【作者】 周琪；

【导师】 吴玉程；

【作者基本信息】 合肥工业大学 ， 材料学， 2014， 博士

【摘要】 针对TiO2在光催化降解反应中存在的光生电子和光生空穴复合快、比表面积小、可见光下光催化效能低等不足，本文以石墨烯改性TiO2，制备石墨烯基TiO2纳米复合材料，从而提升TiO2光催化性能为研究思路。首先制备氧化石墨烯（GO），并以氧化石墨烯为基底材料，以Ti(OBu)4为钛源，以HF为形貌控制剂，采用溶剂热法制备了RGO/TiO2纳米复合材料；通过调控TiO2晶面，采用两步水热法制备了RGO/暴露晶面TiO2纳米复合材料；采用水热法和沉淀-析出法，制备AgBr-RGO/TiO2三元纳米复合材料，探讨了复合材料的光催化性能，主要内容如下：（1）采用改进的Hummers法制备了氧化石墨烯。以鳞片石墨为原料，以浓H2SO4和KMnO4为氧化剂，通过两步法，先制得氧化石墨，再通过超声分散制得氧化石墨烯。通过XRD、TEM、SEM等手段进行表征，实验制得的氧化石墨烯具有单层或者少层结构，其表面含有大量的-OH、-COOH、C-O-C、C=O等含氧基团。含氧基团的存在，增强了氧化石墨烯在水溶液中的分散性，同时也为后期石墨烯基二氧化钛纳米复合材料的制备过程中，二氧化钛晶体形核长大提供大量的活性位点。（2）采用溶剂热法制备RGO/TiO2纳米复合材料。在180℃下通过溶剂热法，以氧化石墨烯和Ti(OBu)4作为初始反应物，在乙醇溶剂中，合成RGO/TiO2纳米复合材料。通过XRD、SEM、TEM、XPS等手段对RGO/TiO2纳米复合材料的进行表征，对该复合材料的形貌及其光催化性能进行讨论。结果表明：氧化石墨烯被还原成石墨烯的同时，石墨烯的表面负载生长锐钛矿二氧化钛颗粒。随着溶剂热时间的延长，氧化石墨烯表面的活性基团减少，还原更加彻底，同时TiO2晶粒有一定的增大趋势；和纯TiO2相比，RGO/TiO2纳米复合材料光催化活性明显提高，石墨烯含量对复合材料的光催化活性有直接的影响。（3）采用两步水热法制备RGO/暴露晶面TiO2纳米复合材料。首先，在180℃下通过水热法，以HF为形貌控制剂，Ti(SO4)2为钛源，可控制备了暴露不同晶面的TiO2纳米结构。通过XRD、TEM、SEM、XPS等手段对制备的TiO2进行了表征，实验证明，HF在暴露不同晶面的TiO2纳米材料的制备中，对TiO2不同晶面的形貌的形成起主导的调节作用。在此基础之上，采用二次水热法，180℃条件下，利用先前制备的氧化石墨烯对暴露晶面的TiO2进行修饰改性，调控氧化石墨烯的含量，制备出RGO/暴露晶面TiO2纳米复合材料，对该复合材料的形貌及其光催化性能进行讨论。结果表明，在紫外光下，RGO/暴露晶面TiO2纳米复合材料的光催化活性优于纯TiO2；当GO含量为1%时，RGO/暴露晶面TiO2纳米复合材料的光催化性能最优。（4）采用水热法和沉淀-析出法制备AgBr-RGO/TiO2三元纳米复合材料。首先，在180℃下通过水热法，以HF为形貌控制剂，以Ti(SO4)2、氧化石墨烯为原料，可控合成RGO/TiO2二元复合物。通过XRD、TEM、SEM、XPS等手段对制备的二元复合物进行表征，其中TiO2具有双截断八棱锥结构的单晶锐钛矿结构。进而以RGO/TiO2二元复合物为中间物，添加AgNO3及KBr，通过沉淀-析出法在RGO/TiO2二元复合物表面沉积了AgBr纳米颗粒，从而制备出石墨烯基TiO2-AgBr三元纳米复合材料，并对该三元复合材料的形貌及其光催化性能进行讨论。研究表明，在可见光下，AgBr-RGO/TiO2三元纳米复合材料的光催化活性要明显优于RGO/TiO2二元复合物。更多还原

【Abstract】 Aiming at the existence of TiO2photoproduction electronic and optical cavitycomposite quickly, small specific surface area, low visible light photocatalyticefficiency in photocatalytic degradation reaction.In this paper, the graphene modifiedTiO2, preparation of TiO2nano graphene-based nanocomposites, so as to improve thephotocatalytic properties of TiO2. First prepared graphene oxide(GO), using grapheneoxide as a substrate material,Ti(OBu)4as titanium source, HF as morphology controlagent. Preparation of graphene/TiO2nanocomposites by solvothermalmethod.Regulation of TiO2crystal surface, preparation of RGO/exposed crystal TiO2nanocomposites by two steps hydrothermal method.Preparation of AgBr RGO/TiO2ternary nanocomposites by hydrothermal method and precipitation-precipitationmethod. After that，discusses the photocatalytic performance of the them. The maincontents are as follows:(1) Prepared graphene oxide by improved Hummers method. With flake graphite asraw materials, with concentrated H2SO4and KMnO4as oxidant, through two-step, firstobtained graphite oxide. Then prepared graphene oxide(GO) by ultrasonic dispersion.We characterized by XRD, TEM, SEM and other means, we find that the obtained GOhas single or several layers structure.On the surface, contains a lot of-OH,-COOH,C-O-C, C=O groups. They enhance the GO dispersion in an aqueous solution, and alsoprovide a large number of active sites for the preparation of the graphene TiO2nancomposites.(2)Preparation of RGO/TiO2nanocomposites by one step solvothermal method.Using Ti(OBu)4and GO as raw materials, controllable synthesis of RGO/TiO2nanocomposites by solvothermal at180℃in Ethanol. Characterized by XRD, TEM,SEM，XPS and other means. And discuss its photocatalytic properties. The results showthat GO was reduced to grapheme.At the same time, the growth of the anatase TiO2particles in the surface of the graphene.With the extension of reaction time, the reactivegroup on the surface of the graphene oxide reduction, reduction more thoroughly,TiO2particles have a tendency to increase. The photocatalytic activity of RGO/TiO2nanocomposites than pure TiO2.The content of grapheme has a direct impact on thephotocatalytic activity of the nanocomposite.(3)Preparation of RGO/exposed crystal TiO2nanocomposites by two stepshydrothermal method. First,Using Ti(SO4)2as titanium source, HF as morphology control agent. Controllable Preparation of different crystal surfaces exposed TiO2nanostructures by hydrothermal method at180℃. Characterized by XRD, TEM,SEM,XPS and other means.Experiments show that, HF plays key role in the regulationof different crystal faces of TiO2. On this basis, the use of secondary hydrothermalmethod, using the GO to modify exposure different crystal TiO2surface by secondaryhydrothermal at180℃. And regulate the content of GO prepared RGO/exposed crystalTiO2nanocomposites. Discuss the morphology and its photocatalytic properties. Theresults show that under ultraviolet light, the photocatalytic activity of TiO2crystalsurface exposed graphene nanocomposites than pure TiO2; When GO content of1%, theRGO/exposed crystal TiO2nanocomposites has the best photocatalytic performance.(4)Preparation of AgBr RGO/TiO2ternary nanocomposites by hydrothermal methodand precipitation-precipitation method. First,using Ti(SO4)2and GO as raw materials,HF as morphology control agent， controllable synthesis of RGO/TiO2Binarycompounds by hydrothermal at180℃.Characterized by XRD, TEM, SEM,XPS andother means. TiO2has TOB structure of single crystal of anatase. And the binarycompounds as intermediate, add AgNO3and KBr, deposited AgBr nanoparticles on thesurface of RGO/TiO2binary compounds by precipitation-precipitation to preparate ofthe graphene TiO2-AgBr ternary nanocomposites. Discuss the morphology andphotocatalytic properties of ternary composites. Research shows that, under visible lightphotocatalytic activity, AgBr-RGO/TiO2photocatalytic activity of ternarynanocomposites to be significantly better than RGO/TiO2binary compounds.更多还原