TiO_2/石墨烯复合锂离子电池负极材料的研究

采用简单、绿色环保的方法制得TiO_2/石墨烯(TiO_2/G)复合材料,并采用SEM、TEM和XRD对TiO_2/石墨烯复合材料进行了表征。研究结果表明,TiO_2纳米颗粒均匀地分散在石墨烯片层中,改善了TiO_2纳米颗粒的导电性和结构稳定性;TiO_2/石墨烯复合材料的首次放电比容量为302mAh/g,循环50周后的放电比容量仍能保持89.93%,具有优异的电化学性能。     

石墨烯/聚苯胺/四氧化三锰纳米复合材料的制备

成功制备了石墨烯/聚苯胺/四氧化三锰(RGO/PANI/Mn_3O_4)纳米复合材料。首先,以过硫酸铵(APS)为氧化剂,在氧化石墨烯(GO)片层上氧化聚合苯胺单体,制备氧化石墨烯/聚苯胺(GO/PANI),再通过水热法将GO还原并热解Mn(Ac)_2·4H_2O从而制得RGO/PANI/Mn_3O_4复合材料。形貌和结构表征结果表明Mn_3O_4纳米颗粒均匀生长在以PANI为导电连接层的RGO片层上。     

炭涂层硅/石墨烯纳米复合材料的制备及其储锂性能

石墨烯、柠檬酸和硅纳米颗粒的乙醇混合物经超声分散、乙醇挥发和热处理(800℃1h)制备出炭涂层硅/石墨烯(Si@C/G)纳米复合材料。透射电镜表明,Si纳米颗粒的表面形成了一层厚度约为2nm的均匀炭涂层,石墨烯片层支撑着Si@C纳米粒子,且两者具有较强的相互作用。作为锂离子电池负极材料,Si@C/G电极具有较高的库仑效率,在500 mA·g-1的电流密度下,100卷循环后比容量为1431mAh·g-1,表现出优越的循环稳定性。Si@C/G优异的电化学性能归因于石墨烯片层的高导热率、高导电率和优良的机械柔韧性。     

不同反应途径制备TiO_2/石墨烯复合材料及其光电催化性能研究

以氧化石墨烯和Ti(SO4)2为初始反应物,通过不同的反应途径制得两种TiO2/石墨烯复合材料。途径一是利用Ti(SO4)2水解,在氧化石墨烯层间成核生长纳米TiO2颗粒,制得TiO2/氧化石墨烯复合材料,再通过还原反应,制得TiO2/石墨烯复合材料。途径二是将氧化石墨烯还原制得石墨烯,再利用Ti(SO4)2水解,在石墨烯层间成核生长而制得TiO2/石墨烯复合材料。通过XRD、FE-SEM、HR-TEM、BET和电化学性能测试等测试手段对复合材料进行表征。以复合材料为工作电极,在可见光照射(λ420nm)和外加电极电压的条件下,通过光电催化降解酸性红B对复合材料的催化性能进行研究。结果表明,(1)不同的反应途径对复合材料的多方面性质有较大影响;(2)途径一所制得的复合材料具有更加优良的光电催化性能。     

石墨烯/纳米银导电油墨导电性能研究

目的 -制备出具有优异导电性能的石墨烯/纳米银复合材料,并作为导电填料,以提高导电油墨的导电性能。方法 -采用Hummers法制备氧化石墨烯,以葡萄糖作为还原剂,采用同步还原法制备石墨烯/纳米银,将石墨烯/纳米银复合物和纳米银按不同比例混合作为导电填料来制备导电油墨。通过透射电镜(TEM)、X射线衍射(XRD)、傅里叶变换红外(FTIR)光谱等分析测试方法表征了石墨烯/纳米银复合材料的微观结构和形貌,并通过四探针法对油墨的导电性进行检测。结果 -纳米银颗粒均匀地负载在石墨烯片层上,纳米银粒径约为35nm;掺杂石墨烯/纳米银复合物质量分数为12%时,导电油墨的电阻率可达到1.08×10~(-7)Ω·m,导电性能提高约64%。结论 -制备的复合材料石墨烯呈片状,结构完好,添加到导电油墨中能明显提高导电性能。     

石墨烯/纳米银导电油墨导电性能研究

目的制备出具有优异导电性能的石墨烯/纳米银复合材料,并作为导电填料,以提高导电油墨的导电性能。方法采用Hummers法制备氧化石墨烯,以葡萄糖作为还原剂,采用同步还原法制备石墨烯/纳米银,将石墨烯/纳米银复合物和纳米银按不同比例混合作为导电填料来制备导电油墨。通过透射电镜(TEM)、X射线衍射(XRD)、傅里叶变换红外(FTIR)光谱等分析测试方法表征了石墨烯/纳米银复合材料的微观结构和形貌,并通过四探针法对油墨的导电性进行检测。结果纳米银颗粒均匀地负载在石墨烯片层上,纳米银粒径约为35 nm;掺杂石墨烯/纳米银复合物质量分数为12%时,导电油墨的电阻率可达到1.08×10~(-7)?·m,导电性能提高约64%。结论制备的复合材料石墨烯呈片状,结构完好,添加到导电油墨中能明显提高导电性能。     

可见光响应的TiO_2/石墨烯复合材料的制备及其光电催化性能

对Hummers方法进行改进,制备出氧化石墨烯。采用氧化石墨烯和Ti(SO4)2作为初始反应物,利用Ti(SO4)2水解,在氧化石墨烯层间成核生长纳米TiO2颗粒,制得TiO2/氧化石墨烯复合材料,再通过水合肼进行还原,制得TiO2/石墨烯复合材料。通过XRD、FE-SEM、HR-TEM、TGA、UV-Vis、BET和电化学性能测试等测试手段对复合材料进行表征。以复合材料为工作电极,铂电极为对电极,饱和甘汞电极为参比电极,在可见光照射(λ420nm)下,通过光电催化降解含偶氮化学健的酸性红B,对复合材料的催化性能进行研究。结果表明,复合材料对可见光响应良好;在外加电极电压的条件下,复合材料的催化活性得到进一步增强。     

石墨烯纳米片增韧Al2O3基纳米复合陶瓷刀具材料

以石墨烯纳米片作为增强相,采用热压烧结工艺制备石墨烯纳米片增韧Al_2O_3基纳米复合陶瓷刀具材料。进行石墨烯纳米片分散实验,研究石墨烯纳米片添加量对刀具材料断裂韧度、抗弯强度和硬度的影响,观察其微观结构和形貌。结果表明:聚乙烯吡咯烷酮(PVP)为石墨烯纳米片的优选分散剂,当PVP添加量为石墨烯纳米片质量的60%时,分散效果最佳;当石墨烯纳米片添加量为0.75%(体积分数)时,刀具材料的断裂韧度和抗弯强度分别达到7.1MPa·m^1/2和663MPa,与未添加石墨烯纳米片的组分相比分别提高了31%和15%;石墨烯纳米片呈卷曲状结构弥散分布于基体材料中,其增韧机理为石墨烯纳米片拉断、拔出和裂纹偏转。与未添加石墨烯的刀具相比,添加石墨烯纳米片的刀具的主切削力、切削温度和前刀面摩擦因数明显降低,表现出良好的减摩、耐磨性。     

水基纳米流体的凝固行为

选用二氧化钛(TiO2)纳米颗粒、碳纳米管(CNT)和石墨烯(graphene)纳米片制备水基纳米流体。采用步冷曲线法测量纳米流体的凝固温度和时间。研究纳米材料形状、尺寸、接触角和比表面积对纳米流体凝固行为的影响。实验发现,TiO2纳米颗粒、CNT纳米管和石墨烯纳米片对纳米流体过冷度和凝固时间的减小作用依次增强。0.034%(质量分数)浓度的石墨烯纳米片可完全消除水的过冷现象,使其凝固起始时间和总时间分别缩短61.22%和30.53%。成核理论分析表明,纳米流体的凝固过冷度主要取决于单位体积纳米流体的成核面积。与接触角、形状和尺寸相比,纳米材料的比表面积对纳米流体过冷度的影响更大。     

ZnxCd1-xS/TiO2核壳型异质结的制备及其光催化性能

通过静电纺丝和水热法联用成功制备了ZnxCd1-xS/TiO2核壳纳米纤维。利用XRD、SEM、UV-vis、EDS、BET对样品结构等进行了表征。结果表明,在TiO2纳米纤维表面生长了一层致密的ZnxCd1-xS纳米颗粒,形成ZnxCd1-xS/TiO2核壳型异质复合材料,且其光催化活性均比纯TiO2纳米纤维高。通过调节水热温度,可以控制ZnxCd1-xS表面形貌和x值。当水热温度为200℃时,x值最大,材料光催化活性最高。     

Copper/silver nanoparticle incorporated graphene films prepared by a low-temperature solution method for transparent conductive electrodes

A facile one-step co-reduction and low-temperature solution process was developed to prepare Cu–graphene (Cu–G), Ag–graphene (Ag–G), and Cu–Ag–graphene (Cu–Ag–G) composite films on glass substrates. Scanning electron microscope and transmission electron microscope images show that Cu/Ag nanoparticles are either distributed on the surface of graphene nanosheets or covered by graphene. The conductivity and transparency of these films were studied, and the results show that incorporation of Cu and Ag nanoparticles into graphene films can improve film conductivity. Ag nanoparticles are more effective in improving film conductivity. The conductivity and transparency of the composite films can be balanced by introducing the optimum amount of Cu or Ag nanoparticles. The conductivity and transparency of Cu–Ag–G films with optimum metal nanoparticle concentration are as good as those of Ag–G composite films. The Cu–Ag–G films meet the requirements of low-cost, high-conductivity, and transparent films that can be used as electrode materials. Thus, the proposed low-temperature solution process is a new route to preparing low-cost transparent and conductive electrodes on various substrates, including glass and flexible polymer substrates.     

ATRP法在纳米TiO_2表面接枝PS及其对SBS的改性

通过溶胶-凝胶法制备金红石型纳米二氧化钛(TiO_2),再利用原子转移自由基聚合(ATRP)法在纳米TiO_2表面接枝聚苯乙烯(PS),并以此对苯乙烯-丁二烯-苯乙烯嵌段共聚物(SBS)进行改性。红外光谱、X射线光电子能谱及透射电镜测试结果表明,PS大分子链成功地接枝到纳米TiO_2粒子表面。力学性能、动态力学分析及热重分析测试结果显示,SBS/TiO_2-g-PS复合材料的力学性能与热稳定性均明显优于纯SBS及SBS/TiO_2复合材料。经紫外光老化后,SBS/TiO_2-g-PS复合材料的力学性能保持率最高。     

纳米碳形貌对纳米碳/聚乙烯导电复合材料性能的影响

分别以纺锤形碳酸钙表面改性的二维片状石墨烯微片（CGM）和多壁碳纳米管（MWCNTs）作为导电剂填充改性聚乙烯（PE）制备导电复合材料。重点研究了二维或一维纳米碳/PE复合材料形成导电网络时力学与电学性能。CGM/PE或MWCNTs/PE复合材料达到抗静电要求时CGM的质量分数为8wt%,而MWCNTs的质量分数为1wt%。填充8wt% CGM的复合材料表现出优异的综合性能,而填充0.5wt% MWCNTs的复合材料综合力学性能达到最大值还未能达到抗静电要求,达到抗静电要求时MWCNTs/PE复合材料的综合力学性能出现下降趋势。通过形貌及流变学分析了复合材料不同的力学与电学性能的微观作用因素。CGM/PE复合材料流变渗流阈值与导电渗流阈值存在比较好的相关性,MWCNTs/PE复合材料达到流变渗流阈值还不能形成导电网络。结果表明,与二维CGM相比,一维MWCNTs不易均匀分散于聚合物基体中,并降低MWCNTs/PE复合材料的力学性能。     

锂离子电池硅/碳纳米管/石墨烯自支撑负极材料研究

通过真空驱动自组装法及蒸汽处理得到结构疏松的硅/碳纳米管/石墨烯自支撑负极材料(Si/CNTs/GP)。纳米硅颗粒(50 nm)为活性物质, 均匀分布在石墨烯片层结构中间; 石墨烯作为碳基体, 通过自组装构筑形成二维导电网络; 碳纳米管(CNTs)具有超高导电性和良好的力学强度, 它通过吸附作用均匀分布在石墨烯基体上形成导电的支撑网络结构。经过蒸汽处理后, 石墨烯层间距明显增大, 层与层之间不再是紧密堆叠的结构, 而是形成一种疏松、褶皱、内部空隙丰富的片层结构。Si/CNTs/GP负极材料中丰富的内部空穴和贯穿孔洞, 提供了材料很高的比表面积, 能有效提高电解液对材料的浸润性, 极大缩短了离子传输距离。同时这些内部空穴也有效缓冲硅充放电时的体积膨胀, 提高了材料的结构稳定性和电化学性能。该负极材料在4 A/g的大电流密度下容量维持在600 mAh/g, 表现出良好的大电流循环稳定性能。     

复合相变储冷材料的制备及性能研究

以十二烷基苯磺酸钠(SDBS)作为分散剂,多层石墨烯、TiO2/石墨烯(m(TiO2):m(石墨烯)=25∶75)和TiO2颗粒作为导热添加剂,加入到二元复合有机储冷材料中(m(壬酸):m(葵醇)=60:40),制备了复合相变储冷材料。通过吸光度、DSC和热导率测试等手段,对复合相变储冷材料的稳定性、相变温度、相变潜热及热导率进行了评价分析。结果表明,分散剂和导热添加剂的加入,对储冷材料的相变温度和相变潜热影响不大,但对热导率影响较大。当分散剂SDBS浓度为0.2 g/L,导热添加剂(分别为TiO2/石墨烯和TiO2颗粒)浓度为0.5 g/L时,复合相变储冷材料具有较好的稳定性,其热导率分别为为0.2211和0.2096 W/(m·K),相比没有加入任何导热添加剂的储冷材料的热导率(0.1738 W/(m·K)),分别提高了27.22%和20.61%;当分散剂SDBS浓度为0.3 g/L,导热添加剂多层石墨烯浓度为0.3 g/L时,复合相变储冷材料处于稳定状态,其热导率为0.2268 W/(m·K),相比0.1738 W/(m·K),提高了30.49%。由此可知,多层石墨烯可以更有效地增加复合相变储冷材料的热导率,这主要是由于石墨烯具有非常高的比表面积,有利于复合材料更加均匀地分散以及形成更加完善的网格结构,从而有效增加复合相变储冷材料的稳定性及热导率。选用多层石墨烯为导热添加剂(0.3 g/L),SDBS为分散剂(0.3 g/L),可以制备出体系最稳定、热导率最高的复合相变储冷材料。     

具有隔离结构的超高分子量聚乙烯/镍高导电复合材料

采用化学镀手段制备金属镍包覆的超高分子量聚乙烯复合粒子,通过热压成型方法制得具有隔离结构的超高分子量聚乙烯(UHMWPE)/镍(Ni)高导电复合材料。通过调节金属(镍)镀层厚度及加工温度考察不同Ni含量及加工温度对复合材料导电性能的影响。结果表明,复合材料具有明显的导电逾渗行为;通过化学镀工艺可有效提高金属填料与基体的结合力,同时实现金属镍在聚合物基体中的选择性稳定分布,构建具有隔离结构的导电网络,使得复合材料的逾渗值降低至1.02%(体积分数)。基于金属填料优异的导电性能,在Ni体积分数仅为2.53%时,复合材料的电导率达到2648S/m。此外,降低复合材料的加工成型温度有助于减少加工过程对导电网络的破坏作用,从而有效降低复合材料的导电逾渗值,对提高复合材料导电性能具有重要意义。     

Self-Compositing: A Efficient Method of Improving the Electrical Conductivity of Graphene Nanoplatelet/Thermosetting Resin Composites

Conductive composites based on thermosetting resins have broad applications in various fields. In this paper, a new self-compositing strategy is developed for improving the conductivity of graphene nanoplatelet/thermosetting resin composites by optimizing the transport channels. To implement this strategy, conventional graphene nanoplatelet/thermosetting resin is crushed into micron-sized composite powders, which are mixed with graphene nanoplatelets to form novel complex fillers to prepare the self-composited materials with thermosetting resins. A highly conductive compact graphene layer is formed on the surface of the crushed composite powders, while the addition of the micron-sized powder induces the orientation of graphene nanoplatelets in the resin matrix. Therefore, a highly conductive network is constructed inside the self-composited material, significantly enhancing the electrical conductivity. The composite materials based on epoxy resin, cyanate resin, and unsaturated polyester are prepared with this method, reflecting that the method is universal for preparing composites based on thermosetting resins. The highest electrical conductivity of the self-composited material based on unsaturated polyester is as high as 25.9 S m⁻¹. This self-compositing strategy is simple, efficient, and compatible with large-scale industrial production, thus it is a promising and general way to enhance the conductivity of thermosetting resin matrix composites.     

纳米二氧化钛含量对秸秆/聚乳酸复合材料性能的影响

目的 为改善纤维增强聚乳酸(PLA)复合材料增强相与基体相之间差的界面结合。方法 以秸秆粉(SP)为填料,纳米二氧化钛(TiO2)作为界面改性剂,构建SP/PLA复合材料相容界面,通过力学性能测试、吸水率测试、扫描电子显微镜(SEM)、X射线衍射(XRD)和热重分析法(TGA)等表征手段,探究不同含量纳米二氧化钛对SP/PLA复合材料力学性能和界面相容性的影响。结果 研究发现,纳米二氧化钛的质量分数为2.0%时,复合材料的拉伸强度和弯曲强度分别达到42.78 MPa和91.25 MPa,其耐水性能、结晶度、耐热性能也达到最好。结论 纳米二氧化钛可有效提高秸秆/聚乳酸复合材料的性能。     

Liquid Metal Droplet and Graphene Co‐Fillers for Electrically Conductive Flexible Composites

Colloidal liquid metal alloys of gallium, with melting points below room temperature, are potential candidates for creating electrically conductive and flexible composites. However, inclusion of liquid metal micro‐ and nanodroplets into soft polymeric matrices requires a harsh auxiliary mechanical pressing to rupture the droplets to establish continuous pathways for high electrical conductivity. However, such a destructive strategy reduces the integrity of the composites. Here, this problem is solved by incorporating small loading of nonfunctionalized graphene flakes into the composites. The flakes introduce cavities that are filled with liquid metal after only relatively mild press‐rolling (<0.1 MPa) to form electrically conductive continuous pathways within the polymeric matrix, while maintaining the integrity and flexibility of the composites. The composites are characterized to show that even very low graphene loadings (≈0.6 wt%) can achieve high electrical conductivity. The electrical conductance remains nearly constant, with changes less than 0.5%, even under a relatively high applied pressure of >30 kPa. The composites are used for forming flexible electrically‐conductive tracks in electronic circuits with a self‐healing property. The demonstrated application of co‐fillers, together with liquid metal droplets, can be used for establishing electrically‐conductive printable‐composite tracks for future large‐area flexible electronics.     

Graphene and carbon black filled conductive nanocomposite films for heating element applications

Graphene has ultra-high electrical and thermal conductivity, which makes graphene as the most encouraging fillers for thermally conductive composites. Graphene and/or carbon black filled conductive polymer composite (CPC) films used as heating element are smarter than the traditional heating elements due to less environmental pollution, ease of application on many surfaces and possess the merits of lightweight. In this study, we investigated mainly the production, characterization and industrial application of graphene/carbon black reinforced styrene acrylic copolymer emulsion matrix composite films deposited on polyvinyl chloride for flexible heating element. After that, the films were dried at room temperature for 24 h in air. Structural and surface properties of the CPC films were characterized by X-ray diffraction and scanning electron microscopy. Temperature, time and voltage relation of the produced composite films were investigated. Heating and electrical properties of the CPC films were determined by using a thermal camera and 4-point probe measurement system, respectively. The electrical resistivity of the CPC films decreases from ~?10⁸ to 10¹ Ω cm with increasing the filler content or using a combination of two fillers. Graphene and carbon black filled conductive polymer composites to be considered as candidates for flexible heating element applications exhibited good electrical and heating properties thanks to synergistic effect of fillers.