B掺杂TiO_2/AC光催化剂的制备及活性

Preparation and Activity of B-doped TiO_2 /AC Photocatalysts

以硼酸和钛酸丁酯为主要原料,以活性炭(AC)为载体,用溶胶-凝胶法制备了B掺杂TiO2/AC光催化剂.用X射线衍射(XRD)、紫外可见漫反射吸收光谱(UV-VIS)对制得的光催化剂进行了表征.以甲基橙水溶液的光催化脱色反应和氧化乐果水溶液的光催化降解反应,考查了不同B掺杂TiO2/AC光催化剂的活性.结果表明,所有B掺杂TiO2/AC光催化剂均为锐钛矿晶相.B的掺杂未导致TiO2/AC光催化剂的吸收带边发生明显的移动.当B-TiO2质量分数分别为2.0%和2.5%时,TiO2/AC光催化剂的活性有明显的提高.B-TiO2质量分数2.0%时活性最高.但是,当B-TiO2质量分数分别为1.5%和3.0%时,TiO2/AC光催化剂的活性降低.B的缺电子特性可能改变了TiO2能带中的电子密度,使光催化反应中光生电子和空穴的俘获方式发生变化;同时,B的缺电子特性也会使光催化剂表面的Lewis酸强度增强,导致表面吸附OH-数量和目标反应物的吸附方式发生变化.这些可能是B-TiO2/AC光催化剂活性发生变化的主要原因.

Using H\-3BO\-3 and Ti(OBt)\-4 and active carbon (AC) as raw materials, B\|doped TiO\-2 supported on AC photocatalysts (B\|TiO\-2/AC) were prepared via sol\|gel and impregnation method. The B\|TiO\-2/AC photocatalysts were characterized by UV\|VIS spectrophotometry and X\|ray diffraction (XRD). Activities of the photocatalysts were evaluated by photocatalytic decolorization of methyl orange aqueous solution and photocatalytic degradation of omethoate aqueous solution, respectively. The XRD results show that only the anatase phase is precipitated on AC. The band edges of the various B\|TiO\-2/AC photocatalysts do not exhibit remarkable shift compared with that of un\|doped TiO\-2/AC photocatalyst. Activities of the photocatalysts are obviously enhanced when B\|TiO\-2 supported on AC with 2.0% and 2.5%, respectively. The photocatalyst shows the highest photocatalytic activity when B\|TiO\-2 supported on AC with 2.0%. But when B\|TiO\-2 content is 1.5% and 3.0%, the activity of photocatalysts reduced. The activity change of photocatalysts is probably ascribed to the electron defect property of B, which reduces the electron density of energy band of TiO\-2 and changes the capture of photogenerated e\| and h\++ of TiO\-2. Meanwhile, as the result of the electron defect property of B, Lewis acid strength of the photocatalysts is enhanced, which result in OH\+- concentration and title reactant adsorption changeal at the surface of photocatalysts. All these may be the main reasons for the change of activity of the B\|TiO\-2/AC photocatalysts.