爆炸法合成石墨烯

以石墨氧化物为前躯体,采用爆炸法合成石墨烯.利用XRD,SEM,XPS,TEM,SAED和Raman等测试手段对石墨烯的形貌,成份和结构进行表征.结果表明,石墨氧化物在爆炸产生的热量和冲击波的作用下发生完全剥离并被还原成石墨烯.新合成的石墨烯呈透明褶皱状,含有2层～5层石墨层,并具有较好的晶体结构.

Abstract：

Graphene nanosheets were synthesized using graphite oxide as a precursor by detonation. The composition,and structure of graphene nanosheets were characterized by X-ray diffraction,X-ray photoelectron spectroscopy,scanning and transmission electron microscopy,selected area electron diffraction,and Raman spectroscopy. Results indicated that the as-prepared material was transparent and wrinkled,and comprised 2-5 graphenes with a highly crystalline structrue. The exfoliation and reduction of graphite oxide to graphene nanosheets was induced by the self-generated thermal energy and shockwave of detonation.     

Effect of Graphene Oxide as a Dopant on the Electrochemical Performance of Graphene Oxide/Polyaniline Composite

A method for preparing a graphene oxide/polyaniline （GO/PANI） composite electrode was developed to investigate the effect of GO doped in PANI. PANI was first prepared by the polymerisation of aniline and then dedoped by NH4OH to form emeraldine base （EB）. The dedoped PANI and as-prepared GO were dissolved in N-methyl-2-pyrrolidone （NMP） to generate a homogeneous dispersion. The GO/PANI composites were redoped in HCI before use as electrode materials. These composites were characterised by Raman spectroscopy, X-ray diffraction, UV-vis adsorption spectroscopy, scanning electron microscopy, atomic force microscopy and electrochemical measurements. The GO/PANI composite electrode （containing 2.5% GO） has an initial gravimetric capacitance of 896 F g-1 at a scan rate of 5 mV s-1 and a retention life of 51% after 500 cycles, which is an improvement over that of pure PANI （23%）. The results show that the synergy of GO and PANI attributes to the good electrochemical performance of the GO/PANI composite electrode.     

SnO_2-Decorated Graphene/Polyaniline Nanocomposite for a High-Performance Supercapacitor Electrode

An Sn O2-decorated graphene/polyaniline(GSP) nanocomposite with homogeneous structure was prepared and adopted to achieve high electrochemical performance for supercapacitor electrode. Graphene sheets were decorated with tin dioxide(Sn O2) particles, which effectively hinder the restacking of graphene nanosheets, and then were used as substrates for an in-situ polymerization of aniline monomers. The GSP nanocomposite was characterized by field emission scanning electron microscopy, X-ray diffraction, Fourier transform infrared, UV-Visible and X-ray photoelectron spectroscopy. The results revealed that polyaniline nanorods were orderly and vertically aligned on the Sn O2-decorated graphene nanosheets via π–π stacking effect between basal planes of graphene nanosheets and phenyl group of polyaniline.The GSP nanocomposite exhibited an excellent specific capacitance of 429 F g-1at a current density of1 A g-1, excellent cycling stability and rate capability, which suggested a promising application for supercapacitor.     

Preparation of Ferrioxalate Submicrorods/Graphene Composites and Their Photocatalytic Properties

Ferrioxalate submicrorods/graphene composites were synthesized through a simple solvothermal process in a mixture of ethylene glycol and water. The in situ growth of ferrioxalate submicrorods and the reduction of graphene oxide （GO） were completed in a one-step reaction. Fourier transform infrared and Raman spectroscopy confirmed the reduction of GO. Uniform rod-like ferrioxalates with diameter of about 600 nm and length of several micrometers were well distributed on the graphene sheets. As-obtained composites exhibited better photocatalytic properties than pure ferrioxalate submicrorods. The influence of different contents of GO on photocatalytic performance was also investigated. A possible photocatalytic mechanism of ferrioxalate submicrorods/graphene composites was proposed.     

Tuning F-doped degree of rGO: Restraining corrosion-promotion activity of EP/rGO nanocomposite coating

Given that graphene features high electrical conductivity, it is a kind of material with corrosion-promotion activity. This study aimed to inhibit the corrosion-promotion activity of graphene in coatings. Here, we report an exciting application of epoxy matrix(EP)/F-doped reduced graphene oxide(r GO) coatings for the long-term corrosion protection of steel. The synthesized F-doped r GO(FG) did not reduce the utilization of r GO by a wide margin and possessed distinctive electrically insulating nature. The electrical conductivity of r GO was approximately 1500 S/m, whereas those of FG-1, FG-2 and FG-3 were 1.17, 5.217 × 10~(-2) and 3.643 × 10~(-11) S/m, respectively. FG and r GO were then dispersed into epoxy coatings. The chemical structures of r GO and FG were investigated by transmission electron microscopy(TEM), scanning probe microscopy(SPM), X-ray photoelectron spectroscopy(XPS), Fourier-transform infrared spectroscopy(FTIR), and X-ray diffraction(XRD). EP/FG coatings exhibited outstanding corrosion protection in comparison with blank EP and EP/r GO coatings mainly because the corrosion-promotion effect of r GO was eliminated.The anticorrosion ability of EP/FG coatings was improved with increased F-doped degree of FG. In addition,electrochemical impendance spectroscopy(EIS) results indicated that the Rcvalues of EP/FG-2 and EP/FG-3 were four orders of magnitude higher than those of EP/r GO in diluent Na Cl solution(3.5 wt.%) after immersion for 90 days.     

Synthesis,Characterization and Electrochemical Study of Graphene Oxide-Multi Walled Carbon Nanotube-Manganese Oxide-Polyaniline Electrode as Supercapacitor

The synthesis of graphene oxide-multi walled carbon nanotube-manganese oxide-polyaniline namely(GMMP) nanocomposite for application in supercapacitor devices was investigated. Morphology of the nanocomposites was studied by X-ray diffraction(XRD), Fourier transform infrared(FT-IR) spectroscopy, scanning electron microscopy(SEM), transmission electron microscopy(TEM) and energy dispersive X-ray microanalysis(EDX). The electrochemical properties of nanocomposite based electrodes were investigated by cyclic voltammetry(CV), galvanostatic charge–discharge and electrochemical impedance spectroscopy(EIS) techniques in 0.5 mol/L Na_2SO_4. The specific capacitances of 173.00, 127.85, 87.50, 58.65 and 12.00(m F cm-2) were obtained for GMMP, GMP(GO–MWCNT–PANI), GMM(GO–MWCNT–Mn O_2),GM(GO–MWCNT) and G(GO) at a scan rate of 10 m V s~(-1), respectively. Also, GMMP nanocomposite retained 90% initial capacitance after 200 cycle of charge–discharge. The good electrochemical response of this nanocomposite is due to the combination of the electrical double layer capacitance of GO and MWCNT and the gradual introduction of pseudo-capacitance through the redox processes of PANI, –COOH,–OH(in MWCNT–COOH, GO–COOH and GO–OH) and Mn O_2. This revealed the synergistic effect of PANI,Mn O_2, –OH –COOH on the carbon based support.     

High-quality liquid phase-pulsed laser ablation graphene synthesis by flexible graphite exfoliation

This work reports a one-pot procedure of laser ablation on a graphite target in a liquid medium, based on the variation of different parameters such as target type, laser wavelength, and ablation medium,to obtain high-quality graphene nanosheets. The morphology of derived products was characterized by the field emission scanning electron microscopy(FE-SEM). Then, the morphology and structure of the optimized sample were characterized by transmission electron microscopy(TEM), X-ray diffraction(XRD), ultraviolet-visible-near infrared(UV–vis-NIR) spectroscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy(XPS). By controlling the laser ablation parameters, we were able to prepare micrometer-sized few-layer graphene nanosheets with mainly less than ten layers. Such synthesized graphene nanosheets were grown at the surface of a flexible graphite target, indicating many potential applications in fundamental research, electrochemical and as hydrophobic surfaces.     

Single step fabrication of N-doped graphene/Si3N4/SiC heterostructures

In-plane heteroatom substitution of graphene is a promising strategy to modify its properties. The ability to dope graphene with electron-donor nitrogen heteroatoms is highly important for modulating electrical properties of graphene. Here we demonstrate a transfer-free method to directly grow large area quasi free-standing N-doped graphene bilayers on an insulating substrate （Si3N4）. Electron-bombardment heating under nitrogen flux results in simultaneous growth of N-doped graphene and a Si3N4 layer on the SiC surface. The decoupling of N-doped graphene from the substrate and the presence of Si3N4 are identified by X-ray photoemission spectroscopy and low-energy electron diffraction. The substitution of nitrogen atoms in the graphene planes was confirmed using high resolution X-ray photoemission spectroscopy which reveals several atomic configurations for the nitrogen atoms： Graphitic-like, pyridine-like, and pyrrolic- like. Furthermore, we demonstrated for the first time that N-doped graphene could be used to efficiently probe oxygen molecules via nitrogen atom defects.     

Surface charge induced tuning of electrical properties of CVD assisted graphene and functionalized graphene sheets

We demonstrate a new approach to tune the electrical properties of graphene and functionalized graphene. Graphene was synthesized using thermal chemical vapour deposition(TCVD) method on copper foil using precursor gas acetylene and co-catalyst H2 gas. TCVD assisted graphene was successfully transferred onto a silicon wafer. Transferred graphene sheet was then functionalized to prepare graphene oxide(GO) and reduced graphene oxide(rGO). Different surface charge carbon nanoparticles, e.g. carbon nanoparticle with net positive charge and carbon nanoparticle with net negative charge were then immobilized on transferred graphene and functionalized graphene sheets. The functionalized graphene and charge mobilized functionalized graphene were characterized by Uv–vis spectroscopy,Fourier transformed infrared spectroscopy, scanning electron microscopy, and Raman spectroscopy. After immobilization of carbon nanomaterials, the ac electrical conductivity was found to increase due to enhancement of the surface charge, electron density, and mobility. It was observed that negative surface charge immobilized graphene and functionalized graphene show higher conductivity. Thus, the electrical property of graphene and functionalized graphene can be tuned by surface modification with different surface charge carbon nanomaterials.     

Comparison of Few-layer Graphene Prepared from Natural Graphite through Fast Synthesis Approach

We report the synthesis of high quality few-layer graphene on a large scale using high purity natural graphite from Sri Lanka. A novel thermal method was adapted to prepare graphene from intermediate graphite oxide, which was obtained by heating the intermediate at low temperature(above 150 °C) in air for 5 min and subsequent heating at 500 °C in Argon for 15 min. The samples were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, Raman spectroscopy etc. The properties and the performance of graphene were observed to depend on the graphite source. The reduced graphite oxide from Kahatagaha graphite source exhibits higher Brunauer–Emmett–Teller specific surface area ~500 m2g-1and stable specific capacity as an anode in Li-ion batteries, whereas Bogala graphite showed higher initial irreversibility and higher capacity as anode, exceeding the theoretical specific capacity of graphite. Both graphenes showed high electrical conductivity. The graphene,which exists in stacks of only a few layers, supposed to be 2–6 layers, would be promising for a vast variety of applications.     

液相制备石墨烯/硫复合材料及其在锂硫电池正极中的应用

采用氧化石墨烯(grapheneoxide,GO)作为制备石墨烯的前驱体,通过液相还原自组装过程与硫纳米颗粒进行复合,获得了高性能的还原氧化石墨烯/硫(r GO/S)复合正极材料。利用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线衍射仪(XRD)、拉曼光谱、X射线光电子能谱分析(XPS)等对材料微观形貌与结构进行表征。结果表明:硫纳米颗粒均匀分布在石墨烯片层间,并且硫纳米颗粒被石墨烯片层有效地封装,硫在35-r GO/S复合物中的质量分数高达83.6%。该35-r GO/S复合正极在0.2C电流密度下初始放电容量可达1197.3mAh·g^-1,经过200次循环后容量仍保持在730mAh·g^-1左右,表现出优异的循环性能。     

Synthesis of high-performance graphene nanosheets by thermal reduction of graphene oxide

High-performance graphene nanosheets have been synthesized by thermal reduction of graphene oxide (GO) under ethanol atmosphere. The reduced GO nanosheets were characterized by X-ray photoelectron spectroscopy, Raman spectroscopy and electrical transport measurements, respectively. The results indicated that the thermal reduction of GO under ethanol atmosphere can effectively remove the oxygen-containing functional groups and restore its graphic structure compared to the ones obtained using hydrazine or hydrogen. The electrical measurements indicated that the electrical mobility of single-layer graphene sheet reduced under ethanol atmosphere at 900 °C can reach 29.08 cm² V⁻¹ S⁻¹.     

A UV-light induced photochemical method for graphene oxide reduction

Chemical reduction of graphene oxide (GO) has been considered as a promising route towards the large scale production of graphene. Herein, a rapid, efficient photochemical method for preparing reduced graphene oxide (RGO) by ultraviolet (UV) irradiation of a mixture solution containing a photoinitiator and Monoethanolamine (MEA) compound in ethanol has been developed. In this route, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (GR-XBPO) was used as the reductant and MEA as the oxygen inhibition agent. After UV irradiation, oxygen-containing groups (OCGs) on GO plane and edges are being largely removed due to the reduction of GO by free radicals generated by photoinitiator decomposition. X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy, Fourier transform infrared spectroscopy, and ultraviolet and visible spectrophotometer showed that GR-XBPO can efficiently reduce GO at room temperature. It is also found that the electrical conductivity of RGO fabricated by this rapid route (~10 min) is more competitive compared to other reported works. Moreover the corresponding reduction mechanism was being discussed. This work puts forward a novel method for preparing graphene, and has great potential in scaling up graphene production and developing graphene materials.     

Preparation and characterization of long-chain alkyl silane-functionalized graphene film

Functionalized graphene (FG) was prepared in one step by treating graphene oxide (GO) successively with hexadecyltrimethoxysilane and triethylamine. The FG sheets were subsequently assembled into a thin film by vacuum extraction filtering. Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, thermogravimetric analysis, X-ray diffraction, and Raman spectroscopy were employed to confirm the reduction and silane functionalization of GO to be simultaneously completed during the treatment. The presence of the long hexadecyl chain made the FG hydrophobic. The graphene film showed a high surface roughness, which consisted of many randomly stacked flakes, exhibiting a contact angle of up to 128.1°.     

Surfactant-assisted synthesis of reduced graphene oxide/polyaniline composites by gamma irradiation for supercapacitors

A series of graphene materials are prepared by intercalation of graphene oxide (GO) with different surfactants, cetyltrimethylammonium bromide (CTAB), n-octyltrimethylammonium bromide, tetramethylammonium bromide, and sodium dodecylbenzene sulfonate, subsequently by γ-ray induced reduction in N-methyl-2-pyrrolidone (NMP) at room temperature. GO can be reduced by the electrons generated from the radiolysis of NMP under γ-ray irradiation, and reduced GO is simultaneously functionalized by the radiolytic product of NMP. Cationic surfactant CTAB with longer alkyl chains can effectively promote the reduction process of GO by preventing the aggregation of graphene sheets, which has been testified by X-ray photoelectron spectroscopy, X-ray diffraction, thermogravimetric analysis, Raman spectroscopy, and Fourier transform infrared spectroscopy analyses. Furthermore, when the as-prepared graphene/polyaniline composites are used for supercapacitor electrode materials, there is a highest specific capacitance of 484 F g^?1 at a current density of 0.1 A g^?1 for the graphene produced in the presence of cationic surfactant CTAB.     

Reduction and disorder in graphene oxide induced by electron-beam irradiation

Structural changes caused by an electron beam with an absorbed dose of 500 kGy were investigated in graphene oxide (GO). In this paper, GO and irradiated GO were characterized by X-ray diffraction, Raman spectroscopy and X-ray photoelectron spectroscopy, respectively. It was found that the interlayer spacing of GO was decreased because of the alteration of functional group percent and the reduction effect. The graphitic structure of GO was also found to be disordered slightly. In addition, the samples were reduced partially after irradiation and electron-beam irradiation of GO appeared to be a promising procedure for large-scale synthesis of graphene.     

Effect of the exposure time of hydrazine vapor on the reduction of graphene oxide films

Preparation of highly uniform graphene with superior electrical properties is one of the key issues in graphene researches. The use of hydrazine vapor for reducing the graphene oxide (GO) has attracted considerable attention in recent year due to the simplicity, reproduciblilty and availibility of one-step procedure. Here, we investigated the effect of the exposure time of hydrazine vapor on the reduction of GO films. Raman spectroscopy, UV-vis spectroscopy, X-ray photoelectron spectrophotometer, and X-ray diffraction results showed that the reduction rate of the GO films by hydrazine vapor was very fast in the initial 10 min, and thereafter the reduction rate slowed down. Upon 12 hours of hydrazine vapor treatment, the reduction came to a level that further hydrazine vapor treatment did not bring about significant improvement of the reduction. We demonstrated that this might be attributed to the slow penetration of hydrazine vapor into the GO films in order to reduce the inner sheets of the GO films.     

Synthesis of graphene soluble in organic solvents by simultaneous ether-functionalization with octadecane groups and reduction

Octadecane-functionalized graphene (OD-G) soluble in organic solvents was produced by combining the Hummers process for graphite oxidation and a simultaneous ether-functionalization and reduction approach with 1-bromooctadecane in pyridine and dimethylformamide (DMF). The exfoliated OD-Gs were testified to be monolayer sheets by transmission electron microscope (TEM) and atomic force microscopy (AFM). The functionalization with octadecane (OD) groups and the effective deoxygenation of graphene oxide (GO) were confirmed by Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and thermogravimetric analysis (TGA). It is proved that the effective reduction and functionalization of GO could be simultaneously completed during the refluxing process. The functionalization with OD groups can effectively prevent the aggregation of GO during the reduction.     

Reduction and functionalization of graphene oxide sheets using biomimetic dopamine derivatives in one step

An easy and environmentally friendly chemical method for the simultaneous reduction and noncovalent functionalization of graphene oxide (GO) using dopamine derivatives is described. The reaction takes place at room temperature under ultrasonication of an aqueous suspension of GO and a dopamine derivative. X-ray photoelectron spectroscopy, FT-IR spectroscopy, and cyclic voltammetry characterizations revealed that the resulting material consists of graphene functionalized with the dopamine derivative. This one-step protocol is applied for simultaneous reduction and functionalization of graphene oxide with a dopamine derivative bearing an azide function. The chemical reactivity of the azide function was demonstrated by a postfunctionalization with ethynylferrocene using the Cu(I) catalyzed 1,3-dipolar cyloaddition.     

Spectrum analysis of the reduction degree of two-step reduced graphene oxide (GO) and the polymer/r-GO composites

In this paper, the reduction degree of graphene oxide (GO) reduced using chemical reduction and thermal reduction methods was characterized by spectrum analysis. The optimized conditions of reducing GO were determined that the hydrazine hydrate is the best reducing agent and the appropriate thermal reduction temperature is at 240 °C. The obtained GO solution was mixed with polystyrene (PS) solution to prepare PS/r-GO composites by using two-step reduction technique under the optimized conditions. The structure and micro-morphology of GO, r-GO and PS/r-GO composites were characterized by Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM) respectively. It is also observed that the two-step reduction pathway is more effective than one-step reduction for improving the reduction degree of GO. Accordingly, the electric conductivity of PS/r-GO composites prepared by two-step reduction technique is as high as 21.45 S m⁻¹, which is much higher than that of composites fabricated by one-step reduction method. The spectrum techniques will highlight new opportunities for investigating the reduction degree of GO in polymer composites.