氧化石墨烯/硒化锌纳米光电材料的制备及其蓝光发射特性

采用一种简单有效的原位水热合成方法,使用石墨烯氧化物（GO）作为反应物和晶体生长基底成功制备出了还原氧化石墨烯/硒化锌（r-GO/ZnSe）纳米复合材料。采用X射线粉末衍射（XRD）、透射电子显微镜（TEM）、高分辨透射电镜（HRTEM）以及红外-可见光谱（FT-IR）等方法对r-GO/ZnSe纳米复合材料进行了检测。结果表明,平均粒径在30 nm的立方闪锌矿晶体结构的ZnSe粒子均匀分散在氧化石墨烯片层上,构成纳米复合结构。 UV-Vis光谱显示,纳米复合材料的光学吸收的起始波长在445 nm附近。PL光谱显示,纳米复合材料在470 nm附近存在一个很强的发射峰。这种石墨烯基纳米复合材料在白光二极管领域中有重要的应用价值。     

液相电化学法制备类金刚石薄膜及其摩擦性能研究

采用自行设计的液相法沉积装置,以甲醇有机溶剂作为碳源,利用液相电化学沉积技术在不锈钢及Si基底上制备了类金刚石薄膜;用扫描电镜、Raman光谱仪表征了沉积薄膜的表面形貌和结构;用UMT-2M摩擦磨损试验机对两种沉积薄膜进行了摩擦性能测试。结果表明:经电化学沉积的类金刚石薄膜均匀、致密,表面粗糙度小;Raman光谱在1 332cm-1处有强的谱峰,与金刚石的特征峰相吻合,其中不锈钢基底上薄膜的sp3含量更高;不锈钢基底沉积膜的摩擦系数为0.12,Si片基底沉积膜的摩擦系数为0.10;不锈钢基底沉积膜的耐磨性较Si片沉积膜高。     

液相电化学法制备类金刚石薄膜及其摩擦性能研究

采用自行设计的液相法沉积装置,以甲醇有机溶剂作为碳源,利用液相电化学沉积技术在不锈钢及Si基底上制备了类金刚石薄膜;用扫描电镜、Raman光谱仪表征了沉积薄膜的表面形貌和结构;用UMT-2M摩擦磨损试验机对两种沉积薄膜进行了摩擦性能测试。结果表明：经电化学沉积的类金刚石薄膜均匀、致密,表面粗糙度小;Raman光谱在1332 cm-1处有强的谱峰,与金刚石的特征峰相吻合,其中不锈钢基底上薄膜的sp3含量更高;不锈钢基底沉积膜的摩擦系数为0.12,Si片基底沉积膜的摩擦系数为0.10;不锈钢基底沉积膜的耐磨性较Si片沉积膜高。     

氧化石墨制备温度对石墨烯结构及其锂离子电池性能的影响

采用改进的Hummers 法, 以石墨粉为原料制备氧化石墨, 然后使用微波还原法制备石墨烯, 最后以石墨烯作为负极材料组装锂离子电池. 系统的研究了高温氧化阶段中温度对氧化石墨的氧化程度、石墨烯的还原程度和比表面积以及锂离子电池性能的影响. 利用场发射扫描电镜(FESEM)、 X射线光电子能谱(XPS)、X射线衍射仪(XRD)、BET测量仪对氧化石墨和石墨烯的微观结构及比表面积等进行测试和表征. XRD, XPS及电化学测试的结果显示当高温阶段氧化温度为90 °C时, 氧化石墨的氧化程度最高, 相应的石墨烯也具有最高的还原程度和最大的比表面积423.2 m²/g, 同时石墨烯锂离子电池也具有更好的性能: 首次放电比容量为1555.5 mAh/g, 充电容量为1024.6 mAh/g, 其循环放电比容量达到600 mAh/g.     

还原温度对氧化石墨烯结构及室温下H_2敏感性能的影响

以氧化石墨凝胶制备的氧化石墨烯(GO)溶胶为前驱体,在100—350℃温度下还原获得不同还原程度的还原氧化石墨烯(rGO)样品,并采用旋涂工艺制备还原氧化石墨烯气敏薄膜元件.采用X射线衍射、拉曼光谱、傅里叶变换红外光谱和气敏测试等手段研究还原温度对样品结构、官能团和气敏性能的影响.结果表明:经热还原处理的氧化石墨烯结构向较为有序的类石墨结构转变,还原温度为200℃时,样品处于GO向rGO转变的过渡阶段,还原温度达到250℃时,则表现出还原氧化石墨烯特性;无序程度随还原温度的升高先由0.85增大至1.59,随后减小至1.41,总体呈现增加趋势;氧化石墨烯表面含氧官能团随还原温度的升高逐渐热解失去,不同含氧官能团的失去温度范围不同;热还原氧化石墨烯具有优异的室温H_2敏感性能,随着还原温度的升高,元件灵敏度逐渐减小,响应-恢复时间逐渐增大,最佳灵敏度为88.56%,响应时间为30 s.     

用化学气相沉积法制备石墨烯薄膜及其电学性能研究

以甲烷作为反应气体、利用高温化学气相沉积法分别在纯硅片和镀镍镉过渡层硅片上沉积石墨烯薄膜,应用金相显微镜和电学特性测试分析了700,900,950℃温度下生长的石墨烯薄膜的表面形貌、伏安特性及其他电学特性.发现镍铬过渡层具有显著的催化作用,可有效降低石墨烯的生长温度.随着生长温度的升高,样品中电子迁移率随之增大,伏安特性的线性度也越好.对纯硅片上生长的石墨烯,发现高温有利于甲烷有效分解和成核,可有效提高表面电子浓度和电子迁移率,其迁移率可达到2.52×104 cm2/V.     

Ag-BaO薄膜内场助光电发射增强现象研究

通过在Ag-BaO薄膜表面真空沉积10nm厚的银电极,成功制备了内场助结构Ag-BaO光电阴极.测试结果显示,Ag-BaO薄膜光电发射电流随内场助偏压的增大而上升.理论分析表明,Ag-BaO薄膜内场助光电发射增强现象产生的机理在于内场助作用下Ag微粒和BaO介质间等效界面位垒的减小及薄膜表面真空能级的相对下降. 关键词： 内场助光电发射 能带弯曲 金属超微粒子 Ag-BaO薄膜     

ZnqCl2薄膜与器件的制备及其光电特性

用热蒸发技术成功地制备了新合成的二氯取代的八羟基喹啉锌(ZnqCl2)薄膜，并制作成有机发光嚣件。紫外吸收谱分析表明，器件在225，290，350，392．5nm处有4个吸收峰。光致发光和电致发光研究衰明，ZnqCl2薄膜有良好的发光特性，器件的发光亮度大。并分析了ZnqCl2薄膜的能级结构。     

Natural Rubber/Graphene Oxide Nanocomposites Prepared by Latex Mixing

Natural rubber/graphene oxide (NR/GO) nanocomposites were prepared by latex mixing. The dispersion state of GO and the mechanical properties of the nanocomposites were studied. It was found that a uniform dispersion of GO in the NR matrix was achieved with the latex mixing method. The well-distributed GO was remarkably effective in improving the tensile strength and storage modulus of NR at very low filler contents, without sacrificing the ultimate strength. The percolation point of GO in the nanocomposites took place at a content of less than 0.1 parts by weight per hundred parts of rubber. The Halpin-Tsai model was used to analyze the reinforcement effect of GO for NR.     

Oxygenated Functional Group Density on Graphene Oxide: Its Effect on Cell Toxicity

The association of cellular toxicity with the physiochemical properties of graphene‐based materials is largely unexplored. A fundamental understanding of this relationship is essential to engineer graphene‐based nanomaterials for biomedical applications. Here, an in vitro toxicological assessment of graphene oxide (GO) and reduced graphene oxide (RGO) and in correlation with their physiochemical properties is reported. GO is found to be more toxic than RGO of same size. GO and RGO induce significant increases in both intercellular reactive oxygen species (ROS) levels and messenger RNA (mRNA) levels of heme oxygenase 1 (HO1) and thioredoxin reductase (TrxR). Moreover, a significant amount of DNA damage is observed in GO treated cells, but not in RGO treated cells. Such observations support the hypothesis that oxidative stress mediates the cellular toxicity of GO. Interestingly, oxidative stress induced cytotoxicity reduces with a decreasing extent of oxygen functional group density on the RGO surface. It is concluded that although size of the GO sheet plays a role, the functional group density on the GO sheet is one of the key components in mediating cellular cytotoxicity. By controlling the GO reduction and maintaining the solubility, it is possible to minimize the toxicity of GO and unravel its wide range of biomedical applications.     

Synthesis and Characterization of Poly(vinyl pyrrolidone)/Reduced Graphene Oxide Nanocomposite

Poly(vinyl pyrrolidone) (PVP)/reduced graphene oxide (RGO) nanocomposites were synthesized by reducing graphene oxide in the polymer matrix at different temperatures. The effects of the GO content on the properties of the nanocomposites were investigated by Fourier-transform infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA). The degree of dispersion of GO in the PVP matrix was examined by field-emission scanning electron microscopy. The results showed that both GO and RGO were well dispersed in the PVP matrix. Under low filler content, the improvement of onset decomposition temperatures of PVP nanocomposites was not obviously observed, but the amounts of residual char of the PVP nanocomposites were clearly increased. In addition, the decomposition temperature peak values of the PVP nanocomposites were increased, while the peak was broadened.     

用静电自组装法制备的石墨烯薄膜特性研究

本文采用静电自组装技术制备石墨烯薄膜,以带正电的聚乙烯亚胺作为粘结剂,将带负电的氧化石墨烯自组装在粘结剂上,形成多层氧化石墨烯/聚乙烯亚胺复合膜,然后在肼蒸汽下还原得到石墨烯薄膜样品,并利用石墨烯薄膜的紫外吸收光谱、椭圆偏振光谱、扫描电镜图谱及拉曼光谱对其层数、厚度、形貌及还原效果进行了研究。研究表明此方法制备的石墨烯薄膜具有杂质含量少、层数与膜厚微观可控且膜厚均匀等优点。通过调节组装材料种类、浓度和组装次数可制备出结构和功能自由控制的石墨烯薄膜,且此方法与微电子工艺兼容,易于制作石墨烯晶体管,因此在石墨烯晶体管领域具有广阔的应用前景。     

Synthesis and Characterization of a Novel Ternary Hematite Nanocomposites Structure with Fullerene and 2D‐Electrochemical Reduced Graphene Oxide for Superior Photoelectrochemical Performance

In this study, a novel ternary hematite nanocomposites photoanode structure with superior photoelectrochemical (PEC) performance consisting of fullerene (C₆₀) and 2D‐electrochemical reduced graphene oxide (eRGO) used as the effective surface passivators is developed. The introduction of both the electron scavenging C₆₀ and highly conducting eRGO has mitigated the high interfacial recombination rate of hematite and led to the superior enhancement in PEC performance. UV–vis analysis reveals that the incorporation of C₆₀ and eRGO can provide a stronger light absorption at the visible light (400 nm < λ < 700 nm) and near infrared (IR) region (λ > 700 nm). Through the electrochemical impedance spectroscopy measurements, it can be concluded that the introduction of C₆₀ and eRGO onto hematite photoanode improves electron transfer and collection, reduces charge‐carrier recombination efficiency, and enhances PEC activity. The resultant ternary hematite photoanode structure exhibits 16.8‐fold enhancement in photocurrent density and 0.8‐fold reduction in charge transfer resistance when compared to the bare hematite structure only. This study has shown that the application of C₆₀, 2D‐eRGO, or in combination as a ternary structure provides the plasmonic effect that can enhance the PEC performance in hematite photoanode structure.     

Functionalization of Graphene Oxide and its Biomedical Applications

Graphene oxide (GO) offers interesting physicochemical and biological properties for biomedicine due to its versatility, biocompatibility, small size, large surface area, and its ability to interact with biological cells and tissues. GO is a two-dimensional material of exceptional strength, unique optical, physical, mechanical, and electronic properties. Ease of functionalization and high antibacterial activity are two major properties identified with GO. Due to its excellent aqueous processability, amphiphilicity, surface functionalization capability, surface enhanced Raman scattering (SERS), and fluorescence quenching ability, GO chemically exfoliated from oxidized graphite is considered a promising material for biological applications. In addition, due to π-π* transitions, a low energy is required for electron movement, a property important in Biosensor and Bioimaging applications of GO. In this article, we present an overview of current advances in GO applications in biomedicine and discuss future perspectives. We conclude that GO is going to play a vital role in Biomedical applications in the near future.     

Synthesis of Fluorinated Graphene Oxide and its Amphiphobic Properties

The richly functionalized basal plane bonded to polar organic moieties makes graphene oxide (GO) innately hydrophilic. Here, a methodology to synthesize fluorinated graphene oxide by oxidizing the basal plane of fluorinated graphite, allowing for tunable hydrophobicity of GO, is reported. Fluorine exists as tertiary alkyl fluorides covalently bonded to graphitic carbons, and using magic‐angle spinning (MAS) ¹³C NMR as a primary tool chemical structures for the two types of synthesized fluorinated graphene oxides (FGOs) with significantly different fluorine contents are proposed. The low surface energy of the C–F bond drastically affects GO's wetting behavior, leading to amphiphobicity in its highly fluorinated form. Ease of solution processing enables the fabrication of inks that are spray‐painted on various porous/non‐porous substrates. These coatings maintain amphiphobicity for solvents with surface tensions down to 59 dyn/cm, thus bypassing existing lithographic means to create similar surfaces. The approach towards fluorinating GO and fabricating graphene‐based surfaces with tunable wettability opens the path towards unique, accessible, carbon‐based amphiphobic coatings.     

化学溶液沉积制备氧化石墨烯掺杂YBCO薄膜

YBCO薄膜在液氮温区具有优异的性能,围绕低成本溶液沉积技术和新型添加剂的研究是目前研究热点.采用化学溶液沉积技术成功制备出氧化石墨烯掺杂YBCO薄膜.通过在YBCO前驱液中引入氧化石墨烯,改变YBCO胶体的热解行为,促进YBCO前驱体的分解.在晶化过程中,氧化石墨烯有利于抑制YBCO晶粒长大.结果表明,适量添加氧化石墨烯可以改善YBCO薄膜的微观形貌和外延生长,提高超导层的性能.     

Synergetic Photocatalytic Nanostructures Based on Au/TiO2/Reduced Graphene Oxide for Efficient Degradation of Organic Pollutants

Recently, there is crucial interest in the design and fabrication of nanocatalysts for efficient decomposition of organic pollutants in wastewater using visible light. This work reports the assembling fabrication of synergetic photocatalytic Au/TiO₂/RGO nanostructures by utilizing the reduced graphene oxide (RGO) as substrate material and efficient separator for electrons and holes. The Au/TiO₂ nanostructures with a ≈7 nm TiO₂ particles size are dispersed uniformly on RGO nanosheets. UV–vis diffuse reflectance spectroscopy verifies that Au/TiO₂/RGO nanocomposites show strong absorption of visible light. The degradation efficiency after 1 h for hydroquinone under visible light and UV light is ≈77% and ≈90%, respectively. Under visible light, the calculated apparent rates (k ) of the Au/TiO₂/RGO nanocomposites are 0.0112 and 0.0174 min^?1 for decomposition of methylene blue and hydroquinone. That are five times greater than that of bare TiO₂. The high photocatalytic activity is mainly attributed to the synergy between RGO and Au/TiO₂ nanostructure. The strategy of composite nanostructures assembling on RGO is ensured to have a great practicable potential for the designing of high efficient multielement composite nanoparticles catalysts.