Enhancing photoluminescence properties of SiC/SiO2 coaxial nanocables by making oxygen vacancies.

Coaxial nanocables (CNs) with an SiC core and a SiO2 shell were fabricated at a large scale by a simple and low cost method. The thickness of the SiO2 shell could be controlled by etching in 1 M NaOH aqueous solution for different amounts of time. XRD, SEM, TEM, HRTEM, PL and UV-Vis spectra were adopted to investigate the morphology and optical properties of the obtained SiC/SiO2CNs. Blue photoluminescence was observed at room temperature from the coaxial structure. The intensity of the single emission band at 468 nm (2.65 eV) exhibited a strong dependence on the thickness of the SiO2 layer and was significantly enhanced when the outer SiO2 shell had a thickness of 2.8 nm. The enhancement effect was attributed to oxygen vacancies (OV) and this was verified by deliberately enriching the surface OV through hydrogen treatment.