Co-assembly Of Garaphene And 1D Nanomaterials For Supercapacitor Application

Tremendous research attention has been focused on nanoscaled materials since the beginning of the 1960s. Due to the wave property of electrons and interaction between atoms, materials at nano scale could obtain various unique properties than materials at macroscopical phase. Nowadays, nanomaterials have been widely applied, including optical, electrical, magnetical, thermal, and quantal fields. However, due to the limitation and defects of one single type of nanomaterials alone, composite nanomaterials are required. In this approach, advantages from different materials could be combined or even enlarged due to synergism, which makes this area a hot topic.Two research works have been introduced in this thesis. The first part is about cadmium sulfide-oxidized graphene (CdS-GO) composite material. Stable and ultralong Cd(OH)2 nanowire was synthesized at first in water solution by the template of ID ionic crystal, then gold nanoparticles were added on the Cd(OH)2 nanowire by electrostatic force to form Cd(OH)2-Au composite, and further, GO was assembly with the Cd(OH)2-Au composite to afford the composite material Cd(OH)2-GO. Based on the reaction between Cd(OH)2 and H2S, Cd(OH)2-GO can be finally changed to CdS-GO composite material. CdS, a typical Ⅱ-Ⅳ semi conduct material with a band gap of 2.4eV, has good optical-electrical translation properties, and GO is an excellent electrochemical material with good solubility and processability. The combination of these two materials could improve the properties and extend the applications in energetic fields.The second part is about the synthesis and application of GO-single wall nano tube (SWNT) composite material. Graphene Oxide-Pristine SWNT composite were obtained by the ultrasonic dispersion of SWNTs with graphene oxide(GO) as a surfactant, followed by a freeze-drying of the sample. The morphology, structure, component and electrochemical property of the compound were characterized by scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and electrochemical measurements. The results showed that the electrochemical properties of the compound were significantly improved due to the doping of SWNTs into a GO matrix. Through changing the ratio between CNTs and graphene oxide, the sample corresponding to a SWNT cotent of 10% showed the best supercapacitor property. At such a optimized mixing ratio, the specific discharge capacitance of the nano-composite were 155F·g-1 when being cycled at a current of 0.5A·g-1 which was nearly doubled compared to pure graphene oxide(81.5F·g-1).This GO-SWNT composite material assembled by simple method could have wide applications in energy storage field.