Preparation And Properties Of Functional Materials Based On Graphene Oxide

Graphene oxide?GO?has the similar two-dimensional structure with Graphene.It is well known that GO is rich in oxygen containing groups,such as hydroxyl,carbonyl and epoxy group,which make GO much more active.Except for the inheritance of the excellent mechanical,electrical as well as the optical properties of its predecessor graphene,GO also has large specific surface area,biocompatibility adsorption and optical properties.Therefore,functional materials based on GO are the best candidates to be applied in the area of solar energy storage,electromagnetic absorption materials and so on.In this paper our works focus on the preparation of the functional materials based on GO,and research on the properties and mechanism of their photo-thermal energy storage and electromagnetic absorption.Firstly,Hummers method was used to prepare GO,the structural of products was investigated with the help of FT-IR,XRD,XPS and SEM.In this paper we report a route to attach azobenzene?AZO?moiety covalently to graphene oxide?GO?to create chromophore/graphene oxide?AZO-GO?hybrid for long-term solar thermal storage.The photoisomerization of trans-to cis-hybrid includes two sections of first-order reaction,and the thermal barrier??35?E_a?of the latter section is reduced.It is found that C-H????interaction between the cis-AZO chromophores and the aromatic rings of the substrate induces collective electronic variations of GO at critical percentage of cis-AZO and influences the?–?*transition of the chromophores directly.The C-H????interaction reduces the time for trans-hybrid to reach photostationary state and also thermally stabilizes the cis-hybrid.Secondly,we prepared the Fe₃O₄ sheets with the diameter of 20 um by hydrothermal method and the structure was characterized by using XRD and SEM.We have studied the absorbing properties of both Fe₃O₄ and GO.Fe₃O₄ sheets exhibit excellent magnetic loss but a poor wave absorber.Although GO shows very deep reflection loss,the agglomeration limits the use of it.It is a better choice to use both GO and Fe₃O₄ sheets as composite materials to solve the problems.In this paper a simple mechanical mixing method was used to prepare the GO-Fe₃O₄composites.The results show that Fe₃O₄ sheets adhere to the GO layer and form a layered structure,which effectively avoids the agglomeration of GO,improves the impedance matching of the material,and introduces the electric-polarization mechanism at the interface.When the content of GO is 10-30 wt%,the composite exhibits a better electromagnetic absorption.Finally,in order to enhance the wave absorbing property of GO-Fe₃O₄,a third dielectric material h-BN was introduced.Simple mechanical mixing method was also used to prepare the BN-GO-Fe₃O₄ composites.The studies illustrate that this material shows enhanced wave absorption performance,which dues to the good impedance match.Electromagnetic waves can effectively enter into the material,thus the magnetic loss will be the main loss mechanism.The BN-GO-Fe3O4 composite exhibits broad band,high absorption and light weight properties.