类石墨烯与铈氧化物复合的制备、结构及性能研究

发布时间：2018-01-05 18:39

本文关键词：类石墨烯与铈氧化物复合的制备、结构及性能研究　出处：《深圳大学》2015年硕士论文　论文类型：学位论文

【摘要】：稀土金属独特的4 f电子构型使其具有优异的光学、电学、磁学性能。其中,铈氧化物尤为受到人们的广泛关注。Ce有Ce4+和Ce3+两种价态氧化物,两种价态转变中的氧化还原电势极低,铈可以在Ce4+和Ce3+两种氧化态之间迅速变化,发生氧化还原循环,因此具有较强的储备功能。Ce2O3属于立方晶系。Ce O2作为功能材料具备Ca F2的面心立方(FCC)萤石结构以及较高的氧空位浓度,这使其具有高效光催化和优异的电化学性能,尤其在多相催化领域中Ce O2表现出独特的储放氧能力。近年来,石墨烯基复合材料受到了人们的广泛关注。石墨烯基纳米复合材料不仅可保留石墨烯作为基体材料和负载材料的原始性能与优点,而且能够产生新的协同作用。石墨烯片的独特二维结构有助于高效地将半导体催化剂固定在其表面,将铈氧化物如Ce O2负载在石墨烯上形成的复合材料有望表现出更为优异的性能。因此,本论文首次将二氧化铈粒子负载到本实验室自制的液态聚丙烯腈低聚物(Liquid Acrylonitrile Oligomer,LANO)表面,将Ce O2与LANO(高温后结构转变为类石墨烯片层结构)进行机械混合再烧结之后得到类石墨烯/铈氧化物(Ceria oxides/graphene-like,COGL)(其中包含Ce(Ⅲ)氧化物与Ce(Ⅳ)氧化物)纳米复合粒子。论文主要内容如下:1.通过液相球磨法制备了类石墨烯/铈氧化物(COGL)复合材料,研究了不同温度下(包括800℃、1000℃、1200℃、1300℃、1400℃以及1500℃)制备得到的COGL纳米复合粒子的形貌、结构与烧结温度的关系,通过不断优化工艺流程得到形貌、结构可控的COGL纳米复合材料;2.利用SEM、TEM及XRD对COGL纳米复合粒子的形貌和晶型构成等进行了表征。结果表明:在1300℃以下温度烧结,LANO交联环化得到的碳石墨化程度较低,主要为无定形碳。且此时LANO不能将+4价铈氧化物还原。当温度升高至1500℃时,Ce含量较低时可制备得到Ce C2/C复合粒子,该粒子具有较强的抗氧化性。当Ce含量高时可制备得到Ce(Ⅲ)氧化物/类石墨烯复合粒子,并且随着温度升高粒子半径减小。光电子能谱结果显示1500℃的COGL90复合物表面存在+3铈氧化物存在,说明Ce O2存在氧空位。Raman光谱表明,当温度高于1300℃时,COGL中碳的石墨化程度较高。随着温度的提高,碳的石墨化程度进一步加强;3.对制备的COGL纳米复合粒子进行光催化降解实验。结果表明,无Ce O2的空白对照组在紫外光下照射360mins几乎没有表现出任何催化性能,纯Ce O2作为光催化剂在同样条件下,其降解率达到4.9%,表明Ce O2在紫外光照射下具有一定的光催化降解作用;而COGL作为光催化剂催化亚甲基蓝降解的速率明显加快,随着Ce O2含量的提高,COGL的光催化效率逐渐提高。对于相同含量的COGL纳米复合粒子,随着烧结温度的提高,COGL的光催化效率逐渐提高。这些结果表明COGL纳米复合粒子具有良好的光催化活性。COGL中的类石墨烯作为光催化反应的电子运载通道和电子受体对于COGL纳米复合粒子的光催化活性起着重要作用。
[Abstract]:Rare earth metal 4 unique f electron configuration which has excellent optical, electrical and magnetic properties. Among them, cerium oxide is widely concerned by people especially.Ce Ce4+ and Ce3+ two kinds of valence oxide, two valence transition in redox potential is extremely low, cerium can quickly change between Ce4+ and Ce3+ two an oxidation state, the redox cycle, so it has strong reserve function.Ce2O3 belongs to cubic.Ce O2 as FCC functional materials with Ca F2 (FCC) fluorite structure and higher concentration of oxygen vacancy, which makes it a highly efficient photocatalytic and excellent electrochemical performance, especially in the field of heterogeneous catalysis Ce O2 displays the unique oxygen storage capacity. In recent years, graphene based composite materials have attracted much attention. The graphene nanocomposites can retain graphene as the substrate material and the material of the original load Performance and advantages, but also can produce new synergy. The unique two-dimensional structure of graphene contributes to efficient semiconductor catalyst fixed on its surface, the cerium oxides such as Ce O2 load composite material formed on graphene is expected to exhibit more excellent properties. Because of this, this paper for the first time two cerium oxide particles supported the self-made liquid polyacrylonitrile (Liquid Acrylonitrile Oligomer LANO, oligomer) surface, O2 and LANO (Ce after high temperature structure of graphene layer structure) after mechanical mixing and sintering to graphene / cerium oxide (Ceria oxides/graphene-like, COGL (including Ce () III) oxide and Ce (IV) oxide) nano composite particles. The main contents are as follows: 1. by liquid phase milling of graphene / cerium oxide was prepared (COGL) composites were investigated at various temperatures (pack The 800 C, 1000 C, 1200 C, 1300 C, 1400 C and 1500 C) morphology of COGL nano composite particles prepared by the relationship between the structure and the sintering temperature, through continuous optimization process were obtained, COGL nano composite structure controlled by SEM; 2., morphology and crystal structure of COGL nano composite the TEM and XRD particles were characterized. The results show that the sintering temperature is below 1300 DEG C, the graphitization degree of carbon LANO cross-linking obtained is low, mainly for the amorphous carbon and the LANO can not be +4 valence cerium oxide reduction. When the temperature rises to 1500 degrees, with low Ce content can be prepared by Ce C2/C composite particles, the particles have strong antioxidant activity. When the content of Ce is prepared by Ce (III) oxide / graphene composite particles, and the particle radius decreases with the increase of temperature. The XPS results showed that 1500 DEG COGL90 composite The surface of existing +3 cerium oxides, Ce O2 oxygen vacancies.Raman spectra show that when the temperature is higher than 1300 DEG C, COGL carbon in high graphitization degree. With the increase of temperature, the graphitization degree of carbon reinforced; 3. COGL nano composite particles were prepared by photocatalytic degradation experiments. The results showed that no Ce O2, blank control group under UV light irradiation 360mins almost did not show any catalytic properties of pure Ce O2 as photocatalyst under the same conditions, the degradation rate reached 4.9%, Ce showed that O2 has certain effects on photocatalytic degradation under UV irradiation; and COGL is the rate of catalytic degradation of methylene blue light catalyst with Ce increased significantly, the content of O2 increased, the photocatalytic efficiency of COGL increased gradually. The COGL nanoparticles content is the same, with the increase of sintering temperature, the photocatalytic activity of COGL was gradually increased. These results indicate that COGL nanocomposite particles have good photocatalytic activity. Graphene in.COGL plays an important role in the photocatalytic activity of COGL nanocomposite particles as the electron transport channel and electron acceptor of photocatalytic reaction.

【学位授予单位】：深圳大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB332

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