Honggang Wang

Chinese Academy of Sciences, Peping, Beijing, China

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Publications (30)86.27 Total impact

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    ABSTRACT: In order to explore the addition effect of fluorinated graphene (FG) on the mechanical and thermal performances of polyimide (PI) matrix, FG sheets are first prepared and employed as the nanofillers to construct PI/FG nanocomposite films. The prepared film is optically transparent at low content of FG and experimental results demonstrate that the addition of FG can effectively enhance the properties of PI matrix. Especially, compared with pure PI matrix, the addition of 0.5 wt% FG in PI can endow 30.4% increase in tensile stress and 115.2% increase in elongation at break. Experimental analyses considering the morphology and microstructure are also conducted, and the results indicate that the improved mechanical properties of the PI/FG nanocomposite films are mainly attributed to the good dispersibility of FG sheets in PI host, and the effective stress transfer between the polymer and the FG.
    Composites Part A Applied Science and Manufacturing 05/2015; 75. DOI:10.1016/j.compositesa.2015.04.005 · 3.01 Impact Factor
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    ABSTRACT: In this work, we report a simple self-assembly way to prepare ceria/graphene oxide (CeO2/GO) composite films on silicon (Si) substrates, which exhibit significant enhancement on tribological performances compared with Si substrates and GO films. Specifically, the friction coefficient is reduced drastically to the one-third of that of Si substrates. What’s more, the antiwear lifetime is markedly prolonged to ∼8 h under a high applied load of 2 N, which is over seven times longer than that of GO films. It is expected that the CeO2/GO composite films may find wide applications in nano/microelectromechanical systems as high-performance solid lubricating films, due to their facile and low cost preparation, nano-scale thickness, lower friction coefficient and desired antiwear lifetime.
    Carbon 04/2015; 84:197-206. DOI:10.1016/j.carbon.2014.11.063 · 6.16 Impact Factor
  • Xiangyuan Ye · Jinqing Wang · Honggang Wang · Shengrong Yang
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    ABSTRACT: Mesoporous silica nanospheres (MSNs), with neat morphology, large Brunauer-Emmett-Teller (BET) surface area and uniform pore diameter, have been synthesized firstly, and then the liquid paraffin as lubricating oil is poured into the pores of the MSNs via a simple wet impregnation method to form paraffin-containing MSNs (abbreviated as PMSNs). The tribological tests are carried out under three different loads (1.0, 1.5, and 2.0 N) by sliding a steel ball (phi = 6 mm) against PMSNs thin films spin-coated on glass slides. The results indicate that the friction coefficient of glass slide reduces greatly from 0.7 to 0.09 due to the effective release of liquid paraffin preserved inside the pores of MSNs under these loads. Meantime, the corresponding wear volumes of glass slides also decrease greatly after the formation of the PMSNs film. As a result, the present work lights a pharos to utilize lubricating oil more effectively via releasing oil preserved inside the pores of the MSNs.
    Microporous and Mesoporous Materials 03/2015; 204:131-136. DOI:10.1016/j.micromeso.2014.11.020 · 3.21 Impact Factor
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    ABSTRACT: Graphene decorated with well-dispersed cubic fluorite ceria (CeO2) nanoparticles was prepared through a simple hydrothermal method. The as-prepared CeO2/graphene composites (COGNCs) were further used as lubricant additives in the base oil of liquid paraffin to investigate their tribological properties by the Optimol SRV-1 oscillating reciprocating friction and wear tests in air (relative humidity, 17%). The results indicated that the introduction of a small amount of COGNCs into the base oil could reduce friction and wear drastically under a high load condition, which was better than the testing results of graphene or CeO2 nanoparticles. Specifically, when 0.06 wt% COGNCs was added into the base oil, the average friction coefficient could be reduced from 0.21 to 0.10, and the wear rate could be decreased to 1.5% of that of base oil. The excellent tribological properties of COGNCs can be explained by the synergistic friction reduction and antiwear effects of graphene and CeO2 nanoparticles.
    RSC Advances 09/2014; 4(87). DOI:10.1039/C4RA09488C · 3.84 Impact Factor
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    ABSTRACT: A novel multi-layered nanocomposite film, abridged as ZrO2/GO (zirconia/graphene oxide), was constructed by a simple layer-by-layer (LBL) self-assembly process. It is expected that the key factor for constructing such a film is the high surface activity of GO nanosheets with various oxygen-containing groups, which ensures the strong bonding with substrate and facilitates the deposition of ZrO2 thin film thereon. The as-constructed film after fifteen cycle deposition with a thickness of 170-260 nm shows outperformed tribological performances (with the friction coefficient of 0.13 ~ 0.17 and anti-wear life of longer than 6000 s) and mechanical property (with a hardness of 12.74 GPa) even without annealing. These outperformed properties are probably ascribed to the multi-layered nanostructures and the synergistic effect of the excellent tribological/mechanical properties of GO nanosheets as well as ZrO2 nanoparticles. Furthermore, after being annealed at 500 °C or 900 °C, the film still presents lower friction coefficient (0.11 ~ 0.14) under the same test conditions. It is expected that this ZrO2/GO multi-layered nanocomposite film can be wildly used as protecting or/and lubricating coating for micro- and nano-electromechanical systems (MEMS/NEMS) not only for its excellent tribological/mechanical properties but also for its simplicity and feasibility of such a construction process.
    RSC Advances 08/2014; 4(75). DOI:10.1039/C4RA06085G · 3.84 Impact Factor
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    ABSTRACT: Series of polyimide (PI)/mesoporous silica nanospheres (MSNs) nanocomposite films with different contents of MSNs were successfully prepared via a simple wet impregnation method. The morphologies, microstructures, mechanical properties, transmittance, and thermal properties of the prepared PI and the PI/MSNs nanocomposite films were investigated in detail. As a result, the thermal stability and mechanical performances of PI were obviously improved by incorporating MSNs into PI. The tensile stress and Young's modulus of the nanocomposite film with 5 wt % MSNs were raised up to 97.65 MPa and 2220.06 MPa, which are greatly higher than the values of 82.51 MPa and 1440.86 MPa for the pure PI film. Experimental results confirmed that the designed polymerization tactic, which occurred in the pores of the MSNs, facilitated to enhance the mechanical and physical performances of the PI/MSNs nanocomposite films, and definitely induced better integration between organic matrix and inorganic nanofillers. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41173.
    Journal of Applied Polymer Science 07/2014; 131(23). DOI:10.1002/app.41173 · 1.64 Impact Factor
  • Xia Wang · Bo Mu · Honggang Wang
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    ABSTRACT: The blends of thermoplastic polyurethane and ultra high molecular weight polyethylene (UHMWPE) were prepared by a co-twin screw extruder. Phase separation morphology of the blends was confirmed by the SEM observations. The incorporation of UHMWPE is detrimental to the mechanical properties of the blends prepared from stiffer TPU, whereas is beneficial to that of TPU with low hardness. The tribological behaviors of neat TPU and its blends were studied by the means of a block-on-ring apparatus. It was found that UHMWPE could greatly improve the tribological properties of TPU matrix both under dry sliding and water lubricating conditions due to the excellent self-lubricating property of the UHMWPE materials and furthermore improve the wear failure limit of TPU. POLYM. COMPOS., 2014. © 2014 Society of Plastics Engineers
    Polymer Composites 04/2014; 36(5). DOI:10.1002/pc.23009 · 1.46 Impact Factor
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    ABSTRACT: A series of Ni/reduced graphene oxide (Ni/RGO) composites were synthesized through a simple solvothermal method. Detailed characterizations of the composite using transmission electron microscopy and field emission scanning electron microscopy indicated that Ni particles were uniformly dispersed on the RGO surfaces. The electrochemical performances of Ni/RGO composites were much higher than their counterparts of Ni and RGO, because of the Ni particles being firmly decorated with the RGO nanosheets and the synergistic effect between both components. Among the prepared composites, Ni/RGO-2 exhibits the best electrochemical performance; namely, a high specific capacitance of 547.3 F g(-1) is obtained in 2 M KOH at 1 A g(-1) and 81% of initial value is remained after a continuous cycling of 1000 times, which make it to be a promising electrode material for supercapacitors.
    Electrochimica Acta 03/2014; 123:560-568. DOI:10.1016/j.electacta.2014.01.005 · 4.50 Impact Factor
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    ABSTRACT: The composite of polytetrafluoroethylene (PTFE) has been generally applied to dynamic seals in Stirling power systems due to its excellent self-lubrication and resilience. In this article, the tribological behavior of polyphenylene sulfide (PPS)-PTFE blends filled with nano-Al2O3 are investigated under different contact loads, sliding speed, and operating temperatures using a block-on-ring friction and wear tester. The results indicate that the addition of nano-Al2O3 could significantly improve the antiwear performance of the PPS-PTFE blend. Nano-Al2O3-filled PPS-PTFE composites have good tribological performance under high-temperature environments. When the content of nano-Al2O3 is 5 wt%, the wear rate of the composite is 276 times better than that of virgin PTFE and more than 150 times better than that of unfilled PPS-PTFE. Dynamic mechanical analysis (DMA) shows that the block of the movement of molecular chains of PTFE with the addition of nano-Al2O3 particles may be responsible for the significant decrease in the wear rate. The greatest impact on the antiwear performance of the composite for Stirling engines is load, followed by temperature, and the minimum effect is due to sliding velocity.
    Tribology Transactions 03/2014; 57(2). DOI:10.1080/10402004.2013.861567 · 1.08 Impact Factor
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    ABSTRACT: Tunable control over the functionalization of graphene is significantly important to manipulate its structure and optoelectronic properties. Yet the chemical inertness of this noble carbon material poses a particular challenge for its decoration without forcing reaction conditions. Here, a mild, operationally simple and controllable protocol is developed to synthesize hydroxylated graphene (HOG) from fluorinated graphene (FG). We successfully demonstrate that under designed alkali environment, fluorine atoms on graphene framework are programmably replaced by hydroxyl groups via a straightforward substitution reaction pathway. Element constituent analyses confirm that homogeneous C-O bonds are successfully grafted on graphene. Rather different from graphene oxide, the photoluminescence (PL) emission spectrum of the obtained HOG becomes split when excited with UV radiation. More interestingly, such transformation from FG facilitates highly tunable PL emission ranging from greenish white (0.343, 0.392) to deep blue (0.156, 0.094). Additionally, both experimental data and density function theory calculation indicate that the chemical functionalization induced structural rearrangement is more important than the chemical decoration itself in tuning the PL emission band tail and splitting energy gaps. This work not only presents a new way to effectively fabricate graphene derivatives with tunable PL performance, but also provides an enlightening insight into the PL origin of graphene related materials.
    Nanoscale 02/2014; 6(6). DOI:10.1039/c3nr05725a · 7.39 Impact Factor
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    ABSTRACT: Based on the magic substance dopamine (DA), a simple and effective one-step solution deposition strategy has been developed for constructing high-performance amorphous zirconium oxide (ZrO2) nanocomposite thin film. DA can be auto-polymerized to form a polydopamine (PDA) coating, which adheres strongly to the silicon substrate and serves as an active platform to induce the subsequent deposition of ZrO2. The obtained ZrO2 nanocomposite thin films with the thickness of about one hundred nanometers presents outstanding mechanical and tribological performances even without a subsequent high-temperature annealing process. More importantly, the preparation process is definitely low-consumption and environmentally friendly. This work overcomes the claim that ZrO2 films obtained by aqueous solution deposition process generally possess low mechanical properties and thus avoid the defects of focusing mainly on nature and performances of heat-treated and crystalline ZrO2. Based on this work, it is believed that the as-deposited ZrO2 nanocomposite film can be widely used as a protecting coating and lubricating material for micro-and nano-electromechanical systems (MEMS/NEMS) and many other systems working in similar conditions.
    RSC Advances 01/2014; 4(12-12):6060-6067. DOI:10.1039/c3ra46169f · 3.84 Impact Factor
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    ABSTRACT: In this work, a series of composites consisting of Ni(HCO3)(2) and graphene nanosheets (GS) have been prepared by a facile solvothermal method, and then their application as electrode materials for supercapacitors has been investigated by cyclic voltammetry (CV) and galvanostatic charge-discharge tests. Morphological and structural analyses by field-emission scanning electron microscopy, high resolution transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy indicated that Ni(HCO3)(2) particles deposited on the GS and formed a loosely packed microstructure, actualizing the successful combination of Ni(HCO3)(2) particles with GS. Among the prepared composites, the sample of Ni(HCO3)(2)/GS2 exhibited the highest capacitance of 1200 F g(-1) at a current density of 4 A g(-1), illustrating that such composite is a promising candidate as electrode material for supercapacitors. Moreover, the Faradic redox mechanism of the Ni(HCO3)(2)/GS composite was further studied in virtue of XRD analysis, which revealed that the Ni(HCO3)(2) phase could be quickly transformed into Ni(OH)(2) phase by an electrochemically induced phase transformation process during the galvanostatic charge-discharge tests. (c) 2013 Elsevier B.V. All rights reserved.
    12/2013; 581:217-222. DOI:10.1016/j.jallcom.2013.07.023
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    ABSTRACT: A non-enzymatic glucose sensor based on Cu nanowires (CuNWs) modified graphene transparent electrode (GTE) was developed as a substitute for indium tin oxide (ITO) electrode or glassy carbon electrode (GCE). GTE was prepared by four steps on the polyethylene terephthalate sheet, and then Cu nanowires were deposited onto GTE to achieve the hybrid electrode of CuNWs/GTE by spin-coating. The morphology and phase structures were characterized by scanning electron microscopy and X-ray power diffraction, respectively. The resistance and electrochemical properties of CuNWs/GTE were investigated by four point probe and cyclic voltammetry, respectively. Results indicated that the as-prepared sensor showed higher electrocatalytic activity toward glucose than pristine CuNWs and GTE; The sensor also showed wider linear response for glucose over concentrations ranging from 0.005 to 6.0 mM with a sensitivity of 1100 mu A/(mM cm(2)), low detection limit of 1.6 mu M (S/N = 3), and excellent anti-interference ability. More importantly, the as-prepared sensor had the similar or even better performances compared to those reported on ITO and GCE.
    Electrochimica Acta 10/2013; 109:602-608. DOI:10.1016/j.electacta.2013.07.153 · 4.50 Impact Factor
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    ABSTRACT: Casein phosphopeptides (CPPs) with abundant phosphoserine clusters can mediate hydroxyapatite (HA) nucleation and growth. In this work, a new type of CPPs-biofuctionalized graphene composite was synthesized by amidation reaction between CPPs and carboxyalated graphene (CGO). When immersed in stimulated body fluid (1.5 × SBF) at 37 °C for different periods, the CPPs layer on the composite facilitated efficient interaction between the CGO surface and mineral ions, which promoted HA nanoparticle formation and shortened mineralization time in comparison with pristine CGO. The synthesis of the composite mimicked the natural biomineralization of bone, demonstrating that CPPs can effectively improve the bioactivity of graphene and be useful for HA formation. The presented biocomposite may have potential biomedical applications in different areas.
    05/2013; 117(20-20):10375-10382. DOI:10.1021/jp312163m
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    ABSTRACT: We have explored a novel photochemical route to synthesize fluorinated graphene via simultaneously fluorinating and reducing graphene oxide (GO) in HF solution at room temperature. This method avoids special equipment, employs simple UV irradiation and utilizes readily available GO as the carbon source.
    RSC Advances 04/2013; 3(18):6327-6330. DOI:10.1039/C3RA22029J · 3.84 Impact Factor
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    ABSTRACT: An easy, low-cost and effective synthesis of fluorinated graphene with tunable C/F atomic ratio (RC/F) has been realized by the reaction between dispersed graphene oxide and hydrofluoric acid. The results show that fluorine is grafted onto the basal plane of graphene, and the RC/F can be easily adjusted by controlling the reaction conditions. The as-synthesized fluorinated graphene exhibits a sheet-like morphology with 1–2 layered thickness and tunable bandgap energy from 1.82 to 2.99 eV, which has potential applications in optoelectronic and photonic devices.
    Carbon 12/2012; 50(15):5403–5410. DOI:10.1016/j.carbon.2012.07.026 · 6.16 Impact Factor
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    ABSTRACT: We report a novel and effective method to prepare fluorinated graphene sheets (FGS) by the cooperative exfoliation of graphite fluoride using cetyl-trimethyl-ammonium bromide and dopamine. This facile, scalable preparation route results in wide (about 2 μm in width), long (at least 3 μm in length) and ultrathin (1–2 layers) FGS with uniform morphology. The chemical composition of FGS was characterized by X-ray photoelectron spectroscopy and energy dispersive X-ray spectroscopy. The obtained FGS exhibits full-color emission when excited by near ultraviolet (NUV) rays, suggesting its potential applications in luminescence devices, such as NUV-pumped FGS-based flexible light-emitting diodes.
    RSC Advances 11/2012; 2(31):11681-11686. DOI:10.1039/C2RA21871B · 3.84 Impact Factor
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    ABSTRACT: Fluorographene (FG), which inherits the properties of graphene and fluorographite (FGi), holds great promise for applications in high-performance materials and devices, including lubricants, nanocomposites, batteries, and nanoelectronics. However, challenges for realizing large-scale preparation and little knowledge concerning FG's physicochemical properties hinder its practical applications. Here, a novel and feasible method is developed to prepare FG through a simple sonochemical exfoliation process in N-methyl-2-pyrrolidone (NMP). Interestingly, FG at a high concentration in NMP displays dramatic stability without any additional stabilizer or modifier, and the C/F ratio of FG can be facilely tuned just by adjusting the sonochemical time. Furthermore, the electrochemical and thermal properties of the prepared FG have been systematically investigated and exhibited regularity with variation of fluorine coverage. On the other hand, based on the solubility of FG in various solvents, a possible dispersion mechanism is proposed to guide FG's further applications in films or polymer-based composites as a mechanical reinforcement.
    Journal of Materials Chemistry 07/2012; 22(33):16950-16956. DOI:10.1039/C2JM32294C · 7.44 Impact Factor
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    ABSTRACT: In this work, we present a simple and feasible method with broad applicability for the in-situ reduction and assembly of graphene lubricant films on various substrates. We adopt graphene oxide hydrosol as the precursor solution and creatively introduce an adherent coating of polydopamine that can be firmly bonded onto a wide range of substrates and acts as an active transition layer and in-situ reducing agent, aiming at obtaining the reduced graphene oxide (rGO) films thereon without addition of exogenous reducing agent. Experimental results prove that rGO nanosheets have been successfully assembled onto the substrates and the in-situ synthesized rGO film presents excellent morphology, outstanding friction reduction and wear resistance properties.
    Journal of Materials Chemistry 03/2012; 22(16):8036-8042. DOI:10.1039/C2JM16656A · 7.44 Impact Factor