Hydrothermal Synthesis Of Silicon Oxide Nanowires In Solid-liquid Phase System

The paper introduced a new idea "liquid-solid phase hydrothermal method" for the synthesis of the silicon oxide nanowires (SiONWS). The yield of SiONWS was improved by rationally designing the ways of embedded iron and proper silica sources and experimental conditions. The optimum experimental conditions were determined by studying main factors of reaction. The acid resistance and thermal stability of SiONWS were investigated in hydrochloric acid and different atmosphere, respectively. Moreover, we found a novel organic-inorganic hybrid structure to our SiONWS before hydrochloric acid washed.Two-step liquid-solid phase hydrothermal synthesis of SiONWS Using fumed silica as silica sourceIn this way baking to embed iron in fumed silica and hydrothermal reaction were essential. The synthesis of SiONWS by liquid-solid phase hydrothermal method, using embedded iron fumed silica and ethylenediamine-water solution as raw materials, was investigated, a novel organic-inorganic hybrid SiOx/en nanowires (en = ethylenediamine) had been found Before hydrochloric acid washed, and inorganic SiONWS with a P2₁2₁2 crystal structure had been found after hydrochloric acid washed. The length of nanowires was 3 um and the diameter was 20nm. The optimum experimental conditions showed that the mol ratio of Si and Fe was 1:0.9, the vol. ratio of ethylenediamine and water was 8:5, the temperature was 200℃, and the reaction time was 4 days.One-step liquid-solid phase hydrothermal synthesis of SiONWS Using silica sol as silica sourceThe synthesis of SiONWS by liquid-solid phase hydrothermal method, using silica sol, Fe nitrate salt and ethylenediamine-water solution as raw materials, was investigated. It was found that the reaction activity rose Because of less baking process and using nano-diameter silica source. As a result the reaction conditions were more moderate and less Fe been used. Moreover, the defect of the incomplete hydrothermal reaction had been solved perfectly in this method, its very significant for the industrialized manufacture of SiONWS.The acid resistance and Thermal Stability of SiONWS synthesized by liquid-solid phase hydrothermal methodThe iron were totally removed by hydrochloric acid washed, and the shape of SiONWS still keep except a small curve. However, the thermal stability experiment proved that the SiONWS could not keep a wire shape after calcineing in air and nitrogen atmosphere, respectively, at the same time, the crystal structure of nanowires had been broken completely, the bad thermal Stability maybe limite the application of the SiONWS.Preliminary study on the organic-inorganic hybrid structure of SiONWS.In the study of structure of SiONWS before hydrochloric acid washed, based on the analysis of IR, XPS spectroscopy and XRD methods, we proved the organic-inorganic hybrid structure of SiONWS, In addition, the possible mechanism of the reaction was proposed.