A brief review of graphene-based material synthesis and its application in environmental pollution management

Graphene is an interesting two-dimensional carbon allotrope that has attracted considerable research interest because of its unique structure and physicochemical properties. Studies have been conducted on graphene-based nanomaterials including modified graphene, graphene/semiconductor hybrids, graphene/metal nanoparticle composites, and graphene-complex oxide composites. These nanomaterials inherit the unique properties of graphene, and the addition of functional groups or the nanoparticle composites on their surfaces improves their performance. Applications of these materials in pollutant removal and environmental remediation have been explored. From the viewpoint of environmental chemistry and materials, this paper reviews recent important advances in synthesis of graphene-related materials and their application in treatment of environmental pollution. The roles of graphene-based materials in pollutant removal and potential research are discussed.     

Applications of graphene-based materials in environmental protection and detection

Many efficient adsorbents and sensors based on graphene and functionalized graphene have been constructed for the removal and detection of environmental pollutants due to its unique physicochemical properties. In this article, recent research achievements are reviewed on the application of graphene-based materials in the environmental protection and detection. For environmental protection, modified graphene can adsorb heavy metal ions in a high efficiency and selectivity, and thus reduces them to metals for recycling. High adsorption capacity of graphene-based materials to kinds of organic pollutants in water was also presented. Several graphene-based sensors with high limit of detection were reported to detect heavy metal ions, toxic gases and organic pollutants in environment. Finally, a perspective on the future challenge of adsorbents and detection devices based on graphene is given.     

Nonlinear optical properties of graphene-based materials

Graphene,a two-dimensional carbon atom sheet,has attracted tremendous attention and research interest because of its exceptional physical properties.Graphene has high mobility and optical transparency,in addition to flexibility,robustness and environmental stability.The main focus so far has been on fundamental physics and electronic devices.However,because the linear dispersion of the Dirac electrons enables ultrawideband tunability,we believe its true potential lies in photonics and optoelectronics.In this review,we introduce recent advances in the nonlinear optical properties of graphene-based materials.The rise of graphene in nonlinear optics is shown by several recent results,ranging from saturable absorbers and the four-wave mixing effect to giant two-photon absorption,reverse saturable absorption and optical limiting.The relevant forms of the graphene-based materials include pure graphene,graphene oxide and graphene hybrids.     

Highly Sensitive and Portable Gas Sensing System Based on Reduced Graphene Oxide

Graphene has been widely used in gas-sensing applications due to its large specific surface area and strong adsorption ability. Among different forms of graphene used as gas-sensing materials, reduced graphene oxide is one of the most convenient and economical materials to integrate with Si-based electronics, which is very important to graphene-based gas sensors. In addition, the stacking structure of graphene oxide flakes facilitates absorption and detection of gas molecules. Based on reduced graphene oxide, a highly sensitive and portable gas-sensing system was demonstrated here. Solution-based graphene oxide was cast on a chip like a TF memory card and then reduced thermally. A signal acquisition system was designed to monitor resistance variation as a sign of gas concentration. This miniature graphene-based gas sensor array demonstrates a new path for the use of graphene in gas-detection technologies. And the creation of a sensitive and portable graphene gas sensor also shows great potential in fields such as medicine and environmental science.     

Unique synthesis of graphene-based materials for clean energy and biological sensing applications

Graphene has unique physical properties,and a variety of proof-of-concept devices based on graphene have been demonstated.A prerequisite for the application of graphene is its production in a controlled manner because the number of graphene layers and the defects in these layers significantly influence transport properties.In this paper,we briefly review our recent work on the controlled synthesis of graphene and graphene-based composites,the development of methods to characterize graphene layers,and the use of graphene in clean energy applications and for rapid DNA sequencing.For example,we have used Auger electron spectroscopy to characterize the number and structure of graphene layers,produced single-layer graphene over a whole Ni film substrate,synthesized well-dispersed reduced graphene oxide that was uniformly grafted with unique gold nanodots,and fabricated graphene nanoscrolls.We have also explored applications of graphene in organic solar cells and direct,ultrafast DNA sequencing.Finally,we address the challenges that graphene still face in its synthesis and clean energy and biological sensing applications.     

Graphene meets biology

Graphene features a shining star in the material sciences since its discovery in 2004. Biomedical application of graphene-family materials has been driven recently. In this paper, we overviewed the cutting-edge research in the biomedical application of graphene-based biomaterials, such as bio-sensing and bio-imaging, drug/gene delivery and scaffold for tissue engineering. We emphasized on the effect of graphene substrates on cellular behaviors of adhesion, proliferation~ and differentiation. The develop- ment of three-dimensional scaffolds based on graphene- based nanomaterials and the potential of these constructs in tissue engineering are discussed. The perspectives and challenges are also addressed.     

A review on hybridization modification of graphene and its polymer nanocomposites

Recently,graphene has attracted numerous interests from both fundamental and applied fields due to its excellent mechanical,thermal,electrical conductivity and other novel properties.This review gives an overview of recent progress on hybridization modifications of graphene with carbon nanomaterials.Some example applications of graphene-based nanohybrids in polymer composites,optical and conducting materials,high performance electrolyte materials and as well as other functional materials are summarized and discussed.     

High-conductivity graphene nanocomposite via facile, covalent linkage of gold nanoparticles to graphene oxide

Graphene and its derivative,graphene oxide (GO) have been substantively used as the main framework for dispersing or building nanoarchitectures because of their excellent properties in electronics and catalysis.The requirement to obtain superior graphene-metal hybrid nanomaterials has led us to explore a facile way to design 4-aminobenzenethiol/1-hexanethiolate-protected gold nanoparticles (aAuNPs)-functionalized graphene oxide composite (aAuNPs-GO) in solution.We demonstrate that when aAuNPs with amino groups are exposed to GO,well-dispersed coverage of Au nanoparticles are mainly observed on the edge of GO sheet.In contrast,when 1-hexanethiolate-protected gold nanoparticles (hAuNPs) without amino groups are exposed to GO,hAuNPs simply aggregate on the surface of GO.This indicates that amino groups located on the surface of Au nanoparticles are an essential prerequisite for attachment of nearly monodispersed aAuNPs.The strategy described here for the fabrication of aAuNPs-GO provides a straightforward approach to develop graphene-based nanocomposites with undamaged sheets structure and good solubility and also improve the conductivity of GO sheets evidently.     

Rapid Preparation and Characterization of Graphene/Carbon Nanotube Hybrid Materials

In this work,a stable,large area sandwich structure of material consisted of carboxylic multiwall carbon nanotubes(c-MWCNTs) and polymer-modified graphene(G) via a self-assembly process was prepared.Positively charged nanomaterial of polymer-modified graphene were prepared via in situ reduction of graphite oxide in the presence of poly(diallyldimethylammonium chloride)(PDDA).Then c-MWCNTs were added into the water-soluble PDDA-modified graphene to form hybrid carbon material via sequential electrostatic self-assembly.Transmission electron microscope(TEM) and scanning electron microscopy(SEM) were used to characterize those hybrid materials.From the figures we can learn that this method has successfully led to the fabrication of a reasonably uniform film with well-interconnected carbon-based hybrid materials.     

Heteroatom-doped graphene for electrochemical energy storage

The increasing energy consumption and envi- ronmental concerns due to burning fossil fuel are key drivers for the development of effective energy storage systems based on innovative materials. Among these materials, graphene has emerged as one of the most promising due to its chemical, electrical, and mechanical properties. Heteroatom doping has been proven as an effective way to tailor the properties of graphene and render its potential use for energy storage devices. In this view, we review the recent developments in the synthesis and applications of heteroatom-doped graphene in supercapacitors and lithium ion batteries.     

石墨烯基TiO_2复合材料的表征及其可见光催化活性研究

以氧化石墨烯与石墨烯为碳源,在熔盐介质中与钛粉反应原位生成石墨烯基TiC中间产物,并通过后续控制氧化制得石墨烯基TiO_2复合光催化剂,结合FTIR、XRD、Raman、SEM等手段,对两种石墨烯材料的结构及形貌差异进行表征,并分析了其对所制复合材料结构、形貌及可见光催化活性的影响。结果表明,所制复合材料仍保持碳源的层片状结构,TiC和TiO_2颗粒均匀包覆在碳源表面;以石墨烯为碳源更有利于表面原位生成TiC晶粒的生长,其晶体结构更为完善;两种结构的石墨烯基TiO_2复合材料均对目标污染物亚甲基蓝有较强的吸附能力和可见光降解能力。     

Preparation and supercapacitor performance of assembled graphene fiber and foam

Graphene-based materials have been full of vigor and tremendous potentiality for application in supercapacitors due to its variety of unique properties such as electronic properties, simple synthesis, etc. In developing new macroscopic nanostructured graphene materials for supercapacitors, considerable efforts have been made by the scientist including our research group. In this account, we describe our development of the construction of the assembled graphene especially fiber and foam, which have great potential in addressing the challenges in the synthesis of graphene-based electrode materials for supercapacitors. As the supercapacitors are reviewed in this article, they are accordant with the rapid development of flexible, lightweight, and wearable-electronic devices, overcoming the major some drawbacks of conventional bulk supercapacitors. We hope that this summary will benefit the further research of graphene-based materials for the applications in electrochemical energy storage devices and beyond.     

石墨烯基电极材料在超级电容器中的应用

随着能源消耗的日渐增长,寻找低成本、环保、寿命长的储能设备迫在眉睫。在超级电容器领域,石墨烯电极材料以其高比电容、优异倍率性能、良好导电性等优势而受到广泛关注。对石墨烯材料的制备方法、电化学性能及相关机制做了总结,目的是研究不同结构的石墨烯材料对超级电容器性能的影响,并找到性能较为优异的石墨烯基材料。最后分析了石墨烯基电极材料发展中存在的问题,并对其研究前景进行了展望。     

石墨烯铝基复合材料超声辅助微铣削工艺研究

超声辅助微铣削作为一种新兴复合加工技术,在加工硬脆材料和复合材料中具有独特的优势.针对石墨烯铝基复合材料在工业应用中存在难加工、加工精度要求高、加工效率低等问题,本文以纯铝及石墨烯铝基复合材料为研究对象,对不同配比的石墨烯铝基复合材料进行了超声辅助微铣削实验.通过正交实验分析石墨烯含量、每齿进给量以及超声振幅对铣削力和加工表面粗糙度的影响,从而确定石墨烯铝基复合材料在超声辅助微铣削下的最佳工艺参数.实验结果表明,当每齿进给量为1 μm/z,超声振幅为3.05 μm时,石墨烯铝基复合材料的加工性能最优.