Researchers at Aalto University in Finland have developed a new and significantly cheaper method of manufacturing direct alcohol fuel cells (DAFCs) fuel cells by preparing a palladium nanoparticle catalyst using atomic layer deposition (ALD). This ALD method for manufacturing fuel cells requires 60% less catalyst than current methods.
Direct alcohol fuel cells (DAFCs) are promising energy sources for low-power demand devices, the team notes in a paper published in the ACS Journal of Physical Chemistry C. However, one of the barriers to commercialization has been the sluggish reaction rate of alcohol oxidation at the anode. This reaction rate can be enhanced in alkaline media, and further enhanced by the use of alcohol oxidation noble metals as catalysts.
In alkaline media, palladium has shown high activity, especially for ethanol and isopropanol oxidation.
To reduce the loading of noble metals on fuel cell catalysts a synthesis method providing evenly distributed nanoparticles on the support surface is needed. Narrow size distribution palladium nanoparticles were prepared on a porous carbon support by atomic layer deposition (ALD), and their activity for ethanol and isopropanol oxidation was studied electrochemically in alkaline media. Palladium particles had smaller average particle sizes on the support material resulting in 50 mV lower onset potential and 2.5 times higher mass activity for alcohol oxidation compared with a commercial catalyst.
The results indicate that the use of ALD allows the preparation of a noble metal nanoparticle catalyst, and this catalyst can provide similar mass activity with lower catalyst loading than current commercial fuel cell catalysts. This would significantly reduce the cost of the cell and provide a competitive advantage compared with other power sources.—Rikkinen et al.
The authors noted that catalyst poisoning by oxidation reaction intermediates still remains a serious obstacle, which they intend to address in future work.
Emma Rikkinen, Annukka Santasalo-Aarnio, Sanna Airaksinen, Maryam Borghei, Ville Viitanen, Jani Sainio, Esko I. Kauppinen, Tanja Kallio, and A. Outi I. Krause (2011) Atomic Layer Deposition Preparation of Pd Nanoparticles on a Porous Carbon Support for Alcohol Oxidation. The Journal of Physical Chemistry C, 115, 23067–23073. doi: 10.1021/jp2083659