多功能石墨烯气凝胶的制备及性能研究

发布时间：2018-05-05 22:19

本文选题：石墨烯气凝胶 + 常压干燥　；参考：《青岛科技大学》2017年硕士论文

【摘要】：石墨烯气凝胶继承了石墨烯和气凝胶的双重优良性能,虽然大量的工作对石墨烯气凝胶的制备及其杂化材料进行了研究,但是通过总结这些工作发现在其在石墨烯的制备,及杂化石墨烯气凝胶性能研究方面仍然存在着不足。本文针对前人工作中的不足之处进行优化,并用各种表征手段对我们工作进行分析、讨论。本文包括以下三个方面:第一,通过两步法结合简单、经济、环保的常压干燥的方法制备了强度可控,亲水性能可以调节的石墨烯/纤维素纳米晶杂化气凝胶。这种杂化石墨烯气凝胶中,一维的纤维素纳米晶被夹杂在石墨烯的片层之间起到了起到了增强作用,杂化的石墨烯墙相互交联形成了石墨烯气凝胶孔状结构。由于纤维素纳米晶表面含有丰富的含氧官能团使其具有一定的亲水性能。得益于两者的协同效应,使得杂化的石墨烯/纤维素纳米晶气凝胶具有两亲性能,同时石墨烯气凝胶的强度以及亲水性能可以通过调节纤维素纳米晶的用量进行调控。当加入50wt%的纤维素纳米晶时其压缩强度达到了11kPa,模量达到了55kPa,同时其接触角减小为0o。炭化后的杂化石墨烯气凝胶比表面积进一步增加,可应用在超级电容方面。实验发现,杂化的石墨烯气凝胶不但能够吸收有机溶剂,还能吸收高锰酸根,有望应用在工业污水处理方面。第二,通过设计方案探究了石墨烯/甲壳素纳米纤维杂化气凝胶的制备,试验发现,经过Tempo氧化制备得到的甲壳素纳米纤维能够很好地与石墨烯进行复合,但是其最终炭化得到的碳气凝胶的比表面积较小。经过部分脱乙酰化得到的甲壳素纳米纤维能与含CNC20wt%的杂化石墨烯气凝胶通过浸泡进行复合,从而得到双网络结构,将该杂化石墨烯气凝胶高温炭化处理后制备成超级电容,通过CV曲线发现其电容有着很好的稳定性。即使在500mv/s下形状仍保持良好,显示了在超级电容方面潜在的应用价值。第三,通过简单环保的常压干燥的方法结合空气泡为模板制备了超轻,超级耐疲劳的纯石墨烯气凝胶,其密度最低可为2.4mg/cm3。较以前方法,孔径较小,在300μm左右,且更加均匀,孔壁更薄。同时其密度和孔壁可以通过调节发泡时的转速以及所用氧化石墨烯的浓度进行调控。并且在5Hz高频压缩比为70%时压缩100万次后仍能很好的保持原来体积,内部受破坏较小,显示了超级耐疲劳特性。这种方法有望实现石墨烯气凝胶的工业化生产,且有望进一步扩展石墨烯气凝胶的应用领域。
[Abstract]:Graphene aerogel inherits the excellent properties of graphene and aerogel. Although a great deal of work has been done on the preparation of graphene aerogel and its hybrid materials, it is found that in the preparation of graphene aerogels, And the study on the properties of hybrid graphene aerogels is still insufficient. In this paper, the shortcomings of previous work are optimized, and various representation methods are used to analyze and discuss our work. This paper includes the following three aspects: firstly, the graphene / cellulose nanocrystalline hybrid aerogels with controllable strength and adjustable hydrophilicity were prepared by a simple, economical and environmentally friendly atmospheric pressure drying method. In this hybrid graphene aerogel, the one-dimensional cellulose nanocrystals were intermingled between the graphene layers, and the interlinked graphene walls formed the graphene aerogel pore structure. Cellulose nanocrystals have hydrophilic properties due to their abundant oxygen functional groups. The hybrid graphene / cellulose nanocrystalline aerogels have amphiphilic properties due to their synergistic effects. The strength and hydrophilicity of graphene aerogels can be regulated by adjusting the amount of cellulose nanocrystals. When 50 wt% cellulose nanocrystals were added, the compressive strength and modulus of the nanocrystals reached 11 KPA, 55 KPA, and the contact angle decreased to 0 o. The specific surface area of the hybrid graphene aerogels after carbonization is further increased, which can be applied to super capacitors. It is found that the hybrid graphene aerogels can absorb not only organic solvents but also high manganese acid, which is expected to be used in industrial wastewater treatment. Secondly, the preparation of graphene / chitin nanofiber hybrid aerogels was investigated through the design scheme. It was found that chitin nanofibers prepared by Tempo oxidation could be well combined with graphene. But the specific surface area of the carbonized aerogels is small. Chitin nanofibers obtained by partial deacetylation can be compounded with hybrid graphene aerogels containing CNC20wt% by soaking, resulting in a double network structure. The hybrid graphene aerogels are carbonized at high temperature to form supercapacitors. It is found that the capacitance has good stability by CV curve. The shape remains good even under 500mv/s, which shows the potential application value in super capacitor. Thirdly, the ultra-light and super fatigue resistant graphene aerogels were prepared by a simple environmentally friendly atmospheric pressure drying method combined with air bubble as a template. The lowest density of the aerogels was 2.4 mg / cm ~ (3). Compared with the previous method, the pore diameter is smaller, about 300 渭 m, more uniform, and the pore wall is thinner. At the same time, the density and pore wall can be regulated by adjusting the speed of foaming and the concentration of graphene oxide. And when the 5Hz compression ratio is 70 times, the original volume can be kept well after 1 million compression times, and the internal damage is small, which shows the super fatigue resistance. This method is expected to realize the industrial production of graphene aerogels and to further expand the application of graphene aerogels.
【学位授予单位】：青岛科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ127.11;TQ427.26

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