Cheap catalyst may lower fuel costs for hydrogen cars

Last Updated : 08 October 2015, 13:03 IST

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 Researchers have found a way to replace the rare and expensive platinum catalyst with dirt-cheap molybdenum disulfide, or "molly", to make hydrogen a less expensive fuel for cars.

The improved catalyst has already released four times the amount of hydrogen ever produced by 37-cents-a-gram molly from water.

"We should get far more output as we learn to better integrate molly with, for example, fuel-cell systems," said lead author Stan Chou, postdoctoral fellow at Sandia National Laboratories in US.

An additional benefit is that molly's action can be triggered by sunlight, a feature which eventually may provide users an off-the-grid means of securing hydrogen fuel.

Hydrogen fuel is desirable because, unlike gasoline, it does not release carbon into the atmosphere when burned.

The combustion of hydrogen with oxygen produces an exhaust of only water.
"The idea was to understand the changes in the molecular structure of molybdenum disulfide, so that it can be a better catalyst for hydrogen production - closer to platinum in efficiency, but earth-abundant and cheap," said Chou.

"We did this by investigating the structural transformations of molybdenum disulfide at the atomic scale, so that all of the materials parts that were 'dead' can now work to make hydrogen," said Chou.

Researchers used computer simulations that suggested which molecular changes to look for.

However they caution that what's been established is a fundamental proof of principle, not an industrial process.

"Water splitting is a challenging reaction. It can be poisoned, stopping the molly reaction after some time period. Then you can restart it with acid. There are many intricacies to be worked out," said co-author Bryan Kaehr.

"But getting inexpensive molly to work this much more efficiently could drive hydrogen production costs way down," he said.

Not requiring electricity to prompt the reaction may be convenient in some circumstances and also keep costs down.

"A molly catalyst is essentially a 'green' technology. We used sunlight for the experiment's motive power. The light is processed through a dye, which harvests the light," said Chou.

"A photocatalytic process stores that energy in the chemical bonds of the liberated hydrogen molecule," he said.

"It's a kind of photosynthesis, but using inorganic materials rather than plants," Chou said.

The study was published in the journal Nature Communications.

Published 08 October 2015, 13:03 IST

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