Green Design

Boosting Nanowires for Better Batteries and Solar Cells

Stanford University engineers have found a novel method for "decorating" nanowires with chains of tiny particles to increase their electrical and catalytic performance. The technique is simpler and faster than earlier methods and could lead to better lithium-ion batteries, more efficient thin-film solar cells, and improved catalysts that yield new synthetic fuels.

"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," explained Xiaolin Zheng, assistant professor of mechanical engineering. "The added nanoparticle decorations, as we call them, are like the branches and leaves, which fan out and greatly increase the surface area."

"Greater surface area means greater opportunity for reactions and therefore better catalytic capabilities in, for example, water-splitting systems that produce clean-burning hydrogen fuel from sunlight," said Yunzhe Feng, a research assistant in Zheng's lab.

Zheng dipped the nanowires in a solvent-based gel of metal and salt, then air-dried them before applying a quick burst of flame. In the process, the solvent burns in a few seconds, allowing the all-important nanoparticles to crystalize into branch-like structures fanning out from the nanowires. Zheng and her team have dubbed the technique the sol-flame method.

(Stanford University)