石墨烯/类金刚石碳复合薄膜的电化学沉积及其场发射性能

采用液相电化学方法在硅基底上制备了石墨烯掺杂的类金刚石碳复合薄膜,探讨了电化学沉积复合薄膜的机理。利用扫描电子显微镜（SEM）、拉曼光谱（Raman）、透射电子显微镜（TEM）和傅里叶变换红外（FTIR）光谱技术对薄膜表面形貌和微观结构进行了分析表征。结果表明,石墨烯片均匀分散沉积在含氢类金刚石碳（a-C：H）基体中,沉积的石墨烯/类金刚石（G/a-C：H）复合薄膜表面相对均匀平整。场发射测试显示石墨烯掺杂使开启电场从4.7 V·μm^-1增加至5.8 V·μm^-1,场发射电流密度从384 μA·cm^-2显著增加至876 μA·cm^-2。     

石墨烯/银复合薄膜的制备及表征

采用静电自组装技术,通过交替沉积聚(二烯丙基二甲基氯化铵)(PDDA)(或硝酸银)和氧化石墨烯,制备氧化石墨烯/PDDA薄膜和氧化石墨烯/硝酸银复合薄膜。然后在600℃下通入氩气和氢气进行气氛还原得到石墨烯薄膜和石墨烯/银复合薄膜。采用AFM、SEM、XPS、UV-Vis以及四探针电阻仪等对薄膜结构及性质进行表征。结果表明,通过静电自组装法可以获得生长均匀的薄膜。对比于相同自组装次数的石墨烯薄膜,石墨烯/银复合薄膜具有更好的透光性和更低的薄膜方块电阻。在λ=500 nm时,四层石墨烯/银复合薄膜的透过率为85%左右,而石墨烯薄膜的透过率为72%左右;石墨烯薄膜的方阻为161.39 kΩ.□-1,而石墨烯/银复合薄膜的方阻为99.11 kΩ.□-1。     

One‐step electrochemical deposition to achieve superhydrophobic cobalt incorporated amorphous carbon‐based film with self‐cleaning and anti‐corrosion

Exploiting a superhydrophobic surface is very significant due to its excellent water repellency which has many practical applications in various fields. In this work, the cobalt incorporated amorphous carbon‐based (Co/a‐C:H) film was prepared successfully on Si substrate via a simple 1‐step electrochemical deposition where electrochemical deposition technology was using cobalt (II) acetylacetonate methanol solution as electrolyte under high voltage, atmospheric pressure, and low temperature. Surprisingly, the as‐prepared film showed a superior superhydrophobic surface with a water contact angle of 153 ± 1° and a sliding angle of 7.6° without any further modification of low surface energy materials. Especially, the tape adhesive, corrosion resistance, and self‐cleaning tests demonstrated that the as‐prepared carbon‐based film could possess fairly well adhesion, superior anti‐corrosion resistance, and self‐cleaning ability, respectively. It indicated that the superhydrophobic Co/a‐C:H film might have potential promising applications in the field of anti‐fouling, anti‐corrosion, and drag resistance, such as the above‐deck structures on icebreaker vessels, ship hulls, and offshore wind turbine blades.     

Controlling wrinkles and assembly patterns in dried graphene oxide films using lyotropic graphene oxide liquid crystals

We fabricated graphene oxide (GO) films on glass substrates by blade coating a lyotropic GO liquid crystal dispersion. Substrate temperature and blading speed were precisely controlled to manipulate the surface morphologies of GO films. The temperature and blade speed influenced the drying rate of film and the amount GO dispersion supplied. By controlling these parameters, film-thickness modulation and three types of surface wrinkle patterns were selectively achieved. We also plotted the wrinkle patterns diagram as functions of the film fabrication conditions. The films exhibited different optical anisotropies depending on wrinkle patterns. GO films with controlled wrinkles can be used as electrodes for supercapacitor applications owing to the large surface areas.     

The antioxygen radiation properties of the nanocomposite film consisted of hydrogenated amorphous carbon (a-C:H) and MoS2

MoS₂/a-C:H multilayer film and MoS₂/a-C:H composite film exhibit excellent tribological properties in vacuum, which can be used as the potential space lubricant. The radiation-protective properties of these two films in atomic oxygen (AO) are evaluated. The influences of AO radiation on structure, morphology, and tribological properties of the films were investigated. The results show that AO radiation mainly causes oxidation and increases sp² C content in both of the films. Furthermore, the MoS₂ sublayer on the surface of the multilayer film is oxidized heavily, whereas both the MoS₂ and the a-C:H matrix on the surface were oxidized in the composite film. As a result of this, the multilayer film exhibits high friction coefficient and short sliding lifetime in vacuum after AO radiation. Compared with that, the composite film exhibits lower friction and longer sliding time more than 3600 seconds in vacuum, which illustrates it has a good AO radiation protection. This indicates that MoS₂/a-C:H composite film is more likely to be used as a potential space lubricant.     

Roll‐to‐Roll printed PEDOT/PSS/GO Plastic Film for Electrochemical Determination of Carbofuran

In this work, we developed a roll‐to‐roll printed poly(3,4‐ethylenedioxythiophene)/polystyrene sulphoanate without graphene oxide (GO) (PEDOT/PSS) and with graphene oxide (PEDOT/PSS/GO) plastic films for the electrochemical determination of carbofuran. Both the PEDOT/PSS and PEDOT/PSS/GO plastic films showed electroactivity towards the oxidation of carbofuran. Incorporation of graphene oxide (GO) improves the electrochemical activity of carbofuran and increased its sensitivity. The printed plastic films were characterized by cyclic voltammetry (CV), linear sweep voltammetry (LSV), surface profilometer, four point probe and atomic force microscopy (AFM). The effects of pH, deposition time, deposition potential and film thickness on the oxidation peak current of carbofuran were investigated. Under the optimized conditions, a dynamic linear range of 1 μM–90 μM with a detection limit of 1.0×10^?7 M (S/N=3) were obtained. The printed PEDOT/PSS/GO plastic electrode was applied for the determination of carbofuran in vegetable and fruit samples with recoveries between 94.4 and 101.8 %.     

Achieving ultra-low friction of a-C:H film grown on 9Cr18Mo steel for industrial application via programmable high power pulse magnetron sputtering

Owing to the high hardness and hydrogen passivation of carbon bonds, hydrogenated diamond-like carbon (a-C:H) film has shown promising potential to achieve ultra-low friction and wear on steel surfaces. Here, a-C:H film was successfully deposited on 9Cr18Mo steel via programmable high power pulse magnetron sputtering and potential application for industrial was evaluated. The a-C:H films against different mating materials of GCr15 steel balls, Al₂O₃, Si₃N₄, ZrO₂, and a-C:H-coated GCr15 balls all showed ultra-low friction under a normal load of 5 N in a dry ambient air environment. Among them, self-mating tribo-system a-C:H films on steel surfaces and a-C:H-coated steel balls achieve best friction performance; the principal reason is that both contacting surfaces coated with a-C:H film have the lower electron affinities compared with other tribo-systems. However, the differences of coefficient of friction (COF) for uncoated-GCr15, Al₂O₃, ZrO₂, Si₃N₄, and a-C:H(GCr15) balls can be attributed to different sizes of clustering in wear debris. This work provides new insights on synthesis and industry application of the a-C:H films with ultra-low friction properties.     

Laser desorption/ionization mass spectrometric assay for phospholipase activity based on graphene oxide/carbon nanotube double-layer films

A new method for quantitative phospholipase activity assays using mass spectrometry (MS) and a supported thin film consisting of a graphene oxide (GO)/carbon nanotube (CNT) double layer as a substrate for laser desorption ionization (LDI) has been developed. Phospholipids were very efficiently analyzed by LDI-time-of-flight (TOF) MS on the GO/CNT films, presumably because of the affinity of phospholipids for the GO/CNT surface. Therefore, the rate of lipid hydrolysis was conveniently measured using LDI-TOF mass spectra obtained from a GO/CNT surface on which the phospholipid hydrolysis reaction mixtures had been spotted by comparing the mass-peak intensities of reactants and products. The present platform for phospholipase assays based on MS and GO/CNT double-layer films enables quantitative measurements at low cost, allows assays to be performed in a short time, and is compatible with an array format, unlike conventional assay methods.     

新型十二烷基三甲氧基硅烷/氧化石墨烯复合膜对430不锈钢耐蚀性能的影响

使用一步电沉积法在430不锈钢上制备出十二烷基三甲氧基硅烷(DTES)/氧化石墨烯(GO)复合膜。 拉曼光谱(Raman)与扫描电子显微镜(SEM)测试表明,氧化石墨烯均匀地混合在硅烷膜中,并用电化学交流阻抗与极化曲线方法对这种复合膜所保护的430不锈钢进行耐蚀性能测试。 结果显示,在3.5%NaCl溶液中,430不锈钢会发生腐蚀反应,而存在硅烷复合膜的430不锈钢的耐蚀性能显著地提高。 研究表明,由于氧化石墨烯出色的阻隔性能一定程度上弥补了硅烷膜的缺陷,而且延长了腐蚀介质通过硅烷基质的路径,因此复合膜有着对基底物质更强的保护性能。     

Surface and Interface Engineering of Graphene Oxide Films by Controllable Photoreduction

We report herein the engineering of the surface/interface properties of graphene oxide (GO) films by controllable photoreduction treatment. In our recent works, typical photoreduction processes, including femtosecond laser direct writing (FsLDW), laser holographic lithography, and controllable UV irradiation, have been employed to make conductive reduced graphene oxide (RGO) microcircuits, hierarchical RGO micro‐nanostructures with both superhydrophobicity and structural color, as well as moisture‐responsive GO/RGO bilayer structures. Compared with other reduction protocols, for instance, chemical reduction and thermal annealing, the photoreduction strategy shows distinct advantages, such as mask‐free patterning, chemical‐free modification, controllable reduction degree, and environmentally friendly processing. These works indicate that the surface and interface engineering of GO through controllable photoreduction of GO holds great promise for the development of various graphene‐based microdevices.     

热辅助存储磁盘硅掺杂非晶碳薄膜氧化的ReaxFF反应力场分子动力学模拟

Heat-assisted magnetic recording (HAMR) is one of the promising ways to extend the magnetic recording area density to 1 Tb·in^-2 in hard disk drives (HDDs).High temperature induced by laser heating can cause carbon overcoat (COC) oxidation.Reactive molecular dynamics (MD) simulations are performed to investigate the oxidation process of silicon-doped amorphous carbon (a-C:Si) films for HAMR application.The atomic details of the structure evolution and oxidation process are investigated, and, the oxidation mechanism of the a-C:Si film is clarified.The effect of the duration of laser irradiation on the oxidation of the a-C:Si film is investigated.The oxidation occurs during heating and the beginning of cooling process.Both volume expansion during heating process and cluster of carbon atoms during cooling process increase the rate of sp² carbon.Because of the decrease in the amount of unsaturated silicon atoms and low diffusion coefficient of atomic oxygen, the oxidation rate of the a-C:Si film decreases with laser irradiation cycles.The molecular oxygen is the oxidant due to surface defect of a-C:Si film.The atomic strains break the O-O bonds in Si-O-O-Si linkages and rearrange the surface oxide layers, and process the oxidation of the a-C:Si film.     

Good electrical and mechanical properties induced by the multilayer graphene oxide sheets incorporated to amorphous carbon films

Multilayer graphene oxide nanosheets were fabricated using commercially available expanded graphite by simple ultrasonic treatment and then were incorporated into the amorphous carbon matrix as fillers by electrochemical deposition. The electrical conductivity of the films was strongly improved due to the contribution of the multilayer graphene oxide sheets. Moreover, the Young’s modulus, hardness and elastic recovery of the composite films were measured to be about 171.1 GPa, 10.1 GPa and 81.4%, respectively, compared to 137.4 GPa, 5.1 GPa and 44.3% of undoped a-C:H films prepared at the same conditions. Additionally, the friction coefficient was tested to be 0.15 (0.5 N, 2 Hz) and the antiwear life was prolonged to about 200 s while the undoped DLC films obtained at the same condition were easy to be frazzled.     

Preparation of porous polyimide/in‐situ reduced graphene oxide composite films for electromagnetic interference shielding

Herein we report an easy and efficient approach to prepare lightweight porous polyimide (PI)/reduced graphene oxide (RGO) composite films. First, porous poly (amic acid) (PAA)/graphene oxide (GO) composite films were prepared via non‐solvent induced phase separation (NIPS) process. Afterwards PAA was converted into PI through thermal imidization and simultaneously GO dispersed in PAA matrix was in situ thermally reduced to RGO. The GO undergoing the same thermal treatment process as thermal imidization was characterized with thermogravimetric analysis, Raman spectra, X‐ray photoelectron spectroscopy and X‐ray diffraction to demonstrate that GO was in situ reduced during thermal imidization process. The resultant porous PI/RGO composite film (500‐µm thickness), which was prepared from pristine PAA/GO composite with 8 wt% GO, exhibited effective electrical conductivity of 0.015 S m^?1 and excellent specific shielding efficiency value of 693 dB cm² g^?1. In addition, the thermal stability of the porous PI/RGO composite films was also dramatically enhanced. Compared with that of porous PI film, the 5% weight loss temperature of the composite film mentioned above was improved from 525°C to 538°C. Moreover, tensile test showed that the composite film mentioned above possessed a tensile strength of 6.97 MPa and Young's modulus of 545 MPa, respectively. Copyright © 2016 John Wiley & Sons, Ltd.     

Effect of nitrogen and ammonia on transfer and deposition of hydrocarbon radicals in different regions of hollow-cathode glow discharge

The effect of addition of nitrogen or ammonia in an amount equal to the flow of methane entering as a 7: 1 H₂/CH₄ mixture into a hollow-cathode dc glow flow discharge on the rate of deposition/erosion of amorphous hydrocarbon (a-C:H) films at 300 K has been studied. The introduction N₂ or NH₃ into the mixture facilitates the transition from deposition to erosion of a-C(N):H films in the hollow cathode, but has a little effect on the growth rate of a-C(N):H films in the positive column and in the afterglow of the discharge. It has been suggested that the changes in the a-C:H film deposition/erosion rate are due to the formation of hydrogen cyanide, mainly, on the hollow-cathode surface.     

Tribological behaviors of DLC films in sulfuric acid and sodium hydroxide solutions

Tribological behaviors of three typical kinds of diamond-like carbon (DLC) films (a-C, a-C:Cr, and a-C:H) in sulfuric acid and sodium hydroxide solutions were investigated. The a-C film showed the lowest stable coefficients of friction (COF) in both sulfuric acid and sodium hydroxide solutions but the worst wear resistance in sulfuric acid solution. The a-C:H film showed the highest COF in sulfuric acid solution and the best wear resistance in both sulfuric acid and sodium hydroxide solutions. The a-C:Cr film exhibited superior comprehensive tribological performance in sulfuric acid solution, while in sodium hydroxide solution, high COF and very poor wear resistance was observed. What is more, friction and wear mechanism was revealed by investigating the friction-induced material evolutions on the sliding surface.     

Layer-by-layer engineered Co-Al hydroxide nanosheets/graphene multilayer films as flexible electrode for supercapacitor

Multilayer films of Co-Al layered double hydroxide nanosheets (Co-Al LDH-NS) and graphene oxide (GO) were fabricated through layer-by-layer (LBL) assembly. By using a three-electrode system, the electrochemical performances of the films were investigated to evaluate their potential as electrode materials to be used in flexible supercapacitor devices. The Co-Al LDH-NS/GO multilayer films exhibited a high specific capacitance of 880 F/g and area capacitance of 70 F/m(2) under the scan rate of 5 mV/s. And the film exhibited good cycle stability over 2000 cycles. After treating the films at 200 °C in H(2) atmosphere, the specific capacitance and area capacitance were largely increased up to 1204 F/g and 90 F/m(2) due to partial reduction of GO. A flexible electrode by depositing Co-Al LDH-NS/GO multilayer film onto PET substrate was prepared to show the potential of Co-Al LDH-NS/GO films for flexible energy storage.     

A novel method for the synthesis of Au nanoparticles incorporated amorphous hydrogenated carbon films

In this communication we report a novel electrochemical route for the preparation of Au nanoparticles incorporated a-C:H films on single crystal silicon substrates by choosing methanol as carbon source and Au nanoparticles as dopant. The morphology, composition and structure of the film have been investigated and the results show that the film obtained in our method is a hydrogenated diamond-like carbon film and zero-valence Au nanoparticles are stable and well-dispersed into the amorphous carbon matrix with unchanged size. It is simplified to achieve the co-deposition of carbon and metal by using metal nanoparticles rather than the metal salt solution as the dopant. The incorporation of Au nanoparticles in the carbon matrix can drastically decrease the resistivity and convert a-C:H films from insulator to semiconductor easily. The growth mechanisms of the Au-DLC films are also discussed.     

碳纳米管/氧化石墨烯/硫复合正极材料的制备及其电化学性能

以碳纳米管和氧化石墨烯(CNTs/GO)为主体材料, 通过化学还原法制备了CNTs/GO 负载硫的复合正极材料CNTs/GO/S. 扫描电子显微镜(SEM)及透射电子显微镜(TEM)测试表明, CNTs 均匀插层在GO片间, 从而形成三维多孔结构, 有利于电解液的浸润; 活性物质硫均匀地负载在CNTs/GO 表面. 电化学测试表明,CNTs/GO/S复合材料具有高的比容量和良好的循环稳定性: 在1C倍率电流密度下, 复合材料首次放电比容量高达904 mAh·g^-1, 经过50圈循环之后, 复合材料的比容量仍保持在578 mAh·g^-1.     

氧化石墨掺杂的电化学活性自支撑聚苯胺膜

以氧化石墨（GO）为掺杂剂和模板,采用化学原位聚合法并通过调节苯胺单体和氧化石墨的质量比,合成了层状结构的聚苯胺/氧化石墨(PANI/GO)层状结构的自支撑膜。SEM和XRD研究表明,当苯胺单体与GO的质量比为67:1时,PANI/GO复合材料具有层间距~1.36 nm的层状结构,证实 GO的模板功能。XPS和FTIR研究表明PANI/GO复合材料中的典型的聚苯胺的掺杂态,进一步证实GO的掺杂功能。此外,电化学和热失重测量表明PANI/GO层状结构的自支撑膜呈现良好的热稳定性和高电化学活性.     

Effect of deposition parameters on the wettability and microstructure of superhydrophobic films with hierarchical micro-nano structures

Superhydrophobic films with hierarchical micro-nano structures were deposited on glass substrates by solution immersion method from a solution containing cobalt chloride, urea and cetyl trimethyl ammonium bromide (CTAB). Subsequently the films were hydrophobized with a low surface energy material like octadecanoic acid under ambient conditions resulting in superhydrophobic surfaces with water contact angle (WCA) of about 168° and contact angle hysteresis of 1°. The effect of deposition parameters such as solution composition, temperature, deposition time and alkanoic acid treatment on surface morphology and wettability of the films was studied. Mechanism of formation of cobalt chloride carbonate hydroxide film is discussed. Addition of CTAB to the solution resulted in a change in the surface morphology of the deposited films with flower-like structures. The wettability of films obtained under different process conditions was correlated to surface roughness using Wenzel and Cassie models.