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MoS2 has been one of a widely researched hydrogen evolution reaction (HER) catalyst materials in recent years. However, the basal plane of MoS2 is considered to be inactive to hinder its further development. Herein, a new mass-scalable and facile intercalation method for the fabrication of multiple products, including pore-rich monolayer MoS2 (PR MoS2) and MoS2 quantum dots (MoS2 QDs), has been developed via the gas phase etching of bulk MoS2 in an acetone vapor atmosphere. The obtained monolayer MoS2 QDs with a narrow lateral size distribution (average size: 2.5 nm) present excitation-independent photoluminescence emission. Furthermore, the PR MoS2 shows a significantly enhanced HER electrocatalytic activity and good stability in 0.5 M H2SO4 solution with a small overpotential of 241 mV at a current density of 10 mA cm−2. These results demonstrate that the as-prepared PR MoS2 is very promising for the application in HER.

In this research, we use a modified sol-gel method to obtain a pure phase new hexagonal CoO on reduced graphene oxide by leading of polar solvent. In the electrochemical test, the CoO/rGO composite shows a remarkable performance of capacity as an anode of a lithium ion battery. The electrochemistry performance shows that the capacity of the composite can remain at 1300 mAh/g in 100 cycles without damping. The pure phase of CoO and its hexagonal morphology have been characterized by XRD, SEM and TEM.

Two kinds of C-C bonded crystalline nanoporous graphenes (NPGs) have been synthesized by using a newly developed decarboxylation reaction. Both NPGs show good electrocatalytic oxygen evolution reaction (OER) activities. The clear pore-edge structures of the synthesized NPGs provide an ideal platform for further OER investigations.

This work describes an interesting morphological control of the microstructures of photoactive spiropyrans. These microstructures exhibit reversible photoisomerization in solid state under different light irradiation. To observe morphological changes intuitively caused by volume expansion of spiropyrans, a special film is synthesized with inverse conical-hole structures by biomimetic method. When a drop of spiropyran-silica mixture ethanol suspension is placed on the film and dried naturally, almost all spiropyran-silica mixture particles gather into inverse conical holes of the film. Then mixture particles in holes start distributing on edge areas of holes on the film under illumination of 365 nm UV light, spread evenly on the whole surface of the film, and finally convert into self-assembled structures. In addition, particle state can recover to its original state, when irradiate with visible light.

Water-soluble graphene dispersions were fabricated by the exfoliation of graphite functionalized with furfuryl alcohol by Diels–Alder cycloaddition reaction. The pristine graphite was firstly heat-treated in N-methyl-2-pyrrolidone (NMP) before it was functionalized with furfuryl alcohol, and then, the increased interlayer spacing is propitious for furfuryl alcohol to enter into the lattice and react with graphite. High-resolution transmission electron microscopy and Raman spectroscopy indicate that the functional graphene is a high-quality product without any significant defects, and atomic force microscopy shows that the functional graphene consists of single to few layers graphene. Moreover, the grafting ratio onto graphene is up to 1.52 mmol/g. Therefore, the method provides a feasible route to produce functional graphene.

The anionic polymerization of (E)-1,3-pentadiene (EP) and (Z)-1,3-pentadiene (ZP) was performed in aromatic solvent using n-butyllithium as initiator. In contrast to poly(ZP)s, the resulting poly(EP)s possessed the predicted molecular weights and narrow molecular weight distributions (Đ ≤ 1.15). However, THF as polar additive has proved its validity to reduce the molecular weight distribution of poly(ZP) from 1.55 to as low as 1.16. The 1H NMR and 13C NMR results indicated that both poly(EP) and poly(ZP) consist of 1,4-addition & 1,2-addition units, without 3,4-addition units. Moreover, a novel, well-defined styrene–pentadiene alternating copolymer has been synthesized in toluene via living anionic copolymerization and the NMR spectra demonstrated that the resulting copolymers obtained possess a strictly alternating structure and much narrower polydispersity (Đ ≤ 1.17). Finally, the living nature of the polymerization was also inspected via sequential copolymerization with methyl methacrylate (MMA) and 2-vinylpyridine (2VP) to yield well-controlled diblock copolymers (poly(EP)-b-poly(MMA) & poly(EP)-b-poly(2VP)).

A photoactive compound extracted from a fungus (Hypocrella bambuase), named hypocrellins, was used as template to synthesize thermally stable mesoporous materials. The synthesized mesoporous titania samples were characterized using a combination of various physicochemical techniques, such as N2 adsorption/desorption measurement, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectroscopy (DRS) and Fourier transform infrared spectroscopy (FT-IR). The results of physicochemical characterizations showed that the as-synthesized sample was a composite of highly crystalline mesoporous anatase titania and graphitic carbon (gc–MTiO2), which implies the dual function of hypocrellins as template and “dopant”. The in situ doped graphitic carbon significantly increased the visible-light absorbance of TiO2. The gc–MTiO2 exhibited efficient photocatalytic activity under visible-light for photodegradation of acetaldehyde, a common indoor air pollutant. The photophysics and electron dynamics in this photocatalytic process were studied by time-resolved FT-IR spectra, in particular on the nano- to milli-second time scale. It is observed that electrons were injected into the conduction band of gc–MTiO2 and they were decayed to deep traps caused by graphitic carbon. The reported strategies could open up new uses for mesoporous titania self-doped with carbon in applications such as solar cells, photocatalysts, photoelectrical devices, and photo-induced sensors.

A polydicyclopentadiene derivative was obtained via ring-opening metathesis polymerization (ROMP) of acetoxy-substituted dicyclopentadiene (AcO-DCPD) using the Grubbs 1st generation catalyst. Analyses of the polymer microstructures indicate that polymers are linear. The glass transition temperatures (Tg) of the linear polymers range from 136 °C to 159 °C, which are much higher than that of linear polydicyclopentadiene.

A dual-switchable surface between hydrophobic and superhydrophobic has been fabricated successfully by com- bining reversible addition-fragmentation chain transfer polymerization (RAFT) polymeric technology and thiol-NCO click chemistry. Well-defined block copolymer, poly(7-(6-(acryloyloxy) hexyloxy) coumarin)-b-poly(N-Isopropylacryl amide), was synthesized by RAFT, and then the block copolymer was grafted onto the surface of SiO2 modified by toluene disocy- nate (TDI) via thiol-NCO click chemistry. The results of nuclear magnetic resonance (NMR) and Fourier Transform Infrared (FTIR) spectroscopies confirmed that the block copolymer (Number average molecular weight (Mn) = 9400, poly- dispersity index (PDI) = 1.22) has been synthesized successfully. The static contact angle (CA) of the surface prepared by SiO2/P (7-6-AC)-b-PNIPAAm switches from 98±2 to 137±2° by adjusting the temperature. Furthermore, the contact angle can also oscillate between 137±2 and 157±2° on the irradiation of UV light at 365 and 254 nm, respectively. The dual-switch- able surfaces exhibit high stability between hydrophilicity and superhydrophobicity. Therefore, the method provides a new method to fabricate the dual-stimuli-responsive surface with tunable wettability, reversible switching, and also be easily extended to other dual-responsive surfaces. This ability to control the wettability by the adjustment of the temperature and UV light has applications in a broad range of fields.

An efficient and convenient method is applied to introduce varieties of simple functionalities onto the graphene surface for the bulk preparation, which begins with pristine graphite that does not require initial oxidative damage of the graphene basal planes. Diazonium compounds functionalized reaction is demonstrated and it successfully prevented the aggregation of graphene for which providing solubility in high polar organic media or even in volatile solvents such as ethanol and acetone. This approach is complemented by the phenyl carboxylic diazonium salt functionalized graphene (PCFG) attachment of a symmetrically substituted zinc phthalocyanine (PCFG-Pc) using the amide reaction, which is used for the covalent introduction of a complex phthalocyanine molecule.

Lignosulfonate is one of the main byproducts of paper industry. The development and research activities on this important substance have drawn widespread interest in the world. Sodium lignosulfonate was modified by heating in acidic environment and then transferred the modified sodium lignosulfonate into sodium hydroxide solution for further stirring. An insoluble fraction was separated and washed thoroughly with de-ionized water to neutral. Finally, the modified sodium lignosulfonate hydrogel particles were obtained. The obtained hydrogel particles were ultrasonically dispersed in water to form a modified sodium lignosulfonate micro-hydrogel with mean sizes of 300–400 nm. This indicated that the modified sodium lignosulfonate hydrogel particles were generated by the agglomeration of modified sodium lignosulfonate micro-hydrogel. The hydrogel particles were characterized by physical and spectral methods involving infrared radiation, thermogravimetric analysis, dynamic light scattering, and scanning electron microscope. The xerogels formed by drying modification of sodium lignosulfonate hydrogel particles showed a high water-adsorption of 31.2 g/g. In addition, the effect of reaction parameters on water swelling capacity and xerogel yield were also investigated, which include heating temperature, base treatment temperature, and concentration of sodium hydroxide solution. The research results indicated that the yield of modified sodium lignosulfonate hydrogel increases with higher heating temperature and decreases with higher alkali treatment temperature and concentration of sodium hydroxide solution. The water swelling capacity of the modified sodium lignosulfonate hydrogel increased slightly with higher heating temperature, but remained unaffected by the alkali treatment temperature and concentration of sodium hydroxide.

3D graphene frameworks/Co

The use of 5-guanosine monophosphate (GMP) with Sr(2+) ions to form G-quadruplex bundles as supramolecular templates for the preparation of hierarchical mesoporous silica nanotube materials is reported here, and some mesopores with a diameter of 4-22 nm were obtained. Furthermore, some mesopore channels which run perpendicularly to the center axis of the tube and penetrate right through the outer wall of the nanotubes were achieved by removing the templates. Besides, porous hollow silica spheres were obtained by changing some of the reaction conditions during the process of preparation. Their structures are stable even after high temperature calcination. A formation mechanism was proposed and discussed, and their structures were characterized using a number of means including X-ray diffraction, IR spectra, N2 adsorption-desorption isotherms, scanning electron microscopy (SEM) and transmission electron microscopy (TEM).

Flexible and electroconductive nanocomposites based on reduced graphene oxide (RGO) and hydroxylated styrene–butadiene–styrene tri-block copolymer (HO-SBS) were prepared by solution blending method. By the introduction of the groups of OH and >C O onto SBS, the compatibility between RGO and SBS was enhanced. Field emission scanning electron microscopy (FE-SEM) and high-resolution transmission electron microscopy (HR-TEM) showed that RGO dispersed homogeneously and formed a compact continuous network in matrix (HO-SBS). The addition of RGO improved the thermal stability of the RGO/HO-SBS nanocomposites while slightly lowered the mechanical property. Moreover, RGO gave the nanocomposites a maximum electrical conductivity up to 1.3 S/m.

In this paper, core-shell TiO2/polystyrene (TiO2/PS) microspheres with superhydrophobic properties were pre- pared via a facile method. Our method needs neither special apparatus nor complicated chemical treatment. The whole process includes two steps: firstly, coupling agent was used to modify TiO2 by sol-gel method; secondly, fabrication of TiO2/PS dispersions was carried out via in-situ free-radical polymerization strategy. The component and structure of the TiO2/PS particles were characterized by Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), field emission scanning electron microscope (FE-SEM) and transmission electron microscopy (TEM). The TiO2 gel particles with average diameter of 1 ∝m exhibited irregular spherical shape and obvious aggregation. Compared with the TiO2 particles, the resulting TiO2/PS particulates showed regular spherical shape, better dispersion and bigger size. By directly depositing the resulted TiO2/PS dispersion on a Cu foil, the coating showed superhydrophobic property which was reflected by the contact angle (CA) of water on the surface with high water adhesion. The apparent CA of water is 153.5±1.5°, suggesting that this composite possesses well superhydrophobicity.

A spiropyran derivative, which is a well-known photochromic molecule, is attached noncovalently to graphene via a specially designed perylenediimide adsorption anchor group. To explore the feasibil...

Hydroxylated poly(styrene-b-butadiene-b-styrene) triblock copolymer (HO-SBS), with crosslinked networks, was prepared using various amounts of toluene diisocyanate (TDI). The amount of TDI was 0, 0.5, 1, 2, and 5 wt %. The effects of different contents of TDI on the microstructure, thermal properties, and mechanical properties of the crosslinked networks were investigated in detail. Fourier transform infrared spectra indicates that the reaction between OH and NCO have take place, and the solid-state nuclear magnetic resonance spectra confirms that the crosslinked structure has been obtained. The results of scanning electron microscopy show that the mode of fracture surfaces transmits gradually from tough fracture to brittle fracture, but the structure of microphase separation is still observed at the same time. Mechanical test indicates that crosslinking is a useful method to regulate mechanical properties of the HO-SBS. The results of dynamic mechanical thermal analysis display that there are two glass transition temperatures, which also means that the microphase separation is still in existence. Moreover, the glass transition temperature of the polybutadiene domains shifts to higher temperature. Accordingly, the microstructure, glass transition temperature, solvent resistance, and mechanical properties of the HO-SBS are influenced obviously by the crosslinking of TDI. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Grafting of photoinitiator-4-maleimidobenzophenone (4-MBP) onto styrene–butadiene–styrene (SBS) triblock copolymer was carried out by free radical polymerization. The grafting ratio was evaluated by varying initiator concentrations, and the structure of grafted copolymer (SBS-g-MBP) was characterized by attenuated total reflectance infrared Fourier transform spectroscopy (ATR-FTIR), proton nuclear magnetic resonance (1H NMR) and X-ray photoelectron spectroscopy (XPS). The results confirmed that 4-MBP was successfully grafted onto the SBS backbone. Thermal gravimetric analyzer (TGA), dynamic mechanical thermal analysis (DMTA), scanning electron microscopy (SEM), and atomic force microscopy (AFM) were used to study the thermal properties and morphology of the SBS-g-MBP. From the data of TGA, the SBS-g-MBP had better thermal stability compared with that of SBS. DMTA testing indicated that the glass transition temperature (Tg) of SBS-g-MBP was higher than that of SBS. With the aid of SEM and AFM, the structure of micro-phase separation can be observed obviously. What is more, the aggregates become smaller compared with those of pure SBS. The experiment of UV-crosslinked SBS-g-MBP revealed that the gel fraction could be facilely controlled by adjusting grafting ratio and exposure time. The results suggested that this novel grafted copolymer could be attractive for its application in biomedical materials such as medical pressure-sensitive adhesive.

In this study, styrene–butadiene–styrene tri-block copolymer (SBS)/multi-walled carbon nanotubes (MWCNTs) nanocomposites were prepared by means of a solution processing method. To enhance the compatibility between SBS and MWCNTs, the hydroxylated styrene–butadiene–styrene tri-block copolymer (HO-SBS) and the acyl chloride-activated MWCNTs (MWCNTs-COCl) were used to replace SBS and MWCNTs, respectively. The pristine MWCNTs were chemically oxidized by a mixture of H 2 SO 4 and HNO 3 and then reacted with thionyl chloride to functionalize them with acyl chloride groups. The resulting nanocomposites have been characterized by the testing of gel fraction and degree of swelling, Raman spectra, FTIR, SEM, TEM, DSC, TGA, and Instron mechanical tester. The results of gel fraction and degree of swelling show that the HO-SBS/MWCNTs nanocomposites have cross-linked structure and exhibit high solvent resistance. The results of Raman spectra and FTIR indicate that there are ester groups on the surface of MWCNTs. The results of SEM, TEM, and DSC show that the well-dispersed MWCNTs not only disturb the microphase-separated structure of HO-SBS but also decrease its order–disorder transition temperature, and the presence of MWCNTs could lead to an increase of glass transition temperatures of PB domains. In addition, mechanical tests reveal that dispersion of MWCNTs-COCl via covalent bond in polymer matrix is a useful method to regulate mechanical properties of the HO-SBS.

Allylic oxidation of cychohexene under atmospheric pressure of molecular oxygen was carried out over cobalt resinate in the absence of solvent. It was shown that cobalt resinate exhibited promising catalytic activity for the oxidation of cyclohexene to 2-cyclohexen-1-ol and 2-cychohexen-1-one under mild condition for the first time.

Cobalt doped mesoporous silica (Co-SBA-15) was synthesized using templating method and used for the photodegradation of methyl violet and methylthionine chloride under solar light. Co-SBA-15 was characterized by a combination of various physicochemical techniques, such as, N2 physisorption, diffuse reflectance UV–vis, X-ray diffraction and FT-IR. It was found that Co-SBA-15 in the absence of titania exhibited an obviously photocatalytic efficiency of degradation dyes under solar light irradiation, and its photodegradation rate is comparable with that of Degussa P25. By contrast, undoped SBA-15 exhibited high adsorption capacities but photocatalytically inactive under solar light.

Cobalt doped mesoporous titania–silica with Ti/Si molar ratio of 0.5 (Co–TiO2–SiO2) was synthesized for the oxidation of diphenylmethane in acetic acid using aqueous hydrogen peroxide as oxidant for the first time. Fast hot catalyst filtration experiment proved that the catalyst acted as a heterogeneous one. Recycling of the catalyst indicates that the catalyst can be used a number of times without losing its activity to a greater extent. The effects of reaction time and reaction temperature on the performance of the catalyst were investigated. Moreover, cobalt doped mesoporous titania with a crystalline structure and cobalt doped mesoporous titania–silica with different molar ratio were also studied. It was found that Co–TiO2–SiO2 with Ti/Si molar ratio of 0.5 showed the highest activity.

In this study, a series of lanthanum doped mesoporous SiO 2 (La-meso-SiO 2 ) were synthesized and characterized by X-ray diffraction, N 2 adsorption–desorption, and Fourier transform infrared spectroscopy. The effects of different Si/La molar ratio, the amount of La-meso-SiO 2 at different contact time, pH and initial concentration of phosphorus solution on phosphate removal have been studied. It was found that La-meso-SiO 2 exhibited fast adsorption kinetics as well as high adsorption capacities. The adsorption rate and capacity of La-meso-SiO 2 for removal of phosphate increase with the increasing of La/Si molar ratio. The phosphate removal would be near 100% with 0.3 g/L La-meso-SiO 2 with Si/La molar ratio ≥10 after 3 h. La-meso-SiO 2 with Si/La molar ratio of 10 was found to be recycled once, and 75% of phosphate was removed from this recycled adsorbent without any considerable damage to the solid. The concentrations of residual lanthanum ions in solution at different conditions were also measured. The results show that the Si/La ratio, amount of La-meso-SiO 2 and initial concentration of phosphorus had little effect on the concentration of residual lanthanum ions, whereas the concentration of residual lanthanum ions decreased with increase in pH of the solution.

Surfactant-modified graphene hybrids containing azobenzene groups were for the first time prepared, and the electrochemical performance was investigated. The hybrids were obtained by electrostatic interactions between cationic azobenzene-surfactants and negatively charged graphene oxide in water. The electrostatic interactions, chemical structure and photoresponse of the hybrids were measured by using zeta potential values, fluorescence spectra, FTIR, XPS, XRD, SEM, UV-Vis absorption, AFM and Raman spectra. The electrochemical performance was estimated using cyclic voltammetry. The results show that strong electrostatic interactions exist between the azobenzene surfactants and graphene oxide. Notably, this azobenzene–graphene hybrid can self-assemble into aggregation structures in aqueous solution. Besides, the self-assembly can be reversibly controlled by ultraviolet light (365 nm) and blue light (455 nm) irradiation. This process is driven by the photoinduced polarity change of the cationic azobenzene surfactant and is responsible for the graphene hybrids’ electrochemical performance. It is the first example of the reversible self-assembly of graphene driven by light irradiation.

Cobalt-doped mesoporous titania with anatase crystalline structure was prepared using 1-dodecylamine as template by cogellation method and was used as a catalyst for the oxidation of cyclohexane to cyclohexanol and cyclohexanone under mild conditions for the first time.

A novel versatile approach for the bulk and facile preparation of graphene dispersion with high concentration is developed, via sonication of graphite that is intercalated by a mixture of benzene d...

3D graphene frameworks/Co3O4 composites are produced by the thermal explosion method, in which the generation of Co3O4 nanoparticles, reduction of graphene oxide, and creation of 3D frameworks are simultaneously completed. The process prevents the agglomeration of Co3O4 particles effectively, resulting in monodispersed Co3O4 nanoparticles scattered on the 3D graphene frameworks evenly. The prepared 3D graphene frameworks/Co3O4 composites used as electrodes for supercapacitor display a definite improvement on electrochemical performance with high specific capacitance (≈1765 F g−1 at a current density of 1 A g−1), good rate performance (≈1266 F g−1 at a current density of 20 A g−1), and excellent stability (≈93% maintenance of specific capacitance at a constant current density of 10 A g−1 after 5000 cycles). In addition, the composites are also employed as nonenzymatic sensors for the electrochemical detection of glucose, which exhibit high sensitivity (122.16 µA mM −1 cm−2) and noteworthy lower detection limit (157 × 10−9 M, S/N = 3). Therefore, the authors expect that the 3D graphene frameworks/Co3O4 composites described here would possess potential applications as the electrode materials in supercapacitors and nonenzymatic detection of glucose.

A facile, efficient, and unique self-assembly process for the preparation of the macroscopic, free-standing, Ag-reduced, graphene oxide (Ag-RGO) Janus films, which exhibit a unique asymmetry of their two surfaces with macroscopic dimensions, is presented. A novel strategy using an evaporation-induced, self-assembly (EISA) process is shown to be a powerful and flexible method for synthesizing well-defined Janus thin films.

A functionalized graft copolymer {poly(styrene–butadiene–styrene) (SBS)-g-4-benzoyl-N,N-dimethyl-N-[2-(2-methyl-1-oxo-2-propenyloxy)ethyl]benzenemethanaminium bromide (4-BBPDMAEMA)}, containing a photoinitiator, quaternary ammonium cations, and many CC double bonds, was synthesized to modify clays, such as Na+–montmorillonite (MMT) clay, for the preparation of organic–inorganic nanocomposite resins via radical photoinduced crosslinking polymerization. The structure of SBS-g-4-BBPDMAEMA was characterized by Fourier transform infrared and 1H-NMR spectroscopy. The corresponding SBS-g-4-BBPDMAEMA was found to have two functions: the capability to ionically exchange with sodium ions in the silicate gallery and the capability to synthesize exfoliated SBS/MMT nanocomposites by the UV crosslinking of intercalation polymerization. The results from the X-ray diffraction primarily reveal that the clay platelets should have been exfoliated or completely disordered. However, the results from transmission electron microcopy confirmed that a mixture of partially exfoliated and intercalated structures presented in the nanocomposites. Dynamic mechanical thermal analysis testing indicated that the glass-transition temperature of the polybutadiene phase and polystyrene phase moved to a lower temperature. Data of thermogravimetric analysis and testing of the mechanical properties showed that the thermal stability and mechanical properties of SBS-g-4-BBPDMAEMA could be regulated by the crosslinking and content of MMT. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Diglycidyl ether of 9,9-bis(4-hydroxyphenyl) fluorene (DGEBF) monomer was successfully synthesized and characterized in detail. The crystal structure of DGEBF was measured by single-crystal X-ray diffraction analysis. Curing kinetics of DGEBF with 4,4-diaminodiphenyl sulfone (DDS), thermal properties, and decomposition kinetics were investigated using nonisothermal differential scanning calorimetry (DSC) according to Kissinger, Ozawa and Crane methods. The glass transition temperature (Tg), thermal properties of cured polymer were estimated by DSC, dynamic mechanical analysis, and thermogravimetric analyses. Epoxy value of DGEBF monomer up to theoretical value leads to higher crosslink density of cured polymers. The cured DGEBF/DDS system exhibited obvious higher Tg and better thermal stability compared to those of DGEBF/diamine systems reported previously. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

A series of stable graphene dispersions in different organic solvents were prepared by the liquid-phase exfoliation of microcrystalline graphite. The pristine graphite was heat-treated in N-methyl-2-pyrrolidone before it was exfoliated in solvents containing 0.1 mg mL−1 polyvinyl pyrrolidone (PVP). X-ray diffraction and scanning electron microscopy (SEM) results implied that the interlayer spacing of graphite increased after the heat treatment. The increased interlayer spacing makes it favorable for organic molecules to enter the lattice of graphite, and is helpful in the exfoliation of graphite for the production of graphene flakes. High resolution transmission electron microscopy (HRTEM) and Raman spectroscopy indicated that the resulting graphene flakes are high-quality products without any significant structural defects. Atomic force microscopy (AFM) showed that the graphene flakes consist of single-to-few layer graphene, and also demonstrated that the concentration of PVP is an essential factor in the deposition of graphene flakes onto a mica substrate. More importantly, the resulting graphene dispersions can be used to fabricate graphene films and disk arrays on quartz glass. Therefore, it is possible that the graphene dispersions in this study can be used for the preparation of large-area graphene films on different substrates.