Mass production of nanowire powders using direct reaction of the component elements:

In this project, we have developed a simple, but scalable, process for the mass production of compound semiconductor nanowire powders. We employ direct reaction of the component elements for the mass production of nanowire powders. For instance, we employed the direct reaction of zinc foils with phosphorus for the formation of Zn3P2 nanowires on top of the foil surfaces. Here, the foils serve as both the source and the substrates for nanowire formation. In order to enhance the surface area of foil available for the formation of nanowires, we have coiled the zinc foils as illustrated in the picture. Following the synthesis, the foil was uncoiled and brushed off to collect 100% phase-pure Zn3P2 nanowires. We have also extended this process for the synthesis of Zn4Sb3 nanowires. The synthesis procedure could also be extended for the production of in-situ functionalized compound semiconductor nanowire powders. Accomplishing this simply requires exposing the nanowires to a vapor of the requisite organic functional molecules immediately after the conclusion of the nanowire synthesis, and before they are removed from the vacuum procedure. Pictorial illustrations of the hot-walled chemical vapor deposition setup useful for the mass production of nanowires, along with those representing a small section of the results obtained, are provided below.

Schematic of the three-zone tube furnace employed for the synthesis and in-situ functionalization of Zn3P2 nanowires, indicating the placement of the coiled zinc foil employed for the large-scale synthesis of Zn3P2 nanowires using phosphorus vapor transport onto zinc foils. Physical Chemistry Chemical Physics 15 (17), 6260-6267 (2013) - Reproduced by permission of the PCCP Owner Societies.

Photograph of a coiled zinc foil (a) before and (b) after the vapor transport of phosphorus. (c) Photograph of Zn3P2 nanowire powder obtained by brushing off the foils. (d) A transmission electron micrograph from a Zn3P2 nanowire indicating that the growth direction of the nanowires was not altered in the second experimental procedure and remained [101]. (e) A scanning electron micrograph of Zn3P2 nanowires obtained by the above-mentioned approach. (f) Photograph of the uncoiled zinc foil covered with Zn3P2 nanowires (green deposit) after the vapor transport of phosphorus onto its surface. Physical Chemistry Chemical Physics 15 (17), 6260-6267 (2013) - Reproduced by permission of the PCCP Owner Societies.