Deakin Research Online This is the published version: Tang, Bin, Hou, Xueliang, Li, Jingliang, Zhang, Mingwen, Sun, Lu and Wang, Xungai 2013, Acceleration effect of reduced graphene oxide on photoinduced synthesis of silver nanoparticles, Physical chemistry chemical physics, vol. 15, no. 26, pp. 11106-11112. Available from Deakin Research Online: http://hdl.handle.net/10536/DRO/DU:30055361 Reproduced with the kind permission of the copyright owner. Copyright : 2013, Royal Society of Chemistry

11106 Phys. Chem. Chem. Phys., 2013, 15, 11106--11112 This journal is c the Owner Societies 2013

Cite this: Phys. Chem.Chem.Phys.,2013,15, 11106

Acceleration effect of reduced graphene oxide onphotoinduced synthesis of silver nanoparticles†

Bin Tang,a Xueliang Hou,a Jingliang Li,a Mingwen Zhang,a Lu Sun*ab andXungai Wang*ab

The photoinduced growth reaction of silver nanoparticles was accelerated by reduced graphene oxide (RGO)

produced from graphene oxide (GO) during the light irradiation process in aqueous solution. X-ray

photoelectron spectroscopy (XPS) and Raman spectroscopy demonstrated that RGO was generated in the

photoinduced process. The acceleration effect of RGO was investigated through monitoring the extinction

spectra of silver nanoparticles during the synthesis process. Moreover, transmission electron microscopy (TEM)

was employed to characterize the evolution of morphologies of silver nanoparticles at different irradiation

times to demonstrate the effect of RGO. The results indicate that RGO accelerates the photoinduced synthesis

of silver nanoparticles. It is proposed that the acceleration effect of RGO on the photoinduced reaction

is attributed to the particular property of high electronic conductivity.

1. Introduction

Silver nanoparticles with well-defined morphologies and localizedsurface plasmon resonance (LSPR) have attracted extensive atten-tion, because of their potential applications in areas such as surfaceenhanced spectroscopy,1,2 biological sensing,3 and optoelectronicdevices.4–7 LSPR properties of the noble metal (including silver andgold) nanoparticles are related to their size, shape, compositionand surroundings.8–11 Many strategies have been developed tosynthesize shape controlled anisotropic silver nanoparticles to tunetheir LSPR optical properties.12–18 Among them, the photoinducedgrowth method is one of the most popular routes.12,13,19–23 Mirkinet al. reported the synthesis of silver nanoprisms through conver-sion of silver seeds by photoinduction.13 The silver seeds wereprepared through reduction of silver nitrate by sodium borohydridein the presence of trisodium citrate and the bis(p-sulfonatophenyl)-phenylphosphine dihydrate dipotassium salt (BSPP). Subsequentlight irradiation induced the silver seeds to grow into silvernanoprisms with multiple plasmon resonance modes. The particlegrowth process was driven by surface plasmon excitations.12,24

Recently, the photochemical process was believed to involve

the reduction of silver cations by citrate on the silver particlesurface and the oxidative dissolution of small silver particles.25

In the meantime, a similar mechanism of photoconversion fromcitrate stabilized silver seeds to nanoprisms was proposed by Wuet al.26 It involved photooxidation of citrate by hot ‘‘holes’’ fromthe plasmon dephasing on the surface of the nanoparticles,oxidative etching of silver in the presence of O2, and selectivereduction of aqueous silver ions on crystalline prisms with ahigh photovoltage. Insight into the photoconversion mechanismof silver nanoparticles could help the development of a photo-induced route for the synthesis of noble metal nanoparticles.

Graphene has a two-dimensional structure and many uniqueproperties, such as great intrinsic carrier mobility, excellentmechanical flexibility, large specific surface area and high electricalconductivity.27–32 As a result, graphene has been developed fornumerous applications including nanoelectronic devices,33

sensing,34–36 energy generation systems,27,37–39 photocatalysis40–42

and transparent conductive films. For example, graphene was usedto combine with titanium dioxide (TiO2) to enhance the photo-catalytic performance of TiO2 even under visible light.40,41,43–46 Itwas suggested that graphene retarded the recombination ofelectron–hole pairs in the excited TiO2 because the high elec-tronic conductivity of graphene leads to facile charge transpor-tation and separation. This resulted in an increased number ofholes participating in the photooxidation process and enhance-ment of the photocatalytic activity of TiO2. In addition,enhanced light absorption and extended light absorptionranges were considered to be the key factors affecting theimprovement of photocatalysis resulting from graphene.40,42,45

a Institute for Frontier Materials, Deakin University, Geelong, Victoria 3216,

Australia. E-mail: xungai.wang@deakin.edu.au, lu.sun@deakin.edu.au;

Fax: +61 3 5227 2539; Tel: +61 3 5227 3247b School of Textile Science & Engineering, Wuhan Textile University,

Wuhan 430073, China

† Electronic supplementary information (ESI) available: HRTEM images of silvernanoprisms and TEM images of RGO nanosheets after photoinduction. See DOI:10.1039/c3cp44312d

Received 1st December 2012,Accepted 7th May 2013

DOI: 10.1039/c3cp44312d

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These prominent features of graphene inspired us to investi-gate the interaction between graphene and silver nanoparticleswith LSPR during the photoinduced process.

Herein, the effect of graphene on the photoinduced growthof silver nanoparticles was observed through adding differentamounts of graphene oxide (GO) solution into the silver seedsolution. The transformation from GO to reduced grapheneoxide (RGO) during light irradiation was investigated. Spectralmeasurements and morphological characterization of silvernanoparticles were performed at different reaction periods.The role of RGO in increasing the photoinduced reaction ratewas observed. Furthermore, the mechanism involving interactionof silver nanoparticles and RGO is discussed.

2. Experimental section2.1 Materials

Graphite, AgNO3 (>99%), trisodium citrate (Z99.0%), sodiumborohydride (>98%) and hydrogen peroxide (30 wt%) werepurchased from Sigma-Aldrich. All the chemicals were analyticalgrade and used as received.

2.2 Synthesis of GO nanosheets

GO was obtained by exfoliating graphite following a reportedmethod with modifications.47 Briefly, 10 g of graphite flakesand 7.5 g of sodium nitrate were added to 300 mL of sulfuricacid (98%), and then 40 g of potassium permanganate wasadded to the reaction slowly over 1 h. The mixture was stirred atroom temperature for 3 days. 1 L of hydrogen peroxide solution(1% in water) was then added into the mixture. Subsequently,the mixture was filtered and washed with deionized water untilpH = 7. The resulting black cake was re-dispersed in de-ionized waterto give a dark brown dispersion, which was subjected to dialysis forone week to remove the residual salts and acids. The brownsuspension was then dried at 40 1C under vacuum. GO nanoparticleswere produced by ultrasonicating the large GO in water for 30 min.The GO dispersion was then centrifuged at 25 000 rpm for 30 minto remove the large nanosheets and particles. The concentrationof as-synthesized GO was 0.4 mg mL�1.

2.3 Photoinduced synthesis of silver nanoparticles

A typical experiment was carried out by a photoconversionprocess. First, silver seeds were prepared by dropwise additionof NaBH4 solution (8.0 mM, 1.0 mL) to an aqueous solution ofAgNO3 (0.1 mM, 100 mL) in the presence of trisodium citrate(1.0 mM) under vigorous stirring. Yellow silver seed solutionswere obtained. Subsequently, the GO solutions of differentvolumes (0.125 mL, 0.25 mL and 0.50 mL) were added into thesilver seed solutions and stirred for 3 min. The silver seedsolutions with GO were then placed under a sodium lamp(NAV-T 70 model from Osram China Lighting Co., Ltd.). Thelamp has a main emission band in the range 560–620 nm afterlighting up over 20 min.48 The color of silver colloids changedfrom yellow to green, and finally to blue during the irradiationprocess. All other experimental conditions were kept consistentfor investigation of the effect of RGO on the photoinduced

synthesis of silver nanoparticles. The reaction solutions werecharacterized at different time periods.

2.4 Characterization

X-ray photoelectron spectroscopy (XPS) analysis was performed ona Thermo ESCALAB 250 spectrometer with a Mg-Ka (1253.6 eV)achromatic X-ray source. Raman spectra were obtained by using aBWTEK-Miniram BTR-111miniature Raman spectrometer with532 nm laser. Extinction spectra of silver nanoparticle solutionswere recorded using a Varian Cary 3E UV/vis spectrophotometer.Transmission electron microscopy (TEM) and high-resolutiontransmission electron microscopy (HRTEM) images were obtainedusing a JEOL JEM-2100 and a JEOL JEM-2100F with an accelera-tion voltage of 200 kV, respectively. Samples for TEM and HRTEManalysis were prepared by dripping a drop of silver nanoparticlesolutions onto the copper grids with (holey) thin carbon filmsand drying them in the air at room temperature. XRD patternswere collected on a Panalytical X’Pert PRO diffraction systemusing Cu Ka radiation.

3. Results and discussion3.1 Transformation of GO into RGO by photoinduction

In the process of light irradiation, GO probably varied due tothe role of light. In order to examine the changes in GO duringphotoinduced growth of silver nanoparticles, XPS and Ramanspectroscopy were employed to analyze the chemical composi-tions of pristine GO and silver nanoparticles with GO afterphotoinduction. Fig. 1A depicts the deconvoluted C 1s XPSspectrum of the pristine GO. The peak centered at 284.9 eV isattributed to the C–C and CQC bonds. The peaks centeredat 287.0, 287.8 and 289.0 eV are assigned to the C–O, CQO andO–CQO bonds, respectively.49–51 While the XPS C 1s spectrumof silver nanoparticles with GO after photoinduction showsonly two peaks centered at 284.5 and 288.1 eV (Fig. 1B). Thepeaks assigned to C–O and CQO almost disappeared in theXPS C 1s spectrum of photoinduced silver nanoparticles withGO, which indicated effective de-oxygenation of GO in thephotoinduced process of silver nanoparticles. However, thepresence of the XPS C 1s peak centered at 288.1 eV (O–CQO)for the as-prepared silver nanoparticles with GO in Fig. 1Breveals that there are still oxygenated carbon species in thephotoinduced products. The XPS results indicate clearly thatthe GO nanosheets have been reduced in the photoinduced

Fig. 1 XPS spectra of (A) pristine GO and (B) silver nanoparticles with GO(actually RGO) after irradiation.

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process of silver nanoparticles. Raman spectroscopy is a powerfultechnique providing structural information on graphite materials.Fig. 2 depicts the Raman spectra of pristine GO and silvernanoparticles with GO after photoinduction. The Raman spectrumof pristine GO shows two prominent peaks at 1595 cm�1 and1353 cm�1, which correspond to the well documented G and Dbands of GO, respectively.28,52 The G band is assigned to the first-order scattering of E2g phonons by sp2 carbon atoms. The D band,considered as a breathing mode of A1g symmetry, is related todisordered conformations and defects of the graphene lattice.53–55

The Raman spectrum of silver nanoparticles with GO after photo-induction displays some new peaks at 795 cm�1, 1051 cm�1 and1628 cm�1 besides the bands at 1587 cm�1 and 1345 cm�1 (curve(a) in Fig. 2B). The new peaks in curve (a) in Fig. 2B are suggested tobe assigned to Raman bands of citrate and its decompositionproducts,56 which is proved by the Raman spectrum of the silvernanoparticles without GO after photoinduction (curve (b) inFig. 2B). A Raman peak at 1628 cm�1 can be seen in curve (b),overlaying the band at 1587 cm�1 in curve (a). To disclose thechanges in the Raman spectrum of GO during the photoinducedprocess, the difference spectrum between curve (a) and (b) inFig. 2B is obtained to remove the influence of the silver nanoprismsin solution (Fig. 2C). The peaks at 1575 cm�1 and 1346 cm�1 inthe difference spectrum are attributed to G and D bands of RGO.55

Compared with the Raman spectrum of GO (Fig. 2A), the G and Dbands of RGO present shifting, which is probably due to reductionof GO and the influence of the combination of silver nanoparticles.The ID/IG ratio is a measure of the relative disorder present ingraphitic/graphenic structures.28,54 In the present study, theintensity ratio of the D band to G band (ID/IG) decreased from0.97 to 0.89 after light irradiation, implying an increase in thesize of sp2 domains.57 It was proposed that the elimination ofoxygen species with the reintroduction of large aromaticdomains resulted in the decrease in ID/IG ratio.54,58 It ispossible that light irradiation diminishes defects and inducesthe formation of more extended networks of conjugated sp2

carbons, which brings about a more locally ordered graphenelattice.57,59 These results confirm that the RGO is producedduring the photoinduced growth of silver nanoparticles.

3.2 Photoinduced growth of silver nanoparticles

Silver nanoprisms were synthesized from silver seeds through aphotoinduced method. The yellow silver seed solution in theabsence of RGO changed to green and finally to blue during the

irradiation process (Fig. 3A). The acquired blue silver nano-particles were triangular in shape, which has been reportedpreviously.12,13,48 Fig. 4A shows the evolution of extinctionspectra corresponding to as-synthesized silver nanoparticles. Ascan be seen, there is only a single extinction band centeredaround 400 nm in the extinction spectrum of silver nanoparticlesafter irradiation for 30 min, which is attributed to LSPR of silverseeds.48 As irradiation continued, there was a new extinctionband arising at a long wavelength after 270 min, which indicates

Fig. 2 Raman spectra of (A) pristine GO before light irradiation, and (B) thesilver nanoparticles (curve (a)) with GO and (curve (b)) without GO afterphotoinduction. (C) Difference spectrum of the Raman spectra (curves (a) and(b)) in (B), corresponding to RGO after photoinduction. All the Raman spectrawere treated through background subtraction and smoothing.

Fig. 3 Photographs of silver nanoparticle solutions irradiated for 30, 150, 270,330, 420 and 510 min with different concentrations of GO: (A) 0 mg mL�1,(B) 0.5 � 10�3 mg mL�1, (C) 1.0 � 10�3 mg mL�1, and (D) 2.0 � 10�3 mg mL�1.

Fig. 4 Extinction spectra of silver nanoparticle solutions at different timesunder irradiation with different concentrations of GO: (A) 0 mg mL�1,(B) 0.5 � 10�3 mg mL�1, (C) 1.0 � 10�3 mg mL�1 and (D) 2.0 � 10�3 mg mL�1.

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that anisotropic silver nanoparticles were fabricated by photoinduc-tion.12,13 The intensity of the extinction band at the long wavelengthincreases while that at around 400 nm decreases. Eventually,the LSPR band of silver seeds vanishes, implying that the silverseeds have been transformed to anisotropic silver nanoparticles(Fig. 4A). The final extinction spectrum of silver nanoparticlesin the absence of RGO displays three bands centered at 332, 510and 706 nm, which are assigned to the out-of-plane quadrupole,in-plane quadrupole and in-plane dipole plasmon resonancemodes of silver nanoprisms, respectively.12,13,48

3.3 Acceleration effect of RGO on photoinduced synthesis

The GO with different concentrations was added into the silverseed solutions to investigate the effect of RGO on the photo-induced synthesis of silver nanoparticles. During the irradiationprocess, colors corresponding to silver nanoparticle solutionswith RGO are similar to that without RGO (Fig. 3B–D). However,it was found that the color changes of silver nanoparticles in thepresence of RGO were faster than those in the absence of RGO.Specifically, when the irradiation time was 270 min, the silvernanoparticles without RGO were still yellow and the silvernanoparticles with RGO became yellow green (for an initial GOof 0.5 � 10�3 mg mL�1) and blue (for an initial GO of 1.0 � 10�3

and 2.0 � 10�3 mg mL�1). This indicates that the presence ofRGO in the reaction system promoted the shape conversion ofsilver nanoparticles. To further verify the influence of RGO onthe photoinduced growth of silver nanoparticles, the extinctionspectra of silver nanoparticles without and with RGO at differentreaction times were compared. The evolution of extinctionspectra of silver nanoparticles with RGO is similar to thatwithout RGO (Fig. 4). Nevertheless, the extinction spectra ofsilver nanoparticles with RGO changed faster than those with-out RGO. The silver nanoparticle solutions with 0.5 � 10�3,1.0 � 10�3 and 2 � 10�3 mg mL�1 of GO show a new extinctionband at a long wavelength after 150, 90 and 90 min respectively(Fig. 4B–D). While, the same extinction band appeared inthe extinction spectra of silver nanoparticles without RGO after270 min (Fig. 4A).

In order to investigate the acceleration effect of RGO indetail, the LSPR band of silver seeds around 400 nm was plottedas a function of photoinducing time (Fig. 5). It has beendemonstrated that the silver nanoprisms were fabricated fromthe conversion of silver seeds in the reaction system.12,13 Thedisappearance of the LSPR band corresponding to silver seedsimplies the completion of the photoinduced reaction of silvernanoparticles. Therefore, the decreasing rate of the LPSR ofsilver seeds can denote the photoinduced reaction rate. As canbe seen from Fig. 5, the decreasing rates of the silver seed LSPRband corresponding to the samples with RGO were faster thanthat without RGO, which reveals that the photoinduced growthrates of silver nanoparticles increased dramatically. The spectralresults demonstrate that the presence of RGO in the reactionsystem increases the photoinduced growth rate of anisotropic silvernanoparticles. It is noted that the change rate of the silver seedLSPR band increased as the concentration of RGO in the solutionincreased (Fig. 5). However, the evolutions of the extinction spectra

corresponding to the silver nanoparticle solution with 1.0� 10�3

and 2 � 10�3 mg mL�1 GO are tending to consensus. Theseresults indicate that the photoinduced reaction rate increasedwith increasing concentration of RGO at a certain concentrationrange of RGO.

To gain further information about the photoinduced growthof silver nanoparticles involving RGO, TEM characterizationwas performed to observe the evolution of morphologies ofsilver nanoparticles. Fig. 6 shows the TEM images of silvernanoparticles without RGO and in the presence of RGO withdifferent concentrations taken at different photoinduced reac-tion times. Most of the silver nanoparticles without and withRGO were still small when the silver seeds were irradiated for30 min (Fig. 6). As the irradiation progressed, the triangularsilver nanoplates have been seen in TEM images of nano-particles with higher concentration of RGO (GO 1.0 � 10�3 and2.0 � 10�3 mg mL�1) after 150 min. But no silver nanoprismsappeared at this time in the corresponding TEM of silver nano-particles without RGO (Fig. 6A) and with lower concentration ofRGO (Fig. 6B). Subsequently, most of the silver nanoparticles havebeen transformed to silver nanoprisms in the presence of RGO(GO 1.0 � 10�3 and 2.0 � 10�3 mg mL�1) after 270 min (Fig. 6Cand D). Comparing the morphologies of silver nanoparticleswithout RGO and those with RGO, it is inferred that the presenceof GO in reaction solution accelerated the shape conversion ofsilver nanoparticles from spheres to prisms under light irradia-tion. The silver nanoparticles without GO were finally convertedinto the silver nanoprisms after 510 min (Fig. 6A). The corners ofsilver nanoprisms with RGO became round when they wereirradiated continually to 510 min (Fig. 6B–D). The TEM resultsprove that the presence of RGO in solution increases the rate ofphotoinduced growth of silver nanoparticles.

3.4 Structural characterization of silver nanoparticles

It has been previously reported that the basal plane of the silvernanoprism is the {111} plane.12,13 In order to observe theinfluence of RGO on the structure of as-synthesized silvernanoprisms, HRTEM characterization was performed on the

Fig. 5 Plots of extinction intensity corresponding to silver seeds as a function ofirradiation time.

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silver nanoprisms. Fig. S1 (ESI†) shows the HRTEM images ofthe silver nanoprisms synthesized by the photoinduced growthmethod recorded perpendicular to their flat faces. The fringes ofthe silver nanoprism without RGO are separated by 2.48 Å (Fig. S1A,ESI†), which can be attributed to the (1/3){422} reflection that isgenerally forbidden for an fcc lattice.12,13,60 The HRTEM image ofthe silver nanoprism with RGO displays the same fringes (2.48 Å),which demonstrates that the presence of RGO did not change the(1/3){422} reflection of silver nanoprisms.

To further identify the crystal structure of these silvernanoprisms, the XRD patterns were investigated. As can beseen from curve (a) in Fig. 7, the XRD pattern of silver nano-prisms without RGO presents a strong peak assigned to {111}facets and three weak peaks ascribed to {200}, {220} and {311}facets, which is consistent with the previous report.61 However,compared with the XRD peaks of the silver nanoprisms withoutRGO, the relative intensity of the XRD peak assigned to the{111} basal planes of silver nanoparticles with RGO decreased(curve (b) in Fig. 7), which implies that the presence of RGO in

the photoinduced reaction could influence the structures of{111} facets of silver nanoprisms.

3.5 Influencing factors involving formation of RGO

Fig. S2 (ESI†) shows the TEM image of RGO in the silver nanoprismsolution after photoinduced reaction. Corrugation of RGO on theTEM image was observed, revealing that the RGO was in sheetform. No conjunction of RGO and silver nanoparticles was seen inthe TEM images. This is probably due to removal of surface oxygengroups (hydroxyl, carboxyl, and epoxy) of RGO after deoxidiza-tion.62,63 It was reported that NaBH4 as a reducing agent couldreduce GO to RGO under certain conditions.51,64 In this study, it ispossible that the GO in solution was reduced by residual NaBH4

used for formation of silver seeds. To examine this, the sameamount of NaBH4 as that used for silver seed preparation wasadded to the GO solution. The solution including GO and NaBH4

with aluminium-foil paper to shade light was placed under asodium lamp for 12 h. The extinction spectrum of the originalGO nanosheet aqueous solution presents an extinction bandcentered at 230 nm (Fig. 8A), which is assigned to p–p* transitionof aromatic C–C bonds.52,62 Compared with the original GOsolution, the solution of GO with NaBH4 does not exhibit anobvious change in the extinction band at 230 nm attributed toGO nanosheets, which reveals that the produced RGO in thesilver nanoprism solution was not derived from the reductionrole of NaBH4 added to silver seeds (Fig. 8A). In addition, theGO solution was irradiated under a sodium lamp for differenttime periods to clarify the effect of light irradiation onreduction of GO. Fig. 8B displays the extinction spectra of GOin the irradiation process. As can be found, the extinction bandof GO solution red-shifts to 256 nm from 230 nm, whichindicates that the GO can be converted to RGO by lightirradiation.59,62,65 These results demonstrate that the RGO inthe silver nanoprisms was generated from GO through lightirradiation, which is consistent with the previous report.57

Fig. 6 TEM images of silver nanoparticles under irradiation for different periods with different concentrations of initial GO. (A) 0 mg mL�1, (B) 0.5 � 10�3 mg mL�1,(C) 1.0 � 10�3 mg mL�1 and (D) 2.0 � 10�3 mg mL�1.

Fig. 7 XRD patterns of the silver nanoprisms (a) without and (b) with RGO.

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3.6 Mechanism of the acceleration effect of RGO

The mechanism of photoinduced growth of silver nanoparticleshas been investigated, previously. The dipole plasmon excita-tion by irradiation induces charge separation on the silver seedsurface and assists the photo-oxidation of citrate on the silverseeds.25,26 A possible anisotropic distribution of charge inducedby dipole plasmon excitation results in the transformation fromthe silver seeds to anisotropic silver nanoprisms. In this growthprocess, it was suggested that larger silver particles served asplasmonic seeds for photo-reduction of silver ions which wereproduced by the oxidation of smaller silver particles.25 In thepresent research, RGO nanosheets involved in the photoinducedprocess increased the growth rate of silver nanoprisms. Aplausible mechanism in which RGO interacts with electronsand silver nanoparticles is depicted schematically in Scheme 1.It is possible that the hot electrons–holes are produced byplasmon dephasing on the surface of silver seeds. Subsequently,citrate is photo-oxidized by hot holes from plasmon excita-tion.25,26 It is well known that graphene can enhance photo-catalytic activity of TiO2 through retarding charge recombinationcaused by a high electronic mobility.41,44 The high electronicconductivity of graphene can promote charge transportation andseparation.40,41,43–46,65 In this study, it is suggested that RGOcould accelerate the charge separation from plasmon dephasingdue to its excellent electron–hole transport property. The hotholes from the plasmon excitation of silver particles could betaken up by the citrate through graphene sheets (Scheme 1). Inaddition, a large specific surface area of RGO possibly advancesthe interaction of RGO and citrate to promote the electrondonation by citrate. The charge transfer could happen fromthe graphene to the metal nanoparticles.59 The electrons in

RGO sheets could transfer to the surface of silver nanoparticlesto fill the hot holes from the plasmon excitation of silvernanoparticles. The photo-assisted oxidation of citrate couldresult in injecting electrons into the RGO sheets. In the photo-induced process, RGO as an electron transfer medium enhancedthe charge separation on the surface of silver particles fromplasmon induction, which accelerated photo-oxidation of citrateand photo-reduction of silver ions in solution.

4. Conclusions

The reduced graphene oxide (RGO) was found to accelerate thephotoinduced growth of silver nanoprisms. XPS and Raman spectro-scopy characterization demonstrated that RGO was produced fromgraphene oxide (GO) by light irradiation during the synthesis ofsilver nanoparticles. The photoinduced reaction rate increased asthe concentration of RGO in solution increased within a certainrange. It is suggested that the acceleration effect of RGO could beattributed to electron transfer between RGO and silver nanoparticles.The investigation into the interaction of RGO and silver nano-particles is in favor of the development of the fabrication of noblemetal nanostructures involving RGO as well as their applications inoptical sensing devices.

Acknowledgements

This research was supported by the Central Research GrantsScheme and Alfred Deakin Postdoctoral Research Fellowshipscheme at Deakin University and partly by the National NaturalScience Foundation of China (NSFC 51273153).

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Scheme 1 Proposed interaction mechanism of RGO and silver nanoparticles inthe photoinduced process.

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