Preparation And Characterization Of SiO₂ Nanowires And ZnO/SiO₂ Composites

Zinc oxide(ZnO),a semiconductor of wide forbidden band,has blue emission near 470 nm,therefore,could be used as blue emission luminescent material.Many researchers believe that the blue emission origins from the defects on the surface of ZnO nanoparticles and its intensity can be strengthened by enhancing the specific area of ZnO nanoparticles.Nanoparticles can be well dispersed and obtain higher specific area by being loaded on other materials.This paper utilizes cheap chrysotile to prepare silica(SiO₂)nanowires by dispersion and acid leaching.Then this paper used the as prepared SiO₂ nanowires to synthesize ZnO/SiO₂ composites.The ZnO/SiO₂ composites have higher blue emission than ZnO,therefore,can be applied as blue emission luminescent material.Furthermore,the ZnO/SiO₂ composites can also be used to deal with dye polluted water since ZnO can degrade dyes and the composites can be easier to be separated from water.The smaller the mineral particle is,the easier it can be leached.With the cooperation of Aerol OT(AOT)and homogenizer,the natural chrysotile was dispersed into chrysotile nanowires.The well dispersed chrysotile nanowire has a length over 10μm and less than 100 nm in diameter.The orthogonal experiment was applied to study the effect of rotation speed,temperature,concentration of AOT and dispersing time on dispersing chrysotile.The result of variance analysis showed that none of the four factors affected the result enormously.The as dispersed chrysotile nanowires were acid leached to produce pure amorphous SiO₂ nanowires and acid solution of magnesium ion.The SiO₂ nanowire is a kind of silica white,based on its high purity and shape, can be applied as a dope of plastic.The acid solution can be used to produce magnesium salt or other magnesium products.Zinc acetate and SiO₂ nanowires were used to synthesize ZnO/SiO₂ composites.The effect of Zn/Si value,stirring time,pH value and concentration of NaOH on the composites' UV-vis absorption and photoluminescent properties were also studied.The characterization of photoluminescent properties showed that the as prepared composites have higher emission intensity of blue light than ZnO.ZnO crytallites can be loaded on SiO₂ nanowires with the diameter between 15 nm and 20 nm, therefore,the as prepared composites can also be used as catalyst in dealing with dye polluted water.