High-performance multifunctional graphene yarns: toward wearable all-carbon energy storage textiles.

The successful commercialization of smart wearable garments is hindered by the lack of fully integrated carbon-based energy storage devices into smart wearables. Since electrodes are the active components that determine the performance of energy storage systems, it is important to rationally design and engineer hierarchical architectures atboth the nano- and macroscale that can enjoy all of the necessary requirements for a perfect electrode. Here we demonstrate a large-scale flexible fabrication of highly porous high-performance multifunctional graphene oxide (GO) and rGO fibers and yarns by taking advantage of the intrinsic soft self-assembly behavior of ultralarge graphene oxide liquid crystalline dispersions. The produced yarns, which are the only practical form of these architectures for real-life device applications, were found to be mechanically robust (Young's modulus in excess of 29 GPa) and exhibited high native electrical conductivity (2508 ± 632 S m(-1)) and exceptionally high specific surface area (2605 m(2) g(-1) before reduction and 2210 m(2) g(-1) after reduction). Furthermore, the highly porous nature of these architectures enabled us to translate the superior electrochemical properties of individual graphene sheets into practical everyday use devices with complex geometrical architectures. The as-prepared final architectures exhibited an open network structure with a continuous ion transport network, resulting in unrivaled charge storage capacity (409 F g(-1) at 1 A g(-1)) and rate capability (56 F g(-1) at 100 A g(-1)) while maintaining their strong flexible nature.

Scalable solid-template reduction for designed reduced graphene oxide architectures.

Herein, we report a solid-state reduction process (in contrast to solution-based approach) by using an environmentally friendly reductant, such as vitamin C (denoted VC), to be directly employed to solid-state graphene oxide (GO) templates to give the highly active rGO architecture with a sheet resistance of as low as 10 Ω sq(-1). In addition, predesigned rGO patterns/tracks with tunable resistivity can be directly "written" on a preprepared solid GO film via the inkjet-printing technique using VC/H2O as the printing-ink. This advanced reduction process allows foreign active materials to be preincorporated into the GO matrix to form quality active composite architectures.

The citrate-mediated shape evolution of transforming photomorphic silver nanoparticles.

The photoconversion of photomorphic silver nanoparticles from discs to prisms via citrate mediated growth on the twin plane faces of the nanoparticles is demonstrated. This systematic shape evolution from discs to hexagons and then prisms of increasing aspect ratios is a result of the growth process being confined to specific faces of the growing nanoparticles.

Nanofibrilar-polyaniline/Carbon nanotube composites: aqueous dispersions and films.

Entirely nanostructured nanofibrilar-polyaniline/multi-walled carbon nanotube (NF-PANI/MWNT) composites with nanotube loadings as high as 50 wt% were synthesized via a facile in-situ chemical polymerization process. These are composed of a nanofibrilar polyaniline (NF-PANI) matrix in which multi-walled carbon nanotubes (MWNTs) are homogeneously embedded and partially covered by polyaniline. Stable and homogeneous aqueous dispersions in concentrations up to 10 mg/ml in water easily were prepared. For the first time, dispersions and casted films of this novel type of NF-PANI/MWNTs composites are characterized. Both, dispersions and films reveal the typical behavior of PANI with slightly changed redox values and with fast reaction kinetics due to the presence of MWNTs. Conductivity of drop cast films reveal values of 20 to 50 S/m. Local SPM measurements confirm the intrinsic fibril structure. Individual fibrils show both semiconducting and metallic behavior with values up to 100 S/m. This new class of nanostructured NF-PANI/MWNT composites with its water-based processing possibilities as well as with its conducting and electrochromic effects will contribute to further progress in the field of smart plastic electronics.

Novel fused-LEDs devices as optical sensors for colorimetric analysis.

The development of a novel, low power optical sensing platform based on light emitting diodes (LEDs) is described. The sensor is constructed from a pair of LEDs fused together at an angle where one LED functions as the light source and the other LED is reverse biased to function as a light detector. Sensor function is based on the level of light received by the detector diode, which varies with the reflectance of the interface between the device and its environment, or the chemochromic membrane that covers the device. A simple microprocessor circuit is used to measure the time taken for the photon-induced current to discharge the detector LED from an initial 5V (logic 1) to 1.7V (logic zero). This sensing device has been successfully used for colour and colour-based pH measurements and offers extremely high sensitivity, enabling detection down to the sub micro molar level of dyes.