化工外文翻譯----合成氮雜石墨烯-銀納米 粒子雜合物（英文）

1、Easy synthesis of nitrogen-doped graphene–silvernanoparticle hybrids by thermal treatment of graphiteoxide with glycine and silver nitrateSundar Mayavan, Jun-Bo Sim, Sung-Min Choi *Department of Nuclear and Quantum Engin

2、eering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro,Yuseong-gu, Daejeon 305-701, Republic of KoreaA R T I C L E I N F OArticle history:Received 23 December 2011Accepted 28 June 2012Available

3、 online 5 July 2012A B S T R A C TNitrogen-doped graphene–silver nanoparticle hybrids were prepared by thermal treatmentof graphite oxide (GO) with glycine and silver nitrate at 500 ?C. Glycine was used to reducethe nitr

4、ate ions, resulting in the decomposition of a glycine–nitrate mixture near 200 ?C.The products of decomposition act as sources for nitrogen doping. The thermal treatmentof a mixture of GO, glycine and silver nitrate resu

5、lts in the formation of silver nanoparticlesat 100 ?C, promotes the reduction of GO near 200 ?C, and generates pyrrolic and pyridinictype nitrogen doping in graphene at 300 and 500 ?C, respectively. The atomic percentage

6、of nitrogen in as-prepared sample is about 13.5%. This approach opens up a new possibilityfor the synthesis of nitrogen-doped graphene decorated with various metallic nanoparti-cles, which could find important applicatio

7、ns in the fields of energy storage and conversiondevices.? 2012 Elsevier Ltd. All rights reserved.1. IntroductionGraphene, a basic building block in all graphitic material, is asingle layer of carbon atoms arranged in ho

8、neycomb lattice.Graphene exhibits unique structure dependent electronic,mechanical, chemical properties and has high surface area(2630–2965 m2g?1) [1–3]. Chemical doping of graphene withforeign atoms like nitrogen has at

9、tracted a great deal of atten-tion due to its potential applications as sensors, catalyst forfuel cell, and electrode for lithium ion batteries [4–6]. Nitrogendoping has been employed to modify the electrical and struc-t

10、ural properties of graphene, and such modification results ingreater electron mobility and induces large number of surfacedefects. The presence of lone pair of nitrogen atoms canresult in great improvement of the reactiv

11、ity and catalyticperformance of graphene. Nitrogen doped graphene (NG)showed a much better activity and stability for oxygen reduc-tion reaction (ORR) than commercial platinum (Pt) catalystunder alkaline conditions [5].

12、The observed high activity ofNG for ORR is due to the high electron accepting ability ofdoped nitrogen atoms which create a net positive charge oncarbon atoms facilitating oxygen adsorption. Nanoparticlesdeposited on NG

13、showed higher electrochemical activity andstability than nanoparticles deposited on un-doped graphene.Pt loaded NG showed higher power density than Pt loadedgraphene for ORR due to increased conductivity of NG and en-han

14、ced Pt-support binding [7]. A recent publication reportedhigh ORR activity for CO3O4 nanocrystals grown on NG thanon graphene [8], adding to the list of proposed application ofNG for catalytic applications.Methods for th

15、e synthesis of NG mainly include chemicalvapor deposition (CVD), arc discharge of graphite in thepresence of nitrogen precursor, laser ablation, and nitrogenor ammonia plasma treatment of graphene [9–11]. All thesemethod

16、s result in NGs with unique characteristics, butinvolve high energy consumption, special expensive0008-6223/$ - see front matter ? 2012 Elsevier Ltd. All rights reserved.http://dx.doi.org/10.1016/j.carbon.2012.06.055* Co

17、rresponding author: Fax: +82 423503810.E-mail address: sungmin@kaist.ac.kr (S.-M. Choi).C A R B O N 5 0 ( 2 0 1 2 ) 5 1 4 8 –5 1 5 5Available at www.sciencedirect.comjournal homepage: www.elsevier.com/locate/carbonof AgN

18、O3–Gly–GO annealed at different temperatures areshown in Fig. 3. The XRD pattern at 100 ?C shows clear peakscorresponding to (111), (200), (220) and (311) of metallic Agalong with peaks corresponding to AgNO3–Gly, which

19、clearlyindicates the formation of Ag nanoparticles. The role of GOin reducing the Ag ions was confirmed by the absence of Agcrystalline peaks when a mixture of AgNO3 and Gly was an-nealed at 100 ?C without GO (Figure S5,

20、 Supporting Informa-tion). This indicates that reduction of Ag ions occurs only inthe presence of GO by electron transfer from the hydroxylfunctional groups on the surface of GO [18]. It was noted thatthe peaks correspon

21、ding to GO were not observed at 100 ?C,indicating the exfoliation of GO [19]. At 200 ?C, the peaks cor-responding to AgNO3–Gly almost disappeared, suggestingthat most of the Gly–nitrate species have been removed(which is

22、 consistent with TGA measurement). A small andbroad peak near 2h ? 25.8? shows up at 200 ?C, which can beattributed to stacking of graphene sheets. At 300 ?C and500 ?C, the peaks corresponding to AgNO3–Gly completely dis

23、-appeared and only the peaks corresponding to Ag crystallineand stacked graphenes were observed.The XPS spectra of AgNO3–Gly–GO annealed at differenttemperature are shown in Fig. 4. For all samples, Carbon (C),oxygen (O)

24、, nitrogen (N) and Ag photo peaks are detected(Fig. 4a). The Ag 3d component is centered at 368.1 and374.1 eV at all temperatures as expected for metallic Ag [20],which is consistent with the XRD results. At 100 ?C, the

25、highresolution C 1 s XPS spectrum (Fig. 4b) shows two separatedpeaks due to the high percentage of oxygen functionalities(epoxide, hydroxyl, carbonyl, lactone, carboxyl) resulted fromgraphite oxidation [21]. Upon increas

26、ing the temperature to300 and 500 ?C, C = C bonds dominate, as shown by one singlepeak (284.5 eV), which implies considerable reduction of oxy-gen containing groups upon thermal treatment. The asym-metric broadening of t

27、he C 1 s peaks toward the highbinding energy side indicates the incorporation of nitrogeninto graphene sheets to form C–N bonded groups [15]. Fur-thermore, the O 1 s spectra decrease with temperature andthe oxygen atomic

28、 composition determined from the XPSspectra decreased from 39.4 wt.% at 100 ?C down to7.38 wt.% in 500 ?C (Figure S6, Supporting Information), indi-cating the reduction of GO during thermal treatment. TheTGA measurement

29、of AgNO3–Gly–GO annealed at 500 ?CFig. 3 – X-ray diffraction patterns of AgNO3–Gly–GO atvarious temperatures.Fig. 1 – (a) FE-SEM image of NG–Ag and (b) FE-TEM image of NG–Ag.Fig. 2 – TGA profiles of AgNO3–Gly and AgNO3–G