell, an Energy Frontier Research Center funded by DOE Office of Basic Energy Sciences. The authors acknowledged helpful discussions with General Motors Fuel Cell Activities.
(A hat-tip to David!)
Deli Wang, Chinmayee V. Subban, Hongsen Wang, Eric Rus, Francis J. DiSalvo and Hector D. Abruña (2010) Highly Stable and CO-Tolerant Pt/Ti0.7W0.3O2 Electrocatalyst for Proton-Exchange Membrane Fuel Cells. J. Am. Chem. Soc., Article ASAP doi: 10.1021/ja102931d