新型三维石墨烯材料的制备及其性能研究

发布时间：2018-08-25 19:16

【摘要】：随着环境问题的日益严重,超级电容器作为一种新型的储能设备备受人们欢迎。而石墨烯作为一种理想的电极材料也一直是人们关注的重点。但是在没有保护剂的存在下,二维石墨烯片层间强的范德华力和π-π堆积作用会导致石墨烯发生团聚,进而降低石墨烯的比表面积,从而限制其性能和应用。本文从石墨烯的该缺点出发,希望通过将二维石墨烯片组装成三维宏观结构来解决石墨烯的团聚问题。本文先利用改良的Hummers法制备氧化石墨烯溶液(GO),再用化学还原法(化学还原剂)还原GO,并在还原过程中巧妙利用其片层间强的范德华力和π-π堆积作用而组装成三维多孔网状结构,成功的防止其团聚。该方法反应温度低、时间短、操作简单;而且还能在不加额外掺杂剂的条件下实现GO的还原和杂原子掺杂的同步进行;同时制备的石墨烯水凝胶得益于其丰富的多孔结构而被作为电极材料应用于超级电容器中。本文采用糖类、四硫富瓦烯(TTF)和二氧化硫脲三种不同类型的还原剂成功制备出杂原子掺杂的三维多孔石墨烯水凝胶,其中TTF和二氧化硫脲既做还原剂又做掺杂剂。1.在氨水存在的碱性条件下,以糖类(果糖、葡萄糖、蔗糖)为还原剂实现了少量氮掺杂,制备出三维多孔网状石墨烯水凝胶(FRGHs、GRGHs、SRGHs)。研究了其电化学性能,氮元素来源及其对电化学性能的影响。研究表明,含氮和含氧官能团能产生一定的赝电容进一步提高其电容值。FRGHs、GRGHs、SRGHs在电流密度为0.3 A g-1时的比电容值分别为153.5 F g-1、145.0 F g-1、150.3 F g-1;电流密度达到20 A g-1时其保持率为61.4%、61.5%、46.9%;在1 A g-1下循环4000次后其比电容保持率高达97.1%、96.6%、92.8%。2.以TTF为还原剂制备出含硫量极高的石墨烯/TTF石墨烯纳米复合物(SGHs)。进一步研究杂原子掺杂对电化学性能的影响。结果显示,SGHs硫掺杂量高达26.23%,电容高达212.5 F g-1,循环4000次后比电容保持率仍能达到98%。3.以二氧化硫脲为还原剂制备出氮硫双掺杂的三维多孔网状结构石墨烯水凝胶(RGHs)。通过控制还原剂的用量,实现了GO不同程度的还原及氮硫的可控性掺杂,从而制备出不同比表面和孔分布的RGHs。研究了氮硫掺杂的协同作用,并对其电化学性能进行研究。研究表明,随着还原剂用量的增加,氮、硫掺杂量逐渐升高,氧含量逐渐降低。GO的还原程度不同,RGHs(RGHs-1、RGHs-2、RGHs-5)的比表面积也不同,但分别可高达173 m2 g-1、189 m2 g-1、135 m2 g-1。RGHs-1、RGHs-2、RGHs-5的氮含量分别为4.10%、4.96%、6.43%,硫含量为0.53%、0.66%、0.84%,氧含量为16.91%、10.43%、9.70%;在电流密度为0.1 A g-1时的比电容值分别为258.6 F g-1、167.3 F g-1、198.3 F g-1,电流密度达到10 A g-1时其值仍分别保持在129.1 F g-1、110.8 F g-1、114.7 F g-1,其保持率为49.9%、66.2%、57.8%。RGHs-1在电流密度为1 A g-1时循环4000次后其保持率高达97.2%。
[Abstract]:With the increasingly serious environmental problems, supercapacitors as a new type of energy storage equipment are popular. As an ideal electrode material, graphene has always been the focus of attention. However, in the absence of protective agent, the strong van der Waals force and 蟺-蟺 stacking effect between two dimensional graphene layers will lead to the agglomeration of graphene, which will reduce the specific surface area of graphene, thus limiting its properties and applications. Based on the shortcoming of graphene, this paper hopes to solve the agglomeration of graphene by assembling two-dimensional graphene into three-dimensional macrostructure. In this paper, the (GO), of graphene oxide solution was prepared by modified Hummers method and then reduced to GO, by chemical reduction method (chemical reductant). In the process of reduction, a three-dimensional porous network structure was formed by using the strong van der Waals force and 蟺-蟺 stacking interaction between the layers. Succeed in preventing his reunion. The reaction temperature is low, the reaction time is short, the operation is simple, and the reduction of GO and the synchronization of hetero-atom doping can be realized without adding additional dopant. The graphene hydrogel prepared at the same time has been used as electrode material in supercapacitors due to its abundant porous structure. In this paper, three different types of reducing agents, carbohydrate, tetrathiafurene (TTF) and thiourea dioxide, were used to prepare three dimensional porous graphene hydrogels doped with hetero atoms. TTF and thiourea dioxide were used as both reductant and dopant. A three-dimensional porous graphene hydrogel (FRGHs,GRGHs,SRGHs) was prepared by doping a small amount of nitrogen with carbohydrates (fructose, glucose, sucrose) in the presence of ammonia. The electrochemical properties, nitrogen sources and their effects on electrochemical properties were studied. Research shows that Nitrogen and oxygen functional groups can produce a certain pseudo-capacitance to further increase the capacitance value. The specific capacitance of GRGHs SRGHs is 153.5 F g-1145.0 F g-1150.3 F g-1 when the current density is 0.3A g ~ (-1); the retention rate is 61.461.5% 46.9 when the current density is 20 A g ~ (-1); and the specific capacitance is 153.5 F g-1145.0 F g-1150.3 F g ~ (-1) when the current density is 0.3A g ~ (-1). After 4000 cycles under A g -1, the specific capacitance retention rate is as high as 97.1and 96.60.92. 8%. Preparation of graphene / TTF graphene nanocomposites (SGHs). With extremely high sulphur content using TTF as reducing agent The effect of hetero doping on electrochemical properties was further studied. The results show that the sulfur doping amount of SGHs is as high as 26.23 and the capacitance is up to 212.5 F g-1.After 4000 cycles, the specific capacitance retention rate can still reach 98.3. Preparation of three dimensional porous graphene hydrogel (RGHs). With double doping of nitrogen and sulfur using thiourea dioxide as reducing agent By controlling the amount of reducing agent, the reduction of GO and the controllable doping of nitrogen and sulfur were realized, and the RGHs. with different specific surface and pore distribution was prepared. The synergistic effect of nitrogen and sulfur doping was studied and its electrochemical performance was studied. The results showed that with the increase of the amount of reductant, the doping amount of nitrogen and sulfur gradually increased, and the oxygen content decreased gradually. The specific surface area of RGHs-1,RGHs-2,RGHs-5 was different with the decrease of oxygen content. But up to 173m2 g-1189 m2 g-1135m2 g-1.RGHs-1 + RGHs-2RGHs-5 were found to have a nitrogen content of 4.10100.960.43a and a sulfur content of 0.530.66660.660.684, and an oxygen content of 16.91A / g = 10.439.70.The specific capacitance of 0.1A g ~ (-1) was 258.6 F g-1167.3 F g-1198.3 F g ~ (-1), and the current density reached 10 A g ~ (-1). The specific capacitance was 258.6 F g-1167.3 F g ~ (-1) F g ~ (-1), and the current density reached 10 A g ~ (-1). Do not keep at 129.1 F g-1110.8 F g-1114.7 F g-1, and its retention rate is 49.9%. The retention rate of RGHs-1 is as high as 97.2B after 4000 cycles at the current density of 1A g ~ (-1).
【学位授予单位】：山东理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ127.11

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