Graphene Hybrid Films Research Articles

The preparation of graphene hybrid films decorated with poly[2-methoxy-5-(2′-ethyl-hexyloxy)-1,4-phenylene vinylene] particles prepared by non-solvent induced precipitation

A hybrid film of graphene decorated with poly[2-methoxy-5-(2′-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) nanoparticles is fabricated by a simple non-solvent induced precipitation method. The structure of the graphene film and graphene/MEH-PPV hybrid film are investigated by scanning electron microscopy, atomic force microscopy and X-ray photoelectron spectroscopy. The large specific surface area of graphene sheets makes it an ideal support for depositing MEH-PPV nanoparticles as well as preventing aggregation of the nanoparticles. The graphene/MEH-PPV hybrid film is superhydrophobic, which is attributed to the increase in surface roughness as a result of random decoration of MEH-PPV nanoparticles on the graphene sheets. The MEH-PPV nanoparticles endow the graphene hybrid film with strong photoluminescence. The hybrid film also shows excellent conductivity and high thermal stability. The graphene/MEH-PPV hybrid film thus prepared may find potential applications in various devices where integrated properties of superhydrophobicity, conductivity and luminescence are required.

Rational Design of Hybrid Graphene Films for High-Performance Transparent Electrodes

Transparent, flexible conducting films were fabricated by using a metallic grid and graphene hybrid film. Transparent electrodes using the hybrid film and transparent substrate such as glass or polyethylene terephthalate (PET) films were assembled. The sheet resistance of the fabricated transparent electrodes was as low as 3 Ω/◻ with the transmittance at ∼80%. At 90% transmittance, the sheet resistance was ∼20 Ω/◻. Both values are among the highest for transparent electrode materials to date. The materials used for the new hybrid electrode are earth-abundant stable elements, which increase their potential usefulness for replacement of indium tin oxide (ITO) in many applications.

Solution-based synthesis and characterization of a silver nanoparticle–graphene hybrid film

A solution-based chemical approach has been used to prepare silver nanoparticle–graphene (Ag–G) hybrids through sequential reduction of graphene oxidation and silver ions. The products can readily form a stable aqueous solution without polymeric or surfactant stabilizers, and this makes it possible to produce graphene–silver hybrids on a large scale using low-cost solution processing techniques. The paper-like Ag–G film obtained by vacuum filtration is glossy and has a high reflectivity and good flexibility. Raman signals of graphene for the film are increased with the dispersion of silver nanoparticles, exhibiting surface-enhanced Raman scattering activity. The increases from three- to eightfold can be obtained with the increase of silver nanoparticle content in the hybrids, indicating that the increase can be tuned by changing the density of silver nanoparticles. The electrochemical properties of the Ag–G film demonstrate their fast electron-transfer kinetics for the Fe ( CN ) 6 3 - / 4 - redox system.

Conductive Behaviour and Self-Conductance Characteristic of Carbon Nanotubes/Functionalized Graphene Hybrid Films

Multi-walled carbon nanotubes (MWCNTs)/Functionalized graphite (FG) hybrid films were fabricated by a simple solution-casting method. The films showed a layered, well-entangled and interconnected porous structure at nanometer scale. Such the nanostructures resulted in the films having the relatively high bulk conductivity and self-conductance characteristics. With increasing MWCNT mass fraction, the conductivity rapidly increased from approximately 10(-9) S/m of the host FG to over 10(-1) S/m. The percolation threshold was found to be about 29.6 wt% of MWCNTs. For the film with 83 wt% MWCNTs the specific capacitance was about 1 F/cm3. The hybrid films are of much higher power factor compared to conventional dielectric capacitors. The energy density of the film with 50 wt% MWCNTs was found to be 0.1 Wh/m3 and the charge-discharge period was very short about 8 seconds. It is believed that the MWCNTs/FG hybrid films have great potential as electrode materials for applications to energy storage.

Flexible Field Emission of Nitrogen‐Doped Carbon Nanotubes/Reduced Graphene Hybrid Films

The outstanding flexible field emission properties of carbon hybrid films made of vertically aligned N-doped carbon nanotubes grown on mechanically compliant reduced graphene films are demonstrated. The bottom-reduced graphene film substrate enables the conformal coating of the hybrid film on flexible device geometry and ensures robust mechanical and electrical contact even in a highly deformed state. The field emission properties are precisely examined in terms of the control of the bending radius, the N-doping level, and the length or wall-number of the carbon nanotubes and analyzed with electric field simulations. This high-performance flexible carbon field emitter is potentially useful for diverse, flexible field emission devices.

Flexible room-temperature NO2 gas sensors based on carbon nanotubes/reduced graphene hybrid films

We present a flexible room temperature NO2 gas sensor consisting of vertical carbon nanotubes (CNTs)/reduced graphene hybrid film supported by a polyimide substrate. The reduced graphene film alone showed a negligible sensor response, exhibiting abnormal N–P transitions during the initial NO2 injection. A hybrid film, formed by the growth of a vertically aligned CNT array (with CNTs 20 μm in length) on the reduced graphene film surface, exhibited remarkably enhanced sensitivities with weak N–P transitions. The increase in sensitivity was mainly attributed to the high sensitivity of the CNT arrays. The outstanding flexibility of the reduced graphene films ensured stable sensing performances in devices submitted to extreme bending stress.