A series of flexible graphene/carbon nanotubes (CNTs) hybrid papers were prepared by a facile impregnation method using cellulose papers as substrate. The impregnation cycles and sequence have a great impact on microstructure, electrical conductivity and electromagnetic interference (EMI) shielding performance of graphene/CNTs hybrid papers. The results showed that the surface of cellulose papers was covered by graphene and CNTs, forming continuous conductive networks. The graphene/CNTs hybrid papers achieved a thickness range of 174.7-253.2 μm and areal density range of 26-35.7 g/m2, which presented a larger advantage than traditional EMI shielding materials. The electrical conductivity was increased from 0.33 S/cm to 7.63 S/cm with the increase of impregnation cycles from 1 to 5. Furthermore, graphene/CNTs hybrid papers delivered a high EMI shielding effectiveness of 22-32 dB in the frequency of 30-1500MHz, which was superior to single graphene or CNTs papers. Moreover, the electrical conductivity and EMI shielding effectiveness of as-prepared graphene/CNTs hybrid papers presented little decline after even bending 100 times at an angle of 180° owing to their excellent flexibility. The graphene/CNTs hybrid papers possess a huge application potential in electromagnetic compatibility (EMC) of electronic device. Key words: graphene; carbon nanotubes; electromagnetic interference shielding; cellulose paper; dielectric polarization
In this paper, we reported on the preparation of porous materials via a reaction under Autogenic Pressure at Elevated Temperature (RAPET) at 700°Cusing natural product and alkoxides as precursors. The RAPET is a new simple efficient method to prepare inorganic materials. The porous carbon and its composite materials were prepared via the method of RAPET using natural products such as sweet potato, coriander, the absorbent cotton and viscose fiber doped by tetrabutyl titanate (TBOT) and tetraethoxysilane (TEOS). The reaction temperature of RAPET was 700°C. The carbon and its composites were studied with scanning electron microscopy (SEM), X-ray diffraction (XRD) and nitrogen adsorption-desorption measurements. The BET surface area of the materials are different from 4m2/g to 405m2/g. The XRD investigation indicates that the phases of the TiO2 in the carbon/TiO2 composites are anatase. The materials show a certain charge-discharge performance.
Conducting polyaniline (PANI) nanofibers were synthesized by interfacial polymerization with ethanol/water, n-butyl alcohol/water and n-hexyl alcohol/water as reaction media, respectively. It was characterized by four-probe method, FTIR, UV-Vis, XRD, SEM techniques etc. The results showed that the n-butyl alcohol/water system provided a better reaction environment for the preparation of PANI nanofibers. The optimal conductivity value of PANI nanofibers was 3.55 S/cm; the diameter was between 60 and 100nm and the length was from 600nm to several microns. The electromagnetic shielding effectiveness of the PANI nanofibers was from 38dB to 79dB, which was measured by coaxial method from 10KHz to 4GHz. According to the results, the PANI nanofibers could be used as electromagnetic shielding materials.
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