Ce及N共掺杂改性TiO2光催化性能及Ce组分的作用

Photocatalytic Properties and the Role of Ce in Co-Doped TiO_2 with Ce and N

以钛酸正丁酯、硝酸亚铈及氨水为前驱体运用溶胶-凝胶法对TiO2进行Ce及N单一和共掺杂改性,以甲基橙光催化降解为探针考察掺杂组分对催化剂的紫外、可见光活性影响,观察到了Ce及N的单一掺杂及共掺杂催化剂紫外、可见光活性的明显提升。运用X射线衍射(XRD)、低温氮气吸附(BET)、紫外-可见漫反射吸收光谱(DRS)、程序升温氧脱附(TPD)和程序升温氧化(TPO)等表征手段从催化剂的晶体结构及形貌、比表面积、紫外及可见光响应特性、表面吸附氧量及吸附氧循环性能等方面尝试理解掺杂组分的光活性影响机制。实验结果表明掺杂改性催化剂中适量Ce组分的作用在于通过抑制催化剂的晶粒长大、团聚和锐钛结构向金红石结构的相转变,提高催化剂的光相应强度和拓展光响应范围,增加催化剂表面吸附氧容量和促进催化剂的表面氧循环,有效捕获光生载流子,衍生各类高活性自由基物种和增大催化剂比表面积等方面增进催化剂的光催化性能。

Ce and/or N doped TiO2 catalysts were prepared by sol-gel process with tetrabutyl titanate, cerium nitrate and ammonia as raw materials. The photo catalytic activity of the as-prepared catalysts under both ultraviolet and visible light irradiation was evaluated by degradation of methyl orange. Significant improvement of photocatalytic activity were observed by codoping of TiO2 with Ce and N. X-ray diffraction（XRD）, low temperature N2 adsorption（BET）, UV-Vis diffuse reflectance spectroscopy（DRS）, temperature programmed desorption of oxygen（TPD）, temperature programmed oxidation（TPO） and transmission electron microscope（TEM） methods were employed to characterize the as-prepared photocatalysts for the elucidation of effects of crystal structure and surface morphology, specific surface area, optical characteristics and oxygen storage/release properties of doped catalyst on its photocatalytic performance. It has been shown that the role of proper amount of Ce in doped catalysts played as to enhance the thermal stability of catalyst for the suppression of growth or aggregation of crystal particles and transition of crystal phase from anantase to rutile, to promote the circulation of oxygen storage/release, and concomitantly, increase the optical absorbance, extend the light response to the visible region,suppress the recombination of charge carrier by trapping of photoinduced electrons, derive active radical species, and simultaneously, have a favorable effect on the BET surface area increase.