石墨烯-硒化银纳米复合材料的制备、表征及光学性能研究

运用简单的一步反应水热法制备了石墨烯-硒化银(G-Ag2Se)纳米复合材料。用X射线粉末衍射(XRD)、傅里叶变换红外光谱(FTIR)和透射电子显微镜(TEM)等手段对所得产物进行了系统的表征。结果表明,反应体系中,硒化银纳米粒子的形成与氧化石墨烯的还原同时进行。石墨烯氧化物被充分地还原为石墨烯,并且Ag2Se纳米粒子均匀地分布在石墨烯的片层上,形成纳米复合材料。对所制备的G-Ag2Se纳米复合材料的光学性质也进行了研究。     

Synthesis and Characterization of Ag/Graphene Nano- composite

采用氧化还原法制备不同银含量的银/石墨烯纳米复合材料 (银质量分数分别为0%, 30%, 46%, 56%, 63%)。并通过X射线衍射(XRD)、光电子能谱仪(XPS)、高倍透射电子显微镜(HRTEM)和拉曼光谱(Raman)分析银含量对银/石墨烯纳米复合材料形态和显微结构的影响。结果表明,氧化石墨和银离子被成功地还原成银/石墨烯纳米复合材料,所得石墨烯由3~4单层碳原子层堆砌缠绕而成,同时银纳米颗粒沉积在石墨烯的表面。银纳米颗粒的介入有效地阻碍了石墨烯的团聚,增大了石墨烯的比表面积。银纳米颗粒的尺寸与银含量相关,当银含量较低时,银纳米颗粒在石墨烯表面具有很好的分散性且粒度基本分布在25~50 nm之间,而当银含量超过46%时将会导致银纳米颗粒的团聚。另外, 银纳米颗粒增强了石墨烯的拉曼效应。     

氧化石墨烯化学接枝提高纳米银的负载效果

目的 分别使用酰氯法和氨基开环法接枝修饰氧化石墨烯(GO),利用接枝分子的"锚定效应"提高纳米银颗粒在GO表面的分散效果.方法 先对GO-Cl-DA(GO经酰氯化后接枝对苯二胺)和GO-DA(采用"一锅法"对GO和对苯二胺直接混合接枝)进行比较,之后又比较了先接枝后沉积纳米粒子(两步法)和接枝/沉积同时进行(一步法)得到的杂化材料.采用红外光谱、X射线衍射谱、X射线光电子能谱和热失重曲线等,分析了材料的组成、热稳定性、接枝方式、银纳米颗粒的负载效果等.结果 在氨基与环氧基开环反应或酰胺键的作用下,对苯二胺分子能有效地接枝在GO表面,其中,"一锅法"(即氨基开环法)的接枝效率较高,操作简便.在沉积银的过程中,两步法对基底还原程度更彻底,纳米银的负载量从一步法的1.01％(原子数分数)提高到了7.22％,且分散性更好,并由此提出了接枝小分子对纳米颗粒的锚定效应.结论 含有氨基的分子对氧化石墨烯进行修饰时,采用氨基开环法既简单,又高效,接枝分子通过锚定效应改善原位沉积的无机纳米粒子,可获得负载效果优异的杂化材料.     

Gr/NiFe2O4纳米复合材料的制备与形成机理研究

以氧化石墨烯(GO)、Fe2(SO4)3和NiSO4为初始反应物,利用一步水热法合成了Gr/NiFe2O4纳米复合材料。采用X射线衍射(XRD)、透射电子显微镜(TEM)和拉曼光谱(RS)等分析手段对Gr/NiFe2O4样品进行了表征。结果表明:经过水热反应GO被还原的同时,纳米NiFe2O4成功地负载到石墨烯上,二者之间存在较强的界面相互作用,而且NiFe2O4纳米粒子增加了石墨烯片层间的距离避免了其再次堆垛,实现了石墨烯与NiFe2O4的良好复合。初步讨论了Gr/NiFe2O4纳米复合材料的形成机制,Ni2+、Fe3+在GO的含氧基团处非均相成核,在水热条件下不断长大,其生长过程遵循Ostwald熟化理论,即小尺寸的NiFe2O4粒子由于其较高的表面能而逐渐溶解,被那些尺寸较大的粒子消耗。     

Facile decoration of polypyrrole nanoparticles onto graphene nanosheets for supercapacitors

A facile approach was developed to prepare the graphene nanosheets (GNS) supported polypyrrole (PPy) nanoparticles via the in situ chemical oxidative polymerization of pyrrole onto the surfaces of the GNS modified with sodium dodecyl sulfonate (SDS) as surfactant for GNS and dopant for PPy simultaneously. The morphologies of the graphene nanosheets supported polypyrrole nanoparticles (GNS/PPy nanocomposites) with different feeding ratios were characterized with transition electron microscopy (TEM). It indicated that the PPy nanoparticles had been successfully decorated onto the GNS surfaces. The electrochemical performances of the GNS/PPy nanocomposites were investigated with cyclic voltammetry (CV), constant current charge–discharge and electrochemical impedance spectroscopy (EIS) techniques. The nanocomposite exhibited specific capacitance of 294 F g⁻¹ at the charge–discharge current density of 10 mA cm⁻² in 1.0 M NaNO₃ electrolyte. It showed that the GNS/PPy nanocomposites might be promising electrode materials for supercapacitors.     

In situ synthesis of Co3O4/graphene nanocomposite material for lithium-ion batteries and supercapacitors with high capacity and supercapacitance

Co₃O₄/graphene nanocomposite material was prepared by an in situ solution-based method under reflux conditions. In this reaction progress, Co²⁺ salts were converted to Co₃O₄ nanoparticles which were simultaneously inserted into the graphene layers, upon the reduction of graphite oxide to graphene. The prepared material consists of uniform Co₃O₄ nanoparticles (15-25 nm), which are well dispersed on the surfaces of graphene nanosheets. This has been confirmed through observations by field emission scanning electron microscopy, transmission electron microscopy and atomic force microscopy. The prepared composite material exhibits an initial reversible lithium storage capacity of 722 mAh g⁻¹ in lithium-ion cells and a specific supercapacitance of 478 F g⁻¹ in 2 M KOH electrolyte for supercapacitors, which were higher than that of the previously reported pure graphene nanosheets and Co₃O₄ nanoparticles. Co₃O₄/graphene nanocomposite material demonstrated an excellent electrochemical performance as an anode material for reversible lithium storage in lithium ion cells and as an electrode material in supercapacitors.     

Growth and photocatalytic activity of ZnO nanosheets stabilized by Ag nanoparticles

The Ag nanoparticles-stabilized ZnO nanosheets were prepared using a liquid-liquid two-phase method with (n-Dodecyl)trimethylammonium bromide (DTAB) as a phase transfer agent at the room temperature. The silver nanoparticles which are conductors with the character of attracting energy can make the ZnO sheets stabilize under the higher energy electrons. The samples are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-vis spectroscopy and fluorescence. The results demonstrate that the silver nanoparticles load on the surface of ZnO sheets and make the ZnO sheets stabilize. Furthermore, the formation mechanism of ZnO sheets stabilized by silver nanoparticles was also proposed and discussed in detail. Moreover, the photocatalysis test shows that the ZnO sheets stabilized by silver nanoparticles exhibit a higher photocatalytic activity than the pure ZnO nanosheets, thereby implying that the Ag/ZnO interfaces promote the separation of photogenerated electron-hole pairs and enhance the photocatalytic activity.     

Assessment of graphene oxide/epoxy nanocomposite as corrosion resistance coating on carbon steel

Graphene and its derivatives are new materials with unique properties. In recent years, various studies about the nanocomposites based on graphene oxide (GO) have been carried out. However, the electrochemical properties of nanocomposite coatings based on GO materials have not been widely studied. In this study, GO/epoxy nanocomposite coatings were prepared by incorporation of different amounts of GO nanosheets into the epoxy matrix via mechanical agitation and sonication process. The dispersion of GO nanosheets in matrix was analysed by optical microscopy, transmission electron microscopy and Fourier transform infrared. The anticorrosive properties of these nanocomposite coatings were investigated by electrochemical impedance spectroscopy tests. Results showed that the corrosion protection of coatings was improved by addition of GO into the coatings material. Furthermore, the best corrosion resistance was achieved in 0·25 wt-%GO/epoxy nanocomposite coatings.     

钽氧纳米片的机械化学法制备及表征

利用固相化学法在800℃合成了前躯体钽酸钾,新型剪切力机械剥离法对其研磨剥离得到了较大面积的钽氧纳米片。主要讨论了机械剥离过程中不同的研磨剂、研磨频率对钽酸钾剥离的影响,不同的超声时间对合成分散性好、均一稳定的钽氧纳米片溶胶浓度的影响。运用X-射线衍射技术,紫外可见分光光度计,透射电子显微镜以及Zeta电位分析仪等对前躯体化合物钽酸钾及钽氧纳米片结构进行分析和表征,证实了在不同条件下钽氧纳米片二维结构的存在。     

Formation of conductive and reflective silver nanolayers on plastic films via ion doping and solid–liquid interfacial reduction at ambient temperature

Conductive and reflective silver layers on both sides of polyimide films have been prepared by doping silver–ammonia ions into the surfaces of polyimide film, and subsequent solid–liquid interfacial reduction, during which double diffusion of silver ions and newly formed silver crystals occurred between the interfaces of polyimide films and the aqueous reducing surroundings. The newly formed silver nanoparticles could migrate and aggregate onto both sides of substrate films, forming continuous and compact silver layers that result in excellent conductivity, i.e. ～0.6 and 0.5 Ω/sq on the upside and downside surfaces, respectively. The surface reflectivity could be detected up to 80% on the downside and 90% on the upside surface as well. The effects of the silver contents and reducing conditions on the morphologies and properties have been investigated comprehensively, and the two-side properties differences were discussed. A convictive relationship between the morphologies and properties has been established, providing reliable and general guidance in terms of preparation of inorganic nanoparticles on plastic substrates. This novel and simple strategy can be extended to fabricate many other metal, metal oxide and metal sulfide nanoparticles on plastic substrates, using proper oxidants or sulfions to replace the diverse reductants. The films were characterized by inductively coupled plasma, contact angle measurement, X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, atomic force microscopy, four-point probe instrument and ultraviolet spectrophotometry.     

氧化铋/二氧化钛复合颗粒的制备及其光催化降解4-氯苯酚的性能

在低温条件下制备在太阳光照射下具有高光催化活性的氧化铋/二氧化钛复合颗粒。并利用XRD、SEM、BET、XPS和DRS对其进行表征。结果表明：将二氧化钛纳米颗粒沉积在氧化铋表面可形成微-纳结构,使该复合材料表现出多孔性,并提高表面羟基的含量。因此,在太阳光的激发下,氧化铋/二氧化钛复合颗粒对4-氯苯酚的催化降解能力高于纯二氧化钛和P25。     

Water/oil repellency and work of adhesion of liquid droplets on graphene oxide and graphene surfaces

The study examines the water/ethylene glycol (EG) repellency of graphene and graphene oxide sheets prepared by the chemical exfoliation of natural graphite powders. The graphene nanosheets were produced by reducing graphene oxide with EG under microwave irradiation. The graphene sheets were assembled into a thin paper, and a facile fluorination was used to coat a thin fluorine layer over the graphene paper. The graphene oxide paper is generally hydrophilic, whereas without aid of any fluorination, the resulting graphene paper displays superhydrophobicity (contact angle: 150.1 ± 2.3°) and low fraction in contact with solid (12.2%). Such low solid fraction may be attributed to the air pocket trapped in (i) the interspaces between graphene powders and (ii) the flake-like voids between graphene sheets, referred to as the Cassie state. The EG repellency of graphene paper can be significantly improved by surface fluorination. Taking into account Young-Duprè's equation incorporated with the Cassie parameter, the W_ad values of the graphene papers for water repellency were found to fall in the region of 9.62-12.5 mJ/m². The low W_ad value between the droplets and the graphene surface can be ascribed to the fact that porous graphene sheets offer an air cushion to repel the drop penetration, inducing the low work required for the movement of droplets on graphene paper. On the basis of the results, this study offers fundamentals on the water and EG repellency of graphene and graphene oxide surfaces.     

Hydroxide Concentration Dependence of Magnetic Behavior at Low Temperature in MnFe2O4 Nanoparticles

MnFe₂O₄ nanoparticles of various particle sizes were prepared by co-precipitation, in which different hydroxide concentrations were employed to control particle growth. X-ray diffraction and scanning electron microscopy were used to investigate the nanoparticle structure and morphology (shape and size). The particle size increased with increasing hydroxide concentration. The magnetization and coercivity field were measured by vibrating sample magnetometry. Changes in magnetic behavior were observed in the magnetic hysteresis loop curves of nanoparticles with increasing hydroxide concentration. In the absence of hydroxide, nanoparticles exhibited paramagnetic behavior. Increasing the hydroxide concentration caused a gradual conversion to ferrimagnetic behavior. An increased Néel temperature was observed with increasing hydroxide concentration, and the saturation magnetization exhibited a sharp decrease. Nonuniform hysteresis was observed in the magnetization curve for the sample prepared from hydroxide and ammonium.     

高疏水及超黏着性石墨烯薄膜的制备及表征

石墨烯因其特殊的二维结构和优异的力热光电性能而备受关注,因此研究石墨烯薄膜的表面性能具有重要的意义。以天然鳞片石墨为前驱体,采用化学氧化还原工艺制备石墨烯纳米片,利用原子力显微镜、拉曼光谱和红外吸收光谱等测试手段对样品进行表征。采用真空抽滤和喷涂两种方法制备石墨烯薄膜,并用光学接触角测量仪对其表面性能进行测试。结果表明:石墨烯纳米片的厚度约为0.8nm,并且表面有C=O、C-O、O-H等基团和缺陷。真空抽滤制备的石墨烯薄膜具有微纳结构,表现为高疏水性;喷涂法制备的石墨烯薄膜结构较为平整,其疏水性受基底影响。两种方法制备的石墨烯薄膜皆具有高黏着性。石墨烯薄膜所具有的优异性能为其在微纳功能部件、微流输运等高新技术领域的应用奠定了基础。     

氧化铜纳米棒/氧化石墨烯的制备及催化性能测试

氧化铜纳米棒/氧化石墨烯（CuO-NRs/GO）新型复合材料通过在氧化铜纳米棒上静电吸附氧化石墨烯而制备出来。通过XRD、TEM、SEM以及FT-IR对其结构和形貌进行了表征,并研究了其在超声条件下对罗丹明B的催化降解性能。结果表明：CuO-NRs/GO对罗丹明B有很好的催化降解性能。     

载银磁性Fe3O4纳米粒子的制备与催化及抗菌性能的研究

利用磁性纳米粒子Fe3O4表面的聚多巴胺 (PDA) 对银离子的吸附作用,采用种子诱导法制备了载银磁性纳米粒子 (PDA-Fe3O4@Ag)。采用UV-Vis (紫外-可见) 光谱对PDA-Fe3O4@Ag纳米粒子的制备过程进行了分析,采用FTIR (红外光谱)、XRD (X射线衍射仪)、TEM (透射电镜) 和VSM (振动样品磁强计) 等手段对所得的PDA-Fe3O4@Ag粒子进行表征;研究了PDA-Fe3O4@Ag对4-硝基苯酚还原反应的催化作用,还测试了其抗菌性能。结果表明,纳米金种子的存在是制备PDA-Fe3O4@Ag纳米粒子的关键;在外加磁场作用下该磁性催化剂可以容易地从反应体系中分离,经多次循环使用后仍具有良好的催化性能;此外PDA-Fe3O4@Ag纳米粒子具有杀菌性能,且经磁分离回收循环利用5次后仍呈现对金黄色葡萄球菌较好的杀菌效果。     

镁合金表面SA/GO耐蚀/耐磨一体化复合涂层EI北大核心CSCD

氧化石墨烯(GO)作为一种典型的二维层状材料在表面防护领域具有较大的应用潜力,然而其团聚现象和表面大量纳米孔隙的存在往往会削弱其对基体的保护作用。将硬脂酸(SA)接枝到GO片层并采用自组装的方法,在AZ31B镁合金表面制备SA-GO复合涂层。采用SEM、XRD和FT-IR表征涂层的表面形貌、结构以及官能团;采用接触角测试仪、电化学工作站和摩擦磨损试验机分别表征涂层的润湿性、耐蚀性以及耐磨性。电化学测试结果表明,该复合涂层的引入使得腐蚀电流密度降低了约三个数量级,显著提高了镁合金基体的耐蚀性,这与涂层孔隙率的降低以及疏水性的增加有关。摩擦测试结果表明:与镁合金基体相比,SA-GO涂层的磨损率降低了99.3%,摩擦因数降低了83.1%,这与SA的自润滑性能以及GO层间距增加导致GO片层更易滑移有关。研究成果为实现金属表面防腐/耐磨一体化防护研究提供了实验依据和理论基础。     

Enhanced thermal diffusivity of copperbased composites using copper-RGO sheets

The synthesis of copper-reduced graphene oxide (RGO) sheets was investigated in order to control the agglutination of interfaces and develop a manufacturing process for copper-based composite materials based on spark plasma sintering. To this end, copper-GO (graphene oxide) composites were synthesized using a hydrothermal method, while the copper-reduced graphene oxide composites were made by hydrogen reduction. Graphene oxide-copper oxide was hydrothermally synthesized at 80 °C for 5 h, and then annealed at 800 °C for 5 h in argon and hydrazine rate 9:1 to obtain copper-RGO flakes. The morphology and structure of these copper-RGO sheets were characterized using scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and Raman spectroscopy. After vibratory mixing of the synthesized copper-RGO composites (0-2 wt%) with copper powder, they were sintered at 600 °C for 5 min under100 MPa of pressure by spark plasma sintering process. The thermal diffusivity of the resulting sintered composite was characterized by the laser flash method at 150 °C.     

Microwave-assisted solid-state decomposition of La[Co(CN)6]·5H2O precursor: A simple and fast route for the synthesis of single-phase perovskite-type LaCoO3 nanoparticles

Pure and single-phase nanoparticles of perovskite-type LaCoO₃ were prepared via microwave-assisted solid-state decomposition of La[Co(CN)₆]·5H₂O precursor in the presence of CuO powder as a strong microwave absorber within a very short reaction time of 10 min. Product was characterized by X-ray diffraction (XRD), Fourier-transformed infrared spectroscopy (FT-IR), Raman spectroscopy, UV–visible spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) and surface area measurement. The method is simple, fast and energy efficient and resulted in fine particles (10–30 nm) with high specific surface area and narrow size distribution. This hybrid microwave heating route is promising for the synthesis of other mixed oxide and related compounds.     

Fe3O4@SiO2@mTiO2-Au复合材料的制备及其催化性能研究

以磁性Fe3O4为核,在其表面负载SiO2,并用介孔TiO2 (mTiO2)进行包覆,用3-氨丙基三甲氧基硅烷对其改性,将纳米金颗粒均匀负载在介孔TiO2表面,制备出核壳型纳米Fe3O4@SiO2 @mTiO2 -Au复合材料。用透射电镜(TEM)、振动样品磁强计(VSM)、X射线光电子能谱分析(XPS)和X射线衍射分析(XRD)等对样品进行表征,确认了核壳结构的存在,尺寸约3 nm的纳米金负载在表面。催化活性测试结果表明,该材料对对硝基苯酚在25 min内降解率达83%,对铁氰酸钾在30 min内降解率达84%。