Yu Jianshu, Ding Hui, Chen Bin, Sun Xuejiao, Zhang Ying, Zhou Zhongfu
School of Materials Science and Engineering, Shanghai University, Shanghai 200444, China.
Inner Mongolia Key Laboratory of Carbon Materials, Baotou 014000, China.
Materials (Basel). 2024 May 24;17(11):2540. doi: 10.3390/ma17112540.
The excellent electrical properties of graphene have received widespread attention. However, the difficulty of electron transfer between layers still restricts the application of graphene composite materials to a large extent. Therefore, in this study, graphene/polyimide films were subjected to a Joule heating treatment to improve the electrical conductivity of the film by ~76.85%. After multiple Joule thermal cycle treatments, the conductivity of the graphene/polyimide film still gradually increased, but the increase in amplitude tended to slow down. Finally, after eight Joule heat treatments, the conductivity of the graphene/polyimide film was improved by ~93.94%. The Joule heating treatment caused the polyimide to undergo atomic rearrangement near the interface bonded to the graphene, forming a new crystalline phase favourable for electron transport with graphene as a template. Accordingly, a model of the bilayer capacitive microstructure of graphene/polyimide was proposed. The experiment suggests that the Joule heating treatment can effectively reduce the distance between graphene electrode plates in the bilayer capacitive micro-nanostructures of graphene/polyimide and greatly increases the number of charge carriers on the electrode plates. The TEM and WAXS characterisation results imply atomic structure changes at the graphene/polyimide bonding interface.
石墨烯优异的电学性能受到了广泛关注。然而，层间电子转移的困难在很大程度上仍然限制了石墨烯复合材料的应用。因此，在本研究中，对石墨烯/聚酰亚胺薄膜进行了焦耳热处理，使薄膜的电导率提高了约76.85%。经过多次焦耳热循环处理后，石墨烯/聚酰亚胺薄膜的电导率仍逐渐增加，但增幅趋于减缓。最终，经过八次焦耳热处理后，石墨烯/聚酰亚胺薄膜的电导率提高了约93.94%。焦耳热处理使聚酰亚胺在与石墨烯结合的界面附近发生原子重排，以石墨烯为模板形成了有利于电子传输的新晶相。据此，提出了石墨烯/聚酰亚胺双层电容微观结构模型。实验表明，焦耳热处理能够有效减小石墨烯/聚酰亚胺双层电容微纳结构中石墨烯电极极板间极板之间的距离，并大幅增加极板上的载流子数量。透射电子显微镜（TEM）和广角X射线散射（WAXS）表征结果表明石墨烯/聚酰亚胺结合界面处存在原子结构变化。
