April 2012

Improving Catalysis by Putting the Best Face Forward

New catalyst structures for fuel cells in vehicles improve activity and stability compared to commercial platinum counterparts.

Click to enlarge photo. Enlarge Photo

Image courtesy of Kibsgaard et al. J. Am. Chem. Soc. 2012, 134: 7758-7765

Top: Structural and atomic models of mesoporous platinum. Bottom: Comparison of the stability of the meso-structured Pt (red) vs. commercial Pt nanoparticles (blue).

The Science

Researchers developed a high surface area platinum (Pt) thin film catalyst, that allows more reactive Pt sites to be exposed to the fuel, which improved catalyst activity and stability.

The Impact

The newly structured catalyst exhibited 55% higher activity and enhanced stability compared to commercially available catalysts in transportation fuel cells. The results suggest a new strategy for developing fuel cell catalysts with increased activity and resistance to corrosion and degradation.

Summary

A key technical challenge for improved performance of the polymer electrolyte fuel cells used in transportation is increasing both activity and stability of the cathode catalyst. The current industry standard for the cathode catalyst is platinum (Pt) nanoparticles on a high-surface area carbon (C). In this study, researchers at the Center on Nanostructuring for Efficient Energy Conversion EFRC at Stanford University developed a high surface area, meso-structured Pt thin film catalyst that exhibits higher specific activity for oxygen reduction than the commercial catalyst. Oxygen reduction to form water is a critical component of the chemical activity in the fuel cell. An accelerated stability test demonstrated that the meso-structured Pt thin film also is significantly more stable than the commercial catalyst.  Research reveals that the high turnover frequency and excellent durability is due to the meso-structure. Specifically, the morphology of the structure results in fewer under-coordinated Pt sites than Pt/C nanoparticles, a key difference that improves the specific activity and surface chemistry. The improved catalyst activity and stability resulting from this structure could enable development of high-performance gas diffusion electrodes resistant to corrosion even under the harsh conditions of start-up, shut-down, and/or hydrogen starvation.

Contact

Thomas Jaramillo
Stanford University
jaramillo@stanford.edu

Stacey Bent and Fritz Prinz
Co-Directors of the Center on Nanostructuring for Efficient Energy Conversion (CNEEC) EFRC
sbent@stanford.edu and fbp@cdr.stanford.edu

Funding

DOE Office of Science, Basic Energy Sciences, Energy Frontier Research Centers (EFRC) Program; Villum Kann Rasmussen Foundation (postdoctoral fellowship for J.K.)

Publications

Jakob Kibsgaard, Yelena Gorlin, Zhebo Chen, and Thomas F. Jaramillo, “Meso-Structured Platinum Thin Films: Active and Stable Electrocatalysts for the Oxygen Reduction Reaction” J. Am. Chem. Soc. 2012, 134, 7758-7765 [DOI: 10.1021/ja2120162External link].

Related Links

Center on Nanostructuring for Efficient Energy Conversion (CNEEC) EFRC

Highlight Categories

Program: BES, EFRCs

Performer/Facility: University

Last modified: 5/10/2013 11:21:32 AM