Anodic composite deposition of RuO2/reduced graphene oxide/carbon nanotube for advanced supercapacitors.

Anodic composite deposition is demonstrated to be a unique method for fabricating a ternary ruthenium dioxide/reduced graphene oxide/carbon nanotube (RuO2 xH2O/rGO/CNT, denoted as RGC) nanocomposite onto Ti as an advanced electrode material for supercapacitors. The rGO/CNT composite in RGCs acts as a conductive backbone to facilitate the electron transport between current collector and RuO2 xH2O nanoparticles (NPs), revealed by the high total specific capacitance (C(S,T) = 808 F g(-1)) of RGC without annealing. The contact resistance among RuO2 xH2O NPs is improved by low-temperature annealing at 150 °C (RGC-150), which renders slight sintering and enhances the specific capacitance of RuO2 xH2O to achieve 1200 F g(-1). The desirable nanocomposite microstructure of RGC-150 builds up the smooth pathways of both protons and electrons to access the active oxy-ruthenium species. This nanocomposite exhibits an extremely high C(S,T) of 973 F g(-1) at 25 mV s(-1) (much higher than 435 F g(-1) of an annealed RuO2 xH2O deposit) and good capacitance retention (60.5% with scan rate varying from 5 to 500 mV s(-1)), revealing an advanced electrode material for high-performance supercapacitors.

Nanoarchitectured graphene-based supercapacitors for next-generation energy-storage applications.

Tremendous development in the field of portable electronics and hybrid electric vehicles has led to urgent and increasing demand in the field of high-energy storage devices. In recent years, many research efforts have been made for the development of more efficient energy-storage devices such as supercapacitors, batteries, and fuel cells. In particular, supercapacitors have great potential to meet the demands of both high energy density and power density in many advanced technologies. For the last half decade, graphene has attracted intense research interest for electrical double-layer capacitor (EDLC) applications. The unique electronic, thermal, mechanical, and chemical characteristics of graphene, along with the intrinsic benefits of a carbon material, make it a promising candidate for supercapacitor applications. This Review focuses on recent research developments in graphene-based supercapacitors, including doped graphene, activated graphene, graphene/metal oxide composites, graphene/polymer composites, and graphene-based asymmetric supercapacitors. The challenges and prospects of graphene-based supercapacitors are also discussed.

Highly Flexible and Conductive Printed Graphene for Wireless Wearable Communications Applications.

In this paper, we report highly conductive, highly flexible, light weight and low cost printed graphene for wireless wearable communications applications. As a proof of concept, printed graphene enabled transmission lines and antennas on paper substrates were designed, fabricated and characterized. To explore its potentials in wearable communications applications, mechanically flexible transmission lines and antennas under various bended cases were experimentally studied. The measurement results demonstrate that the printed graphene can be used for RF signal transmitting, radiating and receiving, which represents some of the essential functionalities of RF signal processing in wireless wearable communications systems. Furthermore, the printed graphene can be processed at low temperature so that it is compatible with heat-sensitive flexible materials like papers and textiles. This work brings a step closer to the prospect to implement graphene enabled low cost and environmentally friendly wireless wearable communications systems in the near future.

Novel synthesis of graphene foils in mesostructured silica between hexagonal and lamellar phases.

The mesostructured silica template between hexagonal and lamellar phases derived from self-assembled tetraethyl-ortho-silicate (TEOS) with uniform adsorption of iron-group metal ions provides an ideal environment for growing highly crystalline graphene foils at a low temperature.

A unique strategy for preparing single-phase unitary/binary oxides-graphene composites.

This study proposes a novel two-step strategy to prepare single-phase unitary/binary oxides-graphene composites: precipitating hydroxides followed by microwave-assisted hydrothermal or solvothermal annealing.

Design and tailoring of the nanotubular arrayed architecture of hydrous RuO2 for next generation supercapacitors.

By use of the membrane-templated synthesis route, hydrous RuO2 (RuO2.xH2O) nanotubular arrayed electrodes were successfully synthesized by means of the anodic deposition technique. The desired three-dimensional mesoporous architecture of RuO2.xH2O nanotubular arrayed electrodes with annealing in air at 200 degrees C for 2 h simultaneously maintained the facility of electrolyte penetration, the ease of proton exchange/diffusion, and the metallic conductivity of crystalline RuO2, exhibiting unexpectedly ultrahigh power characteristics with its frequency "knee" reaching ca. 4.0-7.8 kHz, 20-40 times better than that of RuO2 single crystalline, arrayed nanorods. The specific power and specific energy of annealed RuO2.xH2O nanotubes measured at 0.8 V and 4 kHz is equal to 4320 kW kg-1 and 7.5 W h kg-1, respectively, demonstrating the characteristics of next generation supercapacitors.