The authors investigate stability of several bilayer configurations formed by 6- and 12-zigzag graphene nanoribbons (GNR) in the framework of density function theory. Electronic structure calculations find the AB-α bilayer to be energetically preferred, and the AB-β bilayer is found to converge to the AB-α bilayer in the geometry optimisation process. Besides the AB-α bilayer, the authors find other stable bilayer configurations as local minima on the energy surface obtained by displacing the top layer relative to the bottom layer of GNR. These configurations are associated with the AB-stacking and predicted to be magnetic in nature, thus making the bilayer GNRs to be promising candidates for device applications at nanoscale.

Chemically assisted graphene oxide (GO) is synthesised by improved Hummers’ method. It has been further reduced by hydrazine hydrate by hydrothermal method to form reduced GO (rGO). Raman spectra of GO and rGO suggest the formation of D-band and G-band at 1360 and 1590 cm⁻¹, respectively. Along with D and G modes, 2D and D′ + G′ modes have been observed at 2710 and 2950 cm⁻¹, respectively. Tuinstra and Koenig relation is used to calculate the relative size of the sp²-carbon domain. Scanning electron micrographs reveal the separation of flakes during reduction. The dc conductivity measurement covers the peculiar study of conduction mechanism of rGO. On reduction, a remarkable increase in the room temperature conductivity (from 4.25 × 10⁻¹⁰ to1.9 × 10⁻² S/cm) of GO has been observed. The accomplish study of dc conductivity measurement of rGO in the temperature range of 77–400 K is reported. It is explained on the basis of 3D variable range hopping model. The slope of a plot between activation energy and temperature on logarithmic scale is found to be 0.75 which suits well with the theoretical result.

Graphene is a remarkable material, which is yet to make the transition from unique laboratory phenomenon to useful industrial material. One missing element in the development process is a quick method of quality control of the electrical properties of graphene which may be applied in, or close to, the graphene growth process on an industrial scale. In this study, the authors describe a non-contact method using microwave resonance which potentially solves this problem. They describe the technique, consider its limitations and accuracy and suggest how the method may have future take up.

The current standard material used for transparent electrodes in displays, touch screens and solar cells is indium tin oxide (ITO) which has low sheet resistance (10 Ω/□), high optical transmission in the visible wavelength (85%) and does not suffer of optical haze. However, ITO is mechanically rigid and incompatible with future demands for flexible applications. Graphene materials share many of the properties desirable for flexible transparent conductors, including high optical transparency, high mechanical flexibility and strength. Whilst pristine graphene is not a good transparent conductor, functionalised graphene is at least 1000 times a better conductor than its pristine counterpart and it outperforms ITO. Here the authors review recent work on a novel graphene-based conductor with sheet resistance as low as 8.8 Ω/□ and 84% optical transmission. This material is obtained by ferric chloride (FeCl₃) intercalation into few-layer-graphene (FLG), giving rise to a new system which is the best known flexible and transparent electricity conductor. FeCl₃-FLG shows no significant changes in the electrical and structural properties for a long exposure to air, to high levels of humidity and at temperatures of up to 150°C in atmosphere. These properties position FeCl₃-FLG as a viable and attractive replacement to ITO.

Graphene, an atomically thin two-dimensional material has become an ideal candidate for fabricating nano-electro-mechanical systems resonators because of its excellent mechanical properties and ultra-light weight. Its high tensile strength and Young's modulus coupled with the ability to withstand high strains while functioning make it suitable for use in mechanical resonators. In this study, the authors review the electronic applications of graphene mechanical resonators for future radio frequency communications, ultra-sensitive mass and temperature detection using the consequent changes in resonance frequency of the resonators. Moreover, they experimentally establish the non-linear characteristics of graphene mechanical resonators at high driving amplitudes and envision its applications in future electronics and sensing.

Graphene, a self-supporting monolayer, has excited enormous interest over the 10 years since its discovery due to its remarkable electrical, mechanical thermal and chemical properties. Here the authors describe the authors’ work developing chemical vapour deposition methods to grow monolayer graphene on copper foil substrates and the subsequent transfer process. Raman microscopy, scanning electron microscopy and atomic force microscopy are used to examine the quality of the transferred material. To demonstrate the process, they also describe transfer onto patterned SiO₂/Si substrate which forms free suspended graphene drums. These show interesting mechanical properties which are being explored as nanomechanical resonators.

The presence of voltage controlled negative differential resistance was observed in conduction characteristics recorded at room temperature for 300 nm thick spin-coated films of graphene oxide (GO) sandwiched between indium tin oxide (ITO) substrates and top electrodes of sputtered gold (Au) film. The GO crystallites were found from the X-ray diffraction studies to have an average size in the order of 7.24 nm and to be preferentially oriented along (001) plane. Raman spectroscopy suggested that the material consisted of multilayer stacks with the defects being located at the edges with an average distance of 1.04 nm apart. UV visible spectroscopy studies suggested that the band gap of the material was 4.3 eV, corresponding to direct transitions. The two-terminal ITO/GO/Au devices exhibited memristor characteristics with scan-rate dependent hysteresis, threshold voltage and On/Off ratios. A value of >10⁴ was obtained for On/Off ratio at a scan rate of 400 mVs⁻¹ and 4.2 V.

Graphene (GN), a single layer two-dimensional structure nanomaterial, exhibits exceptional physical, electrical and chemical properties that lead to many applications from electronics to biomedicine. The unique parameters of GN, notably its considerable electron mobility, thermal conductivity, high surface area and electrical conductivity, are bringing heightened attention into biomedical applications. This study assesses the recent advances in GN-based biosensors and its derivatives in different areas to focus on glucose sensing, DNA sensing, drug and gene delivery, cancer therapy and other related biomedical applications (electrochemical sensors, tissue engineering, haemoglobin and cholesterol sensing), together with a brief discussion on challenges and future perspectives in this rapidly developing field.

Electronic sensors based on graphene have a high potential in many applications, due to the unique properties of the graphene material. This study is a review where the authors discuss the properties of graphene which are useful to sensing applications and they report and describe different types of graphene electronic sensors: biological, mechanical, gas and chemical sensors. They also discuss the ways to functionalise graphene and the used device structures. They compare the performance of the main types of biological, mechanical and chemical sensors. Finally, they explain the future challenges of graphene-based sensors, in order to make graphene sensing systems and smart sensors, which would be their main breakthrough application.