A team from Northwestern University, Illinois, USA, has come up with a novel way to purify nanowires. Nanoparticles and other low-aspect-ratio shapes are a common by-product from the solution chemical growth of nanowires, and the presence of these short particles greatly affects the assembly of the nanowires.
Huang and co-workers have applied cross-flow filtration to remove nanoparticle by-products from silver nanowires. This method of purification will improve the quality of nanowire products and thus their overall properties. The researchers state that “The continuous mode of operation makes it readily useful for industrial scale nanowire purification, and especially with large-size filters that can handle thousands of liters of solution.”
To quantitatively describe the effect of purification, they used concepts of molecular weight distribution and polydispersity index to characterize the aspect ratio (i.e. purity) of nanowire samples.