氧化石墨烯还原制备石墨烯的方法研究

以天然鳞片石墨为原料,对Hummers法制备的氧化石墨烯,分别采用氢碘酸、葡萄糖、乙二胺、氢氧化钠进行化学还原,同时对比用快速热处理制备石墨烯。利用傅立叶红外光谱（FT—IR）、拉曼光谱（Raman）、扫描电子显微镜（SEM）对所得产物进行了比较分析。结果表明：对Hummers法制备的氧化石墨烯还原,葡萄糖的还原效果比较好;通过热处理可有效地将氧化石墨烯的含氧官能团还原,是一种高效、可行的方法。     

碘化钾还原氧化石墨烯制备柔性石墨烯薄膜

采用酸性碘化钾（KI）溶液还原由真空抽滤得到氧化石墨烯薄膜制备得到了完整性良好的石墨烯薄膜。研究表明,体系中盐酸浓度和反应时间影响KI还原氧化石墨烯薄膜的效果。当采用盐酸浓度为ImolL-1。的50％KI溶液还原氧化石墨烯膜30min时,制得的石墨烯薄膜具有良好的柔韧性和较高的完整性。     

氢气热处理制备大块导电石墨烯薄膜及表征

通过真空抽滤水中分散良好的氧化石墨烯获得薄膜,并在600℃氢气气氛中保温2h还原即可获得含氧量极低的大片导电石墨烯(GE)薄膜。以X射线衍射(XRD)、红外分析(FT-IR)、拉曼光谱仪(Ramanspectroscopy)研究氢气气氛热处理前后薄膜的物相、官能团组成和分子结构;采用SEM观察石墨烯薄膜的表面形貌;采用四探针测试仪对氢气气氛热处理前后薄膜的电学行为进行了对比考察。实验结果表明,氢气气氛热处理氧化石墨烯可以获得含氧量极低且导电性能优良的石墨烯;96mL浓度为0.0937mg/mL的氧化石墨烯溶液抽滤膜经氢气处理后获得的石墨烯薄膜方阻达到11.3Ω/□,薄膜电阻率为0.6Ω.cm。     

基于化学气相沉积石墨烯/PEDOT-PSS共混复合材料的导电薄膜

采用液相剥离技术制备基于化学气相沉积（CVD）石墨烯/聚乙撑二氧噻吩-聚苯乙烯磺酸（PEDOT-PSS）共混复合材料的导电薄膜。采用原子力显微镜和SEM表征石墨烯/PEDOT-PSS复合薄膜的微观结构;通过紫外吸收谱、X射线光电子能谱、FTIR等分析技术探索该共混复合薄膜的导电机制。结果表明：石墨烯/PEDOT-PSS导电薄膜具有优异的电学特性,其方阻约为8 Ω/□;表面分析表明,石墨烯与PEDOT主链中五元噻吩发生π-π共轭效应,由此引起两作用体之间电子云密度的变化,该变化增加了PEDOT主链的载流子离域化程度,有利于PEDOT导电性的提升,同时提高石墨烯的载流子浓度,使CVD石墨烯/PEDOT-PSS复合薄膜的导电能力增强。     

四苯基卟啉夹层石墨烯复合物的光电子特性研究

以四苯基卟啉和石墨烯为原料,用溶剂-非溶剂共沉淀法制备得到四苯基卟啉夹层石墨烯复合物,通过扫描电镜（SEM）、透射电镜（TEM）、荧光光谱和电化学循环伏安对所得复合物进行表征。分析结果表明,共沉淀过程使得四苯基卟啉成功包裹了石墨烯,它们之间存在电子转移,且四苯基卟啉在654nm和717nm处的荧光淬灭;四苯基卟啉-石墨烯复合物是一个很好的电子给体-受体体系,在新型显示器、光伏电池等方面有潜在的应用价值。     

氧化石墨烯-酚醛树脂薄膜的制备及性能研究

采用化学分散法大量制备氧化石墨烯,并采用直接共混法制备氧化石墨烯/酚醛树脂纳米复合材料.通过AFM、SEM、FT-IR、TG等对其进行表征,结果表明,氧化石墨烯完全剥离,并在基体中分散均匀,而且两者界面相容性好,提高了复合材料的热稳定性.通过高温热处理使复合材料薄膜在兼顾形貌的同时实现导电,当氧化石墨烯含量为2%(质量分数)时,其导电率为96.23S/cm.     

化学还原石墨烯薄膜的制备及结构表征

以天然鳞片石墨为原材料,采用Hummers法成功制备了氧化石墨,并采用化学还原方法制备石墨烯薄膜材料,分别应用X射线衍射(XRD)、能谱分析(EDS)、拉曼光谱分析(Raman)、傅里叶变换红外光谱(FTIR)和扫描电镜(SEM)对氧化石墨和化学还原石墨烯薄膜的性能、结构和形貌进行了表征。实验结果表明,通过控制溶液的pH值为10可防止石墨烯团聚,石墨烯溶液的分散性非常好,碳氧比达到了8.8∶1,扫描电镜图片观察到了较薄的片层。通过XRD图谱可以看出,石墨烯薄膜比原始石墨的层间距变大。拉曼光谱表明,石墨烯薄膜相对氧化石墨的ID/IG值更大,样品在还原的过程中无序度增加。石墨烯薄膜的微观结构研究为其在超级电容器电极或重金属废水过滤膜等方面的应用提供了理论基础。     

石墨烯/聚乳酸复合材料的制备与性能研究

目的制备具有优异阻隔性能及热稳定性的聚乳酸薄膜材料。方法在聚乳酸中添加石墨烯对其进行改性。首先采用改进的Hummers法将鳞片状石墨制备成氧化石墨烯,继而采用热剥离法将氧化石墨烯还原剥离为石墨烯,然后以聚乳酸为基材,还原后的石墨烯为增强相,采用流延法制备石墨烯/聚乳酸复合薄膜,并测试了其结构、热稳定性以及阻隔性能。结果红外分析表明,石墨被强氧化剂氧化后形成了以C—OH,—COOH,C—O—C和C=O等官能团形式存在的石墨层间化合物,还原后获得的石墨烯剥离充分;石墨烯/聚乳酸复合薄膜的热稳定性能和阻隔性能随石墨烯含量的增加而逐渐增强。结论在试验参数范围内,石墨烯/聚乳酸复合薄膜的热稳定性和阻隔性能优于聚乳酸薄膜。     

还原热处理对石墨烯薄膜导电性的影响

用改进的Hummers法制备了氧化石墨,通过超声、沉聚和自组装等工序制得氧化石墨烯薄膜,真空热处理后获得石墨烯薄膜.利用X射线晶体衍射(XRD)、扫描电子显微镜(SEM)、傅里叶变换红外(FT-IR)和拉曼(Raman)光谱等研究了石墨烯薄膜制备过程中各阶段产物的微观特征变化.结果表明,自组装方法制备氧化石墨烯薄膜简单易行,厚度尺寸可控,微观层状结构良好.热处理使石墨烯薄膜具有导电性,随温度升高导电率不断提高,在1 100℃时可达到536 S/cm.     

Stable dispersion of graphene solution prepared by hydrothermai reduction

以天然鳞片石墨为原料,用改进的Hummers法制备氧化石墨。超声分散制备氧化石墨烯溶液,通过加入不同量的水合肼调节溶液的pH值,再通过水热法热还原,制备了在水中稳定分散的石墨烯溶液。利用扫描电子显微镜（SEM）、高分辨透射电镜（HR-TEM）、拉曼光谱（Raman）、原子力显微镜（AFM）、X射线衍射分析（XRD）、zeta电位及光学显微镜对制备的样品进行了表征,研究了不同温度、pH值对石墨烯溶液稳定性的影响。     

Facile chemical synthesis of W-Ag and W-Cu nanocomposites at low temperature

W-Ag (80.2W-19.8Ag, 70.4W-29.6Ag and 60.5W-39.5Ag) and W-Cu (79.7W-20.3Cu, 70.5W-29.5Cu and 59.8W-40.2Cu) nanocomposites in the size range of 24-30 nm have been synthesized by thermal decomposition of W(CO)6/CH3COOAg and W(CO)6/Cu(acac)2 in diphenyl ether as solvent at 220 degrees C in presence of oleic acid and hexadecyl amine and characterized. FTIR spectra have been used to explain the role of oleic acid and hexadecyl amine in the synthesis of W-Ag and W-Cu composite powders. XRD studies show that the tungsten phase is amorphous, whereas both Ag and Cu crystallize in fcc for as-synthesized W-Ag and W-Cu nanocomposites. These composite powders when annealed at 700 degrees C results in the formation of bcc tungsten and peaks corresponding to fcc silver and copper still persists. The particle size, shape and distribution of these nanocomposites of various compositions have been studied by SAXS, ESEM and TEM and found to be nearly spherical with the average diameters below 30 nm.     

Morphologies and microstructures of nano-sized Cu(2)O particles using a cetyltrimethylammonium template

Hollow polyhedra and cubes of nanostructured Cu(2)O particles have been synthesized by reduction of CuSO(4) with ascorbate acid in the solution phase. The nanostructures were obtained when the cetyltrimethylammonium (CTAB) concentration ranged from 0 to 0.03?M in the presence of NaOH. Structural characterizations, by means of x-ray photoelectron spectroscopy (XPS) for measuring Cu valence states and by electron microscopy for microstructure and chemical analyses, suggest that most Cu(2)O nanoparticles are covered with a thin CuO shell arising possibly from reaction of the adsorbed oxygen on the Cu(2)O particle surface. The blue shift is observed as microstructures of Cu(2)O nanoparticles changed from cubic to hollow in ultraviolet and visible (UV-visible) absorption spectra. Both the Cu(2)O hollow and cubic nanostructures show certain quantum-confined effects. A cationic CTAB template mechanism is proposed to interpret the formation of the Cu(2)O nanoparticles.     

SiC颗粒尺寸对Al2O3-SiC纳米复合陶瓷的影响

采用非均相沉积法制备含有不同粒径ＳｉＣ颗粒的Ａｌ２Ｏ３－ＳｉＣ复合粉体,粉体呈Ａｌ２Ｏ３包裹ＳｉＣ的开貌,经热压烧结获得致密烧结体,通过ＳＥＭ观察,Ａｌ２Ｏ３基体晶粒尺寸随着加入ＳｉＣ颗粒粒径的减小而减小。但减小的趋势比Ｚｅｎｅｒ模型预测的弱,力学性能随着加入ＳｉＣ颗粒粒径的减小而得到改善,这主要同ＳｉＣ颗粒对基体的弱化作用减弱及基体粒径变小有关。     

Sinterability, mechanical, and electrical properties of Al2O3/8YSZ nanocomposites prepared by ultrasonic spray pyrolysis

Al2O3 nanoparticles added the YSZ for improving the mechanical property and the ionic conductivity. Al2O3/YSZ nanocomposites were prepared by ultrasonic spray pyrolysis and PECS process. The relative density of the Al2O3/YSZ nanocomposites was fully densified at a sintering temperature of 1100 degrees C. The grain size for 5 vol.% Al2O3/YSZ was less than 100 nm. The fracture toughness and total ionic conductivity of Al2O3/YSZ nanocomposites were improved compared with Al2O3/YSZ nanocomposites by conventional process, due to homogeneous dispersion and uniform particle size of added Al2O3.     

以氢氧化铜为前躯体制备单分散球形氧化亚铜粉末

在不加任何添加剂和高反应物浓度的条件下,于碱性体系中以Cu(OH)2为前躯体,用葡萄糖还原制备了粒径为0.9-2.0μm的单分散球形氧化亚铜粉末。考察了反应温度和反应物(NaOH、葡萄糖、CuSO4)浓度等因素对Cu2O粉末形貌和粒径的影响。利用扫描电镜和X射线衍射分析对Cu2O粉末进行了表征。并根据晶体成核生长理论初步讨论了上述条件对Cu2O粉末形貌和粒径的影响。     

A facile synthesis of Cu(2)O/SiO(2) and Cu/SiO(2) core-shell octahedral nanocomposites

We report here a simple approach to the synthesis of Cu(2)O/SiO(2) core-shell nanocomposites in water solution. The Cu(2)O cores have a perfect octahedral structure with uniform size of about 200-300?nm. A compact SiO(2) shell 9?nm in thickness is located at the surfaces of Cu(2)O octahedra, and it is composed of fine SiO(2) nanoparticles. During the depositing of the SiO(2) particles, as we presumed, dynamic absorbing and disengaging of Na(+) at the interface of Cu(2)O octahedra and the solution made it possible for the formation of Cu-O-Si bonds between core and shell in the composites. The existence of Cu-O-Si bonds in our core-shell composite can be substantiated by peak changes at?1236 and 1080?cm(-1) in the FT-IR spectra. This is the reason why the SiO(2) shell is so compact and uniform. Moreover, these Cu(2)O/SiO(2) core-shell octahedra were further used as precursors, depending on a simple disproportionation reaction of Cu(2)O in acid, to easily achieve Cu/SiO(2) movable multicore-shell octahedral nanocomposites. In the final Cu/SiO(2) core-shell composite, the thin SiO(2) octahedral shell was held, inside of which formed several free Cu nanoparticles 50-80?nm in size. Studies on the Cu(2)O/SiO(2) core-shell octahedral composites and Cu/SiO(2) movable multicore-shell octahedral nanocomposites would be a good thing not only for fundamental research but also for applications.     

加料方式对超细氧化亚铜粉体分散性与粒度稳定性的影响

在不加任何添加剂和高反应物浓度的条件下, 用CuSO₄、NaOH、葡萄糖为原料制备了Cu₂O球形粉体. 利用扫描电镜和smileview软件对Cu₂O粉体进行了表征分析, 主要考察了加料方式对Cu₂O颗料的分散性与粒度稳定性的影响, 并根据Lamer模型初步探讨了其影响机理. 结果表明, 当采用先将NaOH溶液与CuSO₄溶液分步缓慢混合制备Cu(OH)₂作为铜源, 再加入葡萄糖还原Cu(OH)₂制备Cu₂O的加料方式时, Cu₂O颗粒按“爆发成核, 缓慢生长”的模式形成, 制得的Cu₂O粉体分散性高, 粒度稳定性好. 分散性高是由于缓慢的晶核生长有利于通过搅拌作用使初始晶核间的软团聚体再分散, 避免软团聚体进一步通过化学键合发展成为硬团聚. 粒度稳定性好的原因是将NaOH溶液分步缓慢加入到CuSO₄溶液中制备的前驱体Cu(OH)₂热稳定性好, 较好地保持了前驱体升温过程中铜源组分的单一性, 避免了还原过程中出现二次成核现象.     

Effects of temperature and dispersants on the phases and morphology of Ag–Cu nanoparticles

Ultrafine Ag–Cu nanoparticles (NPs) have been synthesized by a rapid one-step reduction within only 10 min. Effects of temperature and dispersants on the phases and morphology of Ag–Cu NPs were investigated. Results showed that citric acid exhibited an advantageous nature to avoid the formation of Cu₂O and form uniform morphology over PVP. The average particle size of the Ag–Cu NPs synthesized simply in ice-cubes bath could be controlled in 8.6 nm about a quarter of that synthesized at room temperature. The synthesized Ag–Cu NPs presented alloy states near the eutectic composition of 72:28. Due to the lower Ostwald ripening rate and citric acid protection, smaller Ag–Cu NPs were achieved in ice-cube bath. Results also showed that the ultrafine Ag–Cu NPs could be expected to sinter at about 330 °C which was much lower than the eutectic temperature (779 °C) of bulk Ag–Cu alloy. The ultrafine Ag–Cu NPs could be applied as potential die attach materials for SiC power devices.     

Oxidation of SiC powders for the preparation of SiC/mullite/alumina nanocomposites

The oxidation behaviour of two types of SiC powder of differing particle size and morphology distribution has been studied in the present work; one submicron-sized and the other micron-sized. It has been observed that the onset-temperature for significant oxidation of the SiC powder of smaller particle size is much lower than that for the SiC powder of larger particle size; namely, about 760 °C as compared with about 950 °C. Furthermore, the rate and extent of oxidation of the former SiC powder is much higher than that of the latter SiC powder. Interestingly, however, the SiC powder of smaller particle size exhibits more controllable oxidation behaviour in the context of the preparation of SiC/mullite/alumina nanocomposites, i.e., in terms of the extent of oxidation, and hence the amount of silica formed as an encapsulating outer layer and the resulting core SiC particle size, than the SiC powder of larger particle size. The SiO₂ layer formed was amorphous when the SiC powders were oxidized below 1,200 °C, but crystalline in the form of cristobalite when they were oxidized above 1,200 °C. Since the presence of amorphous silica can accelerate the sintering of the nanocomposite, oxidation of the chosen SiC powder should thus take place below 1,200 °C.     

Effect of different copper fillers on the electrical resistivity of conductive adhesives

The effects of different copper fillers with different morphology and particle size have been studied in terms of electrical resistivity and thermal stability on the electrically conductive adhesives. The copper fillers used in this study were prepared by wet chemical reduction, electrolytic and gas atomization method, respectively. The as cured ECAs filled with different type of Cu fillers showed significant difference in electrical resistivity. Cu filler with smaller particle size showed higher packing density and larger surface area, which would enhance formation of conductive channels and increased conductive network in the ECAs, leading to a lower electrical resistivity. In addition, thermal stability of the ECAs were investigated under high temperature exposure at 125 °C and high humidity aging at 85 °C/85% RH for 1,000 h. Results showed that ECAs with Cu fillers of relatively small particle size and rough particle surface have excellent thermal stability due to enhanced adhesion and contact area between Cu fillers and the polymer matrix. A very low resistivity at an order of magnitude of 10^?4 ?? cm could be maintained for these ECAs after 1,000 h at 125 and 85 °C/85% RH.