Engineers at Stanford University appear to have come up with a way to make solar cells and batteries more efficient by “decorating” nanowires with chains of nanoparticles. The process has been likened to dressing up the nanowires with jewelry, a step which helps to enhance their catalytic and electrical performance. The process is simpler and faster than previous techniques, and the development could lead to better lithium-ion batteries and more efficient solar cells, according to a study published in the journal Nano Letters.
Adding ornamentation to nanowires doesn’t just make them look pretty under the microscope; it creates intricate patterns that are full of nooks and crannies that increase overall surface area. Changing the surface area at the nanoscale can actually alter the surface chemistry of nanowires, because catalytic activity depends on the availability of active sites on the material’s surface.
“You can think of it like a tree. The nanowires are the trunk, very good at transporting electrons, like sap, but limited in surface area,” Xiaolin Zheng, one of the study’s authors, told the Stanford News office. “The added nanoparticle decorations, as we call them, are like the branches and leaves, which fan out and greatly increase the surface area.”
To decorate the nanowires, Zheng and her team dipped them in solvent-based gel of metal and salt. Then they air-dried them and applied a quick burst of flame. The end result is a bejeweled nanowire covered with a coating of metal nanoparticles that looks a bit like a pipe cleaner when viewed under a microscope or spectroscope. Although they’re still in the early stages of testing these dressed-up nanowires, Sun Cho, a post-doctoral fellow in Zheng’s lab, said ”the performance improvements have so far been dramatic.”
Photos couretsy of Stanford Nanocharacterization Laboratory