Synthesis of amorphous SiO2 nanowires by one-step low temperature hydrothermal process

A novel procedure for the growth of amorphous SiO2 nanowires by a one-step hydrothermal process directly using commercial silicate glass in cheap aqueous ammonium hydroxide without any other catalyst is reported. The effect of concentration of aqueous ammonium hydroxide and reaction time on synthesized product was investigated. It was found that SiO2 nanowires with high aspect ratio can be synthesized using silicate glass at 170 °C in 2.5 mol l−1 aqueous ammonium hydroxide for 7 h. Scanning electron microscopy, high resolution transmission electron microscopy and x-ray diffraction results showed that the products were amorphous SiO2 nanowires with diameters of 20~100 nm and lengths of several tens of micrometers. X-ray photoelectron spectroscopy (XPS) indicated that the SiO2 nanowires retained small amounts of MgO and CaO from the silicate glass. The result of photoluminescence (PL) spectra of the nanowires exhibited a strong, sharp photoluminescence (PL) emission peak, centered at 426 nm. Based on the results, the OH-assisted hydrolysis of the glass has been proposed as the growth mechanism of the SiO2 nanowires.