Co-reporter:Honghui Chen, Zhiyu Huang, Yi Huang, Yi Zhang, Zhen Ge, Bin Qin, Zunfeng Liu, Qian Shi, Peishuang Xiao, Yang Yang, Tengfei Zhang, Yongsheng Chen
Carbon 2017 Volume 124(Volume 124) pp:
Publication Date(Web):1 November 2017
DOI:10.1016/j.carbon.2017.09.007
It is a great challenge to fabricate lightweight microwave absorption materials (MAMs) with strong electromagnetic wave attenuation over wide frequency range. In this work, ultralight multiwalled carbon nanotube (MWCNT)/graphene foams (CGFs) are prepared through a facile solvothermal method and their microwave absorption (MA) properties are fully investigated. The CGFs exhibit tunable complex permittivity and conductivity through regulating MWCNT loading and thermal reduction temperature. The addition of MWCNT remarkably enhances the MA intensity of CGFs in low frequency. A minimum reflection loss value of −39.5 dB and average absorption intensity exceeding 22.5 dB in both C (4–8 GHz) and X (8–12 GHz) bands are obtained. For the optimized CGF, the qualified bandwidth with reflection loss less than - 10 dB reaches up to 16 GHz, which covers the whole measured range of 2–18 GHz and shares the widest qualified bandwidth among open literature reports. Furthermore, a specific MA performance of 12243 dB cm2 g−1 is realized, which is one of the best results among various MAMs. The synergistic effect of MWCNT and graphene and thus obtained three dimensional high loss multilevel network architecture are thought to be the primary causes for the excellent MA performance of CGFs.Download high-res image (375KB)Download full-size image
Co-reporter:Yi Zhang, Yi Huang, Honghui Chen, Zhiyu Huang, Yang Yang, Peishuang Xiao, Ying Zhou, Yongsheng Chen
Carbon 2016 Volume 105() pp:438-447
Publication Date(Web):August 2016
DOI:10.1016/j.carbon.2016.04.070
Macroscopic lossy foam has been expected to be the most promising candidate for lightweight high-performance microwave absorption (MA). However, inferior MA behaviors of conventional foams reported previously are disappointing. The emerging graphene foam (GF) has broken this paradoxical state of affairs. Here, series of GFs with various chemical compositions and physical structures have been prepared via a facile and controllable method and their MA performance is investigated in 2–18 GHz. The in-depth analyses of the GF’s composition, structure and MA property demonstrate that the MA performance of the GF is strongly correlated with the C/O ratio, conjugated carbon domain size and graphene framework’s microstructure. A maximum absorption value of −34.0 dB as well as 14.3 GHz qualified bandwidth with reflection loss below −10 dB is achieved for the GF with an ultralow bulk density of 1.6 mg/cm3, of which the average absorption intensity and the specific MA efficiency are much higher than those of the best available MA materials in previous literature. The composition & structure–performance relationship of MA foams is revealed. The balance between small interfacial impedance gap and high loss characteristic has wide implications in improving the MA performance of the GF and other porous materials.
Co-reporter:Peishuang Xiao;Ningbo Yi;Tengfei Zhang;Huicong Chang;Yang Yang;Ying Zhou ;Yongsheng Chen
Advanced Science 2016 Volume 3( Issue 6) pp:
Publication Date(Web):
DOI:10.1002/advs.201500438
Smart actuators have many potential applications in various areas, so the development of novel actuation materials, with facile fabricating methods and excellent performances, are still urgent needs. In this work, a novel electromechanical bimorph actuator constituted by a graphene layer and a PVDF layer, is fabricated through a simple yet versatile solution approach. The bimorph actuator can deflect toward the graphene side under electrical stimulus, due to the differences in coefficient of thermal expansion between the two layers and the converse piezoelectric effect and electrostrictive property of the PVDF layer. Under low voltage stimulus, the actuator (length: 20 mm, width: 3 mm) can generate large actuation motion with a maximum deflection of about 14.0 mm within 0.262 s and produce high actuation stress (more than 312.7 MPa/g). The bimorph actuator also can display reversible swing behavior with long cycle life under high frequencies. on this basis, a fish-like robot that can swim at the speed of 5.02 mm/s is designed and demonstrated. The designed graphene-PVDF bimorph actuator exhibits the overall novel performance compared with many other electromechanical avtuators, and may contribute to the practical actuation applications of graphene-based materials at a macro scale.
Co-reporter:Yi Zhang;Tengfei Zhang;Huicong Chang;Peishuang Xiao;Honghui Chen;Zhiyu Huang ;Yongsheng Chen
Advanced Materials 2015 Volume 27( Issue 12) pp:2049-2053
Publication Date(Web):
DOI:10.1002/adma.201405788
Co-reporter:Tengfei Zhang, Fan Zhang, Long Zhang, Yanhong Lu, Yi Zhang, Xi Yang, Yanfeng Ma, Yi Huang
Carbon 2015 Volume 92() pp:106-118
Publication Date(Web):October 2015
DOI:10.1016/j.carbon.2015.03.032
To meet the higher requirement of energy storage units, novel devices combining high power performance of supercapacitor and high energy density of Li-ion battery are in urgent demand. Herein we designed and fabricated a Li-ion capacitor device, which is composed of an electrochemical double layer capacitance electrode as the positive electrode and a Li-ion battery type electrode as the negative electrode. Both electrodes consist of graphene-based active materials: a three-dimensional graphene-based porous carbon material with ultrahigh specific surface area, appropriate pore size distribution and excellent conductivity for the positive electrode, and a flash-reduced graphene oxide with open-pore structure and superior rate capability for the negative electrode. With the benefit of the Li-ion capacitor structure, the device exhibits a comprehensive and excellent electrochemical performance in terms of high operating voltage (4.2 V), ultrahigh energy density of 148.3 Wh kg−1 (with power density of 141 W kg−1), maximum power density of 7800 W kg−1 (with energy density kept at 71.5 Wh kg−1) and long cycle life. Such a superior performance indicates that the Li-ion capacitor could be a promising novel energy storage device for wide applications in fast, high efficient and long life energy storage systems.
Co-reporter:Yanhong Lu;Fan Zhang;Long Zhang;Xi Yang
Science Bulletin 2014 Volume 59( Issue 16) pp:1809-1815
Publication Date(Web):2014 June
DOI:10.1007/s11434-014-0297-3
p-Phenylenediamine (PPD) functionalized graphene oxide (GO) materials (PPDG) were prepared through a one-step solvothermal process and their application as supercapacitors (SCs) were studied. The PPD is not only as the spacers to prevent aggregating and restacking of the graphene sheets in the preparing process but also as nitrogen sources to obtain the nitrogen-doped graphene. The structures of PPDG were characterized by Fourier transformed infrared spectroscopy (FT-IR), X-ray diffraction spectroscopy (XRD), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) and the results show that the nitrogen-doped graphene was achieved with nitrogen content as high as 10.85 at.%. The field emission scanning electron microscopy (FE-SEM) and high resolution transmission electron microscopy (HR-TEM) have confirmed that the morphologies of PPDG were loose layered with less aggregation, indicating that PPD molecules, as spacers, effectively prevent the graphene sheets from restacking during the solvothermal reaction. The special loose textures make PPDG materials exhibit excellent electrochemical performance for symmetric SCs with superior specific capacitance (313 F/g at 0.1 A/g), rate capability and cycling stability. The present synthesis method is convenient and may have potential applications as ultrahigh performance SCs.
Co-reporter:JiaJie Liang;Fan Zhang;Yi Zhang
Science China Technological Sciences 2014 Volume 57( Issue 2) pp:284-287
Publication Date(Web):2014 February
DOI:10.1007/s11431-014-5467-7
Strong chemical interactions between the oxygen-containing functional groups on graphene oxide (GO) sheets and the ions of divalent metals were exploited for the softening of hard water. GO membranes were prepared and evaluated for their ability to absorb Ca2+ and Mg2+ ions. These GO membranes can effectively absorb Ca2+ ions from hard water; a 1 mg GO membrane can remove as much as 0.05 mg Ca2+ ions. These GO membranes can be regenerated and used repeatedly.
Co-reporter:Lu Huang;Ningbo Yi;Yingpeng Wu;Yi Zhang;Qian Zhang;Yanfeng Ma ;Yongsheng Chen
Advanced Materials 2013 Volume 25( Issue 15) pp:2224-2228
Publication Date(Web):
DOI:10.1002/adma.201204768
Co-reporter:Yi Huang, Jiajie Liang and Yongsheng Chen
Journal of Materials Chemistry A 2012 vol. 22(Issue 9) pp:3671-3679
Publication Date(Web):20 Jan 2012
DOI:10.1039/C2JM15536B
Compared with traditional actuation materials, such as piezoelectric, ferroelectric and conducting polymer materials which suffered from low flexibility, high driving voltages and low energy efficiency, graphene exhibits outstanding mechanical, electrical, optical properties and chemical stability, which made it a good candidate for actuation materials. In this review, the recent progress in graphene based actuators induced by electric, electrochemical, optical and other stimulations are summarized. Different actuation mechanisms and future developments are discussed. Graphene based materials, combining their many excellent properties, such as material abundance, super mechanical strength with excellent actuation performance, are expected to have great potential for the application in next generation actuators.
Co-reporter:Jiajie Liang, Lu Huang, Na Li, Yi Huang, Yingpeng Wu, Shaoli Fang, Jiyoung Oh, Mikhail Kozlov, Yanfeng Ma, Feifei Li, Ray Baughman, and Yongsheng Chen
ACS Nano 2012 Volume 6(Issue 5) pp:4508
Publication Date(Web):April 18, 2012
DOI:10.1021/nn3006812
Although widely investigated, novel electromechanical actuators with high overall actuation performance are still in urgent need for various practical and scientific applications, such as robots, prosthetic devices, sensor switches, and sonar projectors. In this work, combining the properties of unique environmental perturbations-actuated deformational isomerization of polydiacetylene (PDA) and the outstanding intrinsic features of graphene together for the first time, we design and fabricate an electromechanical bimorph actuator composed of a layer of PDA crystal and a layer of flexible graphene paper through a simple yet versatile solution approach. Under low applied direct current (dc), the graphene–PDA bimorph actuator with strong mechanical strength can generate large actuation motion (curvature is about 0.37 cm–1 under a current density of 0.74 A/mm2) and produce high actuation stress (more than 160 MPa/g under an applied dc of only 0.29 A/mm2). When applying alternating current (ac), this actuator can display reversible swing behavior with long cycle life under high frequencies even up to 200 Hz; significantly, while the frequency and the value of applied ac and the state of the actuators reach an appropriate value, the graphene–PDA actuator can produce a strong resonance and the swing amplitude will jump to a peak value. Moreover, this stable graphene–PDA actuator also demonstrates rapidly and partially reversible electrochromatic phenomenon when applying an ac. Two mechanisms—the dominant one, electric-induced deformation, and a secondary one, thermal-induced expansion of PDA—are proposed to contribute to these interesting actuation performances of the graphene–PDA actuators. On the basis of these results, a mini-robot with controllable direction of motion based on the graphene–PDA actuator is designed to illustrate the great potential of our discoveries for practical use. Combining the unique actuation mechanism and many outstanding properties of graphene and PDA, this novel kind of graphene–PDA actuator exhibits compelling advantages to traditional electromechanical actuation technology and may provide a new avenue for actuation applications.Keywords: electrochromatic; electromechanical actuator; graphene; polydiacetylene; resonance
Co-reporter:Jiajie Liang;Jiyoung Oh;Mikhail Kozlov;Dong Sui;Shaoli Fang;Ray H. Baughman;Yanfeng Ma;Yongsheng Chen
Advanced Functional Materials 2011 Volume 21( Issue 19) pp:3778-3784
Publication Date(Web):
DOI:10.1002/adfm.201101072
Abstract
Exceptionally high specific surface area, mechanical strength, electrical conductivity, and a special two-dimensional structure make graphene a highly promising material for electromechanical actuators. Electromechanical actuators are fabricated using flexible graphene-based paper prepared via a filtration process, and the stroke of these graphene-based actuators is directly measured during electrochemical double-layer charge injection. Actuation strain up to 0.064% was obtained for pristine graphene paper in response to an applied potential of –1 V in 1 M NaCl solution. Double-layer charge injection in graphene sheets is believed to induce actuation strain through a combination of coulombic and quantum-chemical-based expansion. To increase electrochemical-double-layer capacitance and actuator performance, Fe3O4 nanoparticles were used to partially prevent graphene sheets from restacking and allow the electrolyte ions to infiltrate the resulting magnetic graphene paper more easily. The magnetic graphene paper exhibits actuation strain as large as 0.1% at –1 V applied potential, which is about 56% higher than that of the pristine graphene paper.
Co-reporter:Xianglei Kong;Shuqi Li;Sen Zhang
Journal of The American Society for Mass Spectrometry 2011 Volume 22( Issue 11) pp:
Publication Date(Web):2011 November
DOI:10.1007/s13361-011-0221-x
The formation of large even-numbered carbon cluster anions, \( {\text{C}}_{\text{n}}^{ - } \), with n up to 500 were observed in the mass spectra generated by laser ablation of graphene and graphene oxide, and the signal intensity of the latter is much weaker than that of the former. The cluster distributions generated from graphene can be readily altered by changing the laser energy and the accumulation period in the FT - ICR cell. By choosing suitable experimental conditions, weak signals of odd-numbered anions from \( {\text{C}}_{{125}}^{ - } \) to \( {\text{C}}_{{211}}^{ - } \), doubly charged anions from \( {\text{C}}_{{70}}^{{2 - }} \) to \( {\text{C}}_{{230}}^{{2 - }} \) and triply charged cluster anions from \( {\text{C}}_{{80}}^{{3 - }} \) to \( {\text{C}}_{{224}}^{{3 - }} \) can be observed. Tandem MS was applied to some selected cluster anions. Though no fragment anions larger than \( {\text{C}}_{{20}}^{ - } \) can be observed by the process of collisional activation with N2 gas for most cluster ions, several cluster anions can lose units of C2, C4, C6 or C8 in their collision process. The differences in their dissociation kinetics and structures require further calculations and experimental studies.
Co-reporter:Lu Huang;Jiajie Liang;Xiangjian Wan;Yongsheng Chen
Nano Research 2011 Volume 4( Issue 7) pp:675-684
Publication Date(Web):2011 July
DOI:10.1007/s12274-011-0123-z
A series of inkjet printing processes have been studied using graphene-based inks. Under optimized conditions, using water-soluble single-layered graphene oxide (GO) and few-layered graphene oxide (FGO), various high image quality patterns could be printed on diverse flexible substrates, including paper, poly(ethylene terephthalate) (PET) and polyimide (PI), with a simple and low-cost inkjet printing technique. The graphene-based patterns printed on plastic substrates demonstrated a high electrical conductivity after thermal reduction, and more importantly, they retained the same conductivity over severe bending cycles. Accordingly, flexible electric circuits and a hydrogen peroxide chemical sensor were fabricated and showed excellent performances, demonstrating the applications of this simple and practical inkjet printing technique using graphene inks. The results show that graphene materials-which can be easily produced on a large scale and possess outstanding electronic properties-have great potential for the convenient fabrication of flexible and low-cost graphene-based electronic devices, by using a simple inkjet printing technique.
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Co-reporter:Yan Wang, Yi Huang, You Song, Xiaoyan Zhang, Yanfeng Ma, Jiajie Liang and Yongsheng Chen
Nano Letters 2009 Volume 9(Issue 1) pp:220-224
Publication Date(Web):December 12, 2008
DOI:10.1021/nl802810g
Aiming at molecular-based magnets, ferromagnetism of pure carbon-based materials is fundamentally and technologically extremely important for many applications. While it is still not fully understood, many recent theoretical works have suggested that one-atom-thick two-dimensional graphene materials may show ferromagnetism due to the existence of various defects or topological structures as the spin units and the possible long-range ordered coupling among them. Here, we report the experimental results on the ferromagnetism of graphene-based materials at room temperature. The observed room-temperature ferromagnetism is believed to come from the defects on graphene.
Co-reporter:Jiajie Liang;Long Zhang;Yan Wang;Yanfeng Ma;Tianyin Guo ;Yongsheng Chen
Advanced Functional Materials 2009 Volume 19( Issue 14) pp:2297-2302
Publication Date(Web):
DOI:10.1002/adfm.200801776
Abstract
Despite great recent progress with carbon nanotubes and other nanoscale fillers, the development of strong, durable, and cost-efficient multifunctional nanocomposite materials has yet to be achieved. The challenges are to achieve molecule-level dispersion and maximum interfacial interaction between the nanofiller and the matrix at low loading. Here, the preparation of poly(vinyl alcohol) (PVA) nanocomposites with graphene oxide (GO) using a simple water solution processing method is reported. Efficient load transfer is found between the nanofiller graphene and matrix PVA and the mechanical properties of the graphene-based nanocomposite with molecule-level dispersion are significantly improved. A 76% increase in tensile strength and a 62% improvement of Young's modulus are achieved by addition of only 0.7 wt% of GO. The experimentally determined Young's modulus is in excellent agreement with theoretical simulation.
Co-reporter:Xiaoying Yang, Xiaoyan Zhang, Yanfeng Ma, Yi Huang, Yinsong Wang and Yongsheng Chen
Journal of Materials Chemistry A 2009 vol. 19(Issue 18) pp:2710-2714
Publication Date(Web):05 Mar 2009
DOI:10.1039/B821416F
A superparamagnetic graphene oxide –Fe3O4nanoparticles hybrid (GO–Fe3O4) was prepared via a simple and effective chemical precipitation method. The amount of loading of Fe3O4 on GO was estimated as 18.6 wt% by atomic absorption spectrometry. The hybrid was then loaded with doxorubicin hydrochloride (DXR) and the loading capacity was as high as 1.08 mg mg−1. Both of the GO–Fe3O4 hybrids before and after loading with DXR can be dispersed well in aqueous solution. They can congregate under acidic conditions and move regularly under the force of an external magnet. Furthermore, the aggregated hybrid can be redispersed to form a stable suspension under basic conditions. These properties make it a potential candidate for controlled targeted drug delivery and release.
Co-reporter:Xiaoying Yang, Xiaoyan Zhang, Yanfeng Ma, Yi Huang, Yinsong Wang and Yongsheng Chen
Journal of Materials Chemistry A 2009 - vol. 19(Issue 18) pp:NaN2714-2714
Publication Date(Web):2009/03/05
DOI:10.1039/B821416F
A superparamagnetic graphene oxide –Fe3O4nanoparticles hybrid (GO–Fe3O4) was prepared via a simple and effective chemical precipitation method. The amount of loading of Fe3O4 on GO was estimated as 18.6 wt% by atomic absorption spectrometry. The hybrid was then loaded with doxorubicin hydrochloride (DXR) and the loading capacity was as high as 1.08 mg mg−1. Both of the GO–Fe3O4 hybrids before and after loading with DXR can be dispersed well in aqueous solution. They can congregate under acidic conditions and move regularly under the force of an external magnet. Furthermore, the aggregated hybrid can be redispersed to form a stable suspension under basic conditions. These properties make it a potential candidate for controlled targeted drug delivery and release.
Co-reporter:Yi Huang, Jiajie Liang and Yongsheng Chen
Journal of Materials Chemistry A 2012 - vol. 22(Issue 9) pp:NaN3679-3679
Publication Date(Web):2012/01/20
DOI:10.1039/C2JM15536B
Compared with traditional actuation materials, such as piezoelectric, ferroelectric and conducting polymer materials which suffered from low flexibility, high driving voltages and low energy efficiency, graphene exhibits outstanding mechanical, electrical, optical properties and chemical stability, which made it a good candidate for actuation materials. In this review, the recent progress in graphene based actuators induced by electric, electrochemical, optical and other stimulations are summarized. Different actuation mechanisms and future developments are discussed. Graphene based materials, combining their many excellent properties, such as material abundance, super mechanical strength with excellent actuation performance, are expected to have great potential for the application in next generation actuators.
