石墨烯基氧化物的制备及其光催化性能研究

发布时间：2018-07-06 08:45

本文选题：石墨烯 + 氧化物　；参考：《中北大学》2017年硕士论文

【摘要】：光催化是一种新型绿色环保技术,由于其反应条件温和、无二次污染、操作设备简单等优点被广泛地应用于能源、环境等领域。光催化还原二氧化碳(CO_2)能够产生有机燃料,能够在一定的程度上解决能源与环境问题。但是目前单一催化剂具有比表面积小、光生电子-空穴对复合速率快、量子效率低等不足。使用石墨烯与半导体进行复合,制备石墨烯基半导体纳米材料能够有效提升半导体的比表面积、抑制电子-空穴对的复合、活化CO_2,从而提升复合材料光催化还原CO_2的效率。TiO_2、CuO和NiO皆为常见的半导体氧化物,具有价格低廉、制备简单等优点。本文先使用改良Hummers法制备了氧化石墨(GO),然后使用水热(溶剂热)法将其与TiO_2、CuO和NiO进行复合。控制GO的加入量来制备了一系列不同配比的氧化物-石墨烯复合物,并在模拟可见光下考察了其催化还原CO_2的活性。具体的工作内容如下:1、使用溶剂热法制备了不同还原氧化石墨烯(r-GO)配比的Ag-TiO_2/r-GO复合纳米材料。使用X射线粉末衍射(XRD)、透射电子显微镜(TEM)、高分辨透射电子显微镜(HR-TEM)、红外傅立叶变换光谱(FT-IR)、紫外-可见漫反射光谱(UV-VisDRS)、N2吸附-脱附测试以及光致发光光谱(PL)对制备的样品进行表征。结果表明通过Hummers法成功地制备了GO,Ag-TiO_2纳米颗粒粒径均一且均匀地分散在石墨烯的表面。r-GO的复合有效的拓宽了TiO_2的光吸收范围、有效地抑制了电子-空穴对的复合。光催化结果表明,复合r-GO后TiO_2的光催化还原的CO_2活性明显增强。r-GO的配比及催化剂的浓度对光催化的性能具有很大的影响。当r-GO配比为15%,催化剂浓度为1.5g·L-1时,催化剂的活性最高,4h内可以产生40μmol·gcat-1甲醇。循环实验表明催化剂具有较强的光稳定性。2、使用直接沉淀法制备CuO纳米颗粒并用APTES进行氨基改性。使用水热法制备了不同r-GO配比CuO-r-GO复合纳米材料。利用XRD、TEM、FT-IR、UV-VisDRS和PL对制备的样品进行表征。结果表明CuO均匀地附着在了r-GO的表面,r-GO的加入有效地抑制了光生电子-空穴的复合。光催化结果表明单一的CuO由于其较低的氧化-还原电势,并不具有还原CO_2的能力。复合r-GO后复合,复合材料的光催化还原CO_2的能力明显提高。3、使用水热-煅烧法制备了碳球,以碳球为模板制备了中空NiO纳米球。使用水热法制备了不同r-GO配比的中空NiO-r-GO复合纳米材料。使用XRD、TEM、FT-IR、UV-VisDRS和PL对制备的样品进行表征。结果表明制备的NiO纳米球粒径较为均一且在石墨烯上均匀地复合。单一NiO由于其较宽的带隙宽度使其在可见光下催化还原CO_2的能力较弱。复合r-GO后,复合材料的光催化性能具有明显的增强。
[Abstract]:Photocatalysis is a new green environmental protection technology, which has been widely used in energy, environment and other fields because of its mild reaction conditions, no secondary pollution, simple operation equipment and so on. Photocatalytic reduction of carbon dioxide (CO-2) can produce organic fuel and solve energy and environment problems to a certain extent. However, the single catalyst has some disadvantages, such as small specific surface area, fast photoelectron hole pair recombination rate and low quantum efficiency. The preparation of graphene based semiconductor nanomaterials can effectively enhance the specific surface area of semiconductors and inhibit the recombination of electron-hole pairs. Activation of CO2, thus enhancing the efficiency of photocatalytic reduction of CO2 in composites. Both TiO2CuO and nio are common semiconductor oxides, which have the advantages of low price and simple preparation. Graphite oxide (go) was prepared by modified Hummers method, and then it was compounded with TiO2CuO and nio by hydrothermal (solvothermal) method. A series of oxide-graphene complexes with different ratios were prepared by controlling the amount of go, and the catalytic reduction activity of COS _ 2 was investigated under simulated visible light. The specific work is as follows: 1. Ag-TiO2 / r-GO nanocomposites with different ratio of reduced graphene oxide (r-GO) were prepared by solvothermal method. The samples were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HR-TEM), infrared Fourier transform spectroscopy (FT-IR), UV-vis diffuse reflectance spectroscopy (UV-Vis DRS) N _ 2 adsorption-desorption and photoluminescence (PL) spectra. The results show that the composite of go-Ag-TiO-2 nanoparticles with uniform particle size and uniformly dispersed on the surface of graphene by Hummers method can effectively widen the range of optical absorption of TIO _ 2 and effectively inhibit the combination of electron-hole pairs. The photocatalytic results show that the photocatalytic activity of TiO-2 in tio _ 2 is obviously enhanced. The ratio of r -GO and the concentration of the catalyst have a great influence on the photocatalytic performance. When the molar ratio of r-GO is 15 and the concentration of the catalyst is 1.5 g L-1, the maximum activity of the catalyst can produce 40 渭 mol gcat-1 methanol within 4 h. Cyclic experiments showed that the catalyst had strong photostability. CuO nanoparticles were prepared by direct precipitation method and modified with APTES. CuO-r-GO nanocomposites with different r-GO ratios were prepared by hydrothermal method. The samples were characterized by UV-VisDRS and PL. The results show that the addition of CuO to the surface of r-GO effectively inhibits the photo-electron-hole recombination. The photocatalytic results show that a single CuO has no ability to reduce CO2 due to its low redox potential. After composite r-GO, the photocatalytic reduction ability of CO2 was improved significantly. The carbon spheres were prepared by hydrothermal calcination method, and hollow nio nanospheres were prepared using carbon spheres as template. Hollow NiO-r-GO composite nanomaterials with different r-GO ratios were prepared by hydrothermal method. UV-VisDRS and PL were used to characterize the prepared samples. The results showed that the nio nanospheres were homogeneous in size and homogeneously compounded on graphene. Because of its wide bandgap width, the single nio has a weak catalytic reduction of CO2 in visible light. The photocatalytic performance of the composite is obviously enhanced after the composite of r-GO.
【学位授予单位】：中北大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O643.36

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