In 2014, three Japanese, who invention of efficient blue-light LED, won The Nobel Prize in Physics.This marks that commercial gallium nitride (GaN) based Light-emitting Diode (LED) technology has matured. LED has been widely used because of its high efficiency, small size, environmental protection, and other excellent performance.LED is gradually becoming the mainstream of lighting sources, will lighting the future of mankind.In 2010, Two scientists who discover the graphene won The Nobel Prize in Physics. It ignited the enthusiasm of the scientific and technological research on graphene. Graphene is a two-dimensional crystal structure consisted of the hexagonal honeycomb lattice. It has a unique and excellent properties, especially excellent in the optical and electrical properties, so scientists research focuses on the optical and electrical properties of graphene, graphene want to play an active role in the photovoltaic sector and will lead mankind to era of graphene.This thesis, investigations on the application of graphene in GaN LED, aim to find some graphene’s applications in GaN LED. Our exploratory research work consist of direct growth of graphene on GaN, growth of free-standing GaN by using stacked graphene, the wettability of graphene, the preparation for GaN LED with graphene wetting layer and its performance analysis. The main work is as follows: (1) Direct growth of graphene on GaN LED without extra catalyst has been achieved. When methane as a carbon source in the process of direct growth of graphene transparent electrodes on GaN LED, GaN LED is almost no thermal degradation; graphene growth condition is optimized; possible mechanism is proposed: the Ga atoms on GaN surface is catalyst. Considering the acetylene as a carbon source can reduce the growth temperature, thereby, it can reduce the influence to the performance of GaN LED in the graphene growth process. the effect of carbon source, growth temperature and pressure are also studied.(2) Self lift-off GaN epitaxial film has been fabricated by using one graphene stacking on another graphene as sacrificial layer. We note the force between two stacking graphene is physical adsorption in the process of graphene transfer. When the stress in heteroepitaxy over come it, the purpose of lift-off epitaxy can be achieved. The process of self lift-off is analysed and the principle of self lift-off is verifed. The influences of stacking graphene with different fluorination power on the quality of free-standing GaN are compared. The thinner free-standing GaN substrate and the reusable sapphire substrate reduced the cost of GaN homogeneous substrate. It is a very promising technique for preparing GaN homogeneous substrate.(3) Investigations on the wettability of graphene and the graphene nanodrums power.When the morphology of graphene fit to the morphology of substrate, the graphene wettability is partially transparent, no matter plane substrate or patterned substrate. The performances of graphene nondrums were tested. The experiment shows that the direction of induced current is determined by the direction of graphene nanodrums movement, the size of the induced current is closely related to amplitude of graphene. We propose a possible mechanism: electromagnetic induction from the magnetic graphene edges.(4) A transfer-free graphene was grown on c-plane sapphire, this provide a new method for fabricating the graphene covered c-plane sapphire. The advantages of graphene as wetting layer to epitaxial growth III-nitride (III-N): The increase in the migration of metal atoms on the graphene, release stress in epitaxial layer which is next to graphene. GaN LED with graphene wetting layer was prepared and its performance is analysed. The graphene wetting layer increased the surface roughness of the substrate, which is similar to the role of nano-patterned substrate, it can increase the light extraction efficiency. The LED with graphene wetting layer improves the electrical perf
In recent years, with the development of nano-science and nanotechnology, the application of nano technology in people's life becomes more and more popular, nano materials have extensive applications in the field of biology and chemistry. Carbon nano-materials, with thire unique physical and chemical properties, have many successful applications in many fields, especially in the biomedical and material chemistry fields. For example, fullerenes and graphene derivatives can well inhibit the proliferation of tumor cells. However, the molecular-level mechanisms of the anti-tumor activity are still unknown. Therefore, we studied the interaction mechanism between carbon nano-materials and biological macromolecules using the molecular dynamics simulation. The study has two parts. The first part is the interaction of fullerenes and thire hydroxyl derivatives with tumor necrosis factor (TNF-a) and the further rational drug design based on these calculations. The secondpart is the interaction between graphene oxide and cytochrome c.1 The interaction between TNF-a and fullerene or fullerene derivatives Based on molecular dynamics simulation of the interaction between fullerenes and their derivatives with TNF-a, we found that these materials’ binding sites with TNF-a were similar to small molecule inhibitors SPD304 that was previously reported. All were combined in the middle of the binding site of the TNF-a dimer. By the calculation of binding free energy, we found several kinds of carbon nanomaterials C60, C60 (OH) 12, Gd@C60, C82, C82 (OH)12, Gd@C82, Gd@C82(OH)13 and Gd@C82(OH)21 have better inhibiting ability with the TNF-a than the previously reported small molecules. 2 Graphene or its oxide interacting with cytochrome CThrough studying the interaction mechanism between graphene or graphene oxide with cytochrome c, we found that graphene oxide and cytochrome c have strong interaction. The increase of graphene’s oxidation degree of enhances the interaction between them. Through molecular dynamics simulation with the grapheme oxide fixed, we found that graphene oxidation could change the structure of cytochrome c. Through studying the interaction mechanism between double-layer graphene oxide with cytochrome c, we found that the random coil structure of cytochrome c had a stronger interaction with graphene oxide. The above result suggests that graphene oxide has strong influence on the structure of cytochrome c; and that random coil structure plays a main role in their interaction.
Two dimensional atomic crystal materials have only single or several atomic layers. Graphene is the first atomic cystal materials obtained from experiement. It has plenty of peculiar properties. Inspired by the research on graphene, other two-dimensional atomic crystal materials also receive considerable attentions. Now researchers have found and synthesized many two dimensional layer materials, such as h-BN, silicene, germanene, transition metal dichalcogenides (TMDs), black phosphorus, and so on. Different two dimensional materials have different properties. Such diversity of properties provide plenty of research materials for our recent industry. Our main ideas in this thesis are 1) exploring novel two dimensional atomic crystal materials ;2) exploring, and modulating their electronic structures, looking for their potential applications according to their properties; By combining density functional calculation (DFT) with scanning tunneling microscopy (STM) and spectroscopy (STS) measurments, we have the following research findings: 1. Germanene is also a single atomic layer two dimensional materials similar to graphene and silicene. It also has plenty of peculiar properties, and is predicted to have applications in spin quantum Hall effect. Here by combining experimental measurments such as STM, LEED, and XPS with DFT calculations, we investigated the synthesis of monolayer germanene on Pt(111) surface. Geomentric structure calculation and STM simulation confirms the formation of germanene, which is a buckled structure. 2. TMDs (MX2) are a series of materials, composed of M (e.g., M=Mo, W, Nb, Re) and X (e.g., X=S, Se, Te). Among many TMDs, PtSe2 is a less studied layer material. Bulk PtSe2 is metallic. In addition, monolayer PtSe2 is semiconducting with an indirect band gap. Previous studies predicted that monolayer PtSe2 also has great potential applications in electronic, optoelectronic, spintronics, and catalysis areas. However, how to grow large area monolayer PtSe2 with high quality is still a great challenge. Its indirct band gap also limits its application in photoillumination areas. By combining STM and other experimental approaches with DFT calculations, we investigated the synthsis of monolayer PtSe2 on Pt(111) suface. Our DFT calculations also predicted that by applying appropriate strains we can modulate the band structure of monolayer PtSe2, inducing a band gap transition from an indirect band gap to a direct band gap. Strain also can modulated the size of the energy gap of monolayer PtSe2. Our studies provides an effective basement for future applications of monolayer PtSe2. 3. Ferromagnetism and half-metallic two dimensional materials have potential applications in spinstronics. By using first-principles calculations, we studied the geometric, electronic, and magnetic properties of 3d transition-metal randomly doped graphyene nanoribbon. We predicted that at a range of concentrations from 2% to 5% (from medium to high concentration), transition metal doping can induce the ferromagnetism and half-metaillicity of graphyene nanoribbon. Transmission calculations shows that these materials have perfect spin filter effect. The high spin-polarized current can be preserved up to a large bias voltage. 4. Kondo effect is caused by the scattering of conduction electrons in metal by magnetic impurities. The Kondo temperature is proportion to the density of states of substrate near Fermi energy. Theory predicted that by applying a electric field we can modulate the interaction between graphene and the impurity magnetic atoms, thus control the on and off states of Kondo effect. Combining STM and DFT calculations, we first observed and explained the Kondo effect of Co atoms adsorbed on graphene/R(0001) surface. We also find that the ripple of graphene on Ru(0001) can periodically modulate the Kondo effect of Co atoms. Calculations of a Mn adatom and a Mn dimer on graphene/Ru(0001) show that Mn adatoms also tend
After the table two-dimensional material is proved by experiment, scientists pay more attention to the graphene due to the intrinsic physical and chemical property. Integrating graphene into the modern quantum devices and circuits and get a graphene based magnetic devices is one of the important research topics. The magnetism of graphene maily comes from its partially occupied electronic state, like defect or vacancy. However, the magnetism is still too weak to be applied. To get a graphene-based magnetic device, scientists turn to the magnetic atoms on graphene and investigate the spin state of magnetic adatom and spin coupling in magnetic cluster. This dissertation will focus on investigating the substrate induced modulation of spin state of magnetic adatoms and spin coupling in magnetic cluster on graphene surface. In Chapter one, the history of magnetic storage devices will be introduced briefly. People want to increase the storage intensity by using spin state of atom and spin coupling in cluster. Chapter two displays the building and testing process of an mk-9+2+2T-UHV-STM system, including design the damping platform, background knowledge of the system. Combined with high magnetic field, the high spatial resolution and energy resolution make it possible to investigate the spin information in magnetic atom and cluster by means of SES at the atomic scale. Chapter three presents the dI/dV spectra of two-impurity Kondo state when changing the relative lateral distance in weak coupling region. A high TK Kondo singlet will be formed due to the strong coupling between the Co adatom and Ru(0001) surface; while a low TK Kondo state will be generated at the STM tip after adsorbing a Co atom on the STM apex. By doing STS gradually closer to the center of the substrate Co adatom, the intensity of dI/dV specta will decreases first and afterwards increases, leading to a minimum peak intensity in a series of data. The relationship between the relative lateral distance and q factor in Fano formula will be achieved by fitting the STM tunneling function. The weight in each tunneling channel will alter when moving Kondo tip in the lateral direction, leading to a variable q factor. Therefore, we obtain a new way to investigate the space variation of the tunneling matrix elements for the tunneling process in weakly coupled region. The constructed 2IKS is important to study the electronic transport, especially the transport properties in magnetic quantum dot devices. In Chapter four, Kondo effect of cobalt adatoms on a graphene monolayer controlled by substrate-induced ripples is investigated by using low temperature vector magnetic field STM/STS. Moiré pattern of graphene on Ru(0001) surface will be used to tune the DOS of graphene and magnetic moment of Co adatom. First experiment observation of site-specific Kondo effect for magnetic impurity on graphene is found. Theory calculations demonstrate that the modulations of DOS of graphene, exchange coupling between Co and graphene, magnetic moment of Co are caused by the diverse distance between graphene and Ru substrate, which will further influence site-specific Kondo effect. Mn adatom on graphene epitaxial growth on different transition metal are also investigated. Different from the strong coupling interaction between graphene and Ru(0001), graphene on Pt(111) surface behavior like a nearly free-standing one due to the weak coupling. Although magnetic anisotropy with out-of-plane hard axis of Co adatom on graphene/Pt(111) has been reported by other group, we find that Mn adatom on graphene/Pt(111) will manifest a low TK Kondo resonance. A systemic research has finished for the study of spin state of magnetic adatom on epitaxial graphene after changing the magnetic element and metal substrate. Chapter five mainly focus on the spin coupling in magnetic cluster on graphene/Ru(0001) surface. The hexagonal lattice will provide an ideal template for constructing nano spin magnetic. By means
With rapid development of electronic devices, flexible or bendable devices have become an important trend due to their advantages of portable, wearable and non-fragile nature,. Among them, flexible photoelectronic devices, such as flexible solar cells, flexible organic liquid crystal displays, flexible touch panels, flexible light-emitting diodes, all drew great attention of researchers and manufacturers. An important component of flexible photoelectronic device is the flexible transparent conductive films, which are still mainly fabricated with indium tin oxide(ITO) materials. However, as a kind of metal oxide, ITO suffers from its brittle nature, thus it can not meet the need of flexible applications. At the same time, as a rare element, indium is included in this material as a key component, whose price is quite high, thus not beneficial for lowering the production cost. Consequently, to search for a low-cost mass-productive and high-performance transparent conductive substitute material for ITO is still a vital issue in this research area. At present, some other transparent conductive materials, including conductive polymer (PEDOT:PSS), carbon nanotubes (CNTs), graphene, metal nanostructures (metal nanowires, metal thin films and metal nanogrids) and their hybrid materials are also under studying. Among them, graphene is one of the most competitive candidates for flexible transparent conductive films with its unique two-dimentional structure and outstanding chemical and physical properties. This thesis is mostly focused on the preparation of graphene-based flexible transparent conductive films, especially their low-cost and continuously mass productions. Firstly, chemical vapour deposition (CVD) method is applied to grow graphene on copper foil, and the influence of growth condition to the quality and appearance of graphene is systematically studied. Then several different substrates are used for the growth of graphene, and CVD growth conditions are comprehensively studied. To replace the complex transfer step within, a flexible transparent mesh substrate is directly used as the CVD substrate. Through electrospinning technique, self-standing ultrathin nanofiber mesh containing metal and silica are prepared as the CVD substrate. And after graphene deposition, flexible graphene nanofiber mesh films with T of 80% and Rs of 5-10 KΩ sq-1are obtained, and successfully applied into electrochromic devices. Secondly, a much cheaper route for roll-to-roll preparation of large-area high-quality reduced graphene oxide (rGO) thin films is developed. First, the GO material is optimized by selecting low oxidized GO for film fabrication. Then, a Sn2+/ethanol reduction system and a fast coating-drying reduction technique are developed, which can complete the reduction of GO film under mild condition in less than 5 minutes. The optical and conductive performances (T ~ 91% and Rs ~ 3.6 KΩ sq-1) are relatively superior compared with other rGO based thin films. It’s also observed that the lower valent metal ions can be transformed to higher valent metal ions after reduction, which works as p-type dopant for rGO films, and can also be one of the reasons for the superior conductive performances. Because this is a very fast and safe method , it is then applied into the roll-to-roll preparation of rGO film, and large-area rGO flexible transparent conductive films are successfully obtained. And these films are further been fabricated into flexible resistive touch panel devices and flexible transparent wires. Thirdly, graphene-based hybrid film and patterned graphene film are prepared. On the basis of the above method (Sn2+/ethanol reduction system) for preparing rGO film, it’s observed that if the metal oxide product on the rGO film is not removed, continuous crackles on the film surface form naturally after a short-time mild heating. And this can work as a metal deposition template to prepare rGO/metal mesh hybrid films, which further improv
Supercapacitors have attracted a great deal of attention from both industry and academia due to their high power density, superior rate capability, rapid charging/discharging rate, long cycle life. The performance of supercapacitors is controlled by electrode materials. Porous carbon materials are considered to be the most prospective material in the new century, due to their high specific surface area, favorable properties such as adjustable particle size, large surface area, high stability in both acidic and basic environments, controlled porous structure and good electrochemical properties. Compared with different morphology materials, materials with a spherical morphology have the superiorities of high packing density and perfect particle mobility which lead to high volumetric power and energy density.Using cheap phenolic resin as raw material, activated carbon and graphene-activated carbon spheres were prepared by a simple inverse emulsion polymerization without any emulsifier and then followed by heat treatment under nitrogen atmosphere at 800 ℃. The effects of synthesis conditions (stirring speed, the specie and ratio of oil phase and solvent) on the formation of spheres and the diameter of spheres were investigated in detail and the possible mechanism of the formation of spheres was proposed in this work. The effects of synthesis factors on the morphology and structure of carbon spheres were characterized by SEM, XRD, Raman, elemental analysis, and N2 adsorption/desorption isotherms measurement, respectively. The obtained carbon spheres were utilized as supercapacitor electrode materials. The effects of pore structure on electrochemical performance were investigated. Main research contents are as follows:(1) Using Industrial phenolic resin/phenolic resin–graphene oxide as dispersed phase, mixed silicone oil and heat transfer oil or heat transfer oil without emulsifier as continuous phase, phenolic resin and their composites carbon microspheres were prepared by a simple inverse emulsion polymerization. The effects of synthesis conditions on the formation of spheres and the mechanism of the formation of spheres were investigated．Under different conditions (the mass ratio of silicone oil to heat conduction oil, alcohol to phenolic resin and stirring speed), carbon microspheres with good sphericity and a narrow size distribution of 5 – 200 μm were obtained. It was found that the heat transfer oil with low viscosity, high thermal conductivity and forming strong π-π interaction with phenolic resin play major roles in the construction of resin spheres via the above inverse emulsion method. Furthermore, under the optimum conditions, stirring speed is an effective way to adjust to the diameter of carbon microspheres.(2) The diameters of pore were controlled by adding F127 and activating under KOH. It is found that the optimum addition of F127 has little influence on sphericity, whereas it remarkably increases specific surface area and micro/meso pore volume of carbon microspheres. The sample which activated under KOH increases specific surface area and micro- pore volume of carbon microspheres and maintain good sphericity, whereas the pore size distribution of micro- pore were influenced by the different ration of KOH:C. It is found that charge will store in pores smaller than 1 nm, its content and distribution determine capacitance of carbon spheres. There is a trend of increasing the rate of ion transfer/diffusion when the pore size is 1-2 nm.(3) Under the experimental condition, the diameter and sphericity of carbon sphere were not influenced by the addition of graphene, but the configuration and distribution of graphene has a significant effect with the increasing addition of graphene. The configuration of graphene is from the inner to outer carbon spheres with the increasing content of graphene. The pore structure was influenced by the addition of graphene. Thin layer coated carbon spheres with low surface area and pore volume show great electrochemical properties due to good electrical conductivity. Keywords: Phenolic resin, Graphene, Carbon microspheres, Inverse emulsion polymerization, Electrochemical performances
Graphene and nanoporous carbon spheres have received considerable attention as new low-dimensional nanocarbon materials in recent years. The two-dimensional crystal graphene has shown enormous potential applications in catalysis, energy, electronics and biomedicine due to its extraordinary electrical, thermal, optical, mechanical properties and high specific surface area. While nanoporous carbon spheres integrate the advantages of carbon materials with spherical colloids, enabling them with regular geometry, good liquidity, tunable porosity and controllable particle size distribution. These innovative materials present great utilitarian value for catalysis, adsorption, water/air purification and energy-related applications. In this dissertation, we focus on the chemistry of carbon materials and investigate the self-assembly behavior, preparation as well as their functionalized applications of graphene and nanoporous carbon spheres. The main results are as follows:Graphene monoliths with well-defined morphologies have been successfully prepared under hydrothermal conditions. It was found that the graphene sheets randomly distributed in the graphene hydrogel system contacted with each other to produce a permanent graphene framework and interacted with water via hydrogen bond and capillary force, providing strong mechanical properties and excellent resilience to graphene hydrogels. The pH control of graphene oxide exhibited superior efficiency on improving mechanical properties of graphene hydrogels over concentration and reduction time. A pH-dependent self-assembly behavior of graphene hydrogels was further revealed, and the charge state of the remaining carboxyl groups during the reduction process determined the interplay of attraction and repulsion force, consequently determining the self-assembly behavior of graphene. A scalable approach to prepare N-doped graphene in various forms is reported, including stable dispersion, hydrogel and aerogel. The stable dispersion of N-doped graphene mainly consists of single-sheet graphene and the hydrogel is physically cross-linked to be quite strong. For aerogel of N-doped graphene, interconnected macropores were observed. Both the thermal stability and N content of the synthesized N-G proved to be high. Finally, the mechanism of N-doping and reduction is proposed.We demonstrated a novel protocol for the controlled synthesis of mesoporous carbon spheres through self-assembly of colloidal silica. The mesopore size, surface area, pore volume, spherical size and chemical composition of mesoporous carbon spheres can be conveniently modulated by varying the reaction parameters, such as templates, feed ratio, precursors and pyrolysis temperature. The commercial colloidal silica, a versatile and affordable template, used in our strategy guarantees a cost-effective synthesis procedure suitable for industrial production. Mesoporous carbon spheres with a mesopore size of 22 nm, compared to those of 7 and 42 nm, exhibit the best ORR performance in alkaline medium (Half wave potential 0.78 V vs RHE), making it a promising ORR catalyst. The performance can be further enhanced by a straightforward Fe-doping process, comparable to that of state-of-the-art Pt/C catalyst (0.844 V vs 0.85 V). Hierarchically hollow core-shell MnO2/C hybrid spheres were rationally constructed via a facile deposition process on the open porous mesoporous carbon spheres (MCSs). The loading of MnO2 active material in the hybrid was readily controlled in the range of 50-90 wt%. Such hierarchical architecture provides a unique face-to-face contact mode between carbon frameworks and hollow MnO2 nanospheres for robust electrical connection; the well-developed inner voids further endow MnO2 electrode with free space for large volume variation and fast ionic transport, simultaneously improving the mechanical stability, utilization and reaction kinetics of MnO2 anodes. As a consequence, superior cycling performance and excellent rate
Block copolymer (BCP) self-assembly can spontaneously generate periodic arrays of microdomains with versatile morphology and nanoscale feature size below ~100 nm. The self-assembled BCP thin films can act as templates to control the spatial order of other functional materials, which has attracted enormous attention and studies. BCP based nanolithography has been widely recognized as one of the most important next-generation nanolithography technologies, as it is promised to address the conflict between the continuous demanding to shrink the feature size of electronic devices and the technology and cost limits of photolithography. However, the directed self-assembly of BCP thin film to form ordered nanostructures with controlled orientation and localized pattern has been the key challenge for practical nanolithography applications. In this thesis, we present two approaches to achieve perpendicular orientation of BCP film based on graphene with tunable surface energy or graphene coated random polymer. Utilizing electret, we obtain BCP film with orientational, positional control and single cylinder with ultrahigh resolution. This thesis includes the following three topics:(1) Monolayer Graphene-supported Free-standing PS-b-PMMA Thin Film with Perpendicularly Orientated MicrodomainsWe proposed a facile way to fabricate robust free-standing BCP thin films with perpendicularly orientated microdomains on CVD-grown monolayer graphene support. Graphene with tunable surface energy is achievable with UV/Ozone (UVO) treatment, which can be applied to control the orientation of PS-b-PMMA film. We demonstrated that perpendicular orientation of BCP film is obtained on graphene with UVO treatment for 7 min. As graphene can provide robust support for its high mechanical strength, a free-standing BCP film with nanopatterns is achieved. It is proved that the free-standing BCP films can be used as a substrate-independent template to facilitate BCP nano-lithography.(2) Microdomain Orientation Control of PS-b-PMMA Film Enabled by Wettability Relay of GrapheneWe developed a novel method utilizing monolayer graphene-coated random brush without hydroxyl groups as a mediated layer to achieve a perpendicularly oriented microdomain of BCP films. This method is demonstrated as effective to achieve PS-b-PMMA film with orientation control and universal to be applied to various substrates. We also discuss the synergistic effects of graphene and random brush in achieving the versatility in controlling the BCP orientation on various substrates. Graphene is found to exhibit impenetrability to block the random polymer and transparency to transfer the wetting property of the brush layer beneath. The approach of graphene-coated brush will provide potential applications in patterning technology.(3) Directed Block Copolymer Self-assembly Implemented via Surface Embedded ElectretsWe investigated the self-assembled behaviors of PS-b-PMMA film on surface electrets. We proved that SiOx/Si substrates irradiated by e-beam can generate a built-in electric field, which can induce formation of perpendicularly oriented microdomain of BCP film. In addition, integrated with e-beam direct writing technique, the electret directed orientation control of BCP film can be readily scaled up to micron scale with arbitrary lateral pattern in a simple, effective, and non-destructive manner. More intriguingly, we further demonstrate orientation control over individual cylinders, which represents the ultimate resolution limit for directed BCP self-assembly, as a most attractive feature by controlling the size of the surface embedded electrets with a highly focused e-beam.
In this dissertation, the tribological mechanism of a-C:H films in vacuum was discussed based on two aspects of internal stress and carbon phase transition. Based on this, the research further concentrated on improving tribological behavior of a-C:H film in vacuum environment by designing the structure in multi-scales. The main research conclusions are drawn as follows: 1. The friction behavior, morphology and structural evolution of a-C:H film in different friction periods were systematically studied. Afterwards, a dynamic friction mechanism is established. These results indicated that the tribological performance of a-C:H film in vacuum was affected by internal stress and phase structure on sliding surface. 2. The gradient film with low stress was prepared through interface design without changing the intrinsic structure of film. The gradient a-C:H film presented long wear life in vacuum. In addition, a-C:H film with groove structure and low internal stress was prepared by the laser surface texture technology, and the textured films exhibited better tribological performances in vacuum. 3. The tribological performance of several typical carbon materials, such as graphite, highly oriented pyrolytic graphite,graphene and C60 was investigated in vacuum. The results showed that graphene exhibited excellent tribological performance in vacuum environment as it could spontaneously form oriented layered structure at sliding interface. Moreover, we also self-assembled graphene on the surface of a-C:H film, which dramatically prolonged the wear life of a-C:H film in vacuum. 4. A new method was found to grow and control graphene nano-structure in carbon films based on the external-field (including target catalysis and plasma action) induced growth effect. The graphene-like nanostructure awarded a-C:H film excellent mechanical and vacuum tribological properties. Keywords: Carbon-based film, Increasing wear life in vacuum, Friction and wear mechanism, Muti-scale structural design, Graphene