nanoparticles decorated 2d wavy hierarchical carbon nanowalls...

Research ArticleSnO2 Nanoparticles Decorated 2D Wavy Hierarchical CarbonNanowalls with Enhanced Photoelectrochemical Performance

Noor Hamizah Khanis1 Richard Ritikos1 Wee Siong Chiu1

Choon Yian Haw2 Nur Maisarah Abdul Rashid1 Mei Yuen Chia1

Poi Sim Khiew3 and Saadah Abdul Rahman1

1Low Dimensional Materials Research Centre Department of Physics Faculty of Science University of MalayaLembah Pantai 50603 Kuala Lumpur Malaysia2School of Engineering Xiamen University Malaysia Jalan Sunsuria Bandar Sunsuria 43900 Sepang Selangor Malaysia3Faculty of Engineering University of Nottingham Malaysia Campus 43500 Semenyih Selangor Malaysia

Correspondence should be addressed to Noor Hamizah Khanis hamizahkhanisgmailcom

Received 31 July 2017 Accepted 16 October 2017 Published 14 November 2017

Academic Editor Luca Valentini

Copyright copy 2017 Noor Hamizah Khanis et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

Two-dimensional carbon nanowall (2D-CNW) structures were prepared by hot wire assisted plasma enhanced chemical vapordeposition (hw-PECVD) system on silicon substrates Controlled variations in the film structure were observed with increasein applied rf power during deposition which has been established to increase the rate of dissociation of precursor gases Thestructural changes resulted in the formation of wavy-like features on the 2D-CNW thus further enhancing the surface areaof the nanostructures The FESEM results confirmed the morphology transformation and conclusively showed the evolutionof the 2D-CNW novel structures while Raman results revealed increase in 119868D119868G ratio indicating increase in the presence ofdisordered domains due to the presence of open edges on the 2D-CNW structures Subsequently the best 2D-CNW based onthe morphology and structural properties was functionalized with tin oxide (SnO2) nanoparticles and used as a working electrodein a photoelectrochemical (PEC) measurement system Intriguingly the SnO2 functionalized 2D-CNW showed enhancement inboth Mott-Schottky profiles and LSV properties which suggested that these hierarchical networks showed promising potentialapplication as effective charge-trapping medium in PEC systems

1 Introduction

Research interests on carbon based nanomaterials from 0D-fullerene 1D-carbon nanotube (CNT) 2D-carbon nanowall(CNW) and graphene have tremendously increased in thepast decades This is mainly due to the novel propertiesof carbon based nanostructures such as better conductivitychemical compatibility and wide electrochemical stability inaddition to themechanical and thermal characteristic that aretypically exceptional compared to the bulk carbon material[1 2] In particular the study on 2D-carbon nanostructureshas bloomed upon the discovery of graphene which hasincreased the curiosity of researchers on investigating inter-esting properties shown by nanosystems with graphene-likefeatures

To date a plethora of fascinating 2D carbon based nanos-tructures had been successfully developed such as nanoflakesnanohorns nanopetals and carbon nanowalls Commonlymost of these 2D nanowalls are composed of few layersof graphene sheets that are loosely stacked together Thereare reports claiming that these wall-like carbon nanostruc-tures are actually graphene nanowalls with layers of verticalgraphene sheets demonstrating congruent properties [3] Maet al have reported that free standing CNWs possess veryhigh surface area and proved to be an excellent candidate forsurface interaction due to the abundance of active reactionsites available compared to that of fully embedded nanowallin horizontal manner [4] There is also a reported study onfree standing nanowalls which are aligned perpendicularlyto the substrates surface without requiring auxiliary lateral

HindawiJournal of NanomaterialsVolume 2017 Article ID 4315905 11 pageshttpsdoiorg10115520174315905

2 Journal of Nanomaterials

support [5] However relatively fewer reports are foundon 2D-carbon nanowalls (2D-CNWs) grown by hot wireradio frequency assisted plasma enhanced chemical vapordeposition a physical deposition technique which is knownto reproducible and introduces fewer impurities into the filmstructure

In this work the CNW thin films were grown on silicondioxide substrates using a home-built hw-PECVD at differentapplied radio frequency (rf) power The morphology struc-tural properties and composition of 2D-CNW thin filmswere systematically characterized The novelty of the currentstudy is the ability to fabricate CNWs with free standingwavy structures by hw-PECVD These nanowalls structuresare unique due to the expanded outward feature displayingflaky structures with abundance of active edges Such featuresenable these CNWs to serve as matrix for the decoration ofSnO2 nanoparticles to be modified into advanced nanocom-posites which can be employed as a highly reactive activematerial for photoelectrode application Photoelectrochem-ical measurements reflect that these nanocomposites exhibitimproved photoelectrochemical properties in contrast to thatof its single-component counterpart To the best of ourknowledge such special hybrid nanocomposite has neverbeen reported yet and hence it may serve as alternative routesfor the advancement of nanomaterials research as well as infield of photoelectrochemistry

2 Materials and Methods

21 Synthesis of 2D-CNW Thin Films A home-built hw-PECVD system (Kejuruteraan Wing Hung Kuala LumpurMalaysia) equipped with a radio frequency source for gen-erating the plasma was used to fabricate 2D-CNW withAu nanoparticles (Particular GmbH Burgdorf Germany)as catalyst A seven-turn coil of 8mm diameter made fromtungsten wire of 1mm diameter was used as the hot filament(R D Mathis Company Long Beach CA USA) Silicondioxide (SiO2) substrates with size of 1 times 2 cm were placed10mm from the filament The deposition parameters usedin the deposition process of the 2D-CNWs are as followshydrogen flow rate ratio of methane 20 5 sccm depositionpressure 215mbar substrate temperature 420∘C hot fila-ment temperature 1850∘C and deposition time 35 minutesand the rf power was fixed at 0 20 40 60 80 and 100W forthe different sets of samples studied in this work

22 Synthesis of SnO2 Nanoparticles and Deposition of SnO2-2D CNW In a typical synthesis process 975 (669 g) mmolof tin (II) stearate Sn(O2C18H35)2 (Alfa Aesar Haverhill MAUSA) was used as organometallic precursor 4787mmol(099 g) of 12-dodecanediol C12H26O2 (Merck KenilworthNJ USA) and 195ml of n-hexadecane C16H34 (Sigma-Aldrich St Louis MO USA) were subsequently loadedinto a 250mL four-neck round-bottom flask Under constantmagnetic stirring the mixture was heated to 120∘C andsaturated under nitrogen blanket for 1 hour The mixture wasthen raised to 287∘C at 4∘Cmin of ramping rate and furtherrefluxed for 5 hours Under vigorous stirring a change inthe solution from clear to pale yellow indicates the formation

of SnO2 nanoparticles The SnO2 nanoparticles were directlydeposited onto the as-grown 2D-CNW using spin coatingmethod The SnO2 nanoparticles were spin-cast at a rotationspeed of 3000 rpm during 30 seconds Then the sample wasannealed at 350∘C for 1 hour and rapidly cooled to the roomtemperature Two different mass fractions (w) were used inthe preparation of the two nanocomposite samples studied inthis work namely 25 and 50 w

23 Characterization of 2D-CNW and SnO2 Decorated CNWThin Films The as-obtained SnO2 integrated 2D-CNWfilmswere carefully observed using field emission scanning elec-tron microscope (FESEM) using a FEI Quanta 200 FESEM(FEI Company Hillsboro OR USA) A high resolutiontransmission electron microscope (HR-TEM JEM 2100-F)was used to determine the high resolution images of thefunctionalized nanostructuresThe bonding properties of thefunctionalized 2D-CNWthin filmswere ascertained byX-rayphotoemission spectroscopy (XPS) at the beam line BL32(a) and (b) of the Synchrotron Light Research Institute inThailand The Raman spectra were obtained by using RamanMicroscope (Renishaw inVia) The optical properties of thefilms were measured by UV-Vis-NIR spectrophotometer(Cary 5000 Agilent Technologies) The PEC measurementsdone on the SnO2 decorated 2D-CNWthin filmswere carriedout on a three-electrode electrochemical cell system equippedwith platinum coil as counter electrode and AgAgCl asreference electrode respectively Xenon arc lamp (300W)containing solar mass filter is used as a light source for thePEC system that connected to a potentiostat (PGSTAT204Metrohm Autolab) to probe the electrical signal generatedthroughout the irradiation

3 Results and Discussions

31 Formation of Hierarchical 2D-CNW The FESEM imagesof the films as a function of different rf power Prf are rep-resented in Figure 1 Without applying Prf one can observethat there is no distinct formation of carbon nanostructuresas seen in Figure 1(a) The thermal energy sourced fromdeposition temperature whether from the substrate or thehot wire heating is insufficient to induce the formationof 2D-CNW or any form of film Notably it is seen thatthe formation of nanostructured carbon films began to beobserved at Prf as low as 20WThis implies that plasma poweris a vital factor to induce the growth of CNWswhich turn outto be an initial stage of nucleation for the development of 2D-CNWs At this stage the low decomposition rate could havereduced the number of reactive species such as ion (CH1

+CH2+ CH3

+ etc) and hydrocarbon radicals present in theplasma environment due to the lower kinetic energy of theactive species Moreover these active species tend to producehigh surface energy and eventually agglomerate togetherbefore reaching suitable growth sitesWhen Prf was increasedto 40W a sharp morphological change is observed anddistinct sheet-like 2D-CNWs started to form only at Prf of60W which appear to be deposited layer-by-layer forming alarger foam-likematrix covering the entire SiO2 substrate [6]These 2D-CNW structures are typically made up of vertical

Journal of Nanomaterials 3

0W 300 nm

(a)

20W 300 nm

(b)

40W 300 nm

(c)

60W 300 nm

(d)

80W 300 nm

(e)

100W 300 nm

(f)

Figure 1 FESEM images of the CNW thin films grown at the applied rf powers of 0W(a) 20W (b) 40W (c) 60W (d) 80W (e) and 100W(f)

sheets with apparent spatial distribution Conclusively fur-ther increment in Prf could have resulted in the enhancementof momentum density and temperature of electrons thatfacilitated the mobile state of active ions in the gaseous phaseand thus increased the active site density for the formation ofthese novel nanostructures It can possibly be deduced thatthe primary and secondary reactions occurring in this systemare governed by the decomposition rate of precursor whichcan influence the formation of various active species in theplasma The formation of these vertical structures is inducedby the effect of local electric field polarity of the plasmaresulting from anisotropic polarizability [7 8] Further incre-ment of Prf to 80W renders increase of the wall-to-wall

distance and the distribution of the network vertical sheet-like nanostructures as observed in Figure 1(e) At Prf of 100Wit is deduced that the effective ion bombardment increases thekinetic energy of active species which leads to faster growthrate of secondary wavy-like structures [9] Such intriguingfree standing vertically oriented wall structures offer greateractive surface area for materials functionalization which canprovide effective electron pathways and thus can be goodcandidates as ideal photoelectrode for PEC application

Figure 2 illustrates a series ofmagnification TEMviews of2D-CNWs obtained at 80W Figure 2(c) demonstrates highresolution TEM image where the wavy-like 2D-CNW mul-tilayered structures of overlapping plane are clearly visible


Table 1 FWHM peak position of D G and 2D bands and 119868D119868G ratio of 2D-CNW thin films

Rf power (W) FWHM (cmminus1) Peak position (cmminus1) 119868D119868GD G 2D D G 2D0 477 456 1794 13486 15979 26819 2220 609 557 1442 13540 15962 26941 2140 380 516 792 13538 15872 27016 2060 395 466 848 13535 15852 26993 1780 368 371 815 13505 15851 26981 27100 450 546 956 13524 15822 26999 22

(a)

(b)

(c)

50 nm

10 nm5 nm

036 nm

Figure 2 HRTEM images of the CNW prepared at Prf of 80W

One may see that the individual layers of the 2D-CNWstructures are interconnected to each other to form the wavy-like 2D-CNW with thickness sim10 nm while the measuredlattice fringes are about 036 nm which correspond to typicallattice spacing of graphitic materials [10]

Raman spectroscopy was used to characterize the struc-tural properties of the 2D-CNW films prepared at differentPrf Figure 3 shows typical Raman spectra with correctedbaseline and the resulting spectra were deconvoluted intosix components [11 12] The six components are D G and2D bands which were individually deconvoluted by usingLorentzian curve fitting while D1015840 D + D1015840 and D + G bandswere deconvoluted via Gaussian curve fitting The Ramanspectra of the as-fabricated thin films reveal four major peaksat around 1350 1590 2700 and 2940 cmminus1 which can beassigned to D G 2D and D + G bands respectively The Gband is accompanied by a shoulder peak assigned to D1015840 bandat 1620 cmminus1 while a D + D1015840 shoulder peak can be found ataround 2480 cmminus1 [9]The calculated FWHM peak positions

for different bands and 119868D119868G ratios for the correspondingspectra of the films are summarized in Table 1

The appearance of G band at around 1590 cmminus1 ismainly attributed to the stretching vibration mode (E2g) ofa hexagonal carbon lattice which confirms the formation ofgraphitized structure [12] As reported elsewhere G peakposition for graphitic carbon materials can be seen at around1580 cmminus1 [13] However the G peak position of the as-fabricated films grown at 0W and 20W has been shiftedto 1598 and 1596 cmminus1 respectively This shifting and wideFWHMG suggest that the structuresmay be due to the indige-nousness of nanocrystalline graphitic features of 2D-CNW[14] Indeed the corresponding G peak position becomesless prominent as Prf increases which indicates the formationof larger sized graphitic clusters as evidenced from FESEMresults

The strong peak observed at sim1350 cmminus1 can be assignedto D band which originates from the intervalley doubleresonance while the presence of D1015840 band at around 1620 cmminus1


Inte

nsity

(au

) 60W

80W

100W

0W

20W

40W

1500 20001000Raman shift (cmminus1)

DG D

(a)


2DD + G

D + D

Inte

nsity

(au

) 60W

80W

100W

0W

20W

40W

(b)

Figure 3 Deconvolution of the Raman spectra in the region of (a) 1000ndash2000 cmminus1 and (b) 2000ndash3200 cmminus1 as function of applied rf power

is contributed by the intravalley double resonance processThese resonance is produced from the breathing modes ofsixfold rings indicating the activation of defects in graphitestructure Such defects include vacancies strain chain andorring distortion in the 2D-CNW structures It is worth notingthat the large amount of open edges observed on 2D sheetsdue to the formation of multilayered wall-like structuresresults in the more prominent intensities of the D peak ascompared to the G peak intensities as observed in all the thinfilms

The existence of 2D and D + G bands is due to the pres-ence of highly ordered structures with graphene-like domainthat gives rise to second-order Raman vibration modes [15]The presence of 2D band however is strongly correlatedwith the number of layers in the graphene structure [16 17]The 2D peak position of 2D-CNW thin films consistentlyappears at around 2700 cmminus1 as Prf increased The largevalue of FWHM2D indicates that these structures have similarfeatures of the multilayered graphene structures reported byFerrari and Basko and also confirmed by previously observedHRTEM images [18]

The 119868D119868G value varies in range of 17 to 27 which isclose to the 119868D119868G value of 2D-CNW features previouslyreported in the literature [9 19 20] This may be due tothe enhancement in atomic arrangement as a result of theremoval of weak C-C bonds which contribute to the disorder

in the film structure Notably it is found that the 119868D119868G ratioincreases to a maximum of 27 at Prf of 80W but at thesame time narrows the FWHM of the G band indicatingthat there exist two competing mechanisms at this Prf Thissuggests that the CNWs prepared at Prf of 80W consist ofsmall crystallites with relatively high degree of graphitizationwhich correspondwell to the study reported byRout et al andKurita et al [21 22] At maximum Prf 119868D119868G reduced againsuggested that the number of ordered structures increasedand this is perhaps due to the reduction of defects along theedges of 2D-CNW nanostructures

The elemental composition of the films was ascertainedfrom XPS measurements The XPS spectra show the types ofbonds are affiliated to the carbon and oxygen atoms present inthe films Narrow scan spectra of C 1s andO 1s as a function ofPrf are shown in Figures 4(a) and 4(b) respectivelyThese tworegions represent the binding energy in range of 280ndash296 eVand 524ndash540 eV [23] It appears that the intensity of C 1s peakis appreciably lower for the film prepared without applyingPrf On the other hand the corresponding O 1s peak intensityis significantly higher compared to films prepared at Prf of20 to 100W These spectra were then deconvoluted by usingGaussian fitting with nonlinear background extraction forfurther investigation

As shown in Figure 4(c) the C 1s peak of 2D-CNW thinfilm prepared at 80W can be perfectly deconvoluted into


0

2

4

6

8

10

12In

tens

ity (a

u)times10

3

60W80W100W

0W20W40W

284 286 288 290 292 294280 282Binding energy (eV)

(a)

60W80W100W

0W20W40W

532528 536534530 538 540524 526Binding energy (eV)

0

2

4

6

8

10

12

Inte

nsity

(cs

)times10

3(b)

C-C

C-C

O-C=OC-O

Inte

nsity

(cs

)


C 1s 80W

sp2

sp3

(c)

C-O

C-OH

Inte

nsity

(cs

)

532 536528 534 538530

O 1s 80W

Binding energy (eV)

(d)

6

8

10

12

14

70

80

90

100

20 40 60 80 1000Rf power (W)

020

024

028

032

036

sp3s

p2

A

-（+

-+

-=A

４４

()

(e)

Figure 4 XPS analysis of CNW thin films


5 m

(a)

5 m

(b)

5 m

(c)

Figure 5 FESEM image of SnO2 nanoparticle on bare Si substrate (a) and SnO2 nanoparticles decorated CNW at 25 and 50 w for (b) and(c) respectively

four separate peaks The main peak centered at 2843 eVcorresponds to sp2 C=C while secondary prominent peakcentered at 2852 eV was assigned to sp3 C-C The peaksat 2865 and 2887 eV were assigned to C-O and O-C=Orespectively These binding energies are in agreement withthose reported in literature [9 12 24] A similar procedurewas utilized to decompose O 1s into two components such asC-OH and C-O bonds as revealed in Figure 4(d) The peakof C-OH and C-O bonds is centered at 5318 and 5331 eVrespectively [25] When the samples were exposed to air thepresence of oxygen not only was associated with the oxygenor water vapor physical absorption on 2D-CNW surfacebut also indicates the presence of oxygen atoms that arechemically bonded to the structures [26]

In this work although the composition appears to beconstant throughout the range of Prf applied further analysissuggests that the difference in the applied power brings aboutthe change in sp2sp3 ratio as a function of Prf as representedin Figure 4(e) Interestingly the trend shown in sp3sp2 ratiois similar to the Raman 119868D119868G results The sp3sp2 ratiodecreases initially when Prf is increased from 20W to 60Wand then increases significantly at 80W The initial decreasein sp3sp2 ratio supports the earlier suggestion in the Ramanresults analysis which is attributed to the enhancement inthe atomic arrangement The increase in the number ofheterogeneous nucleation sites by reactive H atom in theplasma results in preferential growth of stronger sp2 C=Cbonds in the filmThe increase in sp3sp2 for film deposited atPrf of 80Wcanbe due to the effects produced by the change inthe morphology of the filmThe increase in defects along theedges of the walls which is significant for these films allowsfor the preferential formation of sp3 bonds along these edgesThis is supported by the percentage of oxygen related compo-nents obtained from analysis of O 1s peak in Figure 4(e)

32 Tin Oxide Anchored 2D-CNWs and PhotoelectrochemicalMeasurement Theprogression in 2D-CNWs formation fromcarbon nanostructures at low Prf into 2D-CNWs networkstructures at higher Prf has been realized in microscopicstudies done in the previous sectionThegrowth ofCNWthinfilms (Figure 1) shows that the applied Prf in the 2D-CNWs

deposition gives significant influence to their morphologicalproperties Thus the choice of Prf for CNW growth is crucialfor a study devoted to the fabrication of 2D-CNWs with largewall-to-wall distance network structure suitable for function-alization of SnO2 nanoparticles for PEC studies Architectureof semiconductor photoelectrode is of fundamental aspect inthe perspective of PEC system performance [27] Thereforein this section 2D-CNWs thin film prepared at 80W isselected for functionalization of SnO2 nanoparticles usingsimple spin coating technique to be used as photoelectrodefor PEC measurements

FESEM image of SnO2 and SnO2 nanoparticles func-tionalized 2D-CNWs (SnO2-CNWs) thin films is presentedin Figure 5 It is observed that the distribution of SnO2nanoparticles is not uniform on the smooth surface of SiO2bare substrate Comparatively it was found that 25 wSnO2 nanoparticles tend to be distributed uniformly onto2D-CNWs thin film This could be due to porosity of the2D-CNWs covering the c-Si substrate that renders SnO2nanoparticles easily incorporated into the CNW matrixFurther functionalization of 50 w SnO2 nanoparticles onthe 2D-CNWs results in agglomeration of SnO2 on thesurface of the CNWs

The EDX results of 2D-CNW and SnO2-CNWs thinfilms are presented in Figure 6(a) These spectra detectedC O and Si elements on the film with 2D-CNWs andadditional Sn element for the SnO2-CNWs nanocompositefilmMicrostructural properties can be realized by theRamanspectra of both 2D-CNWs and SnO2-CNWs nanocompositefilms which are shown in Figure 6(b) The Raman spectrumof CNW thin film reveals four peaks at around 1400 15902840 and 3030 cmminus1 assigned to D G 2D and D + Gbands respectively While SnO2-CNWs nanocomposite thinfilm presents three additional peaks at around 358 475 and630 cmminus1 ascribed to Eu Eg and A1g Raman active modeof SnO2 material [28] Figure 6(c) depicts the reflectancespectra of SnO2-CNWsnanocomposite thin filmdeposited atdifferent SnO2 deposition concentration Inset in Figure 6(c)shows enlarged 25 and 50 w SnO2-CNWs nanocompositethin film reflectance spectraThe bandgaps of the as-obtainedthin films are further determined from the analysis on thereflectance spectra which are shown in Table 2 The energy


CO

Si

CNW

C

O

Si

SnO2CNW

Sn Sn

0 05 1 15 2 25 3 35 4 45 5 55

05 1 15 2 25 3 35 4 45 5

(keV)Full Scale 1125 ＝ＮＭ Cursor 0000

(a)

D + G2D

D

G

D + G 2D

G

D

CNWInte

nsity

(au

)

Ａ

1Ａ

Ｏ

1000 1500 2000 2500 3000500Raman shift (cmminus1)

SnO2 CNW

(b)

300 400 500 600 700 800200Wavelength(nm)

0

10

20

30

40

50

Refle

ctan

ce (

)

4

6

8

10

12

Refle

ctan

ce (

)

400 600 800200

Wavelength (nm)

25 Ｑ SnO2 CNW50 Ｑ SnO2 CNW

SnO2

CNW

(c)

Figure 6 (a) EDX spectra of CNW and SnO2 nanoparticles decorated CNW (b) Raman spectra of CNW SnO2 and SnO2 nanoparticlesdecorated CNW (c) Reflectance spectra of SnO2 nanoparticles decorated CNW with different concentration

gaps of CNW and SnO2 are 135 and 374 eV respectivelywhich is close to the value reported by Kawai et al [29 30] Incontrast the energy gap of the SnO2-CNWs nanocompositethin film is found to be in the range of 182 to 280 eVand the value increases with increase in the concentrationof SnO2 nanoparticles The combination of both 2D-CNWsand SnO2 can potentially narrow the bandgap of the SnO2-CNWs nanocomposite thin film photoelectrode because ofelectronic interaction between CNWs and SnO2 that leadsto improvement of light harvesting properties of PEC undervisible irradiation [31 32]

In order to evaluate the surface charges for the corre-sponding films Mott-Schottky (MS) measurements charac-teristic plots are illustrated in Figure 7 The donor density

of the films can be obtained by using Mott-Schottky equa-tion

11198622 =

2119902119860119873119889120576120576119900 [119881bias minus 119881119891119887

119870119879119902 ] (1)

where 119862 is the capacitance of the space charge region 119902 isthe elementary electron charge119860 is the interfacial area119873119889 isdonor density of the films 120576 is the static dielectric constant ofthe films 120576119900 is the permittivity of free space119881bias is the appliedpotential 119881119891119887 is the flat band potential 119870 is Boltzmannrsquosconstant and 119879 is the absolute temperature [33] From theslope in the MS plot 119873119889 for the films are determined asshown in Table 3 The119873119889 values of SnO2 and CNW films arealmost the same However for SnO2-CNWs nanocomposite


SnO2

times1013

00

05

10

15

20

25

30

35

40

00 05 10minus05minus10Potential (V)

1C

2(F

minus2＝Ｇ

4)

(a)

CNW

times1014


00

04

08

12

16

1C

2(F

minus2＝Ｇ

4)

(b)

25 Ｑ SnO2 CNW

times1014

00

02

04

06

08

10

12

00 05minus05minus10Potential (V)

1C

2(F

minus2＝Ｇ

4)

(c)

50 Ｑ SnO2 CNW

times1012

00

10

20

30

40

50

60


1C

2(F

minus2＝Ｇ

4)

(d)

Figure 7 Mott-Schottky plot of the measured capacitance of the SnO2 (a) CNW (b) and the SnO2 decorated CNW thin films with SnO2concentration of 25 w (c) and 50 w (d)

Table 2 Energy gap of SnO2 CNW and SnO2-CNW thin films

Sample Energy gap (eV)SnO2 374CNW 13525 w SnO2-CNW 18250 w SnO2-CNW 206

thin film electrode with SnO2 concentration of 25 w thevalue increases to 116 times 1015 cmminus3 and increases further to130 times 1017 for the film with SnO2 concentration of 50 wThe key improvement in this case can be attributed to theeffective electron transfer between SnO2 and CNW which inturn improves the conductivity of the photoelectrode [34]

The linear sweep voltammogram (LSV) of the SnO2CNW and the SnO2-CNWs nanocomposite thin films withSnO2 concentration of 25 and 50 w determined in thepresence of 01M Na2SO4 without and with illumination arepresented in Figures 8(a) and 8(b) respectively It can beobserved that at positive bias voltage the anodic currentresponse increases with increase in bias voltage SnO2-CNWsnanocomposite thin films with different concentration of 25

Table 3 Carrier density119873119889 of the films

Sample Donor density (cmminus3)SnO2 116 times 1015CNW 218 times 101525 w SnO2-CNW 176 times 101650 w SnO2-CNW 130 times 1017

and 50 w show great enhancement in the anodic currentThis may be due to the increase in donor density in thefunctionalized films More interestingly under illuminationof simulated solar source on the sample the anodic currentincreases for 25 and 50 w SnO2-CNWs nanocompositethin films For instance the current increases from 78mA to118mA at 10 V for 50 w SnO2-CNWs Improvement PECproperties of SnO2-CNWs nanocomposite thin films can beascribed to the fact that SnO2 nanoparticles incorporatedon wavy-like structures provide larger surface area The 2D-CNWs network serves as direct route of charge transportwhich enhance the separation of photogenerated chargecarrier which greatly enhanced the PEC response [35] It isalso can be deduced that the density of SnO2 incorporated



0

2

4

6

8

10

12Cu

rren

t (m

A)


SnO2

CNW

(a)

0

2

4

6

8

10

12

Curr

ent (

mA

)



SnO2

CNW

(b)

Figure 8 Linear sweep voltammograms of the SnO2 CNW and the SnO2 decorated CNW thin films with SnO2 concentration of 25 and50 w without (a) and under illumination (b)

onto 2D-CNW structures contributes to the enhancementof PEC performance as a result of the increased photonabsorption in hybrid materials

4 Conclusion

In summary 2D carbon network has been successfullysynthesized using a home-built hot wire assisted plasmaenhanced chemical vapor deposition system The rf powerapplied is shown to modify the morphology of the 2D-CNWstructures The formation of novel graphitic structures wasconfirmed by Raman spectroscopy and HRTEM analysisThe CNWs were further decorated with SnO2 nanoparticlesemploying a simple spin coating technique From the resultsit is anticipated that 2D-CNW structures provide directpathways of charge transport mitigating recombination ofphotogenerated electron-hole pairs in the SnO2 function-alized 2D-CNW thin film This method could thereforeprovide a new channel in the preparation of novel carbonnanostructures for advanced hybrid materials that couldpotentially be used in PEC applications

Conflicts of Interest

The authors declare no conflicts of interest regarding thepublication of this paper

Acknowledgments

This work was financially supported by Prototype ResearchGrant Scheme (PRGS PR003-2016) University of MalayaResearch Grant (RG39117AFR) and Postgraduate ResearchFund (PG0912014A)

References

[1] K Lehmann O Yurchenko A Heilemann et al ldquoHighsurface hierarchical carbon nanowalls synthesized by plasma

deposition using an aromatic precursorrdquo Carbon vol 118 pp578ndash587 2017

[2] T Itoh ldquoSynthesis of carbon nanowalls by hot-wire chemicalvapor depositionrdquo Thin Solid Films vol 519 no 14 pp 4589ndash4593 2011

[3] B Kumar K Y Lee H-K Park S J Chae Y H Lee andS-W Kim ldquoControlled growth of semiconducting nanowirenanowall and hybrid nanostructures on graphene for piezo-electric nanogeneratorsrdquoACSNano vol 5 no 5 pp 4197ndash42042011

[4] Y Ma H Jang S J Kim C Pang and H Chae ldquoCopper-Assisted Direct Growth of Vertical Graphene Nanosheetson Glass Substrates by Low-Temperature Plasma-EnhancedChemical Vapour Deposition Processrdquo Nanoscale ResearchLetters vol 10 no 1 article no 308 2015

[5] M Zhu J Wang R A Outlaw K Hou D M Manos andB C Holloway ldquoSynthesis of carbon nanosheets and carbonnanotubes by radio frequency plasma enhanced chemical vapordepositionrdquo Diamond and Related Materials vol 16 no 2 pp196ndash201 2007

[6] T Uchida A Baliyan T Fukuda Y Nakajima and Y YoshidaldquoCharged particle-induced synthesis of carbon nanowalls andcharacterizationrdquoRSCAdvances vol 4 no 68 pp 36071ndash360782014

[7] Y Wu and B Yang ldquoEffects of Localized Electric Field on theGrowth of Carbon Nanowallsrdquo Nano Letters vol 2 no 4 pp355ndash359 2002

[8] M Zhu JWang B CHolloway et al ldquoAmechanism for carbonnanosheet formationrdquo Carbon vol 45 no 11 pp 2229ndash22342007

[9] H J Cho H Kondo K Ishikawa M Sekine M Hiramatsuand M Hori ldquoDensity control of carbon nanowalls grown byCH4H2 plasma and their electrical propertiesrdquoCarbon vol 68pp 380ndash388 2014

[10] H G Jain H Karacuban D Krix H-W Becker H Nienhausand V Buck ldquoCarbon nanowalls deposited by inductivelycoupled plasma enhanced chemical vapor deposition usingaluminum acetylacetonate as precursorrdquo Carbon vol 49 no 15pp 4987ndash4995 2011


[11] L Cui J Chen B Yang D Sun and T Jiao ldquoRF-PECVD syn-thesis of carbon nanowalls and their field emission propertiesrdquoApplied Surface Science vol 357 pp 1ndash7 2015

[12] K Yu Z Bo G Lu et al ldquoGrowth of carbon nanowallsat atmospheric pressure for one-step gas sensor fabricationrdquoNanoscale Research Letters vol 6 no 1 pp X1ndash9 2011

[13] A Das B Chakraborty and A K Sood ldquoRaman spectroscopyof graphene on different substrates and influence of defectsrdquoBulletin of Materials Science vol 31 no 3 pp 579ndash584 2008

[14] S K Jerng D S Yu Y S Kim et al ldquoNanocrystalline graphitegrowth on sapphire by carbon molecular beam epitaxyrdquo TheJournal of Physical Chemistry C vol 115 no 11 pp 4491ndash44942011

[15] M A Pimenta G Dresselhaus M S Dresselhaus L GCancado A Jorio and R Saito ldquoStudying disorder in graphite-based systems by Raman spectroscopyrdquo Physical ChemistryChemical Physics vol 9 no 11 pp 1276ndash1291 2007

[16] M Hiramatsu Y Nihashi H Kondo and M Hori ldquoNucle-ation control of carbon nanowalls using inductively coupledplasma-enhanced chemical vapor depositionrdquo Japanese Journalof Applied Physics vol 52 no 1 Article ID 01AK05 2013

[17] X Song J Liu L Yu et al ldquoDirect versatile PECVD growth ofgraphene nanowalls on multiple substratesrdquo Materials Lettersvol 137 pp 25ndash28 2014

[18] A C Ferrari and D M Basko ldquoRaman spectroscopy as aversatile tool for studying the properties of graphenerdquo NatureNanotechnology vol 8 no 4 pp 235ndash246 2013

[19] Z H Ni H M Fan Y P Feng Z X Shen B J Yang and Y HWu ldquoRaman spectroscopic investigation of carbon nanowallsrdquoThe Journal of Chemical Physics vol 124 no 20 Article ID204703 2006

[20] E Sandoz-RosadoW Page DOrsquoBrien et al ldquoVertical grapheneby plasma-enhanced chemical vapor deposition Correlationof plasma conditions and growth characteristicsrdquo Journal ofMaterials Research vol 29 no 3 pp 417ndash425 2014

[21] C S Rout A Kumar and T S Fisher ldquoCarbon nanowallsamplify the surface-enhanced Raman scattering from Agnanoparticlesrdquo Nanotechnology vol 22 no 39 Article ID395704 2011

[22] S Kurita A Yoshimura H Kawamoto et al ldquoRaman spectra ofcarbon nanowalls grown by plasma-enhanced chemical vapordepositionrdquo Journal of Applied Physics vol 97 no 10 Article ID104320 2005

[23] Y Wang J Li and K Song ldquoStudy on formation and photo-luminescence of carbon nanowalls grown on silicon substratesby hot filament chemical vapor depositionrdquo Journal of Lumines-cence vol 149 pp 258ndash263 2014

[24] H H Zou H Bai J H Yu et al ldquoArchitecting graphenenanowalls on diamond powder surfacerdquo Composites Part BEngineering vol 73 pp 57ndash60 2015

[25] N Jiang H XWang H Zhang H Sasaoka and K NishimuraldquoCharacterization and surface modification of carbonnanowallsrdquo Journal of Materials Chemistry vol 20 no 24pp 5070ndash5073 2010

[26] Z Gonzalez S Vizireanu G Dinescu C Blanco and R San-tamarıa ldquoCarbon nanowalls thin films as nanostructured elec-trodematerials in vanadium redox flow batteriesrdquoNano Energyvol 1 no 6 pp 833ndash839 2012

[27] M Zhou X W Lou and Y Xie ldquoTwo-dimensional nanosheetsfor photoelectrochemical water splitting Possibilities andopportunitiesrdquo Nano Today vol 8 no 6 pp 598ndash618 2013

[28] C HawW Chiu N H Khanis et al ldquoTin stearate organometal-lic precursor prepared SnO2 quantum dots nanopowder foraqueous- and non-aqueous medium photocatalytic hydrogengas evolutionrdquo Journal of Energy Chemistry vol 25 no 4 pp691ndash701 2016

[29] S Kawai S Kondo W Takeuchi H Kondo M Hiramatsuand M Hori ldquoOptical properties of evolutionary grown layersof carbon nanowalls analyzed by spectroscopic ellipsometryrdquoJapanese Journal of Applied Physics vol 49 no 6 pp 0602201ndash0602203 2010

[30] V Inderan S Y Lim T S Ong S Bastien N Braidy andH L Lee ldquoSynthesis and characterisations of SnO2 nanorodsvia low temperature hydrothermal methodrdquo Superlattices andMicrostructures vol 88 pp 396ndash402 2015

[31] X Chen Z Zhang L Chi A K Nair W Shangguan and ZJiang ldquoRecent advances in visible-light-driven photoelectro-chemical water splitting Catalyst nanostructures and reactionsystemsrdquo Nano-Micro Letters vol 8 no 1 pp 1ndash12 2016

[32] J Xu and M Shalom ldquoElectrophoretic Deposition of CarbonNitride Layers for Photoelectrochemical Applicationsrdquo ACSApplied Materials amp Interfaces vol 8 no 20 pp 13058ndash130632016

[33] H Uchiyama M Yukizawa and H Kozuka ldquoPhotoelectro-chemical properties of Fe2O3-SnO2 films prepared by Sol-Gelmethodrdquo The Journal of Physical Chemistry C vol 115 no 14pp 7050ndash7055 2011

[34] K Xu N Li D Zeng et al ldquoInterface bonds determined gas-sensing of SnO2SnS2 hybrids to ammonia at room temperaturerdquoACS Applied Materials amp Interfaces vol 7 no 21 pp 11359ndash11368 2015

[35] J Nong and W Wei ldquoDirect growth of graphene nanowallson silica for high-performance photo-electrochemical anoderdquoSurface Coatings Technology vol 320 pp 579ndash583 2017

Submit your manuscripts athttpswwwhindawicom

ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CorrosionInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Polymer ScienceInternational Journal of



CeramicsJournal of


CompositesJournal of

NanoparticlesJournal of



International Journal of

Biomaterials


NanoscienceJournal of

TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Journal of

NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

CrystallographyJournal of


The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014


CoatingsJournal of

Advances in

Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Smart Materials Research



MetallurgyJournal of


BioMed Research International

MaterialsJournal of



support [5] However relatively fewer reports are foundon 2D-carbon nanowalls (2D-CNWs) grown by hot wireradio frequency assisted plasma enhanced chemical vapordeposition a physical deposition technique which is knownto reproducible and introduces fewer impurities into the filmstructure

In this work the CNW thin films were grown on silicondioxide substrates using a home-built hw-PECVD at differentapplied radio frequency (rf) power The morphology struc-tural properties and composition of 2D-CNW thin filmswere systematically characterized The novelty of the currentstudy is the ability to fabricate CNWs with free standingwavy structures by hw-PECVD These nanowalls structuresare unique due to the expanded outward feature displayingflaky structures with abundance of active edges Such featuresenable these CNWs to serve as matrix for the decoration ofSnO2 nanoparticles to be modified into advanced nanocom-posites which can be employed as a highly reactive activematerial for photoelectrode application Photoelectrochem-ical measurements reflect that these nanocomposites exhibitimproved photoelectrochemical properties in contrast to thatof its single-component counterpart To the best of ourknowledge such special hybrid nanocomposite has neverbeen reported yet and hence it may serve as alternative routesfor the advancement of nanomaterials research as well as infield of photoelectrochemistry

2 Materials and Methods

21 Synthesis of 2D-CNW Thin Films A home-built hw-PECVD system (Kejuruteraan Wing Hung Kuala LumpurMalaysia) equipped with a radio frequency source for gen-erating the plasma was used to fabricate 2D-CNW withAu nanoparticles (Particular GmbH Burgdorf Germany)as catalyst A seven-turn coil of 8mm diameter made fromtungsten wire of 1mm diameter was used as the hot filament(R D Mathis Company Long Beach CA USA) Silicondioxide (SiO2) substrates with size of 1 times 2 cm were placed10mm from the filament The deposition parameters usedin the deposition process of the 2D-CNWs are as followshydrogen flow rate ratio of methane 20 5 sccm depositionpressure 215mbar substrate temperature 420∘C hot fila-ment temperature 1850∘C and deposition time 35 minutesand the rf power was fixed at 0 20 40 60 80 and 100W forthe different sets of samples studied in this work

22 Synthesis of SnO2 Nanoparticles and Deposition of SnO2-2D CNW In a typical synthesis process 975 (669 g) mmolof tin (II) stearate Sn(O2C18H35)2 (Alfa Aesar Haverhill MAUSA) was used as organometallic precursor 4787mmol(099 g) of 12-dodecanediol C12H26O2 (Merck KenilworthNJ USA) and 195ml of n-hexadecane C16H34 (Sigma-Aldrich St Louis MO USA) were subsequently loadedinto a 250mL four-neck round-bottom flask Under constantmagnetic stirring the mixture was heated to 120∘C andsaturated under nitrogen blanket for 1 hour The mixture wasthen raised to 287∘C at 4∘Cmin of ramping rate and furtherrefluxed for 5 hours Under vigorous stirring a change inthe solution from clear to pale yellow indicates the formation

of SnO2 nanoparticles The SnO2 nanoparticles were directlydeposited onto the as-grown 2D-CNW using spin coatingmethod The SnO2 nanoparticles were spin-cast at a rotationspeed of 3000 rpm during 30 seconds Then the sample wasannealed at 350∘C for 1 hour and rapidly cooled to the roomtemperature Two different mass fractions (w) were used inthe preparation of the two nanocomposite samples studied inthis work namely 25 and 50 w

23 Characterization of 2D-CNW and SnO2 Decorated CNWThin Films The as-obtained SnO2 integrated 2D-CNWfilmswere carefully observed using field emission scanning elec-tron microscope (FESEM) using a FEI Quanta 200 FESEM(FEI Company Hillsboro OR USA) A high resolutiontransmission electron microscope (HR-TEM JEM 2100-F)was used to determine the high resolution images of thefunctionalized nanostructuresThe bonding properties of thefunctionalized 2D-CNWthin filmswere ascertained byX-rayphotoemission spectroscopy (XPS) at the beam line BL32(a) and (b) of the Synchrotron Light Research Institute inThailand The Raman spectra were obtained by using RamanMicroscope (Renishaw inVia) The optical properties of thefilms were measured by UV-Vis-NIR spectrophotometer(Cary 5000 Agilent Technologies) The PEC measurementsdone on the SnO2 decorated 2D-CNWthin filmswere carriedout on a three-electrode electrochemical cell system equippedwith platinum coil as counter electrode and AgAgCl asreference electrode respectively Xenon arc lamp (300W)containing solar mass filter is used as a light source for thePEC system that connected to a potentiostat (PGSTAT204Metrohm Autolab) to probe the electrical signal generatedthroughout the irradiation

3 Results and Discussions

31 Formation of Hierarchical 2D-CNW The FESEM imagesof the films as a function of different rf power Prf are rep-resented in Figure 1 Without applying Prf one can observethat there is no distinct formation of carbon nanostructuresas seen in Figure 1(a) The thermal energy sourced fromdeposition temperature whether from the substrate or thehot wire heating is insufficient to induce the formationof 2D-CNW or any form of film Notably it is seen thatthe formation of nanostructured carbon films began to beobserved at Prf as low as 20WThis implies that plasma poweris a vital factor to induce the growth of CNWswhich turn outto be an initial stage of nucleation for the development of 2D-CNWs At this stage the low decomposition rate could havereduced the number of reactive species such as ion (CH1

+CH2+ CH3

+ etc) and hydrocarbon radicals present in theplasma environment due to the lower kinetic energy of theactive species Moreover these active species tend to producehigh surface energy and eventually agglomerate togetherbefore reaching suitable growth sitesWhen Prf was increasedto 40W a sharp morphological change is observed anddistinct sheet-like 2D-CNWs started to form only at Prf of60W which appear to be deposited layer-by-layer forming alarger foam-likematrix covering the entire SiO2 substrate [6]These 2D-CNW structures are typically made up of vertical


0W 300 nm

(a)

20W 300 nm

(b)

40W 300 nm

(c)

60W 300 nm

(d)

80W 300 nm

(e)

100W 300 nm

(f)








(a)

(b)

(c)

50 nm

10 nm5 nm

036 nm








Inte

nsity

(au

) 60W

80W

100W

0W

20W

40W


DG D

(a)


2DD + G

D + D

Inte

nsity

(au

) 60W

80W

100W

0W

20W

40W

(b)









0

2

4

6

8

10

12In

tens

ity (a

u)times10

3

60W80W100W

0W20W40W


(a)

60W80W100W

0W20W40W


0

2

4

6

8

10

12

Inte

nsity

(cs

)times10

3(b)

C-C

C-C

O-C=OC-O

Inte

nsity

(cs

)


C 1s 80W

sp2

sp3

(c)

C-O

C-OH

Inte

nsity

(cs

)

532 536528 534 538530

O 1s 80W

Binding energy (eV)

(d)

6

8

10

12

14

70

80

90

100

20 40 60 80 1000Rf power (W)

020

024

028

032

036

sp3s

p2

A

-（+

-+

-=A

４４

()

(e)



5 m

(a)

5 m

(b)

5 m

(c)









CO

Si

CNW

C

O

Si

SnO2CNW

Sn Sn

0 05 1 15 2 25 3 35 4 45 5 55

05 1 15 2 25 3 35 4 45 5


(a)

D + G2D

D

G

D + G 2D

G

D

CNWInte

nsity

(au

)

Ａ

1Ａ

Ｏ


SnO2 CNW

(b)

300 400 500 600 700 800200Wavelength(nm)

0

10

20

30

40

50

Refle

ctan

ce (

)

4

6

8

10

12

Refle

ctan

ce (

)

400 600 800200

Wavelength (nm)


SnO2

CNW

(c)





11198622 =

2119902119860119873119889120576120576119900 [119881bias minus 119881119891119887

119870119879119902 ] (1)



SnO2

times1013

00

05

10

15

20

25

30

35

40


1C

2(F

minus2＝Ｇ

4)

(a)

CNW

times1014


00

04

08

12

16

1C

2(F

minus2＝Ｇ

4)

(b)

25 Ｑ SnO2 CNW

times1014

00

02

04

06

08

10

12


1C

2(F

minus2＝Ｇ

4)

(c)

50 Ｑ SnO2 CNW

times1012

00

10

20

30

40

50

60


1C

2(F

minus2＝Ｇ

4)

(d)











0

2

4

6

8

10

12Cu

rren

t (m

A)


SnO2

CNW

(a)

0

2

4

6

8

10

12

Curr

ent (

mA

)



SnO2

CNW

(b)



4 Conclusion




Acknowledgments


References













































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of



0W 300 nm

(a)

20W 300 nm

(b)

40W 300 nm

(c)

60W 300 nm

(d)

80W 300 nm

(e)

100W 300 nm

(f)








(a)

(b)

(c)

50 nm

10 nm5 nm

036 nm








Inte

nsity

(au

) 60W

80W

100W

0W

20W

40W


DG D

(a)


2DD + G

D + D

Inte

nsity

(au

) 60W

80W

100W

0W

20W

40W

(b)









0

2

4

6

8

10

12In

tens

ity (a

u)times10

3

60W80W100W

0W20W40W


(a)

60W80W100W

0W20W40W


0

2

4

6

8

10

12

Inte

nsity

(cs

)times10

3(b)

C-C

C-C

O-C=OC-O

Inte

nsity

(cs

)


C 1s 80W

sp2

sp3

(c)

C-O

C-OH

Inte

nsity

(cs

)

532 536528 534 538530

O 1s 80W

Binding energy (eV)

(d)

6

8

10

12

14

70

80

90

100

20 40 60 80 1000Rf power (W)

020

024

028

032

036

sp3s

p2

A

-（+

-+

-=A

４４

()

(e)



5 m

(a)

5 m

(b)

5 m

(c)









CO

Si

CNW

C

O

Si

SnO2CNW

Sn Sn

0 05 1 15 2 25 3 35 4 45 5 55

05 1 15 2 25 3 35 4 45 5


(a)

D + G2D

D

G

D + G 2D

G

D

CNWInte

nsity

(au

)

Ａ

1Ａ

Ｏ


SnO2 CNW

(b)

300 400 500 600 700 800200Wavelength(nm)

0

10

20

30

40

50

Refle

ctan

ce (

)

4

6

8

10

12

Refle

ctan

ce (

)

400 600 800200

Wavelength (nm)


SnO2

CNW

(c)





11198622 =

2119902119860119873119889120576120576119900 [119881bias minus 119881119891119887

119870119879119902 ] (1)



SnO2

times1013

00

05

10

15

20

25

30

35

40


1C

2(F

minus2＝Ｇ

4)

(a)

CNW

times1014


00

04

08

12

16

1C

2(F

minus2＝Ｇ

4)

(b)

25 Ｑ SnO2 CNW

times1014

00

02

04

06

08

10

12


1C

2(F

minus2＝Ｇ

4)

(c)

50 Ｑ SnO2 CNW

times1012

00

10

20

30

40

50

60


1C

2(F

minus2＝Ｇ

4)

(d)











0

2

4

6

8

10

12Cu

rren

t (m

A)


SnO2

CNW

(a)

0

2

4

6

8

10

12

Curr

ent (

mA

)



SnO2

CNW

(b)



4 Conclusion




Acknowledgments


References













































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of





(a)

(b)

(c)

50 nm

10 nm5 nm

036 nm








Inte

nsity

(au

) 60W

80W

100W

0W

20W

40W


DG D

(a)


2DD + G

D + D

Inte

nsity

(au

) 60W

80W

100W

0W

20W

40W

(b)









0

2

4

6

8

10

12In

tens

ity (a

u)times10

3

60W80W100W

0W20W40W


(a)

60W80W100W

0W20W40W


0

2

4

6

8

10

12

Inte

nsity

(cs

)times10

3(b)

C-C

C-C

O-C=OC-O

Inte

nsity

(cs

)


C 1s 80W

sp2

sp3

(c)

C-O

C-OH

Inte

nsity

(cs

)

532 536528 534 538530

O 1s 80W

Binding energy (eV)

(d)

6

8

10

12

14

70

80

90

100

20 40 60 80 1000Rf power (W)

020

024

028

032

036

sp3s

p2

A

-（+

-+

-=A

４４

()

(e)



5 m

(a)

5 m

(b)

5 m

(c)









CO

Si

CNW

C

O

Si

SnO2CNW

Sn Sn

0 05 1 15 2 25 3 35 4 45 5 55

05 1 15 2 25 3 35 4 45 5


(a)

D + G2D

D

G

D + G 2D

G

D

CNWInte

nsity

(au

)

Ａ

1Ａ

Ｏ


SnO2 CNW

(b)

300 400 500 600 700 800200Wavelength(nm)

0

10

20

30

40

50

Refle

ctan

ce (

)

4

6

8

10

12

Refle

ctan

ce (

)

400 600 800200

Wavelength (nm)


SnO2

CNW

(c)





11198622 =

2119902119860119873119889120576120576119900 [119881bias minus 119881119891119887

119870119879119902 ] (1)



SnO2

times1013

00

05

10

15

20

25

30

35

40


1C

2(F

minus2＝Ｇ

4)

(a)

CNW

times1014


00

04

08

12

16

1C

2(F

minus2＝Ｇ

4)

(b)

25 Ｑ SnO2 CNW

times1014

00

02

04

06

08

10

12


1C

2(F

minus2＝Ｇ

4)

(c)

50 Ｑ SnO2 CNW

times1012

00

10

20

30

40

50

60


1C

2(F

minus2＝Ｇ

4)

(d)











0

2

4

6

8

10

12Cu

rren

t (m

A)


SnO2

CNW

(a)

0

2

4

6

8

10

12

Curr

ent (

mA

)



SnO2

CNW

(b)



4 Conclusion




Acknowledgments


References













































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of



Inte

nsity

(au

) 60W

80W

100W

0W

20W

40W


DG D

(a)


2DD + G

D + D

Inte

nsity

(au

) 60W

80W

100W

0W

20W

40W

(b)









0

2

4

6

8

10

12In

tens

ity (a

u)times10

3

60W80W100W

0W20W40W


(a)

60W80W100W

0W20W40W


0

2

4

6

8

10

12

Inte

nsity

(cs

)times10

3(b)

C-C

C-C

O-C=OC-O

Inte

nsity

(cs

)


C 1s 80W

sp2

sp3

(c)

C-O

C-OH

Inte

nsity

(cs

)

532 536528 534 538530

O 1s 80W

Binding energy (eV)

(d)

6

8

10

12

14

70

80

90

100

20 40 60 80 1000Rf power (W)

020

024

028

032

036

sp3s

p2

A

-（+

-+

-=A

４４

()

(e)



5 m

(a)

5 m

(b)

5 m

(c)









CO

Si

CNW

C

O

Si

SnO2CNW

Sn Sn

0 05 1 15 2 25 3 35 4 45 5 55

05 1 15 2 25 3 35 4 45 5


(a)

D + G2D

D

G

D + G 2D

G

D

CNWInte

nsity

(au

)

Ａ

1Ａ

Ｏ


SnO2 CNW

(b)

300 400 500 600 700 800200Wavelength(nm)

0

10

20

30

40

50

Refle

ctan

ce (

)

4

6

8

10

12

Refle

ctan

ce (

)

400 600 800200

Wavelength (nm)


SnO2

CNW

(c)





11198622 =

2119902119860119873119889120576120576119900 [119881bias minus 119881119891119887

119870119879119902 ] (1)



SnO2

times1013

00

05

10

15

20

25

30

35

40


1C

2(F

minus2＝Ｇ

4)

(a)

CNW

times1014


00

04

08

12

16

1C

2(F

minus2＝Ｇ

4)

(b)

25 Ｑ SnO2 CNW

times1014

00

02

04

06

08

10

12


1C

2(F

minus2＝Ｇ

4)

(c)

50 Ｑ SnO2 CNW

times1012

00

10

20

30

40

50

60


1C

2(F

minus2＝Ｇ

4)

(d)











0

2

4

6

8

10

12Cu

rren

t (m

A)


SnO2

CNW

(a)

0

2

4

6

8

10

12

Curr

ent (

mA

)



SnO2

CNW

(b)



4 Conclusion




Acknowledgments


References













































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of



0

2

4

6

8

10

12In

tens

ity (a

u)times10

3

60W80W100W

0W20W40W


(a)

60W80W100W

0W20W40W


0

2

4

6

8

10

12

Inte

nsity

(cs

)times10

3(b)

C-C

C-C

O-C=OC-O

Inte

nsity

(cs

)


C 1s 80W

sp2

sp3

(c)

C-O

C-OH

Inte

nsity

(cs

)

532 536528 534 538530

O 1s 80W

Binding energy (eV)

(d)

6

8

10

12

14

70

80

90

100

20 40 60 80 1000Rf power (W)

020

024

028

032

036

sp3s

p2

A

-（+

-+

-=A

４４

()

(e)



5 m

(a)

5 m

(b)

5 m

(c)









CO

Si

CNW

C

O

Si

SnO2CNW

Sn Sn

0 05 1 15 2 25 3 35 4 45 5 55

05 1 15 2 25 3 35 4 45 5


(a)

D + G2D

D

G

D + G 2D

G

D

CNWInte

nsity

(au

)

Ａ

1Ａ

Ｏ


SnO2 CNW

(b)

300 400 500 600 700 800200Wavelength(nm)

0

10

20

30

40

50

Refle

ctan

ce (

)

4

6

8

10

12

Refle

ctan

ce (

)

400 600 800200

Wavelength (nm)


SnO2

CNW

(c)





11198622 =

2119902119860119873119889120576120576119900 [119881bias minus 119881119891119887

119870119879119902 ] (1)



SnO2

times1013

00

05

10

15

20

25

30

35

40


1C

2(F

minus2＝Ｇ

4)

(a)

CNW

times1014


00

04

08

12

16

1C

2(F

minus2＝Ｇ

4)

(b)

25 Ｑ SnO2 CNW

times1014

00

02

04

06

08

10

12


1C

2(F

minus2＝Ｇ

4)

(c)

50 Ｑ SnO2 CNW

times1012

00

10

20

30

40

50

60


1C

2(F

minus2＝Ｇ

4)

(d)











0

2

4

6

8

10

12Cu

rren

t (m

A)


SnO2

CNW

(a)

0

2

4

6

8

10

12

Curr

ent (

mA

)



SnO2

CNW

(b)



4 Conclusion




Acknowledgments


References













































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of



5 m

(a)

5 m

(b)

5 m

(c)









CO

Si

CNW

C

O

Si

SnO2CNW

Sn Sn

0 05 1 15 2 25 3 35 4 45 5 55

05 1 15 2 25 3 35 4 45 5


(a)

D + G2D

D

G

D + G 2D

G

D

CNWInte

nsity

(au

)

Ａ

1Ａ

Ｏ


SnO2 CNW

(b)

300 400 500 600 700 800200Wavelength(nm)

0

10

20

30

40

50

Refle

ctan

ce (

)

4

6

8

10

12

Refle

ctan

ce (

)

400 600 800200

Wavelength (nm)


SnO2

CNW

(c)





11198622 =

2119902119860119873119889120576120576119900 [119881bias minus 119881119891119887

119870119879119902 ] (1)



SnO2

times1013

00

05

10

15

20

25

30

35

40


1C

2(F

minus2＝Ｇ

4)

(a)

CNW

times1014


00

04

08

12

16

1C

2(F

minus2＝Ｇ

4)

(b)

25 Ｑ SnO2 CNW

times1014

00

02

04

06

08

10

12


1C

2(F

minus2＝Ｇ

4)

(c)

50 Ｑ SnO2 CNW

times1012

00

10

20

30

40

50

60


1C

2(F

minus2＝Ｇ

4)

(d)











0

2

4

6

8

10

12Cu

rren

t (m

A)


SnO2

CNW

(a)

0

2

4

6

8

10

12

Curr

ent (

mA

)



SnO2

CNW

(b)



4 Conclusion




Acknowledgments


References













































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of



CO

Si

CNW

C

O

Si

SnO2CNW

Sn Sn

0 05 1 15 2 25 3 35 4 45 5 55

05 1 15 2 25 3 35 4 45 5


(a)

D + G2D

D

G

D + G 2D

G

D

CNWInte

nsity

(au

)

Ａ

1Ａ

Ｏ


SnO2 CNW

(b)

300 400 500 600 700 800200Wavelength(nm)

0

10

20

30

40

50

Refle

ctan

ce (

)

4

6

8

10

12

Refle

ctan

ce (

)

400 600 800200

Wavelength (nm)


SnO2

CNW

(c)





11198622 =

2119902119860119873119889120576120576119900 [119881bias minus 119881119891119887

119870119879119902 ] (1)



SnO2

times1013

00

05

10

15

20

25

30

35

40


1C

2(F

minus2＝Ｇ

4)

(a)

CNW

times1014


00

04

08

12

16

1C

2(F

minus2＝Ｇ

4)

(b)

25 Ｑ SnO2 CNW

times1014

00

02

04

06

08

10

12


1C

2(F

minus2＝Ｇ

4)

(c)

50 Ｑ SnO2 CNW

times1012

00

10

20

30

40

50

60


1C

2(F

minus2＝Ｇ

4)

(d)











0

2

4

6

8

10

12Cu

rren

t (m

A)


SnO2

CNW

(a)

0

2

4

6

8

10

12

Curr

ent (

mA

)



SnO2

CNW

(b)



4 Conclusion




Acknowledgments


References













































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of



SnO2

times1013

00

05

10

15

20

25

30

35

40


1C

2(F

minus2＝Ｇ

4)

(a)

CNW

times1014


00

04

08

12

16

1C

2(F

minus2＝Ｇ

4)

(b)

25 Ｑ SnO2 CNW

times1014

00

02

04

06

08

10

12


1C

2(F

minus2＝Ｇ

4)

(c)

50 Ｑ SnO2 CNW

times1012

00

10

20

30

40

50

60


1C

2(F

minus2＝Ｇ

4)

(d)











0

2

4

6

8

10

12Cu

rren

t (m

A)


SnO2

CNW

(a)

0

2

4

6

8

10

12

Curr

ent (

mA

)



SnO2

CNW

(b)



4 Conclusion




Acknowledgments


References













































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of




0

2

4

6

8

10

12Cu

rren

t (m

A)


SnO2

CNW

(a)

0

2

4

6

8

10

12

Curr

ent (

mA

)



SnO2

CNW

(b)



4 Conclusion




Acknowledgments


References













































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of



































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


nanoparticles decorated 2d wavy hierarchical carbon nanowalls...

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