热处理工艺对TiO_2纳米薄膜光催化性能的影响

INFLUENCE OF HEAT TREATMENT PROCESSING ON THE PHOTOCATALYTIC PROPERTIES OF NANOMETRIC TiO_2 THIN FILMS

通过ｓｏｌ－ ｇｅｌ 工艺在玻璃表面制备了均匀透明的锐钛矿型ＴｉＯ２ 纳米光催化薄膜，ＴｉＯ２ 薄膜由３０ ～１００ ｎｍ 的球形颗粒组成． 每镀一次薄膜的厚度增加约０ ．０８ μｍ ． 薄膜中出现的锐钛矿在（１０１）面具有一定的择优取向． 薄膜中除含有Ｔｉ，Ｏ，Ｃ等元素外，还存在少量从玻璃表面扩散到薄膜中的Ｎａ 和Ｃａ 元素． 甲基橙水溶液的光催化降解实验表明：当薄膜经５００ ℃，ｌｈ 在空气中热处理后，薄膜的表观反应速度常数ｋ 为０．０２６ １ ｍｉｎ－ １． 适当的热处理时间可以明显增强薄膜的光催化效率，这些可以根据薄膜中Ｔｉ３ ＋ 浓度和比表面积的变化来解释．

The uniform, transparent anatase nanometric TiO 2 thin films deposited on glass substrates were prepared by sol-gel processing. TiO 2 films are composed of TiO 2 spheric particles in size of 30～100 nm. Thickness of the films prepared for 1 cycle (from dipping to heat_treatment at 500 ℃,1 h) is 0.08 μm approximately. Anatase TiO 2 films have some orientation effect in the (101) plane. Experimental results show that, besides Ti, O and C elements in the films, there is a small amount of Na and Ca elements diffused from the glass substrates. Photocatalytic degradation of methyl orange aqueous solution indicates that the sol-gel derived TiO 2 films heat_treated at 500 ℃ for 1 h in air show good photocatalytic activity, the apparent degradation rate constant k is 0.026 1 min -1 . It is also found that the suitable heating time at 500 ℃ improves remarkably the photocatalytic activity of the films. These results are explained on the basis of the changes in both the surface structure and Ti 3+ concentration of the films with appropriate heating time.