Graphene with excellent 2D characters has been required to expand their potentials for meeting applicational demands in recent years. As one avenue, several approaches for fablicating 3D porous graphene network structures have been developed to realize multi-functional graphene materials with 2D graphene. Here we overview characteristics of 3D porous graphene for future electronic device applications along with physical insights into "2D to 3D graphene", where the characters of 2D graphene such as massless Dirac fermions are well preserved. The present review thus summarizes recent 3D porous graphene studies with a perspective for providing new and board graphene electronic device applications.
Nanoporous materials represent a versatile solution for a number of applications ranging from sensing, energy applications, catalysis, drug delivery, and many others. The synergy between the outstanding properties of graphene with a three-dimensional porous structure, circumventing the limits of its 2D nature, constitutes therefore a breakthrough for many fields. We report the first three-dimensional growth of epitaxial graphene on a porousified crystalline 4H-SiC(0001). The wafer porosification is performed via a sequence of metal-assisted photochemical and photoelectrochemical etching in hyd…
This paper reports on the topological effects of three-dimensional (3D) porous graphene with tunable pore sizes and a preserved 2D graphene system of Dirac quasiparticles on its electrical properties. This 3D architecture is characterized by the intrinsic curvature of smoothly interconcnected graphene sheets without edges, the structures and properties of which can be controlled with its pore sizes. The impact of pore size on the electrical transport properties was investigated through magnetoresistance measurements. We observed that 3D graphene with small pores exhibits transitioning to weak …
In the framework of density functional theory (DFT) calculations we investigate the electronic and thermal properties of porous graphene (PG) structures passivated with halogen atoms as possible candidates for efficient thermoelectric devices. Armchair and zig-zag halogenated PG nanoribbons are analyzed comparatively. The electronic properties are consistent with the expected behavior for the two types of terminations, however with marked influences introduced by the different halogen atoms. Depending on the pore sizes and halogen type pseudo-gaps in the phononic band structure are visible in …
Sarin is a very lethal synthetic organophosphorated compound that inhibits the nervous system muscle control. Although not used as a chemical weapon anymore, it still worries the authorities regarding possible use by terrorists. Most of the studies about sarin are theoretical/computational due to its high lethality and are concentrated in its detection and degradation. Few studies are about air filtration from sarin gas. Here, the potential of graphene oxide-based membranes to filter air from sarin/air mixtures is investigated by classical molecular dynamics simulations. Membranes formed by on…
Flexible pressure sensors are an attractive area of research due to their potential applications in biomedical sensing and wearable devices. Among flexible and wearable pressure sensors, capacitive pressure sensors show significant advantages, owing to their potential low cost, ultra-low power consumption, tolerance to temperature variations, high sensitivity, and low hysteresis. In this work, we develop capacitive flexible pressure sensors using graphene based conductive foams. In these soft and porous conductive foams, graphene is present either as a coating of the pores in the foam, inside …
The use of a novel three-dimensional graphene structure allows circumventing the limitations of the two-dimensional nature of graphene and its application in hydrogen absorption. Here we investigate hydrogen-bonding on monolayer graphene conformally grown via the epitaxial growth method on the (0001) face of a porousified 4H-SiC wafer. Hydrogen absorption is studied via Thermal Desorption Spectroscopy (TDS), exposing the samples to either atomic (D) or molecular (D2) deuterium. The graphene growth temperature, hydrogen exposure temperature, and the morphology of the structure are investigated …
Multiproperty Atomistic Characterization of a Synthesized Pyrazinic Nitrogen-Doped Porous Armchair Graphene Nanoribbon
Laboratory of NanoEngineering, College of Technology, University of Brasília（巴西利亚大学技术学院纳米工程实验室）；Graduate Program in Physics, Institute of Physics, University of Brasília（巴西利亚大学物理研究所物理研究生项目）；Center for Agri-Food Science and Technology, Federal University of Campina Grande（坎皮纳格兰德联邦大学农业食品科学与技术中心）；Institute of Physics, Federal University of Rio Grande do Norte（北里奥格兰德联邦大学物理研究所）；Department of Applied Physics, Gleb Wataghin Institute of Physics, University of Campinas（坎皮纳斯大学格列布·瓦塔金物理研究所应用物理系）；Department of Electrical Engineering, College of Technology, University of Brasília（巴西利亚大学技术学院电气工程系）
Engineering of SnO2-Graphene Oxide Nano-Heterojunctions for Selective Room-temperature Chemical Sensing and Optoelectronic Devices
Università degli Studi di Milano（米兰大学）；Consorzio Interuniversitario Nazionale per la Scienza e Tecnologia dei Materiali (INSTM)（意大利国家材料科学与技术大学联盟）；The Australian National University（澳大利亚国立大学）
Cyclo-Graphyne: A Highly Porous and Semimetallic 2D Carbon Allotrope with Dirac Cones
Federal University of Parana（巴拉那联邦大学）；Interdisciplinary Center for Science, Technology, and Innovation (CICTI), Federal University of Parana（巴拉那联邦大学跨学科科学与技术创新中心）
Lithium and sodium decorated PHE-graphene for high capacity hydrogen storage: A DFT and GCMC study
Jiangsu Provincial Engineering Research Center of Low-Dimensional Physics and New Energy, College of Science, Nanjing University of Posts and Telecommunications（南京邮电大学理学院低维物理与新能源江苏省工程研究中心）
With the increase in demand of electrical energy storage devices such as batteries and supercapacitors, considerable effort is being put to increase the efficiency and applications of current technology while keeping it sustainable. Keeping this in mind we have persued the preparation and charatization of waste biomass derived carbon powders as supercapacitor/battery electrodes. Additionally, we have evaluated the performance of such carbons in the presence of an external magnetic field as we expect the graphene like structures to possess intrinsic magnetic nature. Here, we report the valoriza…
Graphene as a two-dimensional (2D) topological Dirac semimetal has attracted much attention for its outstanding properties and potential applications. However, three-dimensional (3D) topological semimetals for carbon materials are still rare. Searching for such materials with salient physics has become a new direction for carbon research. Here, using first-principles calculations and tight-binding modeling, we study three types of 3D graphene networks whose properties inherit those of Dirac electrons in graphene. In the band structures of these materials, two flat Weyl surfaces appear in the B…
Graphene has extraordinary mechanical and electronic properties, making it a promising material for membrane based nanoelectromechanical systems (NEMS). Here, chemical-vapor-deposited graphene is transferred onto target substrates to suspend it over cavities and trenches for pressure-sensor applications. The development of such devices requires suitable metrology methods, i.e., large-scale characterization techniques, to confirm and analyze successful graphene transfer with intact suspended graphene membranes. We propose fast and noninvasive Raman spectroscopy mapping to distinguish between fr…
Unit cell of graphene on Ru(0001): a 25 x 25 supercell with 1250 carbon atoms
使用表面X射线衍射研究了Ru（0001）上单层石墨烯的结构。已经确定了令人惊讶的超结构，其中25 X 25石墨烯晶胞位于Ru的23 X 23晶胞上。每个超晶胞包含2 × 2个晶体学上不等价的亚晶胞。超结构棒中的强强度振荡表明Ru衬底也显著地波纹化为几个单层，并且石墨烯和Ru之间的键合是强的，并且不能由范德华键引起。从Ru衬底到石墨烯的电荷转移扩展并削弱了C-C键，这有助于适应面内拉伸应力。这种超结构的阐明为石墨烯作为纳米团簇阵列模板的潜在应用提供了重要信息。
Graphene has recently attracted much interest as a material for flexible, transparent electrodes or active layers in electronic and photonic devices. However, realization of such graphene-based devices is limited due to difficulties in obtaining patterned graphene monolayers on top of materials that are degraded when exposed to a high-temperature or wet process. We demonstrate a low-temperature, dry process capable of transfer-printing a patterned graphene monolayer grown on Cu foil onto a target substrate using an elastomeric stamp. A challenge in realizing this is to obtain a high-quality gr…
In this work, three novel porous carbon-nitride nanosheets with C7N6, C9N4 and C10N3 stoichiometries are predicted. First-principles simulations were accordingly employed to evaluate stability and explore the mechanical, electronic and optical properties. Phonon dispersions confirm the dynamical stability of all predicted nanosheets. Nonetheless, ab-initio molecular dynamics results indicate that only C7N6 and C9N4 are thermally stable. C7N6, C9N4 and C10N3 nanosheets were predicted to exhibit high elastic modulus of 212, 202 and 208 N/m and maximum tensile strengths of 14.1, 22.4 and 15.8 N/m…
Phonon size effects induce ballistic transport in nanomaterials, challenging Fourier's law. Nondiffusive heat transport is captured by the Peierls-Boltzmann transport equation (BTE), commonly solved under the relaxation time approximation (RTA), which assumes diagonal scattering operator. Although the RTA is accurate for many relevant materials over a wide range of temperatures, such as silicon, it underpredicts thermal transport in most two-dimensional (2D) systems, notoriously graphene. Here we present a formalism, based on the BTE with the full collision matrix, for computing the effective …
We report the fabrication and characterization of a simple gate-free graphene device as a pH sensor. The graphene sheets are made by mechanical exfoliation. Platinum contact electrodes are fabricated with a mask-free process using focused ion beam, and then expanded by silver paint. Annealing is used to improve the electrical contact. The experiment on the fabricated graphene device shows that the resistance of the device decreases linearly with increasing pH values (in the range of 4-10)in the surrounding liquid environment. The resolution achieved in our experiments is approximately 0.3 pH i…
Aqueous asymmetric electrochemical capacitor, with their high power density and superior cycle stability in comparison to conventional batteries, are presently considered as the most promising contender for energy storage. However, fabricating an electrode material and choosing a suitable aqueous electrolyte are vital in developing an electrochemical capacitor device with high charge storage capacity. Herein, we report a feasible method to synthesize MnO2/Vertical graphene nanosheets (VGN) and Fe2O3/VGN as positive and negative electrodes, respectively. The surface of VGN skeleton is independe…
A new kind of three-dimensional carbon allotropes, termed carbon honeycomb (CHC), has recently been synthesized [PRL 116, 055501 (2016)]. Based on the experimental results, a family of graphene networks are constructed, and their electronic and phonon properties are calculated by using first principles methods. All networks are porous metal with two types of electron transport channels along the honeycomb axis and they are isolated from each other: one type of channels is originated from the orbital interactions of the carbon zigzag chains and is topologically protected, while the other type o…
The broadband and ultrafast photoresponse of graphene has been extensively studied in recent years, although the photoexcited carrier dynamics is still far from being completely understood. Different experimental approaches imply either one of two fundamentally different scattering mechanisms for hot electrons. One is high-energy optical phonons, while the other is disorder-driven supercollisions with acoustic phonons. However, the concurrent relaxation via both optical and acoustic phonons has not been considered so far, hindering the interpretation of different experiments within a unified f…
Reports of metallic behavior in two-dimensional (2D) systems such as high mobility metal-oxide field effect transistors, insulating oxide interfaces, graphene, and MoS2 have challenged the well-known prediction of Abrahams, et al. that all 2D systems must be insulating. The existence of a metallic state for such a wide range of 2D systems thus reveals a wide gap in our understanding of 2D transport that has become more important as research in 2D systems expands. A key to understanding the 2D metallic state is the metal-insulator transition (MIT). In this report, we demonstrate the existence o…
