Carbon nanotubes could replace platinum and lead to affordable hydrogen cars
The joke about hydrogen-powered cars is that they’re about 10 years away–and always will be. The technology has been held up largely by the high cost of hydrogen fuel cells, but now researchers say they’ve found a way to bring down the cost dramatically by making a key component out of carbon nanotubes instead of platinum. More than half the cost of fuel-cell stacks comes from platinum, according to the Department of Energy. “Fuel cells haven’t been commercialized for larger-scale applications because platinum is too expensive,” says Liming Dai [Technology Review], the lead author of the new study.
Carbon nanotubes
Researcher found that tightly packed, vertically aligned carbon nanotubes doped with nitrogen were more effective as catalysts than platinum, which is usually used to help oxygen react within the fuel cell. That is a vital stage of the fuel cell cycle. Rather than burning fuel to create heat to power a turbine, fuel cells turn chemical energy directly into a flow of electricity. Hydrogen gas, for example, is pumped past one electrode (the anode), where it is split into its constituent electrons and protons. The electrons then flow out of the anode, providing electrical power, while the protons diffuse through the cell. Electrons and protons both end up at a second electrode (the cathode), where they combine with oxygen to form water [New Scientist].
That second reaction is very slow, so engineers have developed cathodes made out of materials that act as chemical catalysts and speed up the reaction. Until now, platinum was considered the best catalyst, but now carbon nanotubes with a trace of nitrogen (the critical ingredient) have left the precious metal in the dust.
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