A new synthesis route of a solution-processed highly conductive self-standing graphite membrane from reassembled graphene oxide (GO) has become one of the intensive research focus, because of its immense application opportunities. Previously demonstrated techniques were limited by the unstable reduced graphene oxide (RGO) dispersion and agglomeration during chemical reduction without any surfactant. This results in poor packing morphology and low electrical conductivity of the RGO membrane. Here, we report a novel synthesis route of a highly concentrated RGO solution from exfoliated GO, which results highly conductive and self-standing RGO membrane without using any binders or organic solvents. Our low-temperature reduction method is significantly different from previous investigations in which controlling the reduction rate by lowering the reduction temperature of the GO solution and collision probability was the key factor in preventing random agglomeration. Further high-temperature reduction of the RGO membrane gave rise to a reassembled graphite structure containing negligible oxygen content (O 1s/C 1s = 0.005), and high electrical conductivity (up to 1.6 × 105 S/m) without disintegration of its self-standing feature. This result is better than any previously reported value. Developed RGO membrane could be mass-produced for various flexible device applications. The in-plane alignment and through-thickness consolidation of GO and RGO membranes using vacuum-filtration and thermal treatment successfully ensured the synthesis of highly conductive, mechanically robust RGO and graphite membranes.

We investigate charge transport in a chemically reduced graphene oxide (RGO) film of sub-micron thickness. The I-V curve of RGO film shows current switching of the order of ∼10(5) above the threshold voltage. We found that the observed I-V curve is consistent with quantum tunnelling based charge transport. The quantum tunnelling based Simmons generalized theory was used to interpret the charge transport mechanism which shows that the current switching phenomenon is associated with transition from direct to Fowler-Nordheim (F-N) tunneling. The absence of current switching in the I-V curve after stripping away the oxygen functional groups from chemically RGO film confirms that the presence of these groups and reduced interaction between adjacent layers of RGO play a key role in charge transport. Such metal-based current switching devices may find applications in graphene-based electronic devices such as high voltage resistive switching devices.

Although the graphene-based materials have a great potential to be used for various energy storage devices, the expected performance of graphene has not been achieved yet seemingly due to the lack of interconnected porosity and actively-exposed surface area that should be developed in the re-stacked graphene electrodes. Herein we used an electrophoretic deposition (EPD) method to fabricate a binderfree porous supercapacitor electrode composed of reduced graphene oxide (RGO) sheets and conductive carbon black (CB) particles. Applying EPD for an electrostatically-stabilized aqueous mixture of RGO and CB nanoparticles, the electrophoretic squeezing force in EPD induced the RGO sheets to align in the in-plane direction along with the CB particles placed in the interlayers of RGO. The developed ladder-like interleaved composite structure allowed a desirable porosity network and conductive path for a facile movement of ions and electrons. Controlling the ratios of concentrations (C s,RGO /C s,CB ) and/or zeta potentials (x RGO /x CB ) of the RGO and CB nanoparticles in aqueous mixtures, different nanostructures of the interleaved RGO/CB laminates could be fabricated. Thoroughly tested as a supercapacitor electrode in an organic electrolyte (TEA BF 4 ), the developed RGO/CB electrodes provided excellent performance of the specific capacitance of 218 F g À1 at a scan rate of 1 mV s À1 (133.3 F g À1 at a current density of 2 A g À1 ), energy density of 43.6 W h kg À1 and power density of 71.3 kW kg À1 .It is believed that an ideal performance of intrinsic graphene properties could be exerted by the unique nanostructure of binder-free interleaved graphene laminates as developed by the scalable in situ EPD process for large-volume production.