SiC nanowires with thickness-controlled SiO2 shells: Fabrication, mechanism, reaction kinetics and photoluminescence properties

SiC nanowires with thickness-controlled SiO 2 shells have been obtained by a simple and efficient method, namely treatment of SiC/SiO2 core-shell nanowires in NaOH solution. The products were characterized by transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), Raman spectroscopy, infrared (IR) spectroscopy, and photoluminescence spectroscopy. The thickness of the SiO 2 shell can be effectively controlled by selecting the appropriate processing time, and pure SiC nanowires were also obtained by alkaline cleaning in 1 mol·L −1 NaOH solution for 40 min at 70 °C. A mechanism for the removal of the SiO 2 shells has been proposed, and a two-phase reaction kinetic equation was derived to explain the rate of the removal of the SiO 2 shells. The validity of this equation was verified by experiment. This work not only describes an effective experimental method for achieving SiC nanowires with thickness-controlled SiO2 coatings but also provides a fundamental theoretical equation with a certain level of generality. In addition, photoluminescence (PL) measurement results showed that the SiC nanowires sheathed with an optimum SiO 2 thickness (3.03 nm) have better photoluminescence properties than either the bare SiC nanowires or SiC nanowires with thicker coatings of SiO 2 .