Scientists have found that common salt could reduce the cost and potentially enable the mass commercial production of silicon nanostructures – materials having huge potential in everything from electronics to biomedicine and energy storage.
By melting and absorbing heat at a critical moment during a “magnesiothermic reaction,” the salt prevents the collapse of the valuable nanostructures that researchers are trying to create.
The molten salt can then be washed away by dissolving it in water, and it can be recycled and used again.
The concept, surprising in its simplicity, should open the door to wider use of these remarkable materials that have stimulated scientific research all over the world.
David Xiulei Ji, an assistant professor of chemistry in the OSU College of Science, said that this could be what it takes to open up an important new industry and there are methods now to create silicon nanostructures, but they are very costly and can only produce tiny amounts.
He said that the use of salt as a heat scavenger in this process should allow the production of high-quality silicon nanostructures in large quantities at low cost and if they can get the cost low enough many new applications may emerge.
Existing technologies to make silicon nanostructures are costly, and simpler technologies in the past would not work because they required such high temperatures. Ji developed a methodology that mixed sodium chloride and magnesium with diatomaceous earth, a cheap and abundant form of silicon.
When the temperature reached 801 degrees centigrade, the salt melted and absorbed heat in the process. This basic chemical concept – a solid melting into a liquid absorbs heat – kept the nanostructure from collapsing.
The sodium chloride did not contaminate or otherwise affect the reaction, researchers said. Scaling reactions such as this up to larger commercial levels should be feasible, they said.
The study also created, for the first time with this process, nanoporous composite materials of silicon and germanium. These could have wide applications in semiconductors, thermoelectric materials and electrochemical energy devices.
The findings have been published in Scientific Reports, a professional journal.