Graphene In Solution Research Articles

Role of poly(N-vinyl-2-pyrrolidone) as stabilizer for dispersion of graphene via hydrophobic interaction

Stable aqueous dispersion of chemically reduced graphene is simply obtained by reducing GO solution in the presence of PVP. Prepared aqueous graphene dispersion was optically clear and stable for several months without any aggregation or precipitation. Graphene/PVP assembly shows decreased optical transmittance (47% at 600 nm) and quenching of photoluminescence of parent GO (8.5% at 375 nm) after reduction. Raman analysis confirms that reduction of GO to graphene is efficient in the presence of PVP. Both DLS and AFM analysis confirm that there is efficient and overall interaction between chemically reduced graphene plates and PVP chains. Hydrophobic interaction between graphene and PVP might be responsible for this solubilization of chemically reduced graphene in solution.

Suspended Graphene Sensors with Improved Signal and Reduced Noise

We report enhanced performance of suspended graphene field effect transistors (Gra-FETs) as sensors in aqueous solutions. Etching of the silicon oxide (SiO(2)) substrate underneath graphene was carried out in situ during electrical measurements of devices, which enabled systematic comparison of transport properties for same devices before and after suspension. Significantly, the transconductance of Gra-FETs in the linear operating modes increases 1.5 and 2 times when the power of low-frequency noise concomitantly decreases 12 and 6 times for hole and electron carriers, respectively, after suspension of graphene in solution from the SiO(2) substrate. Suspended graphene devices were further demonstrated as direct and real-time pH sensors, and complementary pH sensing with the same nanodevice working as either a p-type or n-type transistor was experimentally realized by offsetting the electrolyte gate potential in solution. Our results highlight the importance to quantify fundamental parameters that define resolution of graphene-based bioelectronics and demonstrate that suspended nanodevices represent attractive platforms for chemical and biological sensors.

The Superior Dispersion of Easily Soluble Graphite

Graphene is a 2D one-atom-thick layer that has attracted enormous scientific attention on account of its extraordinary electronic and mechanical properties resulting from the hexagonally arrayed sp-hybridized carbon atom structure. Several efforts have been made to use graphene in devices and composites. The strong covalent bonds of carbon atoms provide high mechanical and thermal properties and chemical stability. The theoretical Young’s modulus of graphene is approximately 1060GPa. In addition, the high electrical conductivity (mobility: 20 000 cmV 1 s , velocity: c/300) through the p-electron cloud makes graphene a promising material in conducting composites and quantum electronics. As in other new materials (such as carbon nanotubes, various quantum dots, etc.), the development of mass productionmethods that can support the demand for graphene in a variety of large-scale applications is of high priority. Thus far, several methods for graphene production have been developed and can be summarized into three areas:mechanical exfoliation, graphene in solution, and epitaxial growth. Mechanical exfoliation produces the highest quality graphene, which is suitable for fundamental studies. Epitaxial growth provides the shortest path to graphene-based electronic circuits. Graphene in solution can offer lower costs and higher throughputs and may be used in a wide range of applications because of the significant practical utility of this material. However, the method is quite complicated and