具有高活性(001)晶面的TiO_2纳米方块的制备及光催化性能

Preparation of Anatase TiO_2 Nanocube with Exposed(001) Facet and Its Photocatalytic Properties

采用水热法制备了尺寸为70～100 nm,具有高活性（001）晶面的锐钛矿相TiO_2纳米方块,利用FE-SEM、TEM、XRD和UV-Vis DRS等手段对催化剂结构和光吸收性能进行分析,同时考察了水热反应温度和溶液p H对TiO_2形貌和（001）晶面暴露率的影响。以酸性红染料为目标污染物,对催化剂的光催化活性进行研究。实验结果表明,合成TiO_2纳米方块的最佳条件为水热温度180℃、溶液p H=4～5。（001）晶面的光催化活性优于（101）晶面,具有33%（001）晶面暴露率的TiO_2纳米方块的光催化活性是普通TiO_2的1.6倍。

Anatase TiO_2 single crystals with exposed（001） facets were successfully synthesized by a one-step hydrothermal route using Ti F_4 as raw material. The crystal phase, morphology, microstructure, and photoabsorption of the samples were analyzed by field emission scanning electron microscope（FE-SEM）, transmission electron microscope（TEM）, X-ray diffraction（XRD）, and ultraviolet-visible diffuse reflectance spectra（UV-Vis DRS）. The influences of hydrothermal temperature and p H of solution on morphology of TiO_2 and exposure of（001） facets were also investigated. Photocatalytic catalysts was evaluated by degradation of acid red dye. Experimental results demonstrated that exposure of（001） facets was beneficial for improving photocatalytic performance. Under ultraviolet light irradiation, TiO_2 nanocube with exposure of（001） facets ca. 33% exhibited significantly higher activity than the common TiO_2 without exposed（001） facets. The photocatalytic efficiency of the former was 1.6 times as high as that of the latter. The sample with the highest exposure of（001） facets was obtained at hydrothermal temperature of 180 ℃and p H of solution 4-5. The corrosion of crystal surface would occur at hydrothermal temperature higher than 180℃. In addition, the p H of solution higher than 6 was unfavorable for the adsorption of F- ions on TiO_2 crystals and the stabilization of（001） facets, which led to the disappearance of（001） facets.