导　　师： 李越湘;罗旭彪

学科专业： H1705

授予学位： 博士

作　　者： ;

机构地区： 南昌大学

摘　　要： 纳米TiO2的光催化活性好,被认为是最有应用前景的光催化剂,在降解有机污染物中有较广的应用。然而,TiO2的禁带太宽,以至于它的光催化活性仅局限于紫外光区,限制了它在太阳光下的应用。为了解决这个缺陷,科学家们进行了许多研究,旨在将TiO2的光响应从紫外光区转移至可见光区,从而提高TiO2在可见光下的光催化活性。因此,通过对TiO2纳米粒子进行合理的改性和修饰,进一步提高其光催化活性,使TiO2纳米粒子能够被实际推广应用。金属离子掺杂是改善TiO2光催化活性的一种有效方法,可阻止光生电子和空穴发生简单复合,能够有效提高TiO2纳米粒子的光催化反应效率。为此,制备了Fe3+掺杂、Fe3+、Al3+共掺杂、Ni2+掺杂TiO2纳米粒子,并对其进行系统表征和光催化性能的研究。另外,增强TiO2纳米粒子对目标物的吸附是提高选择性光催化效果的关键。分子印迹聚合物对目标分子具有特异选择性。所以,通过分子印迹技术制备TiO2纳米粒子,以期提高TiO2选择性吸附和光催化降解目标污染物的能力。本论文围绕以上内容,主要开展了以下几个方面的工作： /(1/)煅烧温度、煅烧时间和Fe3+掺杂量对TiO2光催化性能的影响。以钛酸四正丁酯为先驱物,采用溶胶-凝胶法制备纯TiO2和Fe3+掺杂的纳米TiO2/(Fe3+//TiO2/)光催化剂,并用XRD、UV-Vis等手段进行表征,系统研究煅烧温度、煅烧时间和Fe3+掺杂量对催化剂在太阳光下光催化降解甲基橙性能的影响。制备纯TiO2和Fe3+//TiO2的最佳煅烧时间分别为4 h和3 h,最佳煅烧温度均为773 K。Fe3+的适量掺入可以显著提高纳米TiO2在太阳光下的光催化降解活性,Fe3+//TiO2中Fe3+的最佳掺杂量为1.0 mol/%,相应的脱色效率为28.37/%。 /(2/)Fe3+//Al3+-TiO2复合光催化剂的制备及其光催化性能研究。以钛酸四正丁酯为先驱物,采用溶胶-凝胶法制备铁铝共掺杂的纳米Ti02/(Fe3+//A13+-Ti02/)光催化剂,并用XRD、UV-Vis等手段进行表征,系统研究煅烧温度、H2O2和盐对Fe3+//Al3+-TiO2光催化剂在太阳光下光催化降解甲基橙性能的影响。结果表明,随着煅烧温度的提高,Fe3+//Al3+-TiO2光催化降解甲基橙的效果也随之提高。H2O2可以提高Fe3+//Al3+-TiO2光催化降解甲基橙的能力,而HCO3-和NO2-使Fe3+//Al3+-TiO2的光催化活性有所降低。 /(3/)Ni2+掺杂锐钛矿TiO2//CoFe2O4复合光催化剂在太阳光下光催化降解甲基橙。采用超声法制备核-壳结构的Ni2+掺杂锐钛矿TiO2//CoFe2O4复合光催化剂/(Ni2+-TiO2//CoFe2O4/),通过共沉淀法合成磁核CoFe2O4,采用超声诱导硫酸镍溶液中钛酸四正丁酯水解制备Ni2+掺杂锐钛矿TiO2活性壳。Ni2+-TiO2//CoFe2O4具有磁响应性oNi2+-TiO2//CoFe2O4的光催化活性由太阳光下降解甲基橙的效果来评价。结果表明,Ni2+掺杂浓度和煅烧温度对Ni2+-TiO2//CoFe2O4的光催化活性有影响,Ni2+掺杂有效改善Ni2+-TiO2//CoFe2O4的光催化活性,其最佳掺杂浓度为1.5mol/%。1.5 mol/% Ni2+-TiO2//CoFe2O4的光催化活性是未掺杂TiO2//CoFe2O4的四倍,而且,H2O2辅助Ni2+-TiO2//CoFe2O4光催化降解是去除染料废水的有效途径。 /(4/)表面分子印迹技术制备导电聚吡咯//TiO2纳米复合光催化剂/(MIP-PPy//TiO2/)及其在模拟太阳光下的光催化活性。以甲基橙为模板分子,采用表面分子印迹技术制备导电聚毗咯//TiO2纳米复合光催化剂,样品用SEM.XRD、BET和UV-Vis等手段进行表征。与原位合成的导电聚吡咯//TiO2纳米复合光催化剂/(Control-PPy//TiO2/)相比,MIP-PPy//TiO2的吸收边带红移了10nm,表明MIP-PPy//TiO2的禁带宽度比Control-PPy//TiO2更窄,而且MIP-PPy//TiO2对模板分子的吸附能力比Control-PPy//TiO2更强,其光催化能力是Control-PPy//TiO2的二倍,这归因于在MIP-PPy//TiO2的表面引入了印迹空穴,因此,表面印迹技术是制备PPy//TiO2的新技术。 /(5/)直接法制备分子印迹型TiO2及其光催化性能的研究。通过溶胶-凝胶法直接制备新型分子印迹型纳米TiO2光催化剂,而不采用分子印迹层包覆光催化剂的方法。与非分子印迹型的纳米TiO2光催化剂相比,分子印迹型的纳米TiO2光催化剂不仅对目标污染物有很强的吸附能力,而且对目标污染物的光催化活性也增强,这归因于分子印迹型纳米TiO2光催化剂对目标分子的选择性吸附。 /(6/)直接法制备具有可见光响应的分子印迹型TiO2//WO3纳米复合光催化剂及其光催化性能的研究。通过溶胶-凝胶法直接制备新型分子印迹型TiO2//WO3纳米复合光催化剂。分子印迹型TiO2//WO3纳米复合光催化剂对目标污染物的吸附能力大于非印迹型TiO2//WO3纳米复合光催化剂,其吸附过程符合准一级动力学。而且,分子印迹型TiO2//WO3纳米复合光催化剂对目标污染物的光催化活性高于非印迹型TiO2//WO3纳米复合光催化剂,这归因于分子印迹型TiO2//WO3纳米复合光催化剂对目标分子的选择性吸附。 Nano titanium dioxide /(TiO2/) has long been regarded as the most promising photocatalyst because of its outstanding photocatalytic activity and finds its wide applications in breaking down many kinds of organic pollutants. However, the band gap of TiO2 is so wide that it greatly limits the use of sunlight as an energy source for the photoreaction since only about 3-4/% of solar light falls in the UV range. In response to the defect, many attempts have been made to improve the photocatalytic efficiency of TiO2 under visible-light irradiation by shifting its optical response from the UV to the visible range. Therefore, it is important to improve its photocatalytic activity by reasonable doping or modification to realize practical application of TiO2 nanoparticles. It has been proved that metal doping would be a viable way to improve the photocatalytic activity of TiO2, and prevent the simple combination of photogenerated electrons and holes, consequently improving the photocatalytic efficiency of TiO2. Considering what mentioned above, in the present work, Fe3+, Al3+ doping and co-doping, Ni2+ doping TiO2 were prepared and characterized. Meanwhile, the photocatalytic activity of these TiO2 was investigated. Additionally, increasing the adsorption of the organic pollutants over TiO2 is considered to be an important parameter in enhancing the degradation rates of photocatalytic activity. Molecular imprinted polymer /(MIP/) has unique property of specific affinity for target compound. Therefore, the TiO2 was prepared by molecular imprinting technique in order to enhance its selective adsorption and photocatalytic ability towards the target contaminants. Based on the above mentioned considersations, following research works were carried out: /(1/) The effect of calcination temperature, calcination time and Fe3+-doped amount on the photocatalytic activity of TiO2. Pure and Fe3+-doped TiO2 nanoparticle photocatalysts were prepared by the sol-gel method using Ti/(OC4H9/)4 as precursor and characterized by X-ray diffraction /(XRD/) and UV-Vis. The effect of calcination temperature, calcination time and Fe3+-doped amount on the photocatalytic activity of TiO2 were investigated by photocatalytic degradation of methyl orange irradiated by sunlight. The optimal calcination time for pure TiO2 and Fe3+-doped TiO2 was 4h and 3h, respectively. The optimal calcination temperature was 773K for both pure TiO2 and Fe3+-doped TiO2. The amount of Fe3+-doped can remarkably increase the catalytic activity of TiO2 under nature light irradiation, the optimal amount of Fe3+ in Fe3+-doped TiO2 was 1.0/%, and the corresponding decolorization efficiency was 28.37/%. /(2/) Preparation and photocatalytic activity of Fe3+//Al3+-TiO2 composite photocatalyst and its the photocatalytic activity Fe3+ and Al3+ co-doped TiO2 /(Fe3+//Al3+-TiO2/) nanoparticle photocatalysts were prepared by the sol-gel method using Ti/(OC4H9/)4 as precursor and characterized by X-ray diffraction /(XRD/) and UV-Vis. The effect of calcination temperature, H2O2 and salts in photocatalytic system on the photocatalytic activity of Fe3+//Al3+-TiO2 were investigated by photocatalytic degradation of methyl orange irradiated by sunlight. The photocatalytic activity of Fe3+//Al3+-TiO2 was enhanced with increasing temperature. H2O2 can increace the photocatalytic activity of Fe3+//Al3+-TiO2, but HCO3-and NO2- decreased its photocatalytic activity. /(3/) Photocatalytic degradation of methyl orange by Ni2+-doped anatase TiO2//CoFe2O4 composites under solar light irradiation. Ni2+-doped anatase TiO2//CoFe2O4 /(Ni2+-TiO2//CoFe2O4/) composites with core-shell structure were prepared by an ultrasonic method. The core CoFe2O4 nanoparticles were synthesized via co-precipitation method, and the photoactive shell Ni2+-doped TiO2 nanoparticles were directly coated on the CoFe2O4 by the ultrasonic-induced hydrolysis reaction of tetrabutyl titanate in a nickel /(11/) sulfate aqueous solution, then the composites were calcined at different temperature. The resultant Ni2+-TiO2//CoFe2O4 composites exhibited good magnetic response. The photocatalytic activities of Ni2+-TiO2//CoFe2O4 composites were evaluated by the photocatalytic degradation of methyl orange under solar light irradiation. The results showed that Ni-doping concentration and calcined temperature had effect on the photocatalytic activities of Ni2+-TiO2//CoFe2O4 composites. Ni2+doping effectively improved photocatalytic activities of TiO2//CoFe2O4 composites, and the photocatalytic activities of +4 with an optimal doping concentration of 1.5/% were four times that of undoped TiO2//CoFe2O4. Moreover, H2O2 assisted Ni2+-TiO2//CoFe2O4 composites under solar light irradiation was an effective and promising process for decolorization of dye-containing wastewater. /(4/) Preparation of conductive polypyrrole//TiO2 nanocomposite via surface molecular imprinting technique and its photocatalytic activity under simulated solar light irradiation. Conductive polypyrrole//TiO2 nanocomposites were successfully prepared by surface molecular imprinting technique /(MIP-PPy//TiO2/) using methyl orange as template molecule. The samples were characterized by means of SEM, XRD, BET and UV-vis diffuse reflectance spectroscopy. Compared with conductive polypyrrole//TiO2 nanocomposites prepared by in situ method /(Control-PPy//TiO2/), the absorption edge of MIP-PPy//TiO2 red-shifts 10 nm, indicating that the band gap energy of MIP-PPy//TiO2 is narrower than Control-PPy//Ti02. Moreover, MIP-PPy//TiO2 nanocomposites show higher adsorption capacity for template molecule than Control-PPy//TiO2 nanocomposites, and the photocatalytic activity of MIP-PPy//TiO2 is two times of Control-PPy//Ti02, which is attributed to the introduction of the imprinted cavities on the surface of MIP-PPy//TiO2 nanocomposites. Therefore, surface molecular imprinting method may be considered as a novel technology for the preparation of PPy//TiO2. /(5/) Direct systhesis of molecularly imprinted TiO2 via sol-gel method and its selective phtocatalytic degradation towards template molecule. A Novel type of molecularly imprinted TiO2 was prepared directly via sol-gel method instead of coating photocatalysts with a molecularly imprinted layer. Compared with non-imprinted TiO2, the molecularly imprinted TiO2 not only exhibits a much higher adsorption capacity for the target contaminant but also shows an enhanced photocatalytic activity in degrading the target contaminant. This enhanced photocatalytic selectivity can be attributed to selective adsorption of target molecules on the molecularly imprinted TiO2. /(6/) Direct systhesis of molecularly imprinted TiO2//WO3 nanocomposite via sol-gel method and its selective phtocatalytic degradation towards template molecule. A Novel type of molecularly imprinted TiO2//WO3 was prepared directly via sol-gel method instead of coating photocatalysts with a molecularly imprinted layer. The adsorption capacity of the molecularly imprinted TiO2//WO3 for the target contaminant is higher than the non-imprinted TiO2//WO3. and the adsorption dynamics fit well with the pseudo-first-order kinetic model. Moreover, the molecularly imprinted TiO2//WO3 shows an enhanced photocatalytic activity in degrading the target contaminant. This enhanced photocatalytic selectivity can be attributed to selective adsorption of target molecules on the molecularly imprinted TiO2//WO3.

关 键 词： 二氧化钛 半导体 光催化反应 金属离子掺杂 分子印迹技术

分 类 号： [O6]

领　　域： [理学]