PMMA direct exfoliation for rapid and organic free transfer of centimeter-scale CVD graphene

Despite the various techniques developed for the transfer of large area graphene grown by chemical vapor deposition (CVD), the conventional PMMA transferring technique has been widely applied in laboratories due to its convenience and economical cost. However, the complete removal of PMMA on graphene surface has become a troublesome, and the PMMA residue could degrade the properties of graphene significantly. We report here a facile water assisted technique to directly peel off the PMMA layer over centimeter-sized CVD graphene film for the first time. No organic solvents are involved in the whole transfer process. The transferred graphene film is clean and intact over large area because of the cooperative effect of the capillary force and the van der Waals force which facilitates the conformal contact between graphene film and the substrate. Various types of graphene samples (i.e. monolayer, multilayer, and incomplete domains) can be easily transferred to diverse substrates including silicon wafer, sapphire, and quartz with good integrity. The transferred graphene film is of high cleanliness, and the graphene transistors show higher carrier mobility and lower level of p-type doping comparing to the conventional wet transfer technique.

Modeling of electrotransport properties of Li-intercalated graphene film

In this work, within the framework of density functional theory combined with the method of nonequilibrium Green’s functions the density of states, transmission spectrum, current-voltage characteristics, and differential conductivity of Li-intercalated graphene (LiC6) have been determined. It is shown that in the energy range of -1.3÷-1.05 eV the quasiparticle transport through the nanostructure is disable. The features of IV- and dI/dV-characteristics of LiC6 in the form of decreasing of resistance in the range of -0.4÷0.4 V were revealed, and in the interval of 0.4÷1.4 V formation of negative differential resistance area, related to scattering of quasiparticles. It is established, that LiC6 nanodevice has 12÷13 ballistic channels and has the maximum amount of conductance 12÷13G0 , where Go is the conductance quantum.

Ionic EAP Actuators with Electrodes Based on Carbon Nanomaterials

Flexible polymer-based actuators, often also called artificial muscles, are an essential part of biomimetic systems that mimic the movement principles of animal world creatures. The most used electrode material to force the actuator move is an ensemble of noble metal nanoparticles in the electroactive polymer surface. Noble metal electrodes have enough electrical conductivity and elasticity and are not subjected to oxidation. However, high cost of such electrodes and their tendency to cracking dictate the need for searching other materials, primarily carbon ones. The review considers several options for this search. For example, carbon nanotubes and graphene have excellent properties at the level of a single individually taken nanotube or graphene sheet. However, conservation of these properties in structurally imperfect film electrodes requires a separate study. In addition, there are problems of compatibility of such electrodes with the polymers that requires cumbersome technologies, e.g., hot pressing, which complicates the production of the actuator as a whole. The review concerns the technology options of manufacturing actuators and the results obtained on their basis, both including hot pressing and avoiding this procedure. In particular, the required level of the graphene oxide reduction in hydrazine provides sufficient adhesion at rather high electrical conductivity of the graphene film. The ability to simultaneous achieving these properties is a nontrivial result, providing the same level of actuation as with expensive noble metal electrodes. Actuators that additionally require greater lifetime resource should be obtained in other ways. Among them are using the graphdiyne electrodes and laser processing of the graphene electrodes.

SYNTHESIS THIN FILM ELECTRODES GRAPHENE VIA NOVEL 3D PRINTALBE TECHNIQUE AND DETERMINE PROPERTY ELECTROCHEMICAL

Graphene film electrodes have many important applications, but the fabriacion of these electrodes is difficult dues to the poor processing of graphene. This article describes the preliminary results of using 3D printing technology to fabricate thin-film electrodes from graphene oxide inks. Graphene oxide ink is synthesized by chemical method. The graphene oxide (GO) and reduction graphene oxide (r GO) thin film were chacracterized by filed scanning electron microscopy (FESEM) and Energy-dispersive X-ray spectrocopy (EDX spectrocopy) to make sure the morphological and optical characteristics of the thin film. In addition, the electrochemical aera active studies were also determined by cyclic voltametry (CV) curves. The r GO thin film displays higher electrochemical area active in comparison with GO, which is 2.56 cm2 compare to 0.31 cm2, indicating the best result for the superior conductivity of thin film electrode.