Field effect transistors with graphene channels were interfaced with arrays of semiconductor quantum dots (QD). The electrical characteristics of the elements were assessed. The channel response to white light illumination was also assessed as a function of drain-source and gate-source biases.

The photoelectromagnetic (PEM) investigations are proposed for determination of diffusion length of carriers in graphene. The presented measurements are performed in Corbino configuration using noncontact technique. The circular PEM currents are detected in an outer coil by induction if illumination intensity is periodically varied. The theoretical dependence of PEM response on magnetic field induction, intensity and spatial distribution of illumination as well as on frequency of illumination chopping is presented. Experimental PEM data are presented for graphene films grown by CVD processing on a cooper foil and transferred onto a glass substrate. The presented method of investigations should be essential for development of graphene electronic and optoelectronic devices.

The thermal conductivities of pillared-graphene nanostructures (PGNSs) are obtained using nonequilibrium molecular-dynamics simulation. It is revealed their thermal conductivities are much smaller than the thermal conductivities of carbon nanotubes (CNTs). This fact is explained by examining the density of states (DOS) of the local phonons of PGNSs. It is also found the thermal conductivity of a PGNS linearly decreases with the increase of the inter-pillar distance.

A new class of graphene–polyselenophene (PSe) hybrid nanocomposite was successfully synthesized using an in situ synthetic method. The synthesized graphene–PSe nanocomposite exhibited unique properties including a large voltage window, high conductivity, and good mechanical properties. The graphene–PSe nanohybrid reduced the dynamic resistance of electrolyte ions and enabled high charge–discharge rates, thereby enabling high-performance supercapacitance. The results were attributed to synergetic effects between graphene and conducting polymers (CPs), which enhanced charge transport, surface area, and hybrid supercapacitance by combining the properties of electrolytic double-layer capacitors (EDLCs) with those of psedocapacitors. Additionally, a flexible supercapacitor based on the graphene–PSe nanohybrid was successfully demonstrated. To fabricate binder-free supercapacitors, chemical vapor deposition (CVD) and vapor deposition polymerization (VDP) methods were employed. The fabricated all-solid-state supercapacitor exhibited outstanding mechanical and electrochemical performance, even after several bending motions. The novel graphene–PSe nanocomposite material is promising for new energy storage and conversion applications.

A novel approach to synthesize highly luminescent graphene quantum dots (GQDs) with well-defined sizes was explored based on simple oxidation of herringbone-type carbon nanofibers (HCNFs) and size-selective precipitation. In addition, the upconversion properties of GQD were investigated by applying GQD in working electrode of dye-sensitized solar cells (DSSCs).

We study the thermodynamical properties and lattice dynamics of two-dimensional crystalline membranes, such as graphene and related compounds, in zero temperature limit, where quantum effects are dominant. We find out that, just as in the high temperature classical limit, a fundamental role is played by the anharmonic coupling between in-plane and out-of plane lattice modes, which leads to a strong reconstruction of the dispersion relation of the out-of-plane mode. We identify a crossover temperature, T*, bellow which quantum effects are dominant. We estimate that for graphene T* ∼ 70 - 90 K. Inclusion of anharmonic effects makes the thermal expansion finite in the thermodynamic limit, and below T* it tends to zero as a power law as T→0 as required by the third law of thermodynamics. The specific heat also goes to zero as a power law as T→0, but with a exponent that differs from the one predicted by the harmonic theory.

The mechanical properties of stacked graphene sheets with varying number of layers are examined. The stacked sheets are assembled by manually combining single layer CVD-grown graphene monolayers, resulting in a turbostratic multilayer graphene with irregular layer spacings greater than crystalline graphite. Due to the presence of multiple layers, the material is analyzed as a plate rather than a membrane. Bending stiffness is determined via the deflection of micron-scale cantilevers, prepared using focused ion beam milling, while in-plane tensile stiffness is characterized through center-loading of edge-supported circular specimens. Computational modeling and established analytical solutions are used to extract material and structural property information, and benchmark measured properties relative to complementary results from indentation tests. Stacked, few-layer CVD-grown graphene retains an in-plane elastic modulus of 350N/m/layer (corresponding to 1.04 TPa for an inter-layer spacing of 0.335nm), suggesting good load-sharing between stacked layers. Width-normalized bending stiffness was unmeasurable for cantilevers of 1 and 3 layers, while cantilevers of 5 and 10 layers had values of 11,100nN·nm and 1.3×106nN·nm respectively.

The compression and decompression behaviors of graphite oxide have been investigated using in situ Raman measurements in a diamond-anvil cell at room temperature. The so-called G band (in-plane E2g mode ∼1600 cm-1) was followed to 49 GPa during compression and back to ambient under decompression. The Raman frequency of the G band increases sublinearly with increasing hydrostatic pressure, eventually nearly flattening out at the highest pressure measured. This trend is reversed upon decompression, fully recovering to the ambient spectrum. The increased broadening suggests a reversible disordering of the structure without significant sp2-sp3 rehybridization under pressure.

Liquid-ion gated FET-type flexible graphene-based aptasensor was fabricated for Hg detection in real world samples. Single-layer graphene was grown and transferred onto a flexible substrate and integrated into the liquid-ion gated FET system via surface engineerging process. Field-induced responses to Hg2+ ions in real world samples were highly rapid, sensitive and selective, leading to the high-perfromance graphene aptasensor. The aptasensor also displayed excellent flexibility and mechanical durability.

In this study, we investigated the influence of line defects consisting of pentagon-heptagon (5-7) pairs on the electronic transport properties of zigzag-edged and armchair-edged graphene nanoribbons (GNRs). Using the first-principles density functional theory, we study their electronic properties. To investigate their current-voltage (I-V) characteristics at low bias voltage (∼ 1 meV), we use the nonequilibrium Green’s function method. As a result, we found that the conductance of the GNRs having a connected line defect between source and drain shows better performance than that of the ideal zigzag-edged GNRs (ZGNRs). A detailed investigation of the transmission spectra and the wave function around the Fermi level reveals that the line defects arranged along the transport direction work similar to an edge state of the ZGNRs and can be an additional conduction channel. Our results suggest that such a line defect can be effective for low-resistance GNR interconnects.

We have previously reported on a simple desktop method for producing high quality reduced graphene oxide sheets (RGO) which involved dispersing graphene oxide in an ethanol-water solvent and reducing it with sodium borohydride. Metal salts can also be potent reducing agents. Here we show that when these salts are incorporated into the reduction process, metalized graphene sheets can be formed. Metallic salts were used to form Au, Pt, and AuPt nanoplatelets incorporated into the graphene structure. The nature of these metalized graphene platelets was then examined using FTIR, TEM, and SEM/EDAX. Raman spectroscopy of metalized graphene samples show peak shifts and increased D/G ratios over pure graphene, indicating an increased number of defects in the material and suggesting an attachment of metal atoms to the graphene surface. By using a minimum of metal while maximizing the surface contact area of the graphene sheet, these nanoparticle-RGO composites have potential for use in energy-producing devices and/or as catalysts.