多巴胺还原氧化石墨烯气凝胶的制备与吸附性能

石油和有机液体的泄漏对水体资源构成严重危害,带来不可挽回的经济损失。因此,高效的吸油及油水分离材料极具应用价值。以天然石墨为原料,通过Hummers法制备了氧化石墨烯(GO)。将定量氧化石墨烯水溶液与多巴胺(DA)溶液进行混合,利用多巴胺在水中的自聚合以及还原性能,在常压、较低温度(95℃)下经水热反应制备了绿色无污染的多巴胺还原氧化石墨烯水凝胶,再经冷冻干燥得到结构完好的三维结构的多巴胺还原氧化石墨烯气凝胶(DGA)。通过Raman、XRD、SEM、接触角对其形貌结构进行了表征。研究了气凝胶对不同油品的吸附性能,其最大吸附量可达66~120 g/g,是一种良好的吸附材料。     

各向异性壳聚糖/氧化石墨烯气凝胶的制备及吸附性能研究

通过定向冷冻干燥法制备了具有各向异性孔结构的壳聚糖(CS)/氧化石墨烯(GO)复合气凝胶(M.3CSG),以化学气相沉积工艺对其进行了硅烷化疏水改性,采用扫描电子显微镜、傅里叶红外光谱、力学性能测试、吸附性能测试等手段对材料进行了表征测试。结果表明：M-CSG气凝胶具有各向异性的取向微孔结构,GO的加入提高了M-CSG气凝胶的力学强度。M-CSG气凝胶对多种油和有机溶剂均具有良好的吸附能力,对氯仿的最大吸附量可达62g/g,并在10次循环吸附-解吸后仍保持优异的吸附性能。M-CSG气凝胶作为一种可重复使用的绿色吸附材料在油品回收和环境保护方面具有很大的应用潜力。     

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.     

还原氧化石墨烯-壳聚糖复合膜的制备及其性能

为了研究还原氧化石墨烯(RGO)对壳聚糖(CS)薄膜性能的影响,以氧化石墨和CS为原料,通过超声分散和真空诱导自组装法制备了还原氧化石墨烯-壳聚糖薄膜(RGO-CS),研究了薄膜的各项性能,最后分别将CS和RGO用作表面施胶剂,研究二者对瓦楞纸耐水性能的影响.结果表明:成功制备了RGO-CS薄膜;通过SEM观察到RGO...     

还原氧化石墨烯/MnO_2气凝胶对甲醛的去除

为制备新型高效去除甲醛材料,采用水热法制备了还原氧化石墨烯(RGO)/MnO_2气凝胶,通过SEM、TEM、TGA、XPS和BET对RGO/MnO_2气凝胶的形态结构及性能进行了表征,并研究了RGO/MnO_2气凝胶对甲醛的去除能力。结果表明:在RGO/MnO_2气凝胶的前驱体中,氧化石墨烯(GO)为单层二维纳米材料;MnO_2气凝胶由MnO_2纳米线组成,MnO_2纳米线的直径在40nm左右,长度达5μm以上,且属于隐钾锰矿型结构。RGO/MnO_2气凝胶是一种由片状材料组成的具有三维多孔结构的材料,该片状材料是由均匀分布的RGO纳米片和MnO_2纳米线组成的,RGO将MnO_2纳米线隔开,起到隔板的作用,使MnO_2纳米线在RGO中均匀分布。RGO/MnO_2气凝胶在100℃以下具有良好的热学稳定性。RGO/MnO_2气凝胶对低浓度甲醛具有较好的去除能力,去除率为62.5%,与MnO_2气凝胶相比,相同条件下RGO/MnO_2气凝胶对甲醛的去除率提高了30.0%,证实RGO有助于提高MnO_2对甲醛的去除能力。     

石墨烯透明导电薄膜可控制备及实用性研究

新型二维材料石墨烯,因其优异特性被认为是众多领域的理想新型功能材料,其产业化应用是当前及未来的重要研究课题之一。综述了针对性提高石墨烯导电薄膜透光率和导电性能的可控制备的最新研究进展,包括可控制备大尺寸、大面积石墨烯,以及通过掺杂或与其他材料形成复合材料等方法有效提高石墨烯薄膜的光电性能,并对石墨烯透明导电薄膜电极在触摸屏、显示屏等的实用化应用进行了探讨和展望。     

纳米银/三维还原氧化石墨烯复合材料的制备及其催化性能研究

为解决纳米银催化剂易团聚的问题,选择三维还原氧化石墨烯(3D-rGO)作为载体材料,采用一步绿色水热法制备了纳米银/三维还原氧化石墨烯(Ag/3D-rGO)复合材料,采用SEM、XRD、FTIR、Raman、XPS等方法对材料的形貌和结构进行了系统的表征,并在室温下以对硝基苯酚(4-NP)的催化还原反应为模型,考察了所得复合材料的催化性能。结果表明,成功制备出了Ag/3D-rGO纳米复合材料,材料内部呈3D多孔网络结构,Ag纳米颗粒均匀附着在孔壁表面,颗粒的平均粒径为67 nm,无明显团聚;Ag/3D-rGO纳米复合材料可以在2 min内实现4-NP的催化还原,该催化反应过程遵循一级催化动力学反应规律,对应的一级催化动力学常数为1.8694 min^-1,高于现有报道中同类材料。研究的材料制备方法简便,催化性能优异,在工业催化和环境保护领域具有广阔的应用前景。     

Nafion改性多级孔径石墨烯气凝胶制备与性能研究

通过溶胶-凝胶法制备了孔径小于1 μm的多级孔径新型石墨烯气凝胶。制备过程中, 首先通过Nafion对氧化石墨烯(GO)表面进行化学修饰, 并利用乙二胺还原制备石墨烯水凝胶, 最终通过冷冻干燥形成石墨烯气凝胶。实验发现Nafion可以有效减少制备过程中氧化石墨烯的团聚, 使石墨烯气凝胶形成多级孔径形貌。所得石墨烯气凝胶的孔径可控制在1 μm以内, 远小于传统石墨烯气凝胶材料的孔径(20~100 μm)。这种具有独特结构的石墨烯气凝胶表现出优异的性能, 例如高比表面积, 高孔隙率, 其电化学电容性能相对传统气凝胶提高了约40%。     

丁基橡胶/还原氧化石墨烯复合材料的制备及性能

采用水合肼(HH)为还原剂制备还原氧化石墨烯(rGO),以rGO作为增强填料,丁基胶乳为基体,通过改进的超声胶乳混合和原位还原工艺,制备了力学性能优异的丁基橡胶(IIR)/rGO复合材料。结果表明,在IIR基体中添加较低含量rGO时,rGO显示完全剥离和均匀分散的状态;rGO由于具有较高的比表面积,可以提高其与IIR基体之间的界面相互作用,使得IIR/rGO复合材料的拉伸强度和断裂伸长率共同增大;对比纯IIR,IIR/rGO复合材料的储能模量增加、损耗因子减小,具有更好的阻尼性能和热稳定性。     

氧化石墨烯/丝素蛋白凝胶结构及其性能研究

目前医用凝胶材料普遍存在力学强度较差及生物降解速度过快等问题。以蚕丝丝素蛋白(SF)凝胶为基础材料,加入氧化石墨烯(GO),并将1-乙基-(3-二甲基氨基丙基)碳二亚胺盐酸盐(EDC)及N-羟基琥珀酰亚胺(NHS)作为交联剂制备SF/GO复合凝胶,旨在改善凝胶材料的力学性能,使其在保证复合凝胶材料应有的力学强度的同时,发挥丝素蛋白、氧化石墨烯的生物学效应及凝胶材料的多孔支架作用。实验结果显示,EDC的加入可以使得SF、GO共混形成稳定、均匀的无规卷曲结构,扫描电镜(SEM)显示SF/GO凝胶具有典型的多孔结构。GO的加入可以有效缩短复合材料的凝胶时间,同时复合凝胶材料的力学性能得到明显改善,其压缩强度提高40%以上。GO的加入还可明显延长材料的降解时间。基于SF/GO的复合凝胶在组织修复及再生领域具有较好的应用前景。     

Simple photoreduction of graphene oxide nanosheet under mild conditions

Graphene oxide (GO) nanosheets were reduced by UV irradiation in H2 or N2 under mild conditions (at room temperature) without a photocatalyst. Photoreduction proceeded even in an aqueous suspension of nanosheets. The GO nanosheets reduced by this method were analyzed by X-ray photoelectron spectroscopy and Raman spectroscopy. It was found that epoxy groups attached to the interiors of aromatic domains of the GO nanosheet were destroyed during UV irradiation to form relatively large sp2 islands resulting in a high conductivity. I-V curves were measured by conductive atomic force microscopy (AFM; perpendicular to a single nanosheet) and a two-electrode system (parallel to the nanosheet). They revealed that photoreduced GO nanosheets have high conductivities, whereas nonreduced GO nanosheets are nearly insulating. Ag+ adsorbed on GO nanosheets promoted the photoreduction. This photoreduction method was very useful for photopatterning a conducting section of micrometer size on insulating GO. The developed photoreduction process based on a photoreaction will extend the applications of GO to many fields because it can be performed in mild conditions without a photocatalyst.     

Appropriate conditions for preparing few-layered graphene oxide and reduced graphene oxide

Oxidation time and exfoliated conditions of graphite oxides (GOs) were investigated to prepare few–layer graphene oxide and reduced graphene oxide via a modified Hummers approach. Different oxidative degree of GOs was prepared by changing oxidation time, and the effects of oxidative degree of GOs in different oxidation time were studied by XRD, FT-IR. Afterwards, highly oxidized GOs were used as precursor to prepare graphene oxide and reduced graphene oxide by ultrasonic dispersion method and thermal expansion method. The exfoliated conditions (ultrasonic power and ultrasonic time, thermal exfoliated temperature) were investigated to prepare few-layered graphene oxide and reduced graphene oxide.     

Comparison of performance stability of different chemically reduced graphene oxide under long-term preservation

Chemically reduced graphene oxide (RGO) samples prepared with three different reducing agents, such as sodium borohydride (NaBH₄), hydrazine hydrate (N₂H₄·H₂O), and N, S dual-doped thiourea (CS(NH₂)₂), were prepared (respectively labeled as B-RGO, N-RGO, N/S-RGO) and compared with commercial RGO samples (represented as C-RGO). The changes of their structures and properties over time have been studied to explore the stability of electrochemical performance. Samples preserved for 0 day (fresh sample), 7 days, 30 days, and 90 days were obtained by storing the prepared RGO powder for different times under natural conditions and characterized by means of analytical methods. The results suggested that even though the phase structures and electrochemical performance of the samples were relatively stable, their surface morphology and oxidation degree varied slightly, and the electrical conductivity even changed dramatically, which decreased significantly at the initial stage of storage. It is found that among different reducing agents, N-RGO samples prepared in this work have similar stability in performance and approximate specific capacitance of around 150.0 F/g at 1 A/g compared to that of C-RGO. As for N/S-RGO, it shows the highest conductivity of 107 S/m, but its decline rate is faster than that of N-RGO, which possesses the conductivity of 76 S/m. In this work, we compared the electrochemical performance of different chemically reduced RGO at different storage times and tried to explain the principles of their performance changes over time. This work has focused on investigating the performance stability of RGO during a long preservation period of up to 90 days, complemented extensive relevant test data of various performance changes over time, and especially, filled in the remarkable data gaps in the less-reported conductivity test of different storage time.

     

Self-assembly and embedding of nanoparticles by in situ reduced graphene for preparation of a 3D graphene/nanoparticle aerogel

A 3D graphene architecture can be prepared via an in situ self-assembly of graphene prepared by a mild chemical reduction. Fe(3) O(4) nanoparticles are homogeneously dispersed into graphene oxide (GO) aqueous suspension and a 3D magnetic graphene/Fe(3) O(4) aerogel is prepared during the reduction of GO to graphene. This provides a general method to prepare 3D graphene/nanoparticle composites for a wide range of applications including catalysis and energy conversion.     

An environment-friendly preparation of reduced graphene oxide nanosheets via amino acid

Chemically modified graphene has been studied in many applications due to its excellent electrical, mechanical, and thermal properties. Among the chemically modified graphenes, reduced graphene oxide is the most important for its structure and properties, which are similar to pristine graphene. Here, we introduce an environment-friendly approach for preparation of reduced graphene oxide nanosheets through the reduction of graphene oxide that employs L-cysteine as the reductant under mild reaction conditions. The conductivity of the reduced graphene oxide nanosheets produced in this way increases by about 10(6) times in comparison to that of graphene oxide. This is the first report about using amino acids as a reductant for the preparation of reduced graphene oxide nanosheets, and this procedure offers an alternative route to large-scale production of reduced graphene oxide nanosheets for applications that require such material.     

Mixed-valence manganese oxide/reduced graphene oxide composites with enhanced pseudocapacitive performance

Journal of Materials Science - As typical pseudocapacitive materials, manganese oxides have attracted great interest due to their high theoretical specific capacitance, abundant oxidation states...     

Conductive resilient graphene aerogel via magnesiothermic reduction of graphene oxide assemblies

Graphene aerogels are desirable for energy storage and conversion, as catalysis supports, and as adsorbents for environmental remediation. To produce graphene aerogels with low density, while maintaining high electrical conductivity and strong mechanic performance, we synthesized graphene aerogels by the magnesiothermic reduction of a freeze-dried graphene oxide (GO) self-assembly and subsequent etching of the formed MgO in acid solution. The reduced graphene oxide (rGO) aerogel samples exhibited densities as low as 1.1 mg·cm^?3. The rGO aerogel was very resilient, exhibiting full recoveryeven after being compressed by strains of up to 80%; its elastic modulus (E) scaled with density (ρ) as E～ρ². The rGO aerogels also exhibited high conductivities (e.g., 27.7 S·m^?1 at 3.6 mg·cm^?3) and outperformed many rGO aerogels fabricated by other reduction processes. Such outstanding properties were ascribed to the microstructures inherited from the freeze-dried GO self-assembly and the magnesiothermic reduction process.

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