The Preparation Of Tungsten Trioxide Nanomaterials And Their Photocatalytic Performences

WO3 is a nanoscale functional material with low band energy, which displays a broad application in the fields of electrochromic, photochromic, gas ochromic and photocatalysis etc., having been a research focus currently. In this work, different WO3 photocatalysts have been prepared by changing three important factors in material synthesis according to the structural properties of nanomaterial, and their photocatalytic activities were investigated.Firstly, the factor of impurity species. Sodium chloride, sodium sulfate, sodium oxalate were added as the structure-directing agents to the precursor solution of tungstic acid, and then the morphologies were tuned by the agents. Thus, different WO3 catalysts were prepared. Results showed the morphologies of WO3 were spherical structure assembled by nanosheets, clintheriform assembled by nanosheets, and cluster structure assembled by nanocubes. Besides, the photocatalytic test showed that the catalyst prepared by introducing NaCl could decompose 89wt% of Rh B molecules.Secondly, the factor of NaCl concentration. According to the fact that the adsorptivity on the surface of tungsten trioxide was various when the concentration of the impurity changed, and then different photocatalysts were prepared. A series of characterization techniques showed that the morphology of tungsten trioxide pushed forward from disorderly nanosheets to spherical and biscuit structure with increasing the concentration of NaCl; the fact that NaCl was adsorbed on the surfaces of (002) and (200) leaded to the exposure of high-energy (002) facets. Besides, the slits between the nanosheets and the crystal structure of tungsten trioxide with the exposure of high-energy (002) facets caused the formation of large mesopores. By comparing the photocatalytic activities, results showed that the sample prepared when the mole content addition of sodium chloride is same as sodium tungstate dehydrated owns the best, and the efficiency could reach 92wt% within 4 h under the visible light irradiation.Lastly, the factor of ethanol solvent. Different volumes of ethanol were added to occupy the position of water and tungsten oxide catalysts with different textural properties were prepared by utilizing the property that the ethanol could enhance the resistance. N2 adsorption-desorption tests showed that the BET of WO3 could be controlled by changing the volume of ethanol. SEM results showed that all the photocatalyst were of spherical structure assembled by nanosheets. Specially, the slits between the nanosheets were enlarged, and the aggregate accumulation between the big spherical particles were weakened with increasing the volumes of ethanol. Compared to the other photocatalysts of the catalytic activities, the sample prepared when the volume fraction of ethanol was 2.5%, could decompose 93wt% of Rh B solution under the visible lighter for 4 h. Additionally, the capacity of oxide species follows the order:holes>·O2->·OH.Tungsten trioxide photocatlysts with different morphologies and textural properties were prepared by tuning the growth of nanomaterial, and displayed excellent catalytic activity. Additionally, the mechanisms of material formation and photocatalysis were explored, which not only enriches the study of nanoscale WO3, but also provides the chance to be used in waste water treatment.