Showing papers by "Shanyi Du published in 2014"

Graphene Nanoribbon Aerogels Unzipped from Carbon Nanotube Sponges

Abstract: Graphene nanoribbon aerogels are fabricated by directly unzipping multi-walled carbon nanotube sponges. These fascinating materials have potential applications as high performance nanocomposites and supercapacitor electrodes.

Multifunctional graphene sheet–nanoribbon hybrid aerogels

Abstract: Graphene sheets and nanoribbons are graphene-based nanostructures with different dimensions. Here, we show that these two materials can be combined to form highly porous, ultra-low density, compressible yet elastic aerogels, which can be used as efficient adsorbents and supercapacitor electrodes. The pore walls consist of stacked graphene sheets embedded with uniformly distributed thick nanoribbons unzipped from multi-walled carbon nanotubes as effective reinforcing skeletons. Owing to the large pore-size, robust and stable structure, and the nanoribbon-adhered pore walls, these hybrid aerogels show very large adsorption capacity for a series of organic solvents and oils (100 to 350 times of aerogel weight), and a specific capacitance of 256 F g−1 tested in a three-electrode electrochemical configuration, which is further improved to 537 F g−1 by depositing controlled loading pseudo-polymers into the aerogels. Our multifunctional graphene sheet–nanoribbon hybrid aerogels may find potential applications in many fields such as environmental cleanup and as flexible electrodes for energy storage systems such as supercapacitors and batteries.

Synergistic effect of Ag nanoparticle-decorated graphene oxide and carbon fiber on electrical actuation of polymeric shape memory nanocomposites

Abstract: This study reports an effective approach of significantly improving electrical properties and recovery performance of shape memory polymer (SMP) nanocomposite, of which its shape recovery was triggered by electrically resistive Joule heating. Reduced graphene oxide (GOs) self-assembled and grafted onto carbon fiber, were used to enhance the interfacial bonding with the SMP matrix via van der Waals force and covalent bond, respectively. A layer of Ag nanoparticles was synthesized from Ag+ solution and chemically deposited onto GO assemblies. These Ag nanoparticles were expected to bridge the gap between GO and improve the electrical conductivity. The experimental results reveal that the electrical conductivity of the SMP nanocomposite was significantly improved via the synergistic effect between Ag nanoparticle-decorated GO and carbon fiber. Finally, the electrically induced shape memory effect of the SMP nanocomposite was achieved, and the temperature distribution in the SMP nanocomposites was recorded and monitored. An effective approach was demonstrated to produce the electro-activated SMP nanocomposites and the resistive Joule heating was viable at a low electrical voltage below 10 V.

Surface grafting of carbon fibers with artificial silver‐nanoparticle‐decorated graphene oxide for high‐speed electrical actuation of shape‐memory polymers

Abstract: Poor heat conduction in the interface between the carbon fiber and polymer matrix is a problem in the actuation of shape-memory polymer (SMP) composites by Joule heating. In this study, we investigated the effectiveness of grafting silver-nanoparticle-decorated graphene oxide (GO) onto carbon fibers to improve the electrothermal properties and Joule-heating-activated shape recovery of SMP composites. Self-assembled GO was grafted onto carbon fibers to enhance the bonding of the carbon fibers with the polymeric matrix via van der Waal's forces and covalent crosslinking, respectively. Silver nanoparticles were further self-assembled and deposited to decorate the GO assembly, which was used to decrease the thermal dissimilarity and facilitate heat transfer from the carbon fiber to the polymer matrix. The carbon fiber was incorporated with SMP to achieve the shape recovery induced by Joule heating. We found that the silver-nanoparticle-decorated GO helped us achieve a more uniform temperature distribution in the SMP composites compared to those without decoration. Furthermore, the shape-recovery behavior and temperature profile during the Joule heating of the SMP composites were characterized and compared. A unique synergistic effect of the carbon fibers and silver-nanoparticle-decorated GO was achieved to enhance the heat transfer and a higher speed of actuation. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41673.