Researchers have tried to apply carbon nanotubes to fuel cells for some time now. At first there was hope that carbon nanotubes would help fuel cells better store hydrogen. That dream was dashed and then later resurrected. There has also been the idea that carbon nanotubes could be used as a cheaper alternative to expensive catalysts within fuel cells.
I suppose those are worthy areas of pursuit, but the two main issues that have prevented fuel cells from gaining wider adoption—at least in the area of powering automobiles—are the costs of isolating hydrogen and building an infrastructure that would deliver that hydrogen to the automobiles. The issue of isolating hydrogen has taken precedence of late in nanotech/fuel cell research both at the commercial level and at research labs.
But now researchers from Stanford University are again looking at how carbon nanotubes could replace more expensive catalysts used in oxidizing the hydrogen at the anode within the fuel cell.
Hongjie Dai, a professor of chemistry at Stanford and co-author of the study, believes that a cheaper oxidizing catalyst will facilitate wider adoption of fuel cells.
"Platinum is very expensive and thus impractical for large-scale commercialization," says Dai in the Stanford press release covering the research. "Developing a low-cost alternative has been a major research goal for several decades."
Well, if you could develop a catalyst for this purpose that was essentially free, it still wouldn’t usher in a hydrogen economy any time soon. But I suppose it couldn’t hurt.
The research, which was published in the May 27th online edition of the journal Nature Nanotechnology, showed that when the outer walls of a multi-walled carbon nanotube (MWNT) were shredded—and the inner walls left intact—the catalytic ability of the MWNTs were enhanced while maintaining good electrical conductivity.
What I find most intriguing about the research is the potential to use these imperfect MWNTs for metal-air batteries. The researchers hint at this, though they have yet to fully explore the possibilities.
"Lithium-air batteries are exciting because of their ultra-high theoretical energy density, which is more than 10 times higher than today's best lithium ion technology," Dai says in the Stanford press release. "But one of the stumbling blocks to development has been the lack of a high-performance, low-cost catalyst. Carbon nanotubes could be an excellent alternative to the platinum, palladium and other precious-metal catalysts now in use."
I think it's all together possible that researchers at IBM and the US national labs who have been working on metal-air batteries for years now might be somewhat more interested in this line of research than fuel-cell manufacturers.
Dexter Johnson is a contributing editor at IEEE Spectrum, with a focus on nanotechnology.