氧化锡粒子/石墨烯纳米复合材料真空热还原制备及其在近红外胰腺癌热疗中的应用

利用真空热还原法制备得到氧化锡粒子/石墨烯纳米复合材料(SnO2/GR),该过程中,石墨烯氧化物原料既是氧化锡粒子的有效载体来源,也是新型的活泼氧给体,可同步将零价锡氧化为正四价锡,石墨烯氧化物原料则被还原为石墨烯。利用透射电镜(TEM)、扫描电镜(SEM)、X射线衍射(XRD)和傅里叶变换红外光谱等分别对氧化锡粒子/石墨烯纳米复合材料的形貌和尺寸、结构进行了表征。利用该新型材料在近红外(NIR)激光照射下的强光热转化性能,使相比健康细胞更易受到温度影响的胰腺肿瘤细胞内部产生过高热(Hyperthermia),从而诱导胰腺肿瘤细胞热损伤及细胞凋亡。实验结果表明,在1064nm近红外激光照射下,对照组胰腺肿瘤细胞仍保持较高活性,而实验组的胰腺肿瘤细胞活力则大幅降至5.03%,充分显示了氧化锡粒子/石墨烯纳米复合材料在胰腺肿瘤热疗领域的潜力。     

Structural,optical, and photocatalytic investigation of nickel oxide@graphene oxide nanocomposite thin films by RF magnetron sputtering

Despite the recent advancement in graphene oxide (GO) as a host material in energy and environmental sectors, its composite thin films with metal oxides such as nickel oxide (NiO) and its optical, structural, chemical state, and photocatalytic activities have been poorly explored. Herein, we have reported the GO/NiO thin films preparation by a combination of chemical and physical deposition techniques (i.e. spin coating followed by DC/RF sputtering). The as-prepared composites thin films were characterised using Raman spectroscopy, X-ray diffraction/photoelectron spectroscopy scanning electron microscopy, and atomic force microscopy. The surface topography confirmed the uniform deposition of NiO over thin films of GO. The XPS results showed the formation of NiC along with the partial reduction in GO into graphene with their existing four constituents, i.e. NiO, NiC, GO, in the thin film composites. The classical plasmon, Wemple and Didomenico model, was first time applied for GO/NiO to compute energy loss functions, and dispersion energy parameters. The theoretical calculated values for the deposited GO/NiO thin films were found to be in very close agreement to the standard classical plasmon values. The change in spin orbital movement of Ni is considered due to the interaction between its nanoparticles and basal planes of GO. Thin films applied for the photodegradation of recalcitrant organic pollutant 2-chlorophenol (2-CP) revealed the dependence of photocatalytic efficiency on particle size and also on the interaction of GO with NiO rather than the ratio of NiO and GO in the films.     

Facile synthesis of reduced graphene oxide nanosheets by a sodium diphenylamine sulfonate reduction process and its electrochemical property

We report a new method to convert graphene oxide (GO) to stable colloidal dispersion of reduced graphene oxide nanosheets (RGONS) using sodium diphenylamine sulfonate (SDAS) as a reductant, as well as itself and its redox product as the stabilizer. The as-prepared RGONS have been characterized by X-ray diffraction, Fourier transform infrared spectroscopy, UV–visible spectroscopy, thermo-gravimetric analysis, scanning and transmission electron microscopy, X-ray photoelectron spectroscopy, atomic force microscopy and Raman spectroscopy. The results indicate that the bulk of oxygen-containing functional groups from GO have been removed. Based on the cyclic voltammogram (CV) analyses, it is found that the RGONS-based material exhibits better electrochemical activity in sensing ascorbic acid than GO. The simple method provides a new efficient route for the synthesis of water-soluble RGONS on a large scale and novel composites.     

石墨烯/氰酸酯-环氧树脂复合材料的制备和性能

为优化石墨烯/氰酸酯(CE)复合材料的制备工艺并提高其韧性,制备了对苯二胺(PPD)功能化的氧化石墨烯(GO-PPD),分别以GO和GO-PPD为添加物,以CE和环氧树脂(质量比为7:3)共混物为基体树脂制备了GO/CE-环氧树脂和GO-PPD/CE-环氧树脂复合材料。采用红外和拉曼光谱表征GO和GO-PPD的结构,并研究了二者在溶剂中的溶解性。GO-PPD在乙醇等低沸点和低毒性的有机溶剂中表现出稳定的溶解性,与GO相比,GO-PPD明显改善了复合材料制备的工艺性。性能研究表明,GO和GO-PPD的加入均会降低基体树脂的固化温度,明显提高其力学性能和热性能,使基体树脂的介电常数和介电损耗显著增大,但仍然基本保持良好的耐湿热性和耐腐蚀性。石墨烯表面的化学性质影响石墨烯/CE-环氧树脂复合材料的综合性能,与GO相比,GO-PPD的加入能更明显提高复合材料的力学性能和耐热性。     

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.     

Crystallization,mechanical performance and hydrolytic degradation of poly(butylene succinate)/graphene oxide nanocomposites obtained via in situ polymerization

Poly(butylene succinate) (PBS)/graphene oxide (GO) nanocomposites were fabricated via in situ polymerization with very low GO content (from 0.03 to 0.5 wt%). The microstructures of the nanocomposites were characterized with Raman spectroscopy, fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), sedimentation experiments and atomic force microscopy (AFM). The results showed that PBS chains have been successfully grafted onto GO sheets during in-situ polymerization, accompanied by the thermo-reduction from GO to graphene. The grafted GO displayed a great nucleating effect on PBS crystallization, resulting in largely improved crystallization temperature and decreased spherules size. A simultaneous enhancement in tensile strength and elongation was achieved for PBS/GO nanocomposites fiber. Meanwhile, increase in hydrolytic degradation rate was also observed for these nanohybrids. Our result indicates that using very low content GO is a simple way to achieve good dispersion yet with remarkable property enhancement for polymer/GO nanocomposites.     

Reduced graphene oxide/Cu<Subscript>2</Subscript>O nanostructure composite films as an effective and stable hydrogen evolution photocathode for water splitting

An efficient photocathode consisting of reduced graphene oxide/Cu₂O/Cu (rGO/Cu₂O/Cu) has been successfully prepared in this work via a facile two step method, consisting of chemical oxidation of a copper foil in alkaline solution using (NH₄)₂S₂O₈ as the oxidizing agent, dipping the prepared samples in graphene oxide (GO) solution and calcination at vacuum to form a rGO layer onto Cu₂O/Cu photocathode, which acts as a protective layer. The products were composed of a thin Cu₂O layer topped with a thin rGO film as the protective coating. The chemical composition and rGO amount in the composite materials were easily controlled by changing the immersion time to enhance PEC performance. UV–Vis spectroscopy, Raman spectroscopy, XRD, SEM, TEM and FTIR spectroscopy were used in the optical and morphological characterization of the graphene oxide and prepared photocathodes. Distinct patches of GO film are formed on the Cu(OH)₂ nanostructure surface, as shown by SEM results. Linear sweep voltammetry and chronoamperometry analysis have been applied in the photoelectrochemical characterizations in the dark and under illumination conditions. Photocurrent density provided by rGO/Cu₂O/Cu photocathode ??2.54 mA cm^??2 is three times greater than that of bare Cu₂O/Cu photocathode ??0.82 mA cm^??2 at 0 V vs. RHE under illumination. Low photostability of 42% is exhibited by bare Cu₂O/Cu photocathode after 200 s irradiation whereas rGO/Cu₂O/Cu photocathode shows approximately 98% of the initial photocurrent density. Therefore, a strategy has been developed in this work for the synthesis of this new photocathode using Cu₂O/Cu as an effective photocathode for photoelectrochemical (PEC) water splitting.     

Thermal and electrical conductivity of Al(OH)<Subscript>3</Subscript> covered graphene oxide nanosheet/epoxy composites

Al(OH)₃ functionalized graphene composites (Al–GO) were prepared using a simple sol–gel method. In this protocol, graphene oxide (GO) was prepared according to the Hummers method and functionalized to enhance its reactivity with aluminum isopropoxide by a LiAlH₄ treatment. The functionalized graphene sheets were characterized by X-ray photoelectron spectroscopy, field emission scanning electron microscopy, and transmission electron microscopy. These analyses confirmed that GO had been fabricated and the Al(OH)₃ layer could have a homogeneous distribution with large and dense coverage onto GO sheets. In addition, the thermal and electrical conductivity of the epoxy composites with GO and Al–GO fillers were measured. The thermal conductivities of the composites with graphene-based fillers were enhanced by the addition of fillers. In particular, the thermal conductivity of GO/epoxy composite containing 3 wt% was approximately two times higher than that of pure epoxy resin. In addition, the electrical conductivity of Al–GO embedded composites degenerated compared to GO composites.     

化学还原氧化石墨烯制备高性能石墨烯自组装水凝胶

提出了一种以抗坏血酸钠为还原剂,通过化学还原氧化石墨烯制备高性能石墨烯自组装水凝胶的方法.用扫描电镜,流变及电导率测试,光电子能谱,X-射线晶体衍射和拉曼光谱等手段对该石墨烯水凝胶的结构与性能进行了表征.结果表明:化学还原氧化石墨烯对形成石墨烯水凝胶具有决定性作用.该石墨烯水凝胶具有优异的导电性(1 S·m-1),机械强度和电化学性能.在1 mol·L-1的硫酸电解质溶液中,通过1.2A·g-1恒电流允放电测试,石墨烯水凝胶电极的比电容高达240F·g-1.

Abstract：

Three-dimensional self-assembled graphene hydrogels (SGHs)have been fabricated by chemical reduction of graphene oxide (GO)with sodium ascorbate. The SGHs were characterized by scanning electron microscopy,rheological tests,electrical conductivity measurements,X-ray photoelectron spectroscopy,X-ray diffraction,and Raman spectroscopy. Results indicate that the reduction of GO promotes the assembly of graphene sheets. The SGHs are electrically conductive(1s·m-1)and mechanically strong and exhibit excellent electrochemical performance.In 1 mol·L-1 aqueous solution of H2SO4,the specific capacitance of SGHs was measured to be about 240F·g-1 at a discharge current density of 1.2·-1.     

From agrowaste to graphene nanosheets: chemistry and synthesis

In recent years, graphene oxide (GO) and reduced graphene oxide (r-GO) are being produced using graphite powder as precursor material but the preparation of graphene derivatives from a non-graphitic material without an additional oxidizing agent has not been reported so far. In this work, an agrowaste namely sugarcane bagasse was subjected to pyrolysis at three different temperatures, bypassing the use of toxic chemicals and graphite as a precursor. The chemistry of the effect of temperature and time on the development of graphitic planes in a non-graphitic material was studied. The formation of nanosheets of GO suggested that aromatization and condensation of the glucose monomers might have taken place which led to the glycosidic bond formation, further converging into polyaromatic rings on pyrolysis. The GO was further reduced at 95?°C using thiourea which resulted in the formation of r-GO after 8?hrs.     

三维多孔结构聚苯胺/石墨烯复合材料的制备及电化学性能

以自制聚苯胺水凝胶和氧化石墨烯为原料采用原位聚合法和溶液灌注法制备三维多孔结构的聚苯胺/氧化石墨烯复合材料,然后在氢碘酸的还原下制备聚苯胺/石墨烯复合材料。采用红外光谱法、场发射扫描电子显微镜和热重分析法对制备的复合材料的结构、形貌和组成进行表征,并采用三电极测试方式对其电化学性能进行测试。结果表明,氧化石墨烯的掺入能有效防止聚苯胺和氧化石墨烯的团聚和堆叠问题,获得了具有良好三维多孔结构的聚苯胺/氧化石墨烯复合物;聚苯胺/氧化石墨烯复合材料被氢碘酸还原后,得到的聚苯胺/石墨烯复合材料的热稳定性有所降低,但其比电容和导电性等有了很大的提高,在电流密度为0.5 A/g时,PANI/GO和PANI/r GO的比电容分别为240.38 F/g和321.91F/g。     

Oxidized graphene in ionic liquids for assembling chemically modified electrodes: a structural and electrochemical characterization study

Dispersions of graphene oxide (GO) nanoribbons in ionic liquids, ILs (either 1-butyl-3-methylimidazolium chloride (BMIM-Cl-) or 1-butylpyridinium chloride (-Bupy-Cl-)) have been used to assemble modified screen printed electrodes (SPEs). The graphene oxide/ionic liquid dispersions have been morphologically and structurally characterized by the use of several techniques: X-ray photoelectron spectroscopy (XPS), Fourier transform-infrared (FT-IR) spectroscopy, high-resolution-transmission electron microscopy (HR-TEM). The assembled modified SPEs have then been challenged with various compounds and compared to several electro-active targets. In all cases high peak currents were detected, as well as significant potential shifts, especially in the detection of catecholamines and NADH, compared with the bare SPE and the conventional electrodes, such as glassy carbon (GC) and highly oriented pyrolitic graphite (HOPG). This opens the way to the assembly of new types of sensors and biosensors. The enhanced performances observed are attributed to electrocatalytic effects related to the high electrode surface area, to oxygen-assisted electron transfer, as well as to the disordering effect of the ILs, this latter related to the favorable π-π interactions with the ILs and the GO plane.     

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.     

Facile Synthesis of NiFe_2O_4/Reduced Graphene Oxide Hybrid with Enhanced Electrochemical Lithium Storage Performance

In this work, a facile, one-pot route has been applied to synthesize nanohybrids based on mixed oxide Ni Fe2O4 and reduced graphene oxide(r GO). The hybrid is constructed by nanosized Ni Fe2O4 crystals confined by fewlayered r GO sheets. The formation mechanism and microstructure of the hybrids have been clarified by X-ray diffraction, Raman spectroscopy, scanning electron microscopy, and transmission electron microscopy.Electrochemical tests show that the performance of Ni Fe2O4 can be considerably improved by r GO incorporation. The performance improvement can be attributed to the two-dimensional conductive channels and the unique hybrid structure r GO constructed. The easy synthesis and good electrochemical performance of Ni Fe2O4/r GO hybrid make it a promising anode material for Li-ion batteries.     

CuS nanoplatelets arrays grown on graphene nanosheets as advanced electrode materials for supercapacitor applications

CuS nanoplatelets arrays grown on graphene nanosheets are successfully synthesized via a facile low-temperature solvothermal reaction with graphene oxide (GO), CH₃CSNH₂ and Cu(CH₃COO)₂·H₂O as the reactants. CH₃CSNH₂ plays an important role in being the reducing agent for GO and the sulfur source of CuS. Supercapacitive performance of the graphene/CuS nanocomposite as active electrode materials has been evaluated by cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy measurements. The results indicate that graphene/CuS electrode delivers a high capacitance of 497.8 F g^–1 at a current density of 0.2 A g^–1, which outperforms bare CuS electrode. This excellent performance is ascribed to the short diffusion path and large surface area of the unique hierarchical nanostructure with nanoflakes building blocks for bulk accessibility of faradaic reaction.     

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.     

Graphene oxide effects on the properties of Al_2O_3-Cu/35W5Cr composite

Graphene oxide(GO) nanosheets were dispersed into premixed powders(Cu-0.4 wt% Al/35W5Cr) by wet grinding and vacuum freeze-drying process. The 0.3 wt% GO/Al_2O_3-Cu/35W5Cr and 0.5 wt%GO/Al_2O_3-Cu/35W5Cr composites, used for electrical contacts, were fabricated by vacuum hot-pressing sintering.The microstructure was analyzed by field emission scanning electron and transmission electron microscopy. In addition, the Raman spectroscopy and X-ray photoelectron spectroscopy were used to investigate the structural changes of GO before and after sintering. The arc erosion behavior was investigated by the JF04 C electrical contact testing apparatus. Consequently, the Al_2O_3 nanoparticles were evenly dispersed in the matrix, causing dislocation tangles. GO was converted to reduced graphene oxide after sintering. A group of carbon atoms combined with Cr forming Cr_3C_2 in situ during sintering, which enhanced the interface bonding. Compared with the Al_2O_3-Cu/35W5Cr composite, the tensile strength of the two contact materials containing 0.3 wt% GO and 0.5 wt% GO was increased by 45% and 34%, respectively. Finally, pips and craters were present on the anode and cathode surfaces, respectively.Tungsten has undergone re-sintering during arcing and formed needle-like structures. Compared with Al_2O_3-Cu/35W5Cr, the GO/Al_2O_3-Cu35W5Cr composites have better welding resistance. The final mass transfer direction of the two composites was from the cathode to anode.     

石墨烯/纳米TiO2复合材料的制备及其光催化性能

以氧化石墨烯（GO）和钛酸四丁酯（Ti（OBu）₄）作为初始反应物,采用乙醇溶剂热法合成了石墨烯/纳米TiO₂复合材料,并利用XRD、FE-SEM、TEM、RAMAN和XPS等手段对石墨烯/纳米TiO₂复合材料的晶体结构、形貌及元素形态等性质进行了表征,同时将复合材料应用于光催化降解甲基橙溶液,进行光催化性能评价。结果表明：Ti（OBu）₄在乙醇溶剂中通过化学静电引力吸附到GO表面,经过溶剂热反应,GO被还原成石墨烯的同时,石墨烯的表面负载生长锐钛矿TiO₂颗粒。随着溶剂热反应时间的延长,GO表面的活性基团减少,还原更加彻底,同时TiO₂晶粒有一定的增大趋势;与纯TiO₂相比,石墨烯/纳米TiO₂复合材料光催化活性明显提高,石墨烯含量对复合材料的光催化活性有直接的影响。     

PPy/MWNTs/GO复合材料的制备与电化学性能研究

以吡咯为单体,多壁碳纳米管和氧化石墨烯为模板,过硫酸铵为氧化剂,采用原位化学聚合法制备了聚吡咯/多壁碳纳米管/氧化石墨烯(PPy/MWNTs/GO)复合材料.利用傅里叶变换红外光谱(FTIR)、X射线衍射谱(XRD)、扫描电镜(SEM)、循环伏安法(CV)和电化学交流阻抗谱(EIS)对制备复合材料的结构、微观形貌和电化学性能进行了研究,探讨了多壁碳纳米管/氧化石墨烯比例、吡咯用量对复合材料电容性能的影响.研究结果显示,PPy/MWNTs/GO复合材料具有较大的比电容和良好的循环稳定性,且具有较小的电荷转移电阻,接近于理想的超级电容器用电极材料.     

Green synthesis of nanosilver‐decorated graphene oxide sheets

A green facile method has been successfully used for the synthesis of graphene oxide sheets decorated with silver nanoparticles (rGO/AgNPs), employing graphite oxide as a precursor of graphene oxide (GO), AgNO₃ as a precursor of Ag nanoparticles (AgNPs), and geranium (Pelargonium graveolens) extract as reducing agent. Synthesis was accomplished using the weight ratios 1:1 and 1:3 GO/Ag, respectively. The synthesised nanocomposites were characterised by scanning electron microscopy, transmission electron microscopy, atomic force microscopy, X‐ray diffraction, UV‐visible spectroscopy, Raman spectroscopy, energy dispersive X‐ray spectroscopy and thermogravimetric analysis. The results show a more uniform and homogeneous distribution of AgNPs on the surface of the GO sheets with the weight ratio 1:1 in comparison with the ratio 1:3. This eco‐friendly method provides a rGO/AgNPs nanocomposite with promising applications, such as surface enhanced Raman scattering, catalysis, biomedical material and antibacterial agent.Inspec keywords: silver, nanoparticles, graphene, nanocomposites, scanning electron microscopy, transmission electron microscopy, atomic force microscopy, X‐ray diffraction, ultraviolet spectra, visible spectra, X‐ray chemical analysis, surface enhanced Raman scattering, catalysis, nanofabricationOther keywords: antibacterial agent, biomedical material, catalysis, surface enhanced Raman scattering, rGO‐AgNP nanocomposite, eco‐friendly method, homogeneous distribution, thermogravimetric analysis, energy dispersive X‐ray spectroscopy, Raman spectroscopy, UV‐visible spectroscopy, X‐ray diffraction, atomic force microscopy, transmission electron microscopy, scanning electron microscopy, nanocomposites, reducing agent, geranium, graphene oxide sheets, graphite oxide, silver nanoparticles, green facile method