Engineering news
The research, published this week in the journal
Nature, describes how to make a material with jumbled molecular fragments without harming its conductivity. It's a discovery that seems to break the rules of conductivity, but one that could be extremely useful.
“In principle, this opens up the design of a whole new class of materials that conduct electricity, are easy to shape, and are very robust in everyday conditions,” said John Anderson, an associate professor of chemistry at the University of Chicago and the senior author of the study. “Essentially, it suggests new possibilities for an extremely important technological group of materials,” said Jiaze Xie (PhD’22, now at Princeton University), the first author on the paper. A press release published alongside the paper describes it as like seeing a car driving on water and still going at 70mph.
Conductors – from the originals like copper, gold and aluminium, through to organic ones made through a technique called 'doping' – all share one characteristic, which is that they are made of closely packed rows of atoms or molecules in straight lines. This enables electrons to flow through them quickly, like cars on a motorway.
Xie took a different approach, stringing nickel atoms together with carbon and sulphur. To the scientists’ astonishment, the material easily and strongly conducted electricity. What’s more, it was very stable. “We heated it, chilled it, exposed it to air and humidity, and even dripped acid and base on it, and nothing happened,” said Xie. That is enormously helpful for a device that has to function in the real world.
But, to the scientists, the most striking thing was that the molecular structure of the material was disordered. “From a fundamental picture, that should not be able to be a metal,” said Anderson. “There isn’t a solid theory to explain this.”
Xie, Anderson and their lab worked with other scientists around the university to try to understand how the material can conduct electricity. After tests, simulations and theoretical work, they think that the material forms layers, like sheets in a lasagna. Even if the sheets rotate sideways, no longer forming a neat lasagna stack, electrons can still move horizontally or vertically – as long as the pieces touch.
The end result is unprecedented for a conductive material. “It’s almost like conductive Play-Doh – you can smush it into place and it conducts electricity,” said Anderson.
The discovery could open the way to new design principles for electronics, and new options for processing, as the new material can be made at room temperature. “We think we can make it 2D or 3D, make it porous, or even introduce other functions by adding different linkers or nodes,” said Xie.
Navigate a turbulent future by attending Aerospace & Defence (28 November – 2 December). Register for FREE today.
Content published by Professional Engineering does not necessarily represent the views of the Institution of Mechanical Engineers.