【作者】 李红；

【导师】 车剑飞；

【作者基本信息】 南京理工大学 ， 材料学， 2020， 硕士

【摘要】 本文主要报道了一种用磺化石墨烯量子点（sGQD）和磺化石墨烯（sGO）作为掺杂剂制备聚吡咯（PPy）水凝胶的简单合成方法。重点测试了导电水凝胶的表面形貌、结构组分和电化学储能等方面的性能。首先采用芘作为碳源制备了sGQD。sGQD周围的磺酸基团可以通过静电相互作用或者质子化PPy的氮基团,使得PPy链交联形成具有三维结构的导电水凝胶。与其它结构相比,三维结构具有的坚固的导电骨架可以促进电荷的传输,孔隙度有助于离子和分子的扩散,溶胀特性提供了额外的有效界面。因此三维结构对于电极的电性能具有重要意义。通过SEM、TEM等表征手段对制备的导电水凝胶进行各项测试,结果表明本实验成功的制备了sGQD并将其成功掺杂到导电水凝胶中。通过进一步的电化学性能表征可以发现,与PPy水凝胶相比,制备的水凝胶电极具有较高的比电容。这主要是因为保留了sGQD良好的导电性,并且在充放电过程中,sGQD固定PPy链段使其形成三维结构,进而可以形成离子快速扩散的输运通道,改善了电化学性能。此外,EIS测试表明,得到的水凝胶电极具有较高的导电性、低的扩散电阻和有效的离子扩散能力,其阻抗性能明显优于PPy水凝胶电极。同时,由于引入了具有优异机械强度的sGQD,制备的水凝胶也表现出了增强的循环稳定性。接着采用石墨作为碳源,首先制备了GO,然后利用对氨基苯磺酸制备的重氮盐将GO磺化得到了sGO,最后采用一样的方法将其作为掺杂剂用来制备水凝胶。同样的,经过一系列的测试表明石墨烯表面成功接枝了磺酸基,并且制备的水凝胶具有良好的电化学性能。与sGQD掺杂的PPy水凝胶相比,PPy/sGO水凝胶最突出的优点是拥有极高的比电容,在电流密度为0.5 A·g^-1时,最大比电容可达1268.3 F·g^-1。主要是因为sGO导电性好,强度高,将其作为掺杂剂不仅可以使得PPy链交联形成具有三维结构的导电水凝胶,同时由于sGO具有较高的机械强度,能有效地抑制PPy在重复充放电过程中的膨胀和收缩,可以显著改善PPy电极的电化学稳定性。在本文中,sGQD和sGO作为掺杂剂并且通过简单的一步法制备了PPy基水凝胶电极。该方法简便、高效,可进一步用于制备其他具有理想结构和优良性能的电极材料。同时,从本论文中可以看出,制备的PPy基水凝胶具有作为先进电极材料的潜在应用前景。更多还原

【Abstract】 A simple synthesis method was reported to fabricate soft polypyrrole（PPy）hydrogels with doped sulfonated carbon quantum dots（sGQD）and sulfonated graphene oxide（sGO）.The surface morphology,structure and electrochemical energy storage of the conductive hydrogel were tested.Using graphite as a carbon source,GO was first prepared,then sulfonated with diazo salts prepared with sulfanilic acid to obtain sGO,and finally used as a dopant to prepare hydrogels in the same way.The sulfonic acid groups rimming the sGQD can form electrostatic interactions and protonate the nitrogen groups of PPy,cross-link the PPy chain to form a conductive hydrogel with a three-dimensional structure.Compared to other structures,a solid conducting skeleton of three-dimensional structure facilitates the transfer of charge,porosity facilitates the diffusion of ions and molecules,and swelling properties provide additional efficient interfaces.Therefore,three-dimensional structure is of great significance to the electrical properties of electrodes.sGQD was successfully prepared and doped into the conductive hydrogel proved by SEM,TEM and other tests.Since both electrochemical activity and excellent conductivity are reserved,the as-prepared hydrogel electrode exhibits a higher specifc capacitance compared with PPy hydrogel.In addition,during the charging and discharging process,sGQD and sGO can form transport channels to facilitate fast solvated ion diffusion during charge and discharge process that can contribute to the performance improvement.EIS shows that the prepared hydrogel electrodes have high conductivity,low diffusion resistance and effective ionic diffusion ability,and the impedance performance is significantly better than that of the PPy hydrogel electrode.At the same time,the prepared hydrogel electrodes also show improved cyclic stability due to the introduction of sGQD with excellent mechanical strength.Then,sGO was prepared using graphite as a carbon source and used as a dopant to prepare hydrogels in the same way.Similarly,the surface of graphene was successfully grafted with sulfonic acid group proved by a series of tests,and the hydrogel prepared had good electrochemical properties.Compared with sGQD-doped PPy hydrogel,the most prominent advantage of PPy/sGO hydrogel is extremely high specific capacitance.The maximum specific capacitance can reach 1268.3 F·g^-1 at 0.5 A·g^-1,which be attributed to the good conductivity and high strength of sGO.The sGO as a dopant can not only cross-link the PPy chain to form a conductive hydrogel with three-dimensional structure,but also effectively improve the expansion and contraction of PPy during repeated charging and discharging due to the high mechanical strength of sGO,which can significantly improve the electrochemical stability of PPy electrode.In this paper,sGQD and sGO were used as dopants to prepare PPy based hydrogel electrodes in a simple one-step process.The method is simple,efficient and can be further used to prepare other electrode materials with ideal structure and excellent properties.At the same time,it can be seen that PPy based hydrogel electrodes have potential application prospects as advanced electrode materials.更多还原