Fast growth of branched nickel monosilicide nanowires by laser-assisted chemical vapor deposition

Abstract

Branched nickel monosilicide (NiSi) nanowires (NWs), for the first time, have been synthesized on Ni foams by laser-assisted chemical vapor deposition using disilane precursor molecules. Studies indicate that 600 °C is the threshold temperature for the growth of a large number of branched NiSi NWs with 100-500 nm long branches extending from the main stems. Below the threshold temperature, unbranched NiSi NWs were obtained. The density of the branched NiSi NWs is relatively higher in comparison to that of the unbranched ones. The growth rate of the branched NiSi NWs at 700 °C is estimated up to 10 µm min(-1). High-resolution transmission electron microscopy and energy-dispersive x-ray spectroscopy of the branched NiSi NWs suggest that the formation of these branched nanostructures is ascribed to the Ni-dominant diffusion process. These NiSi NWs with branched nanostructures could bring them new opportunities in nanodevices.

In situ coating of NiO on Ni-silicide nanowires with roughened surfaces for improved electrochemical energy storage

“…The migrated Ni atoms would be oxidized in air, leading to the formation of a NiO coating layer on the Ni-silicide NWs. 37 111) planes. The other visible lattice spacings on the edge of the oxidized NW also belong to NiO (0.208 nm for (200) plane, and 0.24 nm for (111) plane).…”

“…When the surface-roughened NWs were annealed at 400 C, the Ni atoms in the Ni foam substrate become active and could randomly dri onto the NWs. 37 The roughened surfaces could provide preferential sites for O atoms to nucleate with the dried Ni atoms, thus promoting the growth rate of NiO on the NWs. 48 For the HFtreated and oxidized electrodes, HF30-Oxidation shows preferable performances compared to the others.…”

“…2 shows Raman spectra for the samples of As-grown, HF30 and HF30-Oxidation. The peaks at 198, 216, 290 and 360 cm À1 of the as-grown Ni-silicide NWs, as well as the peaks which appeared at 140 and 255 cm À1 of the HF30-Oxidation sample, are the characteristic Raman peaks of Ni-silicide, [36][37][38] while the broad band centered at 525 cm À1 corresponds to the Ni-O stretching mode of NiO, 39 which further conrms the formation of NiO aer oxidization.…”