Thermal nitridation of reduced graphene oxide sheets yields highly conductive (∼1000-3000 S m(-1)) N-doped graphene sheets, as a result of the restoration of the graphene network by the formation of C-N bonded groups and N-doping. Even without carbon additives, supercapacitors made of the N-doped graphene electrodes can deliver remarkable energy and power when operated at higher voltages, in th...

In this article, PtAg alloy nanoislands/graphene hybrid composites were prepared based on the self-organization of Au@PtAg nanorods on graphene sheets. Graphite oxides (GO) were prepared and separated to individual sheets using Hummer's method. Graphene nano-sheets were prepared by chemical reduction with hydrazine. The prepared PtAg alloy nanomaterial and the hybrid composites with graphene we...

Graphene sheets have been exfoliated from bulk graphite using high energy wet milling in two different solvents that were 2-ethylhexanol and kerosene. The milling process was performed for 60 h using a planetary ball mill. Morphological characteristics were investigated using scanning electron microscope (SEM) and transmission electron microscope (TEM). On the other hand, the structural charact...

Using friction force microscopy, we compared the nanoscale frictional characteristics of atomically thin sheets of graphene, molybdenum disulfide (MoS2), niobium diselenide, and hexagonal boron nitride exfoliated onto a weakly adherent substrate (silicon oxide) to those of their bulk counterparts. Measurements down to single atomic sheets revealed that friction monotonically increased as the nu...

Exfoliated oxidized graphene (OG) sheets, suspended in an aqueous solution, were deposited on freshly cleaved HOPG and studied by ambient AFM and UHV STM. The AFM images revealed oxidized graphene sheets with a lateral dimension of 5–10 lm. The oxidized graphene sheets exhibited different thicknesses and were found to conformally coat the HOPG substrate. Wrinkles and folds induced by the deposi...

We have studied the effect of the oxidation path and the mechanical energy input on the size of graphene oxide sheets derived from graphite oxide. The cross-planar oxidation of graphite from the (0002) plane results in periodic cracking of the uppermost graphene oxide layer, limiting its lateral dimension to less than 30 μm. We use an energy balance between the elastic strain energy associated ...

Functionalized and fully characterized graphene-based lubricant additives are potential 2D materials for energy-efficient tribological applications in machine elements, especially at macroscopic contacts. Two different reduced graphene oxide (rGO) derivatives, terminated by hydroxyl and epoxy-hydroxyl groups, were prepared and blended with two different molecular weights of polyethylene glycol ...

Structural changes of few-layer graphene sheets induced by CF4 plasma treatment are studied by optical microscopy and Raman spectroscopy, together with theoretical simulation. Experimental results suggest a thickness reduction of few-layer graphene sheets subjected to prolonged CF4 plasma treatment while plasma treatment with short time only leads to fluorine functionalization on the surface la...

Ultrathin metal layers can be highly active carbon dioxide electroreduction catalysts, but may also be prone to oxidation. Here we construct a model of graphene confined ultrathin layers of highly reactive metals, taking the synthetic highly reactive tin quantum sheets confined in graphene as an example. The higher electrochemical active area ensures 9 times larger carbon dioxide adsorption cap...

In this paper, we demonstrate the seeded growth of graphene under a plasma chemical vapor deposition condition. First, we fabricate graphene nanopowders (~5 nm) by ball-milling commercial multi-wall carbon nanotubes. The graphene nanoparticles were subsequently subject to a direct current plasma generated in a 100 Torr 10%CH4 - 90%H2 gas mixture. The plasma growth enlarged, over one hour, the n...