A novel combined experimental and multiscale theoretical approach to unravel the structure of SiC/SiO core/shell nanowires for their optimal design. | LitMetric
In this work we propose a realistic model of nanometer-thick SiC/SiOx core/shell nanowires (NWs) using a combined first-principles and experimental approach. SiC/SiOx core/shell NWs were first synthesised by a low-cost carbothermal method and their chemical-physical experimental analysis was accomplished by recording X-ray absorption near-edge spectra. In particular, the K-edge absorption lineshapes of C, O, and Si are used to validate our computational model of the SiC/SiOx core/shell NW architectures, obtained by a multiscale approach, including molecular dynamics, tight-binding and density functional simulations. Moreover, we present ab initio calculations of the electronic structure of hydrogenated SiC and SiC/SiOx core/shell NWs, studying the modification induced by several different substitutional defects and impurities into both the surface and the interfacial region between the SiC core and the SiOx shell. We find that on the one hand the electron quantum confinement results in a broadening of the band gap, while hydroxyl surface terminations decrease it. This computational investigation shows that our model of SiC/SiOx core/shell NWs is capable to deliver an accurate interpretation of the recorded X-ray absorption near-edge spectra and proves to be a valuable tool towards the optimal design and application of these nanosystems in actual devices.
In this work we propose a realistic model of nanometer-thick SiC/SiOx core/shell nanowires (NWs) using a combined first-principles and experimental approach. SiC/SiOx core/shell NWs were first synthesised by a low-cost carbothermal method and their chemical-physical experimental analysis was accomplished by recording X-ray absorption near-edge spectra. In particular, the K-edge absorption lineshapes of C, O, and Si are used to validate our computational model of the SiC/SiOx core/shell NW architectures, obtained by a multiscale approach, including molecular dynamics, tight-binding and density functional simulations.
The development of innovative nanosystems opens new perspectives for multidisciplinary applications at the frontier between materials science and nanomedicine. Here we present a novel hybrid nanosystem based on cytocompatible inorganic SiC/SiOx core/shell nanowires conjugated via click-chemistry procedures with an organic photosensitizer, a tetracarboxyphenyl porphyrin derivative. We show that this nanosystem is an efficient source of singlet oxygen for cell oxidative stress when irradiated with 6 MV X-Rays at low doses (0.
Centre for Strategic Nano-Fabrication, School of Mechanical and Chemical Engineering, University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia.
We report a reasonably high yield (~50%) synthesis of silicon carbide (SiC) nanowires from silicon oxides and carbon in vacuum, by novel solar and lamp photothermal ablation methods that obviate the need for catalysis, and allow relatively short reaction times (~10 min) in a nominally one-step process that does not involve toxic reagents. The one-dimensional core/shell β-SiC/SiOx nanostructures-characterized by SEM, TEM, HRTEM, SAED, XRD and EDS-are typically several microns long, with core and outer diameters of about 10 and 30 nm, respectively. HRTEM revealed additional distinctive nanoscale structures that also shed light on the formation pathways.
