Structure Regulation And Application Of Carbon Nanomaterials

Owing to its excellent physics and chemical properties, SP2-hybridized carbon nanomaterials, including carbon nanotubes and graphene, have got a wide attention and rapid development. With the emerging of smart wearable devices, it has been a hot topic to assembling the amazing nanomaterial, especially graphene, into one dimensional macroscopic structure, which could be used as a platform for constructing portable devices. In the assembling process of nanomaterials, unique properties could be achieved by designing assembly structure, such as sensor, smart devices and energy storage devices. In this paper, a serials of unique fiber-shaped structure, including combined graphene fibers, multi-helix graphene fibers and porous graphene fibers, were designed and fabricated by modifying wet-spinning method. Meanwhile, a porous and translucent electrode used in smart supercapacitor was achieved by drilling carbon nanotube film with laser patterning technique. Specific contents were as follow.(1) Firstly, large size, monolayer and high viscosity graphene oxide dispersions were synthesized according to an advanced Hummers method. Then, export swell effect during wet-spinning process was studied in a single spinneret and double spinneret system, respectively. Finally, an interface fusion phenomenon between two graphene oxide fibers was successful adjusted.(2) We have developed a facile wet-spinning approach to fabricate multi-helix graphene oxide fibers which could be controlled by adjusting the channel and rotating speed of the spinneret. Then, multi-helix graphene fibers were successfully obtained by directly reducing the wet-state GO fibers, which have much higher tensile strain(~35%) compared with straight graphene fibers. In addition, these multi-helix fibers show reversible resistance variations under cyclic tension.(3) A porous structure in graphene fibers was instantly induced by a large current passing through an expandable graphene fiber loaded with iodine which was added during chemical reduction process. The expansion process was happened just in 10 millisecond and no obvious damage on graphene flakes was detected. The volume of porous graphene fibers increased about 29 times compared to unprocessed one. The electrochemistry properties of porous graphene fibers also had a great improvement compared the common graphene fibers.(4) A flexible and electrochromic supercapacitor was made basing on a direct and convenient immobilization of PANI Hydrogel onto porous carbon nanotube(CNT) film. The resultant supercapacitor showed a favorable specific capacitance of 315 F/g and a relatively high cycling stability. Furthermore, the supercapacitor displayed a rapid and reversible chromatic transition between different working stages, and its level of stored energy could be quickly determined by our naked eyes in a predictable and noticeable manner.