石墨烯非共价功能化及其应用

石墨烯的湿法化学修饰,主要包括共价及非共价两种,是目前广泛采用的宏量功能化策略,亦是有效避免其团聚而充分发挥其优异纳米性能的重要修饰方法。非共价功能化因可同时保持原有及引入物质的物化性质,并可充分发挥协同作用,近年来已受到比共价修饰更多的研究关注,并已在生物科学与技术、可持续能源储存及转化、医疗和复合材料等诸多领域得到了广泛应用。本文综述了以应用为导向的石墨烯非共价功能化的构建策略,期望文中涉及的湿法组装策略能为进一步构建性能提升的新材料提供参考。     

以实践应用为导向的石墨烯非共价功能化

石墨烯的湿法化学修饰,主要包括共价及非共价两种,是目前广泛采用的宏量功能化策略,亦是解决其易团聚充分发挥纳米性能的重要修饰方法。 非共价功能化因可同时保持原有及引入物质的物化性质,并可充分发挥协同作用,近年来已受到比共价修饰更多的研究关注,并已在生物科学与技术、可持续能源储存及转化、医疗和复合材料等诸多领域得到了广泛的应用。在这里,我们精心遴选了近三年的文献,综述了以应用为导向的石墨烯非共价功能化的构建策略,期望文中涉及的湿法组装策略能为进一步构建性能提升的新材料提供参考。     

层间共价增强石墨烯材料的构筑、性能与应用

大批量石墨烯可控制备技术的逐渐成熟为实现其宏观组装和应用提供了基础。在众多的组装策略中,调节石墨烯层间的界面相互作用可以直接影响组装体的力学、电学、热学以及渗透等性质,具有重要的意义。石墨烯片层间以共价键连接的层间共价石墨烯材料以其可调的层间距、较强的层间作用力、丰富的功能化、以及可能的原子构型重排等特性,受到了广泛的关注和深入的研究。相比于其他非共价的键合手段,共价连接是一种更为牢固的枢纽。本文中我们将总结讨论层间共价石墨烯材料的构筑方法、性能以及应用。在构筑方法中,依据石墨烯本身的制备方法分为氧化还原法以及化学气相沉积法,而在氧化还原法中,以其宏观材料的形貌分为纸状和纤维状来讨论。接着,我们重点介绍了层间共价对其力学和电学性能的影响,并概述了此类宏观组装体材料的应用。层间共价石墨烯材料继承了石墨烯自身优异的特性,同时也具有宏观组装所赋予的性能,有望在多个领域得到广泛的应用。     

功能化石墨烯在第三代电化学生物传感器中的应用研究

石墨烯因具有大的比表面积、完整的?-?共轭结构及良好的生物相容性和优良的导电性能等特性,受到电化学研究者们的广泛关注.然而在应用过程中,本征态石墨烯存在水溶性差、与介质的相互作用较弱、易团聚等问题.通过使用非共价、共价、氮掺杂修饰的方法对石墨烯进行功能化,较好地改善了这一问题,扩展了石墨烯在电化学领域的应用.自2009年首次将功能化石墨烯应用于第三代电化学生物传感器的研究以来,近几年相关研究呈增多的态势.本文系统总结了自2009年以来,功能化石墨烯作为新型电极修饰材料在第三代电化学生物传感器研究中的相关工作,并阐述了其在该领域发展中遇到的问题.     

石墨烯及其聚合物纳米复合材料

石墨烯是一种新型的二维纳米碳材料,具有优异的机械性能、电性能和热性能等,是聚合物纳米复合材料的理想填料。近年来,石墨烯/聚合物纳米复合材料成为聚合物基纳米复合材料的研究热点。本文对石墨烯及其聚合物纳米复合材料的研究进展进行了综述。首先概述了石墨烯的不同制备方法及石墨烯的共价与非共价改性途径。然后重点总结了石墨烯/聚合物纳米复合材料的常用制备方法及其机械性能、导电性、导热性、耐热性及阻隔性能。最后,对该领域所存在的问题进行了总结,并展望了其发展趋势。     

增强功能化石墨烯分散性及热稳定性的共价修饰策略

氧化石墨烯(GO)是石墨烯应用过程中非常重要的前驱体之一,然而源于其热不稳定性且只能分散于高极性溶剂中,限制了它的进一步发展。基于氧化石墨烯的共价功能化技术可以较好地克服以上缺点,对于发展具有阻燃性能的新型复合材料具有重要的理论及实践意义。本文针对GO上不同反应基团,综述了利用共价化学修饰策略制备具有高分散性及热稳定性的功能化石墨烯纳米材料的研究进展。     

湿法纺制石墨烯纤维：工艺、结构、性能与智能应用

石墨烯纤维是由石墨烯片层通过组装过程形成的宏观一维材料。其具有较好的耐热性、导热性、导电性以及轻质高强等优点,是实现高品质、功能化纤维的重要突破口。石墨烯纤维在超轻导线、可穿戴储能、传感、生物电极等领域具有广阔应用前景。目前,湿法纺制技术是石墨烯纤维的最主要制备手段,与现有的化学纤维制备过程兼容,是最有望实现规模化制备高品质石墨烯纤维的技术。本文首先介绍了湿法纺制石墨烯纤维工艺中的关键步骤,重点讨论了制备技术与石墨烯纤维结构之间的关系。论述了提升纤维性能的相关策略,总结了石墨烯纤维在功能/智能纤维领域应用。并对提升石墨烯纤维性能的关键问题进行总结阐述,展望了石墨烯纤维的发展前景。     

石墨烯制备与功能化应用的研究进展

石墨烯作为新型二维原子晶体已掀起了科学界的研究热潮.近年来,石墨烯的研究与产业化发展持续升温,相关材料的制备方法层出不穷.但是,关于石墨烯的可控性生长和功能化应用仍有待于进一步探索,石墨烯的工业化规模生产与相关器件的有效开发成为当前研究的难点和挑战.本文重点阐述了近两年石墨烯领域的最新进展,总结了石墨烯材料的新型制备方法,分析了石墨烯器件的功能化应用,并对石墨烯行业的应用前景与发展趋势进行了展望.     

石墨烯材料生物降解的策略研究

自2004年被发现以来,前沿新材料石墨烯及其衍生物由于其独特的电学、光学和力学性能被广泛关注,在许多领域都展露了光彩,包括新型电池、传感器、新能源和生物医学等领域,尤其在生物医药领域发展迅速.石墨烯及其衍生物良好的生物相容性使其在生物领域中具有重要的应用前景.为了实现石墨烯材料的体内应用,材料的可降解性是值得深入研究的焦点,研究其生物降解行为有助于提高其对环境、生命系统的安全性.到目前为止,石墨烯的生物降解研究主要集中在材料的生物酶促降解,利用一系列方法如异质原子掺杂、表面功能化修饰等对石墨烯材料进行改性,可以调控石墨烯材料的降解.综述了近年来石墨烯材料及其衍生物在生物应用上的降解的研究进展,重点介绍石墨烯的酶促降解和其在生物医学领域的应用前景,为进一步促进石墨烯材料的体内研究提供重要的研究基础和指导意义.     

基于石墨烯及其衍生物的信息存储:材料、器件和性能

石墨烯以其独特的二维结构和高的热导电性、高杨氏模量、高电子/空穴迁移率、高抗拉强度、大的布鲁诺尔-埃米特-特勒表面积和量子霍尔效应等优异性能,备受科研工作者的关注,迅速成为材料、化学、物理和工程领域的热点研究课题。与富勒烯(C₆₀、C₇₀)的功能化一样,利用共价键合修饰或非共价键合修饰的方法可以在石墨烯表面或石墨烯体系中引入功能基团或功能组分,制备出种类繁多的具有特殊光、电、磁和生物效应的石墨烯衍生物。以石墨烯作为数据存储介质的分子级别计算已经引发了一场信息技术产业的革命,它能在更小的空间上,使用更少的能源来存储更多的数据信息, 有望成为目前基于硅半导体存储技术的潜在替代或补充技术。基于石墨烯的存储器件展现出优良的数据存储性能、器件稳定性和可靠性,为使这类器件具有更好的实际应用前景,人们采用许多技术手段来调控和优化器件性能。本文综述了近年来引起广泛关注的诸如石墨烯、共价修饰的石墨烯、石墨烯基复合材料、石墨烯/无机材料异质结等基于石墨烯及其衍生物的存储器件及相关材料研究进展,以及石墨烯/还原的氧化石墨烯透明电极在存储器件中的应用。探讨了该领域存在的亟待解决的关键基础问题和未来发展方向。     

Preparation and Characterization of Graphene from Refined Benzene Extracted from Low-Rank Coal: Based on the CVD Technology

Industrial preparation of graphene has been a research hotspot in recent years. Finding an economical and practical carbon source and reducing the cost of production and instrument is significant in industrial graphene production. Coal is a common carbon source. Efficient improvement and utilization in the cleaning of coal has recently been a popular research area. In this study, we developed a set of graphene preparation methods based on Anhui Huainan’s low-rank gas coal (HNGC). Using self-built experimental equipment, benzene precursor was prepared from HNGC and used as carbon source to realize graphene growth. The quality of the graphene was characterized by a high-resolution microscope and Raman spectrometer. This study provides a new idea and method for the preparation of low-rank coal-based graphene.     

Dual Protection of Sulfur by Carbon Nanospheres and Graphene Sheets for Lithium–Sulfur Batteries

Well‐confined elemental sulfur was implanted into a stacked block of carbon nanospheres and graphene sheets through a simple solution process to create a new type of composite cathode material for lithium–sulfur batteries. Transmission electron microscopy and elemental mapping analysis confirm that the as‐prepared composite material consists of graphene‐wrapped carbon nanospheres with sulfur uniformly distributed in between, where the carbon nanospheres act as the sulfur carriers. With this structural design, the graphene contributes to direct coverage of sulfur to inhibit the mobility of polysulfides, whereas the carbon nanospheres undertake the role of carrying the sulfur into the carbon network. This composite achieves a high loading of sulfur (64.2 wt %) and gives a stable electrochemical performance with a maximum discharge capacity of 1394 mAh g^?1 at a current rate of 0.1 C as well as excellent rate capability at 1 C and 2 C. The improved electrochemical properties of this composite material are attributed to the dual functions of the carbon components, which effectively restrain the sulfur inside the carbon nano‐network for use in lithium–sulfur rechargeable batteries.     

基于石墨烯基材料的非金属液相催化反应

非金属碳基催化剂因其具有合成简单、结构稳定、比表面积大、可调控性强等特点受到了研究者的关注,已成为最活跃的研究领域之一。以二维、单原子层、六方结构的碳为基础的石墨烯和其高度氧化形态——氧化石墨烯是一类新兴的碳基材料。这类材料在催化领域的应用在近五年内才刚刚兴起。此类材料可用于烃类转化、有机化学合成、能源转化等多种催化反应,本文主要综述了采用化学氧化还原法制备的石墨烯和氧化石墨材料为催化剂的各类催化反应的最新研究进展。     

New Insights into the Diels–Alder Reaction of Graphene Oxide

Graphene oxide is regarded as a major precursor for graphene‐based materials. The development of graphene oxide based derivatives with new functionalities requires a thorough understanding of its chemical reactivity, especially for canonical synthetic methods such as the Diels–Alder cycloaddition. The Diels–Alder reaction has been successfully extended with graphene oxide as a source of diene by using maleic anhydride as a dienophile, thereby outlining the presence of the cis diene present in the graphene oxide framework. This reaction provides fundamental information for understanding the exact structure and chemical nature of graphene oxide. On the basis of high‐resolution ¹³C‐SS NMR spectra, we show evidence for the formation of new sp³ carbon centers covalently bonded to graphene oxide following hydrolysis of the reaction product. DFT calculations are also used to show that the presence of a cis dihydroxyl and C vacancy on the surface of graphene oxide are promoting the reaction with significant negative reaction enthalpies.     

Recent trends in carbon nanomaterial-based electrochemical sensors for biomolecules: A review

Carbon nanomaterials are advantageous for electrochemical sensors because they increase the electroactive surface area, enhance electron transfer, and promote adsorption of molecules. Carbon nanotubes (CNTs) have been incorporated into electrochemical sensors for biomolecules and strategies have included the traditional dip coating and drop casting methods, direct growth of CNTs on electrodes and the use of CNT fibers and yarns made exclusively of CNTs. Recent research has also focused on utilizing many new types of carbon nanomaterials beyond CNTs. Forms of graphene are now increasingly popular for sensors including reduced graphene oxide, carbon nanohorns, graphene nanofoams, graphene nanorods, and graphene nanoflowers. In this review, we compare different carbon nanomaterial strategies for creating electrochemical sensors for biomolecules. Analytes covered include neurotransmitters and neurochemicals, such as dopamine, ascorbic acid, and serotonin; hydrogen peroxide; proteins, such as biomarkers; and DNA. The review also addresses enzyme-based electrodes that are used to detect non-electroactive species such as glucose, alcohols, and proteins. Finally, we analyze some of the future directions for the field, pointing out gaps in fundamental understanding of electron transfer to carbon nanomaterials and the need for more practical implementation of sensors.     

Impedance Based Nanotoxicity Assessment of Graphene Nanomaterials at the Cellular and Tissue Level

The interest in graphene for biomedical applications has grown substantially in the past few years creating a need for biocompatibility testing. Biomedical engineering applications using graphene such as biosensing devices, microbial detection, disease diagnosis, and drug delivery systems are progressing rapidly, perhaps overlooking any possible hazards as graphene nanomaterials may interact with biological materials differently than other graphitic materials such as carbon nanotubes and fullerenes. As a potential application for graphene is drug delivery, the toxicity of graphene was tested against an in vitro model of the blood brain barrier (BBB) by measuring trans-endothelial-electrical resistance (TEER). A new approach in terms of electrical impedance sensing was also utilized to kinetically analyze the cytotoxicity of graphene nanomaterials towards the BBB model's individual components, rat astrocytes (CRL-2006) and mouse endothelial cells (CRL-2583), in real time by measuring the impedimetric response. Graphene showed little or no toxicity toward both individual cell types as the resistance measurements were similar to those of the control and further, graphene did not interrupt the integrity of the BBB model as a whole showing the biocompatibility of graphene and the broad potential of using these new nanomaterials for biomedical applications.     

Chemical methods for the generation of graphenes and graphene nanoribbons

Synthetic carbon allotrope chemistry is currently among the most rapidly growing topics in materials chemistry. The youngest and at the same time probably the most promising representative of new carbon allotropes is graphene. In this article we outline our recent contributions to chemical graphene formation and functionalization.     

新碳源制备活性炭和石墨烯及其非等电极电容水系超级电容器

Carbon materials can offer various micro- and nanostructures as well as bulk and surface functionalities; hence, they remain the most popular for manufacturing supercapacitors. This article critically reviews recent developments in the preparation of carbon materials from new precursors for supercapacitors. Typical examples are activated carbon (AC) and graphene, which can be prepared from various conventional and new precursors such as biomass, polymers, graphite oxide, CH₄, and even CO₂ via innovative processes to achieve low-cost and/or high specific capacitance. Specifically, when producing AC from natural biomasses or synthetic polymers, either new, spent, or waste, popular activation agents, such as KOH and ZnCl₂, are often used to process the ACs derived from these new precursors while the respective activation mechanisms always attract interest. The traditional two-step calcination process at high temperatures is widely employed to achieve high performance, with or without retaining the morphology of the precursors. The three-step calcination, including a post-vacuum treatment, is also the preferred choice in many cases, but it can increase the cost per capacity (kWh∙g⁻¹). More recently, one-step molecular activation promises a better and more economical approach to the commercial application of AC, although further increase of the yield is necessary. In addition to activation, graphitization, N doping, and template control can further improve ACs in terms of the charging and discharging rates, or pseudocapacitance, or both. Considerations are also given to material structure design, and carbon regeneration during activation. Metal-organic frameworks, which were initially used as templates, have been found to be good direct carbon precursors. Various graphene structures, including powders, films, aerogels, foams, and fibers, can be produced from graphite oxide, CO₂, and CH₄. Similar to AC, graphene can possess micropores by activation. Self-propagating high-temperature synthesis and molten salt processing are newly-reported methods for fabrication of mesoporous graphene. Macroporous graphene hydrogels can be produced by hydrothermal treatment of graphite oxide suspension, which can also be transferred into films. Hierarchically porous structures can be achieved by H₂O₂ etching or ZnCl₂ activation of the macroporous graphene precursor. Sponges as templates combined with KOH activation are applied to create both micro- and macropores in graphene foams. Graphene can grow on fibers and textiles by electrodeposition, dip-coating, or filtration, which can be woven into clothes with a large area or thick loading, illuminating the potential application in flexible and wearable supercapacitors. The key obstacles in AC and graphene production are high cost, low yield, low packing density, and low working potential range. Most Carbon materials derived from new precursors work very well with aqueous electrolytes. Charge storage occurs not only in the electric double layer (i.e., the "carbon | electrolyte" interface), but also via redox activity in association with the bulk and surface functionalities, and the resulting partial delocalization of valence electrons. The analysis of the capacitive electrode has shown a design defect that prevents the working voltage of a symmetrical supercapacitor from reaching the full potential window of the carbon material. This defect can be avoided in AC-based supercapacitors with unequal electrode capacitances, leading to higher cell voltages and hence higher specific energy than their symmetrical counterparts. There are also emerging ways to raise the energy capacity of AC supercapacitors, such as the use of redox electrolytes to enable the Nernstian charge storage mechanism, and of the three dimensional printing method for a desirable electrode structure. All these developments are promising carbon materials from various precursors of new and waste sources for a more affordable and sustainable supercapacitor technology.     

Structural correlations in heterogeneous electron transfer at monolayer and multilayer graphene electrodes

As a new form of carbon, graphene is attracting intense interest as an electrode material with widespread applications. In the present study, the heterogeneous electron transfer (ET) activity of graphene is investigated using scanning electrochemical cell microscopy (SECCM), which allows electrochemical currents to be mapped at high spatial resolution across a surface for correlation with the corresponding structure and properties of the graphene surface. We establish that the rate of heterogeneous ET at graphene increases systematically with the number of graphene layers, and show that the stacking in multilayers also has a subtle influence on ET kinetics.     

石墨烯基材料在毛细管电泳中的应用进展

石墨烯基材料(石墨烯、氧化石墨烯、还原氧化石墨烯和石墨烯量子点)是一种新型的单层片状结构碳纳米材料,具有巨大的比表面积、良好的热稳定性和化学稳定性、较强的π-π电子共轭作用、疏水作用及氢键作用等,在分离科学领域展现了非常理想的应用前景。该文主要综述了石墨烯基材料近年来在毛细管电泳(CE)中的研究进展,包括作为背景电解质的添加剂、毛细管电色谱柱的固定相、CE-电化学检测电极的修饰材料和CE样品前处理的新型吸附剂材料等,并对其在CE领域未来的发展和应用进行了展望。