Flexible, highly reactive metals could make zero-emission cars more accessible

A new technique that increases the flexibility and reactivity of incredibly thin metal ‘nanosheets’ could make environmentally friendly cars “more accessible for everybody”, researchers have claimed.

Chemical and biomolecular engineer Chao Wang and colleagues at Johns Hopkins University in Maryland reportedly improved the catalyst activity of metals by 10-20 times, using 90% less material than currently required by hydrogen fuel cells.

The work could lead to faster, cheaper electrical power for cars, the researchers said, but it could also boost the production of bulk chemicals and materials such as hydrogen, which has a number of modern uses.

In the study Wang and colleagues manipulated the strain effect – distance between atoms – of materials, causing them to change dramatically. Changing the strain effect involved making intricate ‘lattices’ at the atomic level much thinner, making the overall material much easier to manipulate – “like how one piece of paper is easier to bend than a thicker stack of paper”, the researchers said.

“By tuning the material's thinness, we were able to create more strain, which changes the material's properties, including how molecules are held together,” said Wang. “This means you have more freedom to accelerate the reaction you want on the material's surface.”

The team, which also included researchers from Purdue University in Indiana and the University of California, tuned metal nanosheets used as electrocatalysts, which make up electrodes in fuel cells. One of the biggest challenges with fuel cells for emission-free vehicles is the high cost of precious metal catalysts such as platinum and palladium, the team said, limiting their viability for many potential buyers. A more active catalyst for fuel cells could reduce cost and clear the way for widespread adoption of clean transport using renewable energy.

“We hope that our findings can some day aid in the production of cheaper, more efficient fuel cells to make environmentally friendly cars more accessible for everybody,” said Wang.

The team said it hopes to test the method on a variety of metals. “We demonstrated the concept in the present paper by using ultrathin palladium nanosheets, but our concept is generally applicable to a broad range of metals, including platinum, cobalt, nickel, gold, silver, etc.," Wang told Professional Engineering. "In our paper, we have performed calculations on the other metals to show similar effects as we have seen experimentally in palladium.”

The work was published today (22 February) in Science.