There is some controversy regarding the effects of HNO3 on films of single-walled carbon nanotubes (SWCNTs). In this study we examined the change in sheet resistance of an HNO3-modified SWCNT film after different drying times at 85 degrees C using various analytical techniques. The shift and suppression in the Raman spectra, bleaching of the transition peaks related to van Hove singularities and a shift in the original peak in the C 1s XPS spectra provided evidence for p-type doping. A decrease in sheet resistance was also observed in the SWCNTs films due to the removal of residual N-methylpyrrolidone solvent on the surface and bundle of SWCNTs. These results suggest that p-type doping has a larger effect on the sheet resistance than the removal of residual N-methylpyrrolidone by an HNO3 treatment.

The intrinsic properties of initially p-type doped graphene (grown by chemical vapor deposition (CVD)) can be recovered by buffered oxide etch (BOE) treatment, and the dominant factor governing p-type doping is identified as the H(2)O/O(2) redox system. Semi-ionic C-F bonding prevents the reaction between the products of the H(2)O/O(2) redox system and graphene. BOE-treated graphene field effect transistors (FETs) subsequently exposed to air, became p-type doped due to recovery of the H(2)O/O(2) redox system. In comparison, poly(methyl methacrylate) (PMMA)-coated graphene FETs had improved stability for maintaining the intrinsic graphene electronic properties.

self-powered electronics for which novel high-performance materials and low-cost fabrication processes are highly sought. Graphene, which exhibits remarkably high specific surface area, thermal conductivity, current density, transparency, and impermeability, [1] is an ideally suited system for exploring conceptually novel flexible electronics including energy harvesting devices. [2] An easy and scalable approach for graphene preparation is the liquid-phase exfoliation of chemically functionalized graphite, such as graphite oxide or graphite intercalated compounds, which allows the separation of the bulk material into individual atomically thin layers in a liquid medium to produce graphene suspensions. However, there are several issues associated with the films deposited from such suspensions, especially those comprising graphene oxide (GO): they are insulating and need to be converted into reduced graphene oxide (rGO) through harsh chemical or thermal processes, [3] which creates defects in the crystallographic structure of graphene, leading to poor electronic performance. Alternatively, pristine graphite (PG) can be directly exfoliated by various techniques such as ball or three-roll milling, sonication, and high-shear mixing to obtain graphene suspensions. [4,5] Such suspensions are stabilized by using organic solvents, [6] or surfactants to prevent reaggregation of the graphene flakes. [7] In particular, PG exfoliation by highshear mixing leads to a significant improvement in the quality of graphene, when compared with other exfoliation methods, and allows the production of more than 100 L h −1 of defect-free graphene water-based suspension. [5,8] Despite the recent developments in the production of graphene suspensions, the integration of high-quality graphene films obtained from water-based exfoliation of PG in emerging applications, such as flexible electronics, is lagging behind. Specifically, emerging and integrating technologies of water-based exfoliation of PG for haversting human energy that convert mechanical energy into electricity using various effects are still in its infacty, and more research is needed to develop and implement triboelectric nanogenerators (TENGs) as self-charging devices for flexible and wearable electronics. This is due to several issues associated with the deposition Wearable technologies are driving current research efforts to self-powered electronics, for which novel high-performance materials such as graphene and low-cost fabrication processes are highly sought.The integration of highquality graphene films obtained from scalable water processing approaches in emerging applications for flexible and wearable electronics is demonstrated. A novel method for the assembly of shear exfoliated graphene in water, comprising a direct transfer process assisted by evaporation of isopropyl alcohol is developed. It is shown that graphene films can be easily transferred to any target substrate such as paper, flexible polymeric sheets and fibers, glass, and Si substrates. By combining gra...

Easily soluble expanded graphite (ESEG) is synthesized by one‐step exfoliation process using a fluorinated graphite intercalation compound (see image). Due to the severe expansion state, the ESEG obtained is sufficiently dispersed in aqueous solutions using an ordinary surfactant (SDS and SDBS) and in various organic solvents such as NMP, DMAc, DEG, toluene, DMF, and DCM.

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Single-walled carbon nanotube (SWCNT) film was deposited with MnO2 using a spontaneous redox reaction between MnO4 ̅ ions and the SWCNTs. Doping and dedoping had a significant effect on the sheet resistance of the resulting SWCNT film. The injection of holes in the SWCNT film bleached the van Hove singularity transitions (E 11 S) observed by optical absorption spectroscopy. The observed doping was not permanent, and spontaneous reduction under ambient conditions restored the defects and dedoped the SWCNT film. Dedoping increased the Fermi level and restored the van Hove singularity transitions (E 11 S). The doping and dedoping mechanism of these films was investigated. Transmission electron microscopy, X-ray photoelectron spectroscopy, and optical transmission spectroscopy were used to characterize the films.