Ni催化制备纤维素基石墨化材料的研究

以纤维素为原料,经过炭化后在Ni的催化作用下制得了石墨化材料。通过X射线衍射(XRD)、拉曼光谱和高分辨率透射电镜(HRTEM)确定了最优反应条件。结果表明:在反应温度1 400℃、Ni负载量3 mmol/g、反应时间3 h的条件下,由纤维素炭化得到的无定形炭发生了有效的石墨化转化,形成了多于40层的环状石墨化结构,而未添加金属的对照样经过相同处理后仍为无定形碳结构;电导率测试结果显示在压力为20 MPa时,石墨化产物的电导率为54 S/cm,为未加入金属的2倍。

腐殖酸基石墨化材料的制备及其电化学性能

以腐殖酸为前驱体,通过高温热处理制备锂离子电池负极材料。采用扫描电子显微镜(SEM)、X射线衍射(XRD)和电化学测试系统对该材料的形貌、微晶结构和电化学性能进行表征。结果表明,腐殖酸基石墨化材料呈现出较为规整的石墨片层结构,且随着石墨化温度的升高,所得材料的石墨化度也越来越高。腐殖酸基石墨化材料均表现出良好的电化学性能,石墨化温度为2 800℃所制备的石墨化材料的首次放电比容量为356.7 mAh/g,充电比容量为277.6 mAh/g,首次充放电的库仑效率为77.81%,在1C和2C倍率下50次充放电循环后的容量保持率分别高达99.4%、95.9%,是一种理想的锂离子电池负极材料。

二硒化钼/石墨烯复合材料的非线性光学性质

采用溶剂热法合成了二硒化钼/石墨烯(MoSe_(2)/rGO)复合材料,进一步通过滴涂法制备了二硒化钼/石墨烯/聚乙烯醇(MoSe_(2)/rGO/PVA)薄膜。通过X射线衍射仪(XRD)、激光拉曼光谱仪、傅里叶变换红外光谱仪(FT-IR)、透射电子显微镜(TEM)、X射线光电子能谱仪(XPS)和紫外可见分光光度计(UV-Vis)对MoSe_(2)/rGO复合材料和薄膜材料的结构、形貌、成分和吸收特性进行分析。采用Z-扫描技术,在激光光源为1064和532 nm,脉冲宽度为4 ns条件下,研究了MoSe_(2)/rGO溶液和薄膜的三阶非线性光学(NLO)性质。结果表明,MoSe_(2)/rGO/PVA薄膜的三阶NLO性质明显高于MoSe_(2)溶液、MoSe_(2)/rGO溶液和MoSe_(2)/PVA薄膜。在入射能量25μJ,激发波长532 nm条件下,MoSe_(2)/rGO/PVA薄膜材料显示了更大的非线性吸收系数。本工作为过渡金属硫族化合物/石墨烯复合材料在光限幅和激光锁模中的应用奠定基础。

石墨烯/炭黑杂化材料：新型、高效锂离子电池二元导电剂

采用CTAB为表面活性剂将氧化石墨烯和炭黑均匀分散,经水热过程将二者组装到一起,进而高温热处理得到石墨烯/炭黑杂化材料。该材料是一种具有独特结构和良好性能的石墨烯/炭黑杂化材料作为锂离子电池二元导电剂。炭黑颗粒均匀分布在石墨烯表面,可防止石墨烯片层团聚并进一步提高电子导电效率。由于炭黑可增加对电解液的吸附,促进电极内部锂离子的传输过程,最终提高锂离子电池的倍率性能。结果表明,使用质量分数5%900℃热处理之后的二元导电剂的LiFePO4,在10C时比容量为73mAh/g,优于使用10%炭黑导电剂时的LiFePO4(10C比容量为62mAh/g)。按照整个电极质量计算,前者的比容量性能比后者提高了近25%,同时在循环性能方面,前者的稳定性也优于后者。

氧化亚锰/石墨烯复合材料的简易合成及其高效储锂性能(英文)

在不添加锰源的情况下,将改进Hummers法制备的硫酸锰/氧化石墨烯悬浊液直接通过NaOH碱溶液原位沉淀形成四氧化三锰/氧化石墨烯复合物,并在氢气气氛下处理得到氧化亚锰/石墨烯复合材料。将该复合材料用于锂离子电池的负极材料,锂离子电池性能优良。在100mA·g-1电流密度下,其比容量达到870mAh·g-1,明显高于相同电流密度下氧化亚锰的比容量(456mAh·g-1)。即使在1600mA·g-1的高电流密度下,其比容量达390mAh·g-1。这种简单、高效的合成方法可为合成锰基氧化物和石墨烯的复合材料提供一种新思路。

聚丙烯腈/氧化石墨烯的偕氨肟化复合材料的制备及其对铀的吸附行为

合成了一种新型的具有高吸附量和较好吸附选择性的聚丙烯腈/氧化石墨烯的偕氨肟化复合材料(■-AO/GO)吸附剂,采用XRD、红外光谱对■-AO/GO进行了表征,通过静态吸附实验研究了pH值、固液比、吸附时间、铀溶液初始质量浓度等因素对吸附剂吸附铀的影响,并探讨了吸附过程的热力学和动力学。结果表明,吸附剂对铀的吸附量随吸附剂用量、吸附时间及铀酰离子初始浓度的增加而增加,但当这些因素达到一定值时,吸附达到平衡。在pH=5、固液比0.6g/L、吸附时间60min、铀初始质量浓度150mg/L的最佳吸附条件下,■-AO/GO对铀的吸附量达237mg/g。■-AO/GO对铀的吸附遵循Langmuir吸附等温线,说明■-AO/GO对铀的吸附属于单层吸附。■-AO/GO对铀的吸附较好地符合准二级动力学模型,表明吸附主要为化学吸附过程。

石墨烯携载无机纳米粒子的制备及拉曼性能研究

通过原位复合的方法,在石墨烯片层间掺杂纳米银颗粒,制备出石墨烯/银纳米杂化材料(RGO/Ag)。利用紫外吸收光谱、傅里叶红外光谱、透射电子显微镜(TEM)、XRD、拉曼光谱等对氧化石墨烯(GO)、还原氧化石墨烯(RGO)和石墨烯/银纳米杂化材料(RGO/Ag)进行表征。发现复合材料中的银对石墨烯/银材料有拉曼增强作用,结合TEM对这种增强作用进行研究,发现银颗粒的团聚对这种增强作用有减弱作用。

Nitrogen⁃doped 3D graphene⁃carbon nanotube network for efficient lithium storage

A 3D nitrogen⁃doped graphene/multi⁃walled carbon nanotube(CS⁃GO⁃NCNT)crosslinked network mate⁃rial was successfully synthesized utilizing chitosan and melamine as carbon and nitrogen sources,concomitant with the incorporation of multi⁃wall carbon nanotubes and employing freeze drying technology.The material amalgamates the merits of 1D/2D hybrid carbon materials,wherein 1D carbon nanotubes confer robustness and expedited elec⁃tron transport pathways,while 2D graphene sheets facilitate rapid ion migration.Furthermore,the introduction of nitrogen heteroatoms serves to furnish additional active sites for lithium storage.When served as an anode material for lithium⁃ion batteries,the CS⁃GO⁃NCNT electrode delivered a reversible capacity surpassing 500 mAh·g^(-1),mark⁃edly outperforming commercial graphite anodes.Even after 300 cycles at a high current density of 1 A·g^(-1),it remained a reversible capacity of up to 268 mAh·g^(-1).

石墨烯用于有机废水处理的优势与挑战

石墨烯与废水处理的结合应用是我国＂十三五＂发展规划中的重要方向。本文介绍了石墨烯用于吸附处理废水的特性与优势,以及我国发展石墨烯废水处理技术的机遇,并从技术逻辑层次探讨了可能经历的几个发展阶段,为产业的客观与健康发展提供参考。

聚丙烯原位碳化合成石墨烯负载碳球纳米杂化材料研究

本研究以氧化石墨烯（GO）为模板负载氢氧化镍（Ni（OH）2）和氢氧化钴（Co（OH）2）纳米粒子,并分别熔融共混到聚丙烯（PP）中,利用PP原位碳化方法成功制备出GO负载碳球纳米杂化材料。利用X射线衍射（XRD）和拉曼波谱分析（Raman）对合成的Ni（OH）2、Co（OH）2、GO负载Ni（OH）2和GO负载Co（OH）2进行表征。采用透射电子显微镜（TEM）、XRD和Raman等对合成的石墨烯负载碳球纳米杂化材料的形貌结构和物理性质进行表征。结果表明：利用PP原位碳化可成功制备两种不同类型的石墨烯负载碳球纳米杂化材料。

催化裂解聚丙烯合成石墨烯碳纳米杂化材料及其电化学应用

研究了氧化石墨烯(GO)负载Co-Ni催化剂原位催化聚丙烯(PP)进行三维石墨烯碳纳米杂化材料的合成,同时考察材料作为超级电容器电极的电化学应用。将乙酸钴和乙酸镍按比例加入GO水溶液中,利用聚醚胺400(D-400)将二者还原为氢氧化物并自组装负载在GO表面,制备出GO负载Co-Ni催化剂(GO/Ni-Co)。将GO/Ni-Co熔融共混到PP中,在氮气保护下裂解碳化共混得到石墨烯基碳纳米杂化材料。采用SEM、TEM、XRD和Raman等对其形貌结构进行表征。结果表明:利用该方法可成功制备一种三维石墨烯碳纳米杂化材料(RGO/C)。将所制备的RGO/C应用于超级电容器,在扫描速率为2m V/s时,最大比电容达到595F/g,并且具有良好的循环稳定性。

Synthesis of Cu_2O/reduced graphene oxide composites as anode materials for lithium ion batteries

A facile way was used to synthesize Cu2O/reduced graphene oxide （rGO） composites with octahedron-like morphology in aqueous solution without any surfactant. TEM images of the obtained Cu2O/rGOs reveal that the Cu2O particles and rGO distribute hierarchically and the primary Cu2O particles are encapsulated well in the graphene nanosheets. The electrochemical performance of Cu2O/rGOs is enhanced compared with bare Cu2O when they are employed as anode materials for lithium ion batteries. The Cu2O/rGO composites maintain a reversible capacity of 348.4 mA？h/g after 50 cycles at a current density of 100 mA/g. In addition, the composites retain 305.8 mA？h/g after 60 cycles at various current densities of 50, 100, 200, 400 and 800 mA/g.

Three-dimensional MoS_2/reduced graphene oxide aerogel as a macroscopic visible-light photocatalyst

Photocatalysis is regarded as an ideal technology for solving the urgent environmental and energy issues that we face today.Among the reported photocatalysts,molybdenum disulfide（MoS2） is very promising for applications in hydrogen production and pollutant photodegradation.However,its lack of active sites and the difficulty of recovering catalysts in powder form have hindered its wide application.Here,we report the successful preparation of a macroscopic visible-light responsive MoS2/reduced graphene oxide（MoS2/RGO） aerogel.The obtained MoS2/RGO aerogel exhibits enhanced photocatalytic activity towards hydrogen production and photoreduction of Cr（Ⅵ） in comparison with the MoS2 powder.In addition,the low density（56.1 mg/cm^3） of the MoS2/RGO aerogel enables it to be used as an efficient adsorption material for organic pollutants.Our results demonstrate that this very promising multifunctional aerogel has potential applications in environmental remediation and clean energy production.

Effect of WS_2 addition on electrical sliding wear behaviors of Cu-graphite-WS_2 composites

Four kinds of Cu-based composites with different mass ratios of graphite and WS2 as lubricants were fabricated by hot-pressing method. Electrical sliding wear behaviors of the composites were investigated using a block-on-ring tribometer rubbing against Cu-5%Ag alloy ring. The results demonstrated that 800 ~C was the optimum sintering temperature for Cu-graphite-WS2 dual-lubricant composites to obtain the best comprehensive properties of mechanical strength and lubrication performance. Contact voltage drops of the Cu-based composites increased with increasing the mass ratio of WS2 to graphite. The Cu-based composite with 20% graphite and 10% WS2 showed the best wear resistance due to the excellent synergetic lubricating effect of graphite and WS2. The reasonable addition of WS2 into the Cu-graphite composite can remarkably improve the wear resistance without much rise of electrical energy loss which provides a novel principle of designing suitable sliding electrical contact materials for industrial applications.

Preparation of uniform flower-like CuO and flower-like CuO/graphene composite and their application in lithium ion batteries

Flower-like CuO and flower-like CuO/graphene composite were prepared successfully by hydrothermal method. They were characterized by X-ray diffraction, scanning electron microscopy, nitrogen adsorption, temperature-programmed reduction, and thermogravimetric analysis. It is found that the flower-like CuO microspheres, which are composed of CuO nanosheets, possess an average diameter of 4.2 μm and a Brunauer–Emmett–Teller surface area of 12.6 m2/g. Compared with the flower-like CuO, the obtained flower-like CuO/graphene composite shows an enhanced electrochemical performance with a higher capacity of 603 mA-h/g at 0.1 C rate and 382 mA-h/g at 1 C rate, and exhibits a better cycle stability with a high capacity retention of 95.5 % after 50 cycles even though at 1 C rate.

Magnetic and microwave absorbing properties of M-type barium ferrite/graphene oxide composite microwave absorber

In order to improve the absorbing properties of M- type barium ferrite absorbing materials, M-type barium ferrite/graphene oxide composites with different graphene oxide contents were synthesized by the sol-gel autocombustion method. X-ray diffraction （XRD）, a scanning electronic microscopy （ SEM ）, a physical properties measurement system （PPMS-9）, and a vector network analyzer were used to analyze their structure, surface morphology, magnetic and absorbing properties, respectively. The results show that the absorbing band of the composite absorbing material is widened and the absorbing strength is increased compared with the pure M-type barium ferrite. The sample with the content of doped graphene oxide of 3% has the minimum reflectivity at 10 to 18 GHz frequencies. Hence, the doped graphene oxide effectively improves the absorbing properties of M-type barium ferrite.

Ultrasonic synthesis of CoO/graphene nanohybrids as high performance anode materials for lithium-ion batteries

A facile ultrasonic method was used to synthesize CoO/graphene nanohybrids by employing Co4（CO）12 as a cobalt precursor. The nanohybrids were characterized by SEM, TEM and XPS, and the results show that CoO nanoparticles （3-5 nm） distribute uniformly on the surface of graphene. The CoO/graphene nanohybrids display high performance as an anode material for lithium-ion battery, such as high reversible lithium storage capacity （650 mA-h/g after 50 cycles, almost twice that of commercial graphite anode）, high coulombic efficiency （over 95%） and excellent cycling stability. The extraordinary performance arises from the structure of the nanohybrids： the nanosized CoO particles with high dispersity on conductive graphene substrates are beneficial for lithium-ion insertion/extraction, shortening diffusion length for lithium ions and improving conductivity, thus the lithium storage performance was improved.

In situ synthesis of a nickel boron oxide/graphdiyne hybrid for enhanced photo/electrocatalytic H_(2) evolution

Developing highly active catalysts for photo/electrocatalytic water splitting is an attractive strategy to produce H2 as a renewable energy source.In this study,a new nickel boron oxide/graphdiyne(NiBi/GDY)hybrid catalyst was prepared by a facile synthetic approach.Benefitting from the strong electron donating ability of graphdiyne,NiBi/GDY showed an optimized electronic structure containing lower valence nickel atoms and demonstrated improved catalytic performance.As expected,NiBi/GDY displayed a high photocatalytic H2 evolution rate of 4.54 mmol g^(-1)h^(-1),2.9 and 4.5 times higher than those of NiBi/graphene and NiBi,respectively.NiBi/GDY also displayed outstanding electrocatalytic H2 evolution activity in 1.0 M KOH solution,with a current density of 400 mA/cm^(2)at an overpotential of 478.0 mV,which is lower than that of commercial Pt/C(505.3 mV@400 mA/cm^(2)).This work demonstrates that GDY is an ideal support for the development of highly active catalysts for photo/electrocatalytic H2 evolution.

Synthesis of graphene/tourmaline/TiO_2 composites with enhanced activity for photocatalytic degradation of 2-propanol

We report the construction of a graphene/tourmaline/TiO2(G/T/TiO2)composite system with enhanced charge‐carrier separation,and therefore enhanced photocatalytic properties,based on tailoring the surface‐charged state of graphene and/or by introducing an external electric field arising from tourmaline.A simple two‐step hydrothermal method was used to synthesize G/T/TiO2composites and poly(diallyldimethylammonium chloride)‐G/T/TiO2composites.In the photocatalytic degradation of2‐propanol(IPA),the catalytic activity of the composite containing negatively charged graphene was higher than of the composite containing positively charged graphene.The highest acetone evolution rate(223?mol/h)was achieved using the ternary composite with the optimum composition,i.e.,G0.5/T5/TiO2(0.5wt%graphene and5wt%tourmaline).The involvement of tourmaline and graphene in the composite is believed to facilitate the separation and transportation of electrons and holes photogenerated in TiO2.This synergetic effect could account for the enhanced photocatalytic activity of the G/T/TiO2composite.A mechanistic study indicated that O2??radicals and holes were the main reactive oxygen species in photocatalytic degradation of IPA.