Concurrent Phosphorus Doping and Reduction of Graphene Oxide

Doped graphene materials are of huge importance because doping with electron‐donating or electron‐withdrawing groups can significantly change the electronic structure and impact the electronic and electrochemical properties of these materials. It is highly important to be able to produce these materials in large quantities for practical applications. The only method capable of large‐scale production is the oxidative treatment of graphite to graphene oxide, followed by its consequent reduction. We describe a scalable method for a one‐step doping of graphene with phosphorus, with a simultaneous reduction of graphene oxide. Such a method is able to introduce significant amount of dopant (3.65 at. %). Phosphorus‐doped graphene is characterized in detail and shows important electronic and electrochemical properties. The electrical conductivity of phosphorus‐doped graphene is much higher than that of undoped graphene, owing to a large concentration of free carriers. Such a graphene material is expected to find useful applications in electronic, energy storage, and sensing devices.     

Hydrogenated Graphene and Hydrogenated Silicene: Computational Insights

Density functional calculations are performed to study the energetic, structural, and electronic properties of graphene and silicene functionalized with hydrogen. Our calculations predict that H atoms bind much more strongly to silicene than to graphene. The adsorbed H atoms tend to cooperatively stabilize each other leading to a two‐dimensional nucleation and growth mechanism. The different structural and electronic modifications induced by H in fully functionalized graphene and silicene (known as graphane and silicane) are also explained. Finally, the electronic properties of defective graphane with multiple hydrogen vacancies are investigated. Engineering the vacancies in graphane offers a way to modify the electronic properties of this material.     

Control of electronic structure of graphene by various dopants and their effects on a nanogenerator

It is essential to control the electronic structure of graphene in order to apply graphene films for use in electrodes. We have introduced chemical dopants that modulate the electronic properties of few-layer graphene films synthesized by chemical vapor deposition. The work function, sheet carrier density, mobility, and sheet resistance of these films were systematically modulated by the reduction potential values of dopants. We further demonstrated that the power generation of a nanogenerator was strongly influenced by the choice of a graphene electrode with a modified work function. The off-current was well quenched in graphene films with high work functions (Au-doped) due to the formation of high Schottky barrier heights, whereas leakage current was observed in graphene films with low work functions (viologen-doped), due to nearly ohmic contact.     

High‐Quality Three‐Dimensional Nanoporous Graphene

We report three‐dimensional (3D) nanoporous graphene with preserved 2D electronic properties, tunable pore sizes, and high electron mobility for electronic applications. The complex 3D network comprised of interconnected graphene retains a 2D coherent electron system of massless Dirac fermions. The transport properties of the nanoporous graphene show a semiconducting behavior and strong pore‐size dependence, together with unique angular independence. The free‐standing, large‐scale nanoporous graphene with 2D electronic properties and high electron mobility holds great promise for practical applications in 3D electronic devices.     

Armchair型石墨纳米带的电子结构和输运性质

利用第一性原理的电子结构和输运性质计算方法, 研究了扶手椅(armchair)型单层石墨纳米带(具有锯齿边缘)的电子结构和输运性质及其边缘空位缺陷效应. 研究发现, 完整边缘的扶手椅型石墨纳米带是典型的金属性纳米带, 边缘空位缺陷的存在对扶手椅型纳米带能带结构有一定的影响,但并不彻底改变其金属性特征.     

Preferential binding of peptides to graphene edges and planes

Peptides identified from combinatorial peptide libraries have been shown to bind to a variety of abiotic surfaces. Biotic-abiotic interactions can be exploited to create hybrid materials with interesting electronic, optical, or catalytic properties. Here we show that peptides identified from a combinatorial phage display peptide library assemble preferentially to the edge or planar surface of graphene and can affect the electronic properties of graphene. Molecular dynamics simulations and experiments provide insight into the mechanism of peptide binding to the graphene edge.     

拉曼光谱表征石墨烯材料的研究进展

石墨烯独特的二元化电子价键结构使其在纳米电子器件中具有良好的应用发展前景。拉曼光谱作为一种灵敏、便捷的技术,已被成功地用作表征石墨烯的结构和特性。本综述着重对沉积在不同基底以及掺杂的石墨烯拉曼光谱研究做了一个简单的总结。通过对铟锡氧化物、蓝宝石和玻璃基底上的石墨烯拉曼光谱进行观察,发现在不同基底上的石墨烯拉曼G峰与2D峰峰值会有不同程度的偏移,但2D峰峰值可判断石墨烯层数这一结论仍适用。掺杂可改变石墨烯的荷电状态,使石墨烯表现出空穴（p）型或电子（n）型掺杂特性,通过石墨烯拉曼光谱的变化可以定性石墨烯的掺杂类别并定量表征石墨烯的载流子浓度。     

Interaction of Inorganic Nanoparticles with Graphene

The changes in the electronic and magnetic properties of graphene induced by interaction with semiconducting oxide nanoparticles such as ZnO and TiO₂ and with magnetic nanoparticles such as Fe₃O₄, CoFe₂O₄, and Ni are investigated by using Raman spectroscopy, magnetic measurements, and first‐principles calculations. Significant electronic and magnetic interactions between the nanoparticles and graphene are found. The findings suggest that changes in magnetization as well as the Raman shifts are directly linked to charge transfer between the deposited nanoparticles and graphene. The study thus demonstrates significant effects in tailoring the electronic structure of graphene for applications in futuristic electronic devices.     

Diels-Alder chemistry of graphite and graphene: graphene as diene and dienophile

The zero-band-gap electronic structure of graphene enables it to function as either the diene or the dienophile in the Diels-Alder reaction, and this versatile synthetic method offers a powerful strategy for the reversible modification of the electronic properties of graphene under very mild conditions.     

Polymer brushes on graphene

A critical bottleneck for the widespread use of single layer graphene is the absence of a facile method of chemical modification which does not diminish the outstanding properties of the two-dimensional sp(2) network. Here, we report on the direct chemical modification of graphene by photopolymerization with styrene. We demonstrate that photopolymerization occurs at existing defect sites and that there is no detectable disruption of the basal plane conjugation of graphene. This method thus offers a route to define graphene functionality without degrading its electronic properties. Furthermore, we show that photopolymerization with styrene results in self-organized intercalative growth and delamination of few layer graphene. Under these reaction conditions, we find that a range of other vinyl monomers exhibits no reactivity with graphene. However, we demonstrate an alternative route by which the surface reactivity can be precisely tuned, and these monomers can be locally grafted via electron-beam-induced carbon deposition on the graphene surface.     

Electronic structure and magnetic properties of the graphene/Fe/Ni111 intercalation-like system

The electronic structure and magnetic properties of the graphene/Fe/Ni(111) system were investigated via combination of the density functional theory calculations and electron-spectroscopy methods. This system was prepared via intercalation of thin Fe layers (1 ML) underneath graphene on Ni(111) and its inert properties were verified by means of photoelectron spectroscopy. Intercalation of iron in the space between graphene and Ni(111) changes drastically the magnetic response from the graphene layer that is explained by the formation of the highly spin-polarized 3d(z(2)) quantum-well state in the thin iron layer.     

Patterning graphene through the self-assembled templates: toward periodic two-dimensional graphene nanostructures with semiconductor properties

Periodic graphene nanostructures are fabricated via patterning graphene through the self-assembled monolayers of monodisperse colloidal microspheres. The resulting structures exhibit promising electronic properties featuring high conductivities and ON-OFF ratios up to 10. The apparent advantages of the presented method are the possibilities of fabricating periodic graphene nanostructures with different periodicities, ranging from ～100 nm to several μm, and also varying the periodicity and the neck width independently. The use of the presented method yields graphene nanostructures with variable electronic properties.     

The electrochemistry of CVD graphene: progress and prospects

The unique electronic properties of graphene, a one atom thick carbon layer, were reported by scientists in 2004. Since this time graphene has subsequently been found to display several more unique and fascinating electrical, optical and mechanical properties. One particular area in which graphene has reportedly made an impact is in the field of electrochemistry, such as in providing enhancements in energy storage/generation and electrochemical sensing applications. Since 2005, when graphene was shown to be fabricated by the so-called 'Scotch tape technique' where multiple layers of graphene are peeled from a slab of Highly Ordered Pyrolytic Graphite using adhesive tape and transferred onto an appropriate substrate, other fabrication methodologies of graphene have emerged. In the majority of cases, graphene is produced and supplied in solution, such that graphene has to be immobilised onto the desired surface. A fabrication process where graphene is grown upon a substrate and is ready for implementation is the Chemical Vapour Deposition (CVD) of graphene. In this perspective article we overview recent developments in the fabrication of CVD graphene and explore its utilisation in electrochemistry, considering its fundamental understanding through to applications in sensing and energy related devices.     

Advances in two-dimensional heterostructures by mono-element intercalation underneath epitaxial graphene

Two-dimensional (2D) materials have displayed many remarkable physical properties, including 2D superconductivity, magnetism, and layer-dependent bandgaps. However, it is difficult for a single 2D material to meet complex practical requirements. Heterostructures obtained by vertically stacking different kinds of 2D materials have extensively attracted researchers’ attention because of their rich electronic features. With heterostructures, the constraints of lattice matching can be overcome. Meanwhile, high application potential has been explored for electronic and optoelectronic devices, including tunneling transistors, flexible electronics, and photodetectors. Specifically, graphene-based van der Waals heterostructures (vdWHs) by intercalation are emerging to realize various functional heterostructures-based electronic devices. Intercalating atoms under epitaxial graphene can efficiently decouple graphene from the substrate, and is expected to realize rich novel electronic properties in graphene. In this study, we systematically review the progress of the mono-element intercalation in graphene-based vdWHs, including the intercalation mechanism, intercalation-modified electronic properties, and the practical applications of 2D intercalated heterostructures. This work would inspire edge-cutting ideas in the scientific frontiers of 2D materials.     

Tuning the magnetic and transport properties of metal adsorbed graphene by co-adsorption with 1,2-dichlorobenzene

A fundamental understanding of the properties of various metal/graphene nanostructures is of great importance for realising their potential applications in electronics and spintronics. The electronic and magnetic properties of three metal/graphene adducts (metal = Li, Co or Fe) are investigated using first-principles calculation. It is predicated that the metal/graphene adducts have strong affinity to aromatic molecule 1,2-dichlorobenzene (DCB), and the resultant DCB-metal/graphene sandwich structures are much more stable than the simple DCB/graphene adduct. Importantly, it is found that the adsorption of DCB slightly enhances the magnetic moment of the Co/graphene, but turns the Fe/graphene from magnetic to nonmagnetic. A detailed theoretical explanation of the different magnetic properties of the DCB/Co/graphene and DCB/Fe/graphene is achieved based on their different d-band splitting upon DCB adsorption. In addition, the transport property study indicates that the Fe/graphene is a better sensing material for DCB than the pristine graphene.     

Covalent 2D Patterning,Local Electronic Structure and Polarization Switching of Graphene at the Nanometer Level

A very facile and efficient protocol for the covalent patterning and properties tuning of graphene is reported. Highly reactive fluorine radicals were added to confined regions of graphene directed by laser writing on graphene coated with 1-fluoro-3,3-dimethylbenziodoxole. This process allows for the realization of exquisite patterns on graphene with resolutions down to 200 nm. The degree of functionalization, ranging from the unfunctionalized graphene to extremely high functionalized graphene, can be precisely tuned by controlling the laser irradiation time. Subsequent substitution of the initially patterned fluorine atoms afforded an unprecedented graphene nanostructure bearing thiophene groups. This substitution led to a complete switch of both the electronic structure and the polarization within the patterned graphene regions. This approach paves the way towards the precise modulation of the structure and properties of nanostructured graphene.     

石墨烯的功能化及其在储能材料领域中的应用

石墨烯是由sp~2杂化的碳原子紧密堆积成的单原子层二维碳材料,由于其优异的物理和化学性质被视为最有前景的新型材料之一。但由于石墨烯片层之间在范德华力的作用下易发生不可逆团聚,丧失其单层二维纳米片的结构特性,以及石墨烯表面呈现惰性状态,致使其与其他介质的相互作用较弱,难以均匀分散在极性或非极性的溶剂中,因而石墨烯的应用受到限制。对石墨烯进行功能化可以调控其分子结构、电子能级和化学性质,不仅可以有效抑制石墨烯的团聚而且能够改善其在溶剂中的分散性和稳定性,从而实现石墨烯基材料的多元化应用。本文综述了近年来共价键和非共价键功能化石墨烯以及其复合材料在储能领域的研究进展,并对功能化石墨烯的发展前景进行了展望。     

褶皱石墨带的电子输运性质

利用递推格林函数方法,我们研究了褶皱石墨带的电子输运性质.当石墨带具有褶皱时,对于锯齿型石墨带,在第一个范霍夫奇点内,发现了电导隙和伴随着电导振荡的微带.然而,对于金属性扶手型石墨带,在费米能附近仅发现了电导隙,说明扶手型石墨带发生了金属-半导体转变.随着石墨带的褶皱加强,无论是锯齿型还是扶手型石墨带,平均电导都逐渐减小,并趋于0.结果有利于我们理解真实构型石墨带的电子输运性质,并且有助于设计基于石墨带的纳米器件.     

激光诱导三维网状石墨烯的一步法制备及应用

三维多孔石墨烯作为一种优异的石墨烯碳材料, 其独特的多孔结构使得材料在具有较大比表面积的同时还保持着足够高的电子迁移率和机械稳定性, 在电子器件中得到了广泛的应用. 本文介绍的激光诱导石墨烯是一种以一步法直接制备得到的三维网状石墨烯材料, 该技术将三维石墨烯的制备和图案化相结合, 无需进行湿化学反应处理, 制作方法更简便, 材料性能更优异. 目前研究主要集中在通过掺杂提高性能和利用转移法实现不同基底器件的制备. 激光诱导石墨烯自身特有的属性如多孔微纳米结构和大的比表面积等使其在超级电容器和传感器等领域拥有较高的应用价值.     

Tight binding description on the band gap opening of pyrene-dispersed graphene

Opening up a band gap in graphene holds a crucial significance in the realization of graphene-based electronics. Doping with organic molecules to alter the electronic properties of graphene is perceived as an effective band gap engineering approach. Using the tight binding model, we examined the band gap opening of monolayer graphene due to the adsorption of pyrene molecules on both of its sides. It was found that the breakdown of the sublattice symmetry in pyrene-dispersed graphene leads to a band gap of ～10 meV.