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A simple method was reported to fabricate self-cleaning and water–oil separation fabrics sprayed with hot-iron-treated graphene oxide (GO). The GO solution was prepared with a modified Hummers' method and coated on the fabrics by spraying or soaking method. A 160 °C hot iron was pressed at the surface of the fabrics to make it flat, dry, thermally reduced in part, and strongly bonded. Afterward, the fabrics were thermally reduced at 250 °C for 20 minutes in an oven. The reduced graphene oxide (rGO) coated fabrics exhibited a superhydrophobic nature with a water contact angle of 129.4°, through which water could barely permeate the fabrics, in contrast to oil and organic solvents of low polarity. Additionally, this rGO fabric presented outstanding mechanical properties as well as a reusable stability.

Graphene oxide membrane (GOM) has attracted extensive attraction as a molecular sieve for the separation of water, ions, and gases. However, A-level control of the GOM interlayer spacing for separating the specific size of gas molecule is difficult and the vertical transport mechanism of molecules through the GOM is highly complex because of the existence of several possible pathways. Here we fabricated GOMs with different A-scale interlayer spacing through heat treatment and made them allow horizontal entrance and transport of gas molecules. The GOMs with angstrom channels exhibited superior performance in permeance in horizontal mode and moderate selectivity for H2/CO2 and He/CO2 by tuning the sieving size of the channels. Molecular dynamics (MD) simulations reveal that the precisely controlled interlayer spacing plays a primary role as a molecular sieve indeed, but increased graphitic area, a result of heat treatment, also affects observed selectivity. Our results provide insight into the transport mechanism of gas molecules through GO nanochannel, which has not been accurately identified due to its complex behavior and suggest the possibility of studying nanochannels as effective vehicle for separating molecules precisely.

Graphene oxide (GO) membranes have attracted attention as a promising candidate for selective ion permeation due to narrow interlayer spacing. Among several methods to control the interlayer spacing, the reduction of GO membranes has great potential for desalination and water purification. To apply GO membranes for ion separation, investigating ion transport of sub-nanometer channels of reduced GO membranes is needed. In this study, thermally and chemically reduced GO membranes were fabricated with different interlayer spacing ranging from 3.7 to 8.0 A in a dry state. It was experimentally determined that the minimum spacing allowing water permeation was 5.7 A (9.6 A in water), and no water permeated at 5.0 A or less. For ion permeation, a pure GO membrane exhibited similar permeability for most ions, while the permeability of GO membrane with 5.7 A spacing was strongly dependent of the size and charge of ions. The permeability of cations significantly changed along with the ionic radius, while there was a noticeable cutoff for permeability of multivalent anions such as SO42− and Fe(CN)63−. Our reduced GO membrane could be used to effectively block the permeation of large ions and multivalent anions.

We report the restoration of electrical properties found in graphene field-effect transistors (G-FETs) Joule heated with water. Since polymer contaminates the graphene surface during the transfer process and device fabrication, the graphene becomes p-doped so that we can hardly measure its charge neutrality point (CNP) with a gate voltage even up to 100 V. When the p-doped G-FET covered by water is Joule heated, on the other hand, the CNP is restored almost to the zero gate voltage. Based on the results derived from I d–V g characteristics and Raman spectroscopy, we argue that the polymers on graphene were removed whilst it was Joule heated, resulting in high de-doping of the graphene, leading to the easy process for the fabrication of high performance G-FET.

The field emission (FE) device based on quantum dot (QD) films as a cathodoluminescent (CL) material has not emerged yet due to the relatively low quantum efficiency and weak photostability of nanocrystals (NCs). Here we improve film stability and luminescence yields by preparing neat films of well-packed core-multishell QDs using spray coating method and then using low-temperature atomic layer deposition (ALD) to infill the pores of these films with metal oxides to produce inorganic nanocomposites. The ALD coatings to protect oxidation and degradation by electrons prevent internal atomic and molecular diffusion and decrease surface trap densities of QD films. Furthermore, the CL of the core-multishell QD films is 2.4 times higher than before ALD infilling. We fabricate the FE device by combining cathode structure with carbon nanotube (CNT) emitters and anode plates with QD thin film and successfully can get brilliant images of the light-emitting FE device. Our research opens a way for developing new quantum optoelectronics with high-performance. (C) 2013 Optical Society of America