Various viologens have been used to control the doping of single-walled carbon nanotubes (SWCNTs) via direct redox reactions. A new method of extracting neutral viologen (V(0)) was introduced using a biphase of toluene and viologen-dissolved water. A reductant of sodium borohydride transferred positively charged viologen (V(2+)) into V(0), where the reduced V(0) was separated into toluene with high separation yield. This separated V(0) solution was dropped on carbon nanotube transistors to investigate the doping effect of CNTs. With a viologen concentration of 3 mM, all the p-type CNT transistors were converted to n-type with improved on/off ratios. This was achieved by donating electrons spontaneously to CNTs from neutral V(0), leaving energetically stable V(2+) on the nanotube surface again. The doped CNTs were stable in water due to the presence of hydrophobic V(0) at the outermost CNT transistors, which may act as a protecting layer to prevent further oxidation from water.

A CMOS-like inverter was integrated by using ambipolar carbon nanotube (CNT) transistors without doping. The ambipolar CNT transistors automatically configure themselves to play a role as an n-type or p-type transistor in a logic circuit depending on the supply voltage (V DD) and ground. A NOR (NAND) gate is adaptively converted to a NAND (NOR) gate. This adaptiveness of logic gates exhibiting two logic gate functions in a single logic circuit offers a new opportunity for designing logic circuits with high integration density for next generation applications.

Despite the availability of large-area graphene synthesized by chemical vapor deposition (CVD), the control of a uniform monolayer graphene remained challenging. Here, we report a method of acquiring monolayer graphene by laser irradiation. The accumulation of heat on graphene by absorbing light, followed by oxidative burning of upper graphene layers, which strongly relies on the wavelength of light and optical parameters of the substrate, was in situ measured by the G-band shift in Raman spectroscopy. The substrate plays a crucial role as a heat sink for the bottom monolayer graphene, resulting in no burning or etching. Oscillatory thinning behavior dependent on the substrate oxide thickness was evaluated by adopting a simple Fresnel's equation. This paves the way for future research in utilizing monolayer graphene for high-speed electronic devices.

Page 3780. In ref 7, a leading reference to a conformationally dynamic metal-based asymmetric catalyst was omitted. Reference 7 should contain the following:For a leading example of a conformationally dynamic metalbased asymmetric catalyst in which the conformational chirality was dynamically transferred to the catalytic center, see: (d) Yu, J.; RajanBabu, T. V.; Parquette, J. R.

The mechanism of doping carbon nanotubes (CNTs) with a salt solution was investigated using the density functional theory. We propose that the anion-CNT complex is a key component in doping CNTs. Although the cations play an important role in ionizing CNTs as an intermediate precursor, the ionized CNTs are neutralized further by forming a stable anion-CNT complex as a final reactant. The anion-CNT bond has a strong ionic bonding character and clearly shows p-type behavior by shifting the Fermi level toward the valence band. The midgap state is introduced by the strong binding of carbon and anion atoms. These localized charged anion sites are highly hygroscopic and induce the adsorption of water molecules. This behavior provides a new possibility for using anion-functionalized CNTs as humidity sensors.

Hygroscopic effects on AuCl 3 -doped single-walled carbon nanotubes (SWCNTs) were investigated. Various concentrations of AuCl 3 solution were dropped on the random network SWCNT transistors, where the doping effect was confirmed by I-V g characteristics and a blue shift in the Raman G band. The AuCl 3 -doped SWCNT transistor was highly sensitive to water vapor in the I-V g curve, especially in the positive gate bias region, compared with the undoped SWCNT transistors. We also found the selective response of water from ambient gases, such as O 2 and N 2 , in AuCl 3 -doped SWCNTs. This investigation could be beneficial for high-performance water sensor applications.

No abstract

A charge trapping layer can serve not only for designing multilevel nonvolatile memory but also for type conversion from p‐ to n‐type and vice versa of carbon nanotube (CNT) channels. Type conversion from p‐ to n‐type and vice versa for CNT field effect transistors can be realized by changing the polarity of trapped charges (see figure).