Graphene’s cousin: the present and future of graphane
© Zhou et al.; licensee Springer. 2014
Received: 16 August 2013
Accepted: 7 December 2013
Published: 13 January 2014
Skip to main content
© Zhou et al.; licensee Springer. 2014
Received: 16 August 2013
Accepted: 7 December 2013
Published: 13 January 2014
The so-called graphane is a fully hydrogenated form of graphene. Because it is fully hydrogenated, graphane is expected to have a wide bandgap and is theoretically an electrical insulator. The transition from graphene to graphane is that of an electrical conductor, to a semiconductor, and ultimately to an electrical insulator. This unique characteristic of graphane has recently gained both academic and industrial interest. Towards the end of developing novel applications of this important class of nanoscale material, computational modeling work has been carried out by a number of theoreticians to predict the structures and electronic properties of graphane. At the same time, experimental evidence has emerged to support the proposed structure of graphane. This review article covers the important aspects of graphane including its theoretically predicted structures, properties, fabrication methods, as well as its potential applications.
Graphene has unique properties with tremendous potential applications, such as chemical sensors [36, 37], nanoelectronic devices , hydrogen storage systems , or polymer nanocomposites . Graphene could be considered as a prototypical material to study the properties of other two-dimensional nanosystems. Several two-dimensional structures have been explored in the literature [41, 42]. Graphene-like two-dimensional silicon carbide [43, 44], silicon [45, 46], germanium [47, 48], boron nitride [49, 50], and zinc oxide  have been explored in the literature.
This review article is intended to focus on the fabrication and structure features of graphane (or graphane-like [54, 55]) and the potential application of graphane (or graphane-like) and properties. It covers the latest developments and new perspectives of graphane-based hydrogen storage  and transistor  with the special discussions on the merits and limitations of the material. Except for presenting a brief overview of the synthesis processes of single-layer graphane, graphane-like, graphene-graphane, graphane nanoribbons [58, 59], respectively, the structure features of graphane, particularly related to hydrogen storage and transistor, have been discussed.
Predicted energy per atom in unit cell, cell parameter values, and carbon-carbon distances for graphene and chair-like and boat-like graphane, respectively
Energy (Ha) (1 Ha = 27.211 eV)
C-C bond length (Ả)
Dora et al.  used density functional theory, which studies the density of states in monolayer graphene (MLG) and bilayer graphene (BLG) at low energies in the presence of a random symmetry-breaking potential. And it had a breaking potential, which opens a uniform gap, and a random symmetry-breaking potential also created tails in the density of states.
The transition from graphene to graphane is that of an electrical conductor to a semiconductor and ultimately to an insulator, which is dependent upon the degree of hydrogenation.
In 2009, the graphane was synthesized by exposing the single-layer graphene to a hydrogen plasma .
SG and LC
LCH and LCC
P-3 m1 (164),
H: (0.3333, 0.6667, 0.5893)
a = b = 2.504; c = 15.0
C: (0.3333, 0.6667, 0.5153)
H1: (0.4328, 0.1235, 0.2500)
a = 15; b = 7.681; c = 2.544
C1: (0.4981, 0.0563, 0.2500)
C1-C1: 1.539; C1-C2: 1.541
H2: (0.6364, 0.1190, 0.2500)
C2: (0.5731, 0.1934, 0.2500)
C2-C2: 1.540; C2-C1: 1.541
H: (0.0000, 0.3983, 0.5085)
a = 2.549; b = 15.0; c = 3.828
C: (0.0000, 0.3639, 0.4620)
H: (0.5000, 0.2562, 0.5922)
a = 15.0; b = 4.585; c = 4.328
C: (0.4622, 0.5939, 0.4317)
C-C: 1.542, 1.548, 1.573
H: (0.3987, 0.4932, 0.5036)
a = 2.529; b = 4.309; c = 15.0
C: (0.5000, 0.1822, 0.5216)
C-C: 1.537; 1.570
H: (0.1215, 0.4079, 0.5609)
a = 4.417; b = 15.0; c = 4.987
C: (0.0904, 0.4788, 0.6154)
C-C: 1.542; 1.548; 1.562
Mechanical parameters of graphene and graphane nanosheets
Fcr, N (×10-9)
σcr, N/m2 (×109)
0.61 σ (0.54 e)
0.57 σ (0.52 e)
Peng et al.  investigated the effect of the hydrogenation of graphene to graphane on its mechanical properties using first-principles calculations based on the density functional theory. The results show that graphane exhibits a nonlinear elastic deformation up to an ultimate strain, which is 0.17, 0.25, and 0.23 for armchair, zigzag, and biaxial directions, respectively, and also have a relatively low in-plane stiffness of 242 N/m2, which is about 2/3 of that of graphene, and a very small Poisson ratio of 0.078, 44% of that of graphene. There has been a good idea which states that such unique mechanical properties make the graphane a good candidate for materials used in building the tubes or pipelines that transfer materials in high speed under applied high pressure.
Ao et al.  used the density functional theory to investigate the thermal stability of graphene/graphane nanoribbons (GGNRs). They found that the energy barriers for the diffusion of hydrogen atoms on the zigzag and armchair interfaces of GGNRs were 2.86 and 3.17 eV, respectively, while the diffusion barrier of an isolated H atom on pristine graphene was only approximately 0.3 eV. These results unambiguously demonstrated that the thermal stability of GGNRs could be enhanced significantly by increasing the hydrogen diffusion barriers through graphene/graphane interface engineering. Similarly, Costamagna et al.  used large scale atomistic simulations to study the thermal fluctuations of graphane. Rajabpour et al.  used nonequilibrium molecular dynamics simulations to investigate the thermal conductivity of hybrid graphene-graphane nanoribbons. Neek-Amal and Peeters  used atomistic simulations to determine the roughness and the thermal properties of a suspended graphane sheet. Compared with graphene, graphane had a larger thermal contraction, a wide range corresponding to length scales in the range 30 to 125 Ǻ at room temperature. The estimated heat capacity was 29.32 ± 0.23 J/mol . K which was 14.8% larger than the one for graphene.
In addition, graphane or graphane-like structures have magnetic properties and thermal performance. Neek-Amal and Peeters  investigated the lattice thermal properties of graphane, including thermal contraction, roughness, and heat capacity. Results showed that the roughness, amplitude, and wave lengths of the ripples were very different. The thermal contraction effect of graphane is larger than for graphene. Above 1,500 K, graphane is buckled and starts to lose H atoms at the edges of the membrane. Roughness of graphane is larger than that of graphene and the roughness exponent in graphene decreases versus temperature (from 1.2 to 1.0), while for graphane, it stays around 1.0 implying random uncorrelated roughness. Heat capacity of graphane is found to be 14.8%, which is larger than that of graphene.
In Universal optical properties of graphane nanoribbons: A first-principles study by Yang et al. , the results indicated that the optical properties of graphane nanoribbons were independent of their edge shapes and widths. Their unique optical properties make graphane nanoribbons suitable for various applications in nanoscale optical and optoelectronic devices.
León and Pacheco  studied on the electronic and dynamical properties of a molecular wire consisting of molecules with structures of graphane and a graphane nanoribbon. Bubin and Varga  had discussed the response of graphene and graphane fragments to strong femtosecond laser pulses and the results showed that the hydrogenation was controllable by strong femtosecond laser pulses. Before that, Chandrachud et al.  had been systematic studied on electronic structure from graphene to graphane. Simultaneously, their results revealed that it was possible to design a pattern of hydrogenation so as to yield a semiconducting sheet with a bandgap much lower than that of graphane. Nanyang Technological University's Hwee Ling Poh et al.  investigated the electrochemical behavior of hydrogenated graphene synthesized under various pressures and temperatures for comparison and showed that hydrogenation of graphene (towards graphane) resulting in a decrease in the observed heterogeneous electron transfer rates as measured by cyclic voltammetry and an increase in the charge transfer resistance as measured by impedance spectroscopy as compared to graphene.
Lee and Grossman  used the first-principles calculations based on the density functional theory (DFT) to explore the magnetic properties of graphene-graphane superlattices with zigzag interfaces and separately varying widths. The results displayed that the magnetic properties of the superlattices were entirely determined by the graphene region due to the π character of the spin density. It was a potential for future spintronics applications with a variable spin-current density. Berashevich and Chakraborty , Schmidt and Loss , Şahin et al. , and Hernández et al.  also did the related research on the magnetism of graphane, such as sustained ferromagnetism, tunable edge magnetism, magnetization of graphane by dehydrogenation, graphane nanoribbons magnetic, and so on.
Graphene can be functionalized by varied methods. Haldar et al.  used Fe to replace the hydrogen on the plane of graphane. The work showed that the response of the two channels, the armchair and the zigzag channels, were different. Hussain  and AlZahrani  reported the strain induced lithium functionalized graphane as a high-capacity hydrogen storage material and used the manganese adsorption graphene and graphane as magnetic materials. Graphane's derivatives were not only just about functionalization of the surface atoms, but also by changing the substrate atoms to achieve its function. For example, Lu et al. , from the University of Science and Technology of China, studied the chemical modification with –OH or -NH2 group on planar polysilane and graphane. Hőltzl et al. , Artyukhov and Chernozatonskii , Bianco , Garcia et al.  reported separately in cis-polyacetylene and graphane, carbon monofluoride and graphane, germanium graphane analogue, group-IV graphene, graphane-like nanosheets, and so on.
Therefore, we can fabricate many derivatives of graphane by changing the substrate atoms (like C, Si, Ge, P) and the surface atoms (like H, –OH, -NH2, He, Li, Fe, Mn, and all the VII A element).
As mentioned in many articles, graphane or graphane-like materials can be applied in many fields. Nechae  considered the thermodynamic and experimental backgrounds of the condensed hydrogen storage problem, and an effective method was put forward to produce a high-density hydrogen carrier which was hydrogen intercalation in carbonaceous nanomaterials at relevant temperatures and pressures (at the cost of the hydrogen association energy). The result displayed the intercalated solid molecular hydrogen in graphane-like nanofibers (17 wt.% H2). Compared with the US Department of Energy (DOE)'s strategic objectives for the year 2015 which include a minimum 'gravimetric’ capacity (weight of stored H2/system weight) of 9.0 wt.% of reversible hydrogen and a 'volumetric’ capacity (density) of 0.081 g(H2)/cm3(system), graphane-like nanofibers are much more acceptable and efficient hydrogen storage technology.
Gharekhanlou et al.  reported that graphane materials can be used as bipolar transistor. Cudazzo et al.  provided an exact analytic form of the two-dimensional screened potential. Gharekhanlou et al.  introduced a 2D p-n junction based on graphane with hydrogen deficiency to reduce the bandgap effectively. And using basic analysis has shown that within the approximation of Shockley law of junctions, an exponential ideal I-V characteristic is expectable. This broadens the graphane or graphane-like application in transistor devices. Savini et al.  used p-doped graphane to fabricate a prototype high-Tc electron–phonon superconductor, which has Tc as high as 150 K for a 1-nm nanowire, higher than copper oxides. Loktev and Turkowski  and Kristoffel and Rägo  considered the superconducting properties of multilayer graphane by taking into account the fluctuations of the order parameter. The result showed that in the single-layer case, the BKT critical temperature which corresponds to the vortex SC is equal to the MF temperature 100 K beginning from a rather low value of doping less than 0.01. And they estimated that the critical temperature may reach values 150 K, which is significantly higher than the maximal temperature under ambient pressure in cuprates. Nechaev  said that the high-density hydrogen carrier intercalation in graphane-like nanostructures can be used in fuel cell-powered vehicles. Hussian et al. [104, 105] used polylithiated (OLi2) functionalized graphane as a potential hydrogen storage material, the storage capacity to achieve 12.9 wt.%.
Exceptional physical properties, chemical tunability, potential electronic, and transistor applications of graphane have definitely gained the interest of materials and electronics researchers. This review article is intended to focus on the fabrication and structural features of graphane (or graphane-like material) and the potential applications of graphane (or graphane-like) and graphane-based nanocomposites. It covers the latest advancement and new perspectives of graphane as a potential material for hydrogen storage and transistor with the special discussions on the merits and limitations of the material. After presenting a brief overview of the synthesis processes of single-layer graphane, graphane-like, graphene-graphane, and graphane nanoribbons, the structure features of graphane, particularly related to the hydrogen storage and transistor, have been discussed.
By reversible hydrogenation, one can make the graphene material from conductor to insulator. Thus, we can control the degree of hydrogenation to modulate the conductive properties. Through this process, graphene-graphane mixed structures offer greater possibilities for the manipulation of the material's semiconducting properties and they can be potentially applied in the field of transistor, electron–phonon superconductor and others applications. The behavior of graphene to graphane or graphane to graphene is the progress of hydrogen energy storage or release. Graphane or graphane-like material can be used as hydrogen storage material for fuel cells. Because of its wide range of conductivity, it can be used for nanosensors with exceptional sensitivity.
Certainly, most notably we can fabricate many derivatives of graphane by changing the substrate atoms (like C, Si, Ge, P, S) and the surface atoms (like H, –OH, -NH2, He, Li, Fe, Mn, Ag, and all the VII A element) so as to promote its application value and expand the application field.
This work was supported by the Shanghai Major Construction Projects (11XK18B, XKCZ1205), Shanghai Science and Technology Capacity Building Project Local Universities (11490501500), and Shanghai University of Engineering Science Innovation Project (13KY0410).
This article is published under license to BioMed Central Ltd. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.