Nanoarchitectured Graphene‐Based Supercapacitors for Next‐Generation Energy‐Storage Applications

Tremendous development in the field of portable electronics and hybrid electric vehicles has led to urgent and increasing demand in the field of high‐energy storage devices. In recent years, many research efforts have been made for the development of more efficient energy‐storage devices such as supercapacitors, batteries, and fuel cells. In particular, supercapacitors have great potential to meet the demands of both high energy density and power density in many advanced technologies. For the last half decade, graphene has attracted intense research interest for electrical double‐layer capacitor (EDLC) applications. The unique electronic, thermal, mechanical, and chemical characteristics of graphene, along with the intrinsic benefits of a carbon material, make it a promising candidate for supercapacitor applications. This Review focuses on recent research developments in graphene‐based supercapacitors, including doped graphene, activated graphene, graphene/metal oxide composites, graphene/polymer composites, and graphene‐based asymmetric supercapacitors. The challenges and prospects of graphene‐based supercapacitors are also discussed.     

国外印刷电子产业发展概述

近年来印刷电子有了快速发展,许多有关印刷电子的科研成果,已从实验室投入了生产,初步形成了印刷电子产业体系。本文介绍了应用于印刷电子的各类有机、无机材料及工艺装备,特别详细列举了各类印刷电子产品及其应用情况,这些印刷电子产品已开始进入人们日常生活的多个方面。虽然印刷电子产业尚处于发展初级阶段,市场不够成熟,但已显示出十分光明的发展前景。文中还指出政府机构的重视和支持是国外印刷电子产业发展的重要因素。     

Graphene and Graphene/Polymer Composites as the Most Efficient Protective Coatings for Steel,Aluminum and Copper in Corrosive Media: A Review of Recent Studies

The metal corrosion is considered as a severe threat to the national economy and industry structure, capable of triggering significant economic losses and severe damages, involving innumerable fields in daily life and industries. This review provides an overview of the physioelectrochemical studies on anticorrosive properties of various types of graphene coatings. Required electrochemical techniques for the investigation of anticorrosive efficiency, various types of graphene‐based materials coatings along with different routes to provide desirable coated layers are discussed in detail. After all, we intend to show that the modified graphene nanosheets can be regarded as effective protective layers against metal corrosion not only because of their extraordinary mechanical strength and toughness, which can be reached with a vastly thin layer, but also for their high transparency, cost‐efficiency and stability.     

DNA adsorbed on graphene and graphene oxide: Fundamental interactions,desorption and applications

Interfacing DNA oligonucleotides with graphene-based materials, especially graphene oxide, has produced many new sensors and devices. Since graphene oxide is an excellent fluorescence quencher, fluorescently labeled DNAs (probes) are nearly fully quenched upon adsorption. Addition of the complementary DNA results in probe desorption and fluorescence enhancement. Aside from its analytical applications, this system provides a fascinating topic for biointerface science. DNA can be adsorbed by graphene oxide via π–π stacking and hydrogen bonding, while it must overcome electrostatic repulsion at the same time. The mechanism of DNA-induced probe desorption has also been a topic of extensive discussion. In this article, DNA adsorption and desorption reactions and interactions with graphene oxide and related materials (e.g. graphene) are reviewed based on the current understandings. A few representative applications based on these processes are also described briefly.     

Recyclable catalysts for the synthesis of heterocyclic compounds using carbon materials

Heterogeneous catalytic reactions play a major role in the industry to produce a number of compounds that are essential in our daily life. Synthesis of heterocyclic compounds using heterogeneous catalysis is one of the rapidly growing research areas. Inherent ability to produce high selectivity and potentiality to recycle, the catalyst makes the heterogeneous systems more attractive, especially on the industrial scale. Various recyclable catalytic systems have been extensively developed for the synthesis of heterocyclic compounds via dehydration, partial oxidations, three-component couplings, dehydrogenations, and others. Different supports like polymers, metal oxides, and quite recently carbon supports like carbon nanotubes (CNTs), graphene oxide (GO), graphitic nitride (GCN), and nitrogenous carbon materials (NGr) have been widely used to synthesize diverse heterocycles. The use of GO in the synthesis of heterocyclic compounds has been reviewed recently, hence we did not focus on GO in this review. The aim of this review article is to explore the emerging areas of carbon-based heterogeneous materials such as CNTs, GCN, and NGr in the synthesis of heterocycles. This review also focused on the most recent examples, their preparation, and recycling studies of highly excited catalytic systems used for the heterocycles.     

Development of Materials for Blue Organic Light Emitting Devices

The success of organic light emitting diodes (OLED) has been witnessed by the commercialization of this technology for manufacturing the vivid and colorful displays used in our daily life now. The prospective growth of OLED technology on display industry will be optimistic. Over the last three decades, many different approaches on material and device designs have been implemented for improving the efficiency and stability of OLED devices. These efforts install main cornerstones to support the great achievement of OLED technology. However, until now, the performance and stability of blue OLEDs still have some concerns. This troublesome issue should be totally conquered before the large‐scale manufactures dominated over other display technologies, particularly liquid crystal‐based displays, takes place. Though significant progress has already been made to achieve high performance and long lifetime blue OLEDs, this topic still remains as one of the hot researches in OLEDs. We have been working on this area for about two decades and made some notable contributions. Consequently, in this personal account we have outlined our efforts to obtain better performing blue OLEDs by utilizing a range of emitters based on fluorescence, phosphorescence, delayed fluorescence and exciplex systems. We have also developed some novel host materials for blue OLEDs, which are worth mentioning in this account.     

石墨烯玻璃:玻璃表面上石墨烯的直接生长

玻璃是一种历史悠久、用途广泛的无定形硅酸盐材料,而石墨烯则是近年来发现的仅由碳原子组成的二维层状材料。石墨烯具有超高的机械强度、导电性、导热性和透明性,恰好与传统的玻璃形成互补。将石墨烯与玻璃结合在一起,在保持透明性的基础上,同时赋予普通玻璃导电性、导热性和表面疏水性,具有非常重要的实际意义和理论价值。相比于液相涂膜或者转移的方法,直接在玻璃表面生长石墨烯能够从根本上避免由于污染和破损引起的石墨烯性能的下降,从而发展出一种新型材料——石墨烯玻璃。本文介绍了我们研究组在各种玻璃表面直接生长石墨烯的研究进展,其中包括石墨烯在固态耐高温玻璃和熔融态玻璃表面的高温生长,以及利用等离子体辅助手段实现石墨烯在普通玻璃表面的低温生长,并以此为基础发展出多种基于石墨烯玻璃的应用实例。总结展望了石墨烯玻璃的制备和应用的未来挑战与发展方向。     

Graphene Based Electrochemical Sensors and Biosensors: A Review

Graphene, emerging as a true 2‐dimensional material, has received increasing attention due to its unique physicochemical properties (high surface area, excellent conductivity, high mechanical strength, and ease of functionalization and mass production). This article selectively reviews recent advances in graphene‐based electrochemical sensors and biosensors. In particular, graphene for direct electrochemistry of enzyme, its electrocatalytic activity toward small biomolecules (hydrogen peroxide, NADH, dopamine, etc.), and graphene‐based enzyme biosensors have been summarized in more detail; Graphene‐based DNA sensing and environmental analysis have been discussed. Future perspectives in this rapidly developing field are also discussed.     

Steam etched porous graphene oxide network for chemical sensing

Oxidative etching of graphene flakes was observed to initiate from edges and the occasional defect sites in the basal plane, leading to reduced lateral size and a small number of etch pits. In contrast, etching of highly defective graphene oxide and its reduced form resulted in rapid homogeneous fracturing of the sheets into smaller pieces. On the basis of these observations, a slow and more controllable etching route was designed to produce nanoporous reduced graphene oxide sheets by hydrothermal steaming at 200 °C. The degree of etching and the concomitant porosity can be conveniently tuned by etching time. In contrast to nonporous reduced graphene oxide annealed at the same temperature, the steamed nanoporous graphene oxide exhibited nearly 2 orders of magnitude increase in the sensitivity and improved recovery time when used as chemiresistor sensor platform for NO(2) detection. The results underscore the efficacy of the highly distributed nanoporous network in the low temperature steam etched GO.     

Electron transport and excitations in graphene

Graphene is a two-dimensional, single atomic layer carbon structure with many unique physical and chemical properties. In this article, I will focus on electron transport through graphene, both incoherent and coherent, the control of the current through external electric fields, and the realization of high frequency transistors based on graphene. I will also discuss briefly graphene.’s optical properties and how they can be used to create wide wavelength range, ultra-fast photodetectors. Finally, I will present results on the field-induced opening of a tunable band-gap in bi-layer graphene.     

Sulfur‐Doped Graphene Derived from Cycled Lithium–Sulfur Batteries as a Metal‐Free Electrocatalyst for the Oxygen Reduction Reaction

Heteroatom‐doped carbon materials have been extensively investigated as metal‐free electrocatalysts to replace commercial Pt/C catalysts in oxygen reduction reactions in fuel cells and Li–air batteries. However, the synthesis of such materials usually involves high temperature or complicated equipment. Graphene‐based sulfur composites have been recently developed to prolong the cycling life of Li–S batteries, one of the most attractive energy‐storage devices. Given the high cost of graphene, there is significant demand to recycle and reuse graphene from Li–S batteries. Herein, we report a green and cost‐effective method to prepare sulfur‐doped graphene, achieved by the continuous charge/discharge cycling of graphene–sulfur composites in Li–S batteries. This material was used as a metal‐free electrocatalyst for the oxygen reduction reaction and shows better electrocatalytic activity than pristine graphene and better methanol tolerance durability than Pt/C.     

Toluene chemiresistor sensor based on nano-porous toluene-imprinted polymer

In this work, the application of molecularly imprinted polymer (MIP) as the recognition element of a chemiresistor sensor was introduced. Toluene-imprinted polymer and non-imprinted polymer (NIP) were synthesized and then mixed with carbon black powder in the presence of melted n-eicosane as the binder agent. The obtained composites were applied for the construction of chemiresistor sensors. The sensor, fabricated with toluene-imprinted polymer, showed a significant response towards toluene. Moreover, the response of the NIP-based (polymer synthesized without solvent) chemiresistor sensor was very small and negligible. The components of the MIP-based sensing composite were found to strongly influence the sensor sensitivity. Response surface experimental design methodology was applied to optimize the important parameters of the proposed sensor. Cross-sensitivity of the MIP-based chemiresistor sensor for different vapours was investigated and a satisfactory result was found for toluene vapour recognition. It was shown that the sensor response to toluene concentration in air was linear in the concentration range of 3.8 to 46.4?ppm. The detection limit and relative standard deviation (for five separate determinations) of the designed sensor were calculated equal to 0.8?ppm and 5.6%, respectively.     

Understanding Self-assembly,Colloidal Behavior and Rheological Properties of Graphene Derivatives for High-performance Supercapacitor Fabrication

Graphene derivatives, such as graphene oxide(GO) and reduced graphene oxide(RGO), have been widely used as promising twodimensional nanoscale building blocks due to their fascinating properties, cost-effective production, and good processability. Understanding the intrinsic self-assembling, colloidal, and rheological features of graphene derivatives is of critical importance to establish the formation-structureproperty relationship of graphene-based materials. This article reviews recent progresses in our studies of these interesting properties of graphene derivatives for developing high performance supercapacitors. The content is organized to include characteristics of the dispersions of graphene derivatives, self-assembly of nanosheets from liquid medium, colloidal behavior, rheological properties of the dispersions, processing methods based on the properties, and performance of the fabricated supercapacitors. GO and RGO nanosheets are proved to form different types of assembled structures with unique morphologies, such as ultrathin layer-by-layer films, porous aggregates, and nanoscrolls. The unique rheological properties of GO dispersions and hydrogels, feasible for both the traditional wet-processing and newly-developed technology like three-dimensional printing, are highlighted for their potential in structural manipulation and scalable fabrication of graphene-based devices. The research devoted to up-grading the performance of supercapacitors is presented in some details, which could be applicable for fabricating other graphene-based energy storage devices. Some challenges and perspectives in our point of view are given in the last part of this feature article.     

石墨烯的制备、表征及其在透明导电膜中的应用

近年来,石墨烯因其优异的电学和光学等特性,越来越受到人们的广泛关注。研究人员应用多种方法来合成石墨烯并且探讨其潜在的应用价值。本文首先简要介绍了石墨烯的结构及其基本的物理性质,并简单回顾了石墨烯的合成方法和表征手段。在此基础上,讨论了石墨烯/银复合薄膜在透明导电膜中的应用,并详细介绍了我们在该领域的研究成果。用化学气相沉积法（CVD）和多羟基法分别制备了双层石墨烯及银纳米线,成功合成了石墨烯/银复合薄膜,结果表明复合薄膜的方块电阻可降低至26 Ω·□-1,展示了其在光电器件上广泛的应用前景。     

仿鲍鱼壳石墨烯多功能纳米复合材料

石墨烯具有力学性能高、电导率优异等特点,然而单层石墨烯纳米片在组装成为宏观纳米复合材料的过程中,往往会出现片层团聚、界面作用弱、无规取向等问题,导致宏观石墨烯纳米复合材料性能远低于单片石墨烯。因此,如何将微观石墨烯纳米片层的高性能在宏观纳米复合材料中体现出来,是目前研究的热点和难点。本专论结合目前石墨烯纳米复合材料的研究现状,简要讨论了受天然鲍鱼壳的“砖-泥”结构的启发,仿生构筑高性能石墨烯纳米复合材料的最新研究进展。并对本课题组在仿鲍鱼壳石墨烯多功能纳米复合材料领域近年来的工作进行介绍,包括石墨烯纤维、薄膜和块材等多种宏观石墨烯纳米复合材料,系统总结构筑仿鲍鱼壳结构和反鲍鱼壳结构两种策略,在一定程度上解决了石墨烯在组装过程中的科学问题。同时,详细阐述了仿鲍鱼壳石墨烯多功能纳米复合材料的增强增韧机制和功能化策略,分析了今后研究工作中可能遇到的问题,并展望了未来的发展趋势。     

Structural Characterization of Graphene Nanosheets for Miniaturization of Potentiometric Urea Lipid Film Based Biosensors

The present article describes a miniaturized potentiometric urea lipid film based biosensor on graphene nanosheets. Structural characterization of graphene nanosheets for miniaturization of potentiometric urea lipid film based biosensors have been studied through atomic force microscopy (AFM) and transmission electron microscopy (TEM) measurements. UV‐Vis and Fourrier transform IR (FTIR) spectroscopy have been utilized to study the pre‐ and postconjugated surfaces of graphene nanosheets. The presented potentiometric urea biosensor exhibits good reproducibility, reusability, selectivity, rapid response times (～4 s), long shelf life and high sensitivity of ca. 70 mV/decade over the urea logarithmic concentration range from 1×10^?6 M to 1×10^?3 M.     

Nitrogen-doped graphene as an excellent candidate for selective gas sensing

The toxic gases,such as CO and NO,are highly dangerous to human health and even cause the death of person and animals in a tiny amount.Therefore,it is very necessary to develop the toxic gas sensors that can instantly monitor these gases.In this work,we have used the first-principles calculations to investigate adsorption of gases on defective graphene nanosheets to seek a suitable material for CO sensing.Result indicates that the vancancy graphene can not selectivly sense CO from air,because O2 in air would disturb the sensing signals of graphene for CO,while the nitrogen-doped graphene is an excellent candidate for selectivly sensing CO from air,because only CO can be chemisorbed on the pyridinic-like N-doped graphene accompanying with a large charge transfer,which can serve as a useful electronic signal for CO sensing.Even in the environment with NO,the N-doped graphene can also detect CO selectively.Therefore,the N-doped graphene is an excellent material for selectively sensing CO,which provides useful information for the design and fabrication of the CO sensors.     

石墨烯基吸附剂的设计及其对水中抗生素的去除

抗生素的大量使用,所带来的环境污染问题受到广泛关注。吸附法因去除效率高、普遍适用性强,呈现出广阔的应用前景,开发新型吸附剂是高效能吸附处理的关键。近年来石墨烯优良的物理和化学性质以及吸附性能,使其成为重要的抗生素吸附剂。由于石墨烯自身的局限性以及对石墨烯吸附剂处理效能和稳定性的要求,基于石墨烯设计开发了多种石墨烯基吸附材料。而目前基于水体中抗生素的石墨烯基复合材料的设计、合成及其吸附作用机制缺乏相关的系统性综述。本文综述了目前水体中抗生素的危害,针对石墨烯基复合吸附材料中,广泛关注的磁性石墨烯吸附剂、聚合物/石墨烯吸附剂、三维石墨烯凝胶和石墨烯/生物炭吸附剂的设计和制备方法进行了总结和概述,并阐述了石墨烯基吸附材料对水体中抗生素的主要吸附作用机制。最后,本文对石墨烯基吸附材料去除水体中抗生素未来的发展方向进行了展望。     

Influence of Gold Nanoparticle Film Porosity on the Chemiresistive Sensing Performance

The porosity of 1‐hexanethiol‐functionalised gold nanoparticle films was assessed and utilised as chemiresistor sensors. Electrochemical capacitance measurements showed that the accessibility of electrolytes of different ionic strengths into the pores depended on the thickness of the electric double layer formed. A large variation in capacitance was measured in 0.01–1000 mM NaClO₄, implying a wide pore size distribution. The change in morphology of the nanoparticle films upon storage in air, water and ethanol for two weeks was investigated. There was a significant decrease in the electrochemical capacitance at high electrolyte concentrations for the ethanol‐stored films compared to the freshly‐prepared films suggesting a decrease in the number of small pores of radii in the range of 0.3–3 nm. This was further supported by optical topographical measurements where a decrease in the thickness of ethanol‐stored films was observed relative to the freshly‐prepared films. The porous nature of the nanoparticle films was found to have an effect on the chemical sensing behaviour. When used as chemiresistor sensors, for the detection of heptane in water, the ethanol‐stored films provided larger resistance changes and longer response times. This suggests that the more densely packed ethanol‐stored films provided more sites that enabled film swelling, and that diffusion of the analyte occurred through the narrower water‐filled pores. This demonstrates the effect of different storage conditions on film morphology and subsequently sensor response.     

石墨烯材料在蛋白质和核酸分离/检测中的应用进展

石墨烯是碳材料家族新兴成员之一,因其具有化学性质稳定、良好生物兼容性、催化性、零带隙、特殊的电子能带等特点而受到科学家们广泛关注。 石墨烯特殊的六元环基底平面对很多分子、离子具有亲和性,可通过非共价键或共价键将目标物质富集于表面,大多数情况下被吸附的物质在特定条件下易解吸且不会引起其结构和性质的改变。 石墨烯因而在生物成像、生物医学、光催化、生物传感、药物载体和释放、 环境等方面应用前景广阔。 本文主要论述石墨烯和它的衍生物在生命大分子( 蛋白质和核酸) 分析化学方面的应用,并展望了其发展趋势。