多孔氮化硼纳米片的制备及其在气体吸附领域的应用

发布时间：2018-04-06 00:38

本文选题：氮化硼纳米片　切入点：多孔材料　出处：《北京理工大学》2015年硕士论文

【摘要】：氮化硼因其出众的物理和化学性能而受到人们的广泛关注,多孔氮化硼材料在解决能源问题和环境污染方面展示出广阔的前景,可以普遍应用于储氢,污水处理,染料吸附等领域。本文采用硼酸和尿素通过简单、无模板的一步法制备出多孔的氮化硼纳米片。通过改变反应物比例,反应时间,反应温度,载气比例等工艺条件不断优化氮化硼纳米片的形貌,确定合成多孔氮化硼纳米片的最优工艺条件。使用扫描电子显微镜,透射电子显微镜,X射线衍射,X射线光电子能谱,原子力显微镜和拉曼光谱表征氮化硼纳米片的形貌,成分和物相。发现制备的氮化硼是多孔纳米片形貌且晶格畸变明显,其(0002)晶面间距0.365nm比标准值偏大。XPS结果表明产物中B元素和N元素含量比B:N=0.97:1。拉曼光谱E2g振动峰与标准图谱匹对良好,峰位稍向高频移动至1474cm-1且半峰宽拓宽达40cm-1,说明样品中存在弱的层间相互作用且晶粒尺寸较小。BET分析表明氮化硼纳米片的比表面积735m2/g,总孔容量1.24cm3/g,是多孔氮化硼结构中孔容量最大的。较大的比表面积和孔容量使得氮化硼纳米片表现出优异的气体吸附性能,在77K常压条件下可逆储存氢气质量分数1.50%,孔径0.93nm的微孔对物理吸附性能起决定性作用,极性的B-N键使氢气与氮化硼表面有相互作用,一定量的O元素掺杂会降低氢气分子在氮化硼表面吸附所消耗的能量,对提高储氢性能有贡献作用。在273K常压下可逆吸附二氧化碳质量分数11.92%,介孔的存在可以给二氧化碳在氮化硼纳米片内迁移提供通道,降低二氧化碳的扩散阻力,使微孔有效的吸附面积大大增加。
[Abstract]:Because of its outstanding physical and chemical properties, boron nitride has attracted extensive attention. Porous boron nitride materials show broad prospects in solving energy problems and environmental pollution, and can be widely used in hydrogen storage and sewage treatment.Dye adsorption and other fields.In this paper, boric acid and urea were used to prepare porous boron nitride nanocrystals by a simple, template-free one-step method.The optimum technological conditions for the synthesis of porous boron nitride nanocrystals were determined by changing the ratio of reactants, reaction time, reaction temperature and the ratio of carrier gas to optimize the morphology of boron nitride nanocrystals.Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), atomic force microscopy (AFM) and Raman spectroscopy (Raman) were used to characterize the morphology, composition and phase of boron nitride nanocrystals.It was found that the prepared boron nitride was porous and the lattice distortion was obvious, and the crystal plane spacing of boron nitride was larger than the standard value. The results showed that the content of B element and N element in the product was higher than that of B: n element 0.97: 1.The E _ 2g vibrational peak of Raman spectrum was matched well with the standard spectrum.The peak position moved slightly to high frequency to 1474cm-1 and the width of the half peak widened to 40cm-1, which indicated that there was weak interlaminar interaction in the sample and the grain size was smaller. BET analysis showed that the specific surface area of boron nitride nanocrystals was 735m2 / g, the total pore capacity was 1.24cm3 / g, and it was a porous boron nitride structure.With the largest mesopore capacity.The large specific surface area and pore capacity make the boron nitride nanocrystals exhibit excellent gas adsorption performance. The reversible storage hydrogen mass fraction is 1.50 at 77K atmospheric pressure. The pore size of 0.93nm plays a decisive role in the physical adsorption performance.Polar B-N bond makes hydrogen interact with boron nitride surface. A certain amount of O doping can reduce the energy consumed by hydrogen molecules adsorbing on the surface of boron nitride and contribute to the improvement of hydrogen storage performance.At 273K atmospheric pressure, the reversible adsorption carbon dioxide mass fraction is 11.92. The existence of mesoporous carbon dioxide can provide a channel for carbon dioxide migration in boron nitride nanocrystals, reduce the diffusion resistance of carbon dioxide, and increase the effective adsorption area of micropores greatly.
【学位授予单位】：北京理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ128;TB383.1

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