research article 3d cu(oh) hierarchical frameworks: self

Hindawi Publishing CorporationJournal of NanomaterialsVolume 2013 Article ID 797082 8 pageshttpdxdoiorg1011552013797082

Research Article3D Cu(OH)2 Hierarchical Frameworks Self-Assembly Growthand Application for the Removal of TSNAs

Hongwei Hou1 You Zhu2 and Qingyuan Hu1

1 China National Tobacco Quality Supervision amp Test Center No 2 Fengyang StreetZhengzhou High amp New Technology Industries Development Zone Zhengzhou 450001 China

2 Shandong Tobacco Quality Supervision and Testing Station Xinluo Street High amp New Technology Industries Development ZoneJinan 250101 China

Correspondence should be addressed to Hongwei Hou houhwztricomcn and Qingyuan Hu huqyztricomcn

Received 25 March 2013 Accepted 7 May 2013

Academic Editor Zhenhui Kang

Copyright copy 2013 Hongwei Hou et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

The 3D hierarchical Cu(OH)2frameworks were successfully prepared via a simple and surfactant-free chemical self-assembled

route The frameworks were characterized by X-ray powder diffraction field-emission scanning electron microscopy and energydispersive X-ray spectroscopy The experimental investigations suggest that certain concentrations of NaOH and K

2S2O8are

required for the self-assembly and growth of Cu(OH)2 In addition the orthorhombic crystal structure of Cu(OH)

2may prove

to be ideal for the structural development of the final 3D Cu(OH)2hierarchical frameworks The nitrogen adsorption and

desorption measurements indicate that the Cu(OH)2frameworks possess a Brunauer-Emmett-Teller surface area of approximately

16376m2 gminus1 Barrett-Joyner-Halenda measurement of the pore size distribution as derived from desorption data presented adistribution centered at 305 nm Additionally 10mg of the Cu(OH)

2framework can remove 47 of the N-nitrosonornicotine and

53of the 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone in cigarette smokeThese results indicate that theCu(OH)2frameworks

may be a potential adsorbent for removing tobacco-specific N-nitrosamines (TSNAs) from cigarette smoke

1 Introduction

Self-assembled materials are the building blocks of the 21stcentury just as alloys plastics and semiconductors are thebuilding blocks of the 20th century These materials areformed by interatomic and intermolecular interactions otherthan the traditional covalent ionic and metallic bondingforces [1] Opportunities offered by self-assembled materialsare becoming a significant factor in current research direc-tions Biological life forms demonstrate an intricate patternof macroscopic structures and functions formed through ahierarchical series of forces A consequence of this ldquointelligentself-assemblyrdquo is the functional utility of self-replication andself-repair

Until recently the application of self-assembly to buildinorganic structures with morphological diversity and com-plexity of natural minerals reflects a remarkable level ofcontrol over high-order organization of inorganic materials[2ndash4] In the process surfactant as an important control

factor has been widely used [5ndash7] This generally introducedheterogeneous impurities and limited the application andfurther research of inorganicmaterials due to trace surfactantabsorption Orthorhombic Cu(OH)

2with layered structure

has opened a new challenging field in chemistry biotechnol-ogy and materials science due to its potential applicationsin sensors [8 9] Meanwhile the magnetic property ofCu(OH)

2 which is sensitive to the intercalation of molecular

anions has made the material a promising candidate for thepreparation of copper-based biomineral such as orthorhom-bic Cu

2(OH)3Cl [10 11] Inspired by the layered structure and

its accompanying fundamental and practical applicationsCu(OH)

2and the self-assembly synthesis of its elaborate

morphologies have attracted considerable attentionThere is growing interest in the synthesis and morpho-

logical control of the Cu(OH)2nanoribbons nanowires

nanotubes and nanorods [12ndash23] Despite the excellentapproaches on the synthesis routes of low-dimensionalCu(OH)

2 only a few pieces of work on the 3D architectures of

2 Journal of Nanomaterials

Cu(OH)2have been reported M Y Hanrsquos group reported the

3D nanoarchitectures of dendritic Cu(OH)2[23]The oxygen

from the atmosphere induced the spontaneous oxidationreaction of copper foil in the presence of formamide andCu2+ ions were released continuously from the copper foilinto the formamide solution while oxygen was reduced Thereleased copper ions can be captured by coordinating withformamide molecules to form copper complexions (Cu +12O2+ H2O + 4HCONH

2rarr [Cu(HCONH

2)4]2++

2OHminus) which transformed into 3D dendritic copper hydrox-ide on substrate in 10 days

The removal of tobacco-specific nitrosamines (TSNAs)N-nitrosonornicotine (NNN) 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) N-nitrosoanatabine (NAT)and N-nitrosoanabasine (NAB) from cigarette smoke hasattracted growing interest over the past years because ofthe potent carcinogens in animal studies of TSNAs [24ndash26]The design and preparation of new materials are crucial forremoving carcinogenic compounds from tobacco smokeHowever to the best of our knowledge the reduction ofTSNAs in cigarette smoke using the 3Dhierarchical Cu(OH)

2

frameworks has not been reported until nowIn this work a fast and template-free approach for the

progressive production of 3D hierarchical Cu(OH)2frame-

works was developed from the oxidation of copper metalunder a highly alkaline condition The high-order shell-ornamented self-assembled structures keep the frameworkin the foreground of research in natural biominerals orsynthetic materials This unexplored Cu(OH)

2frameworks

with interesting morphologies and high surface area are theextension of the work of 3D epitaxial scrolls on the Cu(OH)

2

ribbons on the copper foil [14] On the basis of a series ofcomparative experiments the formation mechanism and theTSNAs reduction rate of the 3DCu(OH)

2hierarchical frame-

works in cigarette smoke were proposed and thoroughlyinvestigated It is expected that the impressive 3D frameworksof Cu(OH)

2might bring new ways to reduce carcinogenic

compounds in cigarette smoke in the near future

2 Experimental Methods

A typical synthesis of 3D Cu(OH)2hierarchical frameworks

on copper foil was performed as follows an aqueous solu-tion was prepared in a 50mL glass bottle by mixing 84 gof NaOH (7mol Lminus1) 108 g of K

2S2O8(013mol Lminus1) and

30mL of water that were analytically pure A piece of 9999copper foil (5 times 25 times 025mm3) which was cleaned in 30nitric acid for 20 s rinsed in deionized water and ultrasoni-cally cleaned in acetone was immersed in the solution After30min the copper foil was taken out of the solution andrinsed with distilled water

The phase identification of the samples was carriedout using X-ray powder diffraction (XRD) patterns with aMAC Science Co Ltd MXP 18 AHF X-ray diffractometerwith Cu K120572 radiation (120582 = 154056 A) The morphologyof the products was in situ measured by scanning elec-tron microscopy (FE-SEM JEOL JSM-6700F FEI PHILIPSXL30 ESEM-TMP) and energy dispersive X-ray spectroscopy

10 20 30 40 50 60 70 80

110 111

200 220

2120579 (deg)

Inte

nsity

(au

)

111lowast

200lowast

220lowast

Figure 1 XRD pattern of the as-prepared sample with [NaOH] =7mol Lminus1 and [K

2S2O8] = 013mol Lminus1 for 30min (peaks marked

with ldquolowastrdquo correspond to the copper foil)

(EDS OXFORD INCA400) The nitrogen adsorption anddesorption isotherms at 77K were measured with a Micro-metrics ASAP 2020 analyzer Before measurement the sam-ples were degassed in vacuum at 140∘C for at least 6 h

The content of TSNAs in cigarette smoke was analyzedby liquid chromatography with tandem mass spectrometry(LC-MSMS API 5500 triple quadruple mass spectrometerApplied Biosystems Foster City CA USA) For the wetcut tobacco a certain amount of Cu(OH)

2hierarchical

frameworks was dispersed in water to form an emulsion witha concentration of 50 g Lminus1 Subsequently the cut tobaccowas sprayed with different volumes of emulsion to obtain10mg cigaretteminus1 The wet cut tobacco samples were driedat 40∘C until the moisture content was approximately 12The cut tobacco treated by this method was used to makecigarettes with an automated process and the final weight was850plusmn30mg Before smoking the cigarettes were conditionedat 295 plusmn 1K and 60 plusmn 2 relative humidity for 48 h and thensmoked by a Cerulean SM 450 smoking machine under thestandard ISO regime (ISO 4387)

3 Results and Discussion

The composition of the sample was examined by X-raydiffraction (XRD) A typical XRD pattern of the sample isshown in Figure 1 All of the diffraction peaks can be indexedto the orthorhombic phase Cu(OH)

2(space group Cmc2

1

JCPDS card No 13-420) except those marked with an ldquolowastrdquowhich were from the copper substrate

The panoramic morphology of the sample as examinedby scanning electron microscopy and shown in Figure 2(a)indicated that the hierarchical framework with spherulitictexture grew onto the copper surface Single particles hada round shape and a uniform size of 10 120583m and peanut-or dumbbell-like particles were formed when two particlesmerged together Other shapes were also produced whenthree or more particles fused together The structure and

Journal of Nanomaterials 3

10120583m

(a)

0

5

O

Cu

Cu

Cu

Cou

nts

0 2 4 6 8 10Energy (keV)

1120583m

(b)

Figure 2 (a) FESEM image of the 3D Cu(OH)2hierarchical

framework prepared with [NaOH] = 7mol Lminus1 and [K2S2O8] =

013mol Lminus1 for 30min (b) EDS analysis of the hierarchical frame-work

composition of the hierarchical frameworkwas characterizedby energy dispersive X-ray spectroscopy (EDS) as shownin Figure 2(b) The appropriate molar ratio of Cu O = 1 2which confirmed well to the XRD results

The images of a typical single framework are shown inFigures 3(a) and 3(b) which indicated a flower-like morphol-ogy with lamellar and hierarchical structure The magnified3D spherical morphology confirmed that the highly porousstructure with ultrathin lamellar structures of sim25 nm inthickness was identical throughout the hierarchical crystalFigure 3(c) shows the submicrometer Cu(OH)

2structures

prepared in a previous study with [KOH] = 25mol Lminus1 and[K2S2O8] = 013mol Lminus1 for 15min at 40∘C [14] The

products on the ribbons were Cu(OH)2epitaxial scrolls Fur-

thermore from the magnified images shown in Figure 3(d)these submicrometer structures were wool balls growingfrom the ribbons and formed from the lamellar structuresThe difference in concentration of alkalinity and K

2S2O8was

the sole contributing factor for the different morphologiesin the as-prepared samples This observation suggested thatan appropriate concentration of alkalinity and K

2S2O8was

essential to the unique and interesting morphology

In the present approach the formation of Cu(OH)2on

copper foil involved a simple oxidation process described asfollows

Cu + 2 NaOH + K2S2O8997888rarr Cu (OH)

2

+ Na2SO4+ K2SO4

(1)

It is well known that in order to attain the desired self-assembled structures the effect of salts and ionic speciesin the system cannot be ignored [27] This also suggeststhat a certain level of NaOH and K

2S2O8concentration

was required for the growth of the self-assembled Cu(OH)2

hierarchical frameworkTo thoroughly investigate the formation mechanism of

the Cu(OH)2hierarchical framework the influence of the

concentrations of NaOH and K2S2O8to the Cu(OH)

2mor-

phology was examined The Cu(OH)2samples produced

under different concentrations of NaOH with [K2S2O8] =

013mol Lminus1 for 30min were observed by SEM as shown inFigures 4(a)ndash4(d) At a lower concentration of [NaOH] =013mol Lminus1 the oxidation process was slow and the finalproduct was a few multiped crystals on the foil When[NaOH] = 1mol Lminus1 many ribbons emerged When[NaOH] = 3mol Lminus1 the products were some flower-likestructures scrolled on the ribbons After the concentration ofNaOH was increased to 9mol Lminus1 the bulk crystals appearedon the foil Similarly the Cu(OH)

2samples produced under

different concentrations of K2S2O8with [NaOH] = 7mol Lminus1

for 30min were examined and the corresponding SEMimages are shown in Figure 5 At a lower K

2S2O8concen-

tration of 0033mol Lminus1 a mass of acicular crystals formedon the Cu foil as shown in Figures 5(a) and 5(b) When[K2S2O8] = 017mol Lminus1 some scrolling floccule structures

appeared and scrolled on the ribbons as shown in Figures5(c) and 5(d)

A comparison of the FESEM images of the Cu(OH)2

structures prepared under different reaction times with[NaOH] = 7mol Lminus1 and [K

2S2O8] = 013mol Lminus1 showed

that the oxidation process was fast Namely the high alka-linity and the effect of the oxidant determined the rapidrate of growth Through the careful analysis of the samplesproduced under different reaction times a possible growthprocess may be proposed Under the initial high alkalinitythe copper foil oxidized expeditiously and produced crystalswith a prism-like morphology (Figure 6(a)) After 5minmany spindle-like multiped crystals were found as shownin Figure 6(b) which were 500 nm in length on average andconsisted of several nanoribbons Spindle-like structures havebeen validated as one of the structures of hydroxide [28]As the reaction proceeded the coherent nanoribbons begancurving as shown in Figure 6(c) After 15min the straightnanoribbons were edged out by curved ones (Figure 6(d))After 20min the outline of the structures was finalized witha much smaller size (Figure 6(e)) Then at 30min the 3Dhierarchical framework formed as shown in Figure 6(f)

Based on the above discussions of Cu(OH)2morphology

the orthorhombic crystal structure of Cu(OH)2may prove to

be ideal for the development of the final Cu(OH)2structure


2120583m

(a)

1120583m

(b)

5120583m

(c)

500nm

(d)

Figure 3 ((a) (b)) FESEM image of the 3D Cu(OH)2hierarchical framework with [NaOH] = 7mol Lminus1 and [K

2S2O8] = 013mol Lminus1 for

30min ((c) (d)) FESEM image of the Cu(OH)2scrolling structures on the Cu(OH)

2submicrometer ribbons with [KOH] = 25mol Lminus1 and

[K2S2O8] = 013mol Lminus1 for 15min at 40∘C

2120583m

(a)

3120583m

(b)

5120583m

(c)

3120583m

(d)

Figure 4 FESEM images of Cu(OH)2structures prepared under different concentrations of NaOHwith [K

2S2O8] = 013mol Lminus1 for 30min

(a) [NaOH] = 013mol Lminus1 (b) [NaOH] = 1mol Lminus1 (c) [NaOH] = 3mol Lminus1 (d) [NaOH] = 9mol Lminus1


20120583m

(a)

3120583m

(b)

120583m5

(c)

2120583m

(d)

Figure 5 FESEM images of Cu(OH)2structures prepared under different concentrations of K

2S2O8with [NaOH] = 7mol Lminus1 for 30min

((a) (b)) [K2S2O8] = 0033mol Lminus1 ((c) (d)) [K

2S2O8] = 017mol Lminus1

[29] as demonstrated by Huang [30ndash32] In the process therapid rate of nucleation resulted in the small concentration ofnucleus which provided the possibility of anisotropic nucleargrowth and determined the structure of Cu(OH)

2 The

schematic illustration of the proposed development of theCu(OH)

2structure is shown in Figure 7 It is known thatCu2+

ions prefer square planar coordination by OHminus (shown inFigure 7(a)) which leads to an extended chain (Figure 7(b))The chains can be connected through the coordinationof OHminus to dz2 of Cu2+ forming two-dimensional (2D)ultrathin sheet-like structures (Figure 7(c)) Finally the 2Dlayers are stacked through the relatively weak hydrogen bondinteractions and two or more adjacent hierarchical crystalscan further expand and eventually self-organizemerge intocontinuous porous networks [33 34] and an intricate three-dimensional (3D) crystal (Figure 7(d))

The self-assembly process involves forces such as hydro-gen bonding dipolar forces other van der Waals forceshydrophilic or hydrophobic interactions (all frequentlyreferred to as ldquosupramolecular interactionsrdquo) chemisorp-tion surface tension and gravity Forces involving ionsand ligands (the ldquocoordinate-covalent bondrdquo) have resultedin supramolecular structures [12] Considering the relatedexperimental results and the possible development ofCu(OH)

2structure we predict that a certain level of con-

centration of NaOH and K2S2O8is required for the self-

assembly and growth of Cu(OH)2 and the lamellar structure

of Cu(OH)2is the determining factor for the final hierarchical

framework That is the potential self-assembly forces inCu(OH)

2will induce the formation of the 3D hierarchical

framework under the appropriate concentration of NaOHand K

2S2O8 Using experimental results we propose the

possible mechanism for the assembly and growth of theCu(OH)

2hierarchical framework After the initial nucle-

ation the newly formed Cu(OH)2will grow into nanopar-

ticles followed by the formation of primary radical andspindle-like multiped structures (as shown in Figure 6) as theresult of the anisotropic nature of the Cu(OH)

2structure

Under the appropriate levels of NaOH and K2S2O8 the

copper foil will be further eroded while making the Cu(OH)2

structure evolve rapidly from the lamellar structure to the 3Dhierarchical framework Namely the spindle-like multipedstructureswill continue to fissure and grow driven by the self-assembly forces as mentioned earlier [35 36]

Nitrogen adsorptiondesorption measurements wereconducted to characterize the Brunauer-Emmett-Teller(BET) surface area and internal pore structure The recordedadsorption and desorption isotherms for the 3D Cu(OH)

2

hierarchical frameworks are shown in Figure 8 The BETspecific surface area of the sample was calculated from N

2

isotherms to be approximately 16376m2 gminus1 Barrett-Joyner-Halenda (BJH) measurements for the pore-size distributionas derived from desorption data presented a distributioncentered at 305 nm The smaller pores presumably arose


400nm

(a)

400nm

(b)

400nm

(c)

600nm

(d)

1120583m

(e)

5120583m

(f)

Figure 6 FESEM images of the Cu(OH)2structures prepared with [NaOH] = 7 mol Lminus1 and [K

2S2O8] = 013mol Lminus1 for (a) 1min (b)

5min (c) 10min (d) 15min (e) 20min and (f) 30min

Table 1 The amount of four TSNAs in cigarette smoke produced by cut tobacco with the 3D Cu(OH)2 hierarchical framework

Compounds Blank cigarettelowast 10mg cigaretteminus1 3D Cu(OH)2 Reduction ()NNN

ng cigminus14956 2625 47

NAT 2822 2035 28NAB 1521 1156 24NNK 1820 862 53Tar mg cigminus1 1350 1280 5lowastThe blank cigarette was identical to the one with no Cu(OH)2

from the spaces within the hierarchical structure The resultsshowed that the obtained hierarchical frameworks wereporous and confirmed well with the FESEM images

The as-prepared 3D Cu(OH)2hierarchical frameworks

were wetted and put into the cut tobacco to study the TSNAs

content in cigarette smoke Table 1 shows the content offour TSNAs in cigarette smoke after adding 3D Cu(OH)

2

hierarchical frameworks into cut tobacco which was ana-lyzed by LC-MSMS Compared with ldquoblankrdquo cigarettes withno 3D Cu(OH)

2 the TSNAs contents of cigarettes with


Growthripenessgrowth

Nucleation

(d)

(c)(b)(a)

Figure 7 Schematic illustration of the proposed development ofthe Cu(OH)

2structure (a) The layered structure of orthorhombic

Cu(OH)2 (b) further growing of layered structure (c) formation of

a two-dimensional (2D) ultrathin sheet-like structure (d) the wholegrowth process of self-assembling and ripening of the 3D Cu(OH)

2

hierarchical framework

90

80

70

60

50

40

Volu

me a

dsor

bed

(cm

3g

)

00 02 04 06 08

Relative pressure (pp0)

AdsorptionDesorption

10

0016

0012

0008

0004

0000Pore

vol

ume (

cm3g

)

0 10 20 30 40 50

(a)

(b)Pore diameter D (nm)

Figure 8 N2absorption and desorption isotherms and pore size

distribution (inset) for the 3D Cu(OH)2hierarchical framework

10mg cigaretteminus1 Cu(OH)2were selectively reduced with no

changes in tar content which may influence the cigarettesmoke quality The adsorptive capacity of Cu(OH)

2for

NNN NAT NAB and NNK is 47 28 24 and 53respectively Because the Cu(OH)

2could block the NndashNO

group and hamper the formation of TSNAs [25] the 3DCu(OH)

2hierarchical framework added into the cut tobacco

not only influenced cigarette combustion but also workedas adsorbents that reduce the amount of TSNAs WhenCu(OH)

2with sophisticated morphology was added into the

wet tobacco chemical transitions took place during burningand showed to be more effective than zeolite

A cigarette sample added Cu(OH)2frameworks and a

blank sample (with no Cu(OH)2frameworks) were smoked

under the standard ISO regime (ISO 4387) Toxicology testsincluding cytotoxic test mutagenicity testing of salmonellatyphimurium and in vitro micronucleus test were used to

detect the influence of health The three smoke toxicol-ogy tests showed that there were no significant differencesbetween the two samples

4 Conclusions

A template-free chemical route involving a simple oxida-tion process to grow self-assembled 3D Cu(OH)

2hierarchi-

cal frameworks was developed In comparison with otherapproaches the alternative route is fast safe simple andinexpensive and this effective and convenient method issuitable for modern chemical synthesis of 3D hierarchicalframeworks The experimental investigations suggest thatcertain concentrations of NaOH and K

2S2O8are required for

the self-assembly and growth of Cu(OH)2 Furthermore the

orthorhombic crystal structure of Cu(OH)2may prove to be

ideal for the structural development of the final Cu(OH)2

hierarchical frameworks The BET specific surface area ofthe sample was calculated from N

2isotherms to be approx-

imately 16376m2 gminus1 The BJH for the pore-size distributionpresented a distribution centered at 305 nm It was foundthat 10mg of Cu(OH)

2framework can remove 47 of the

NNN and 53 of the NNK in cigarette smokeThe successfulfabrication of the hierarchical morphology provides newapplications in reducing the carcinogenic compounds incigarette smoke

Acknowledgments

Financial support from the National Natural Science Foun-dation of China (no 20701040) is gratefully acknowledgedThe authors thank the Hefei National Laboratory for PhysicalSciences at theMicroscale as well as the University of Scienceand Technology of China for the assistance with structuralcharacterization

References

[1] W M Tolles ldquoSelf-assembled materialsrdquo MRS Bulletin vol 25no 10 pp 36ndash38 2000

[2] J Aizenberg A Tkachenko S Weiner L Addadi and GHendler ldquoCalcitic microlenses as part of the photoreceptorsystem in brittlestarsrdquo Nature vol 412 no 6849 pp 819ndash8222001

[3] D L Beke ldquoOn the composition andpressure dependence of theself-diffusion coefficient in liquid metalsrdquo International Journalof Materials Research vol 101 no 3 pp 353ndash355 2010

[4] R K Bortoleto-Bugs T Mazon M Tarozzo Biasoli A PavaniFilho J Willibrordus Swart and M Roque Bugs ldquoUnder-standing the formation of the self-assembly of colloidal coppernanoparticles by surfactant a molecular velcrordquo Journal ofNanomaterials vol 2013 Article ID 802174 8 pages 2013

[5] J Texter Journal of DispersionScience and Technology vol 22no 1 5 pages 2001

[6] B Russell M Payne and L C Ciacchi ldquoDensity functionaltheory study of Fe(II) adsorption and oxidation on goethitesurfacesrdquo Physical Review B vol 79 no 16 Article ID 1651012009


[7] A Nazari and S Riahi ldquoPhysical and mechanical behaviorof high strength self-compacting concrete containing ZrO

2

nanoparticlesrdquo International Journal of Materials Research vol102 no 5 pp 560ndash571 2011

[8] W Fujita and K Awaga ldquoReversible structural transformationand drastic magnetic change in a copper hydroxides intercala-tion compoundrdquo Journal of the American Chemical Society vol119 no 19 pp 4563ndash4564 1997

[9] W Fujita and K Awaga ldquoIntercalation of stable organic radicalsinto layered copper hydroxidesrdquo Synthetic Metals vol 122 no3 pp 569ndash572 2001

[10] H C Lichtenegger T Schoberl M H Bartl H Waite and GD Stucky ldquoHigh abrasion resistance with sparsemineralizationcopper biomineral in worm jawsrdquo Science vol 298 no 5592 pp389ndash392 2002

[11] S Weiner and L Addadi ldquoBiomineralization at the cuttingedgerdquo Science vol 298 no 5592 pp 375ndash376 2002

[12] XWenW Zhang S Yang Z R Dai and Z LWang ldquoSolutionphase synthesis of Cu(OH)

2nanoribbons by coordination self-

assembly using Cu2S nanowires as precursorsrdquo Nano Letters

vol 2 no 12 pp 1397ndash1401 2002[13] W Z Wang C Lan Y Z Li K Q Hong and G H Wang ldquoA

simple wet chemical route for large-scale synthesis of Cu(OH)2

nanowiresrdquo Chemical Physics Letters vol 366 no 3-4 pp 220ndash223 2002

[14] W X Zhang X G Wen and S H Yang ldquoControlled reactionson a copper surface synthesis and characterization of nanos-tructured copper compound filmsrdquo Inorganic Chemistry vol42 no 16 pp 5005ndash5014 2003

[15] XWenWZhang and S Yang ldquoSynthesis ofCu(OH)2andCuO

nanoribbon arrays on a copper surfacerdquo Langmuir vol 19 no14 pp 5898ndash5903 2003

[16] W Zhang X Wen S Yang Y Berta and Z L Wang ldquoSingle-crystalline scroll-type nanotube arrays of copper hydroxidesynthesized at room temperaturerdquo Advanced Materials vol 15no 10 pp 822ndash825 2003

[17] G H Du and G Van Tendeloo ldquoCu(OH)2nanowires CuO

nanowires and CuO nanobeltsrdquo Chemical Physics Letters vol393 no 1ndash3 pp 64ndash69 2004

[18] X Song S Sun W Zhang H Yu and W Fan ldquoSynthesis ofCu(OH)

2nanowires at aqueous-organic interfacesrdquo Journal of

Physical Chemistry B vol 108 no 17 pp 5200ndash5205 2004[19] C Lu L Qi J Yang D Zhang N Wu and J Ma ldquoSimple

template-free solution route for the controlled synthesis ofCu(OH)

2and CuO nanostructuresrdquo Journal of Physical Chem-

istry B vol 108 no 46 pp 17825ndash17831 2004[20] S-H Park and H J Kim ldquoUnidirectionally aligned copper

hydroxide crystalline nanorods from two-dimensional copperhydroxy nitraterdquo Journal of the American Chemical Society vol126 no 44 pp 14368ndash14369 2004

[21] P Gao M Zhang Z Niu and Q Xiao ldquoA facile solution-chemistrymethod for Cu(OH)

2nanoribbon arrays with notice-

able electrochemical hydrogen storage ability at room tempera-turerdquo Chemical Communications no 48 pp 5197ndash5199 2007

[22] Y Ni H Li L Jin and J Hong ldquoSynthesis of 1D Cu(OH)2

nanowires and transition to 3D CuO microstructures underultrasonic irradiation and their electrochemical propertyrdquoCrystal Growth amp Design vol 9 no 9 pp 3868ndash3873 2009

[23] W Jia E Reitz H Sun H Zhang and Y Lei ldquoSynthesisand characterization of novel nanostructured fishbone-likeCu(OH)

2and CuO from Cu

4SO4(OH)

6rdquoMaterials Letters vol

63 no 5 pp 519ndash522 2009

[24] K A Wagner N H Finkel J E Fossett and I G GillmanldquoDevelopment of a quantitative method for the analysis oftobacco-specific nitrosamines in mainstream cigarette smokeusing isotope dilution liquid chromatographyelectrospray ion-ization tandem mass spectrometryrdquo Analytical Chemistry vol77 no 4 pp 1001ndash1006 2005

[25] Y Zhu H W Hou G L Tang and Q Y Hu ldquoSynthesis ofthree-quarter-sphere-like 120574-AlOOH superstructures with highadsorptive capacityrdquo European Journal of Inorganic Chemistryno 6 pp 872ndash878 2010

[26] W Xiong H Hou X Jiang G Tang and Q Hu ldquoSimulta-neous determination of four tobacco-specific N-nitrosaminesin mainstream smoke for Chinese Virginia cigarettes by liquidchromatography-tandem mass spectrometry and validationunder ISO and ldquoCanadian intenserdquo machine smoking regimesrdquoAnalytica Chimica Acta vol 674 no 1 pp 71ndash78 2010

[27] Z P Zhang X Q Shao H D Yu Y B Wang and M YHan ldquoMorphosynthesis and ornamentation of 3D dendriticnanoarchitecturesrdquo Chemistry of Materials vol 17 no 2 pp332ndash336 2005

[28] H Hou Y Xie and Q Li ldquoLarge-scale synthesis of single-crystalline quasi-aligned submicrometer CuO ribbonsrdquo CrystalGrowth amp Design vol 5 no 1 pp 201ndash205 2005

[29] H Hou Y Xie Q Yang Q Guo and C Tan ldquoPreparationand characterization of 120574-AlOOH nanotubes and nanorodsrdquoNanotechnology vol 16 no 6 pp 741ndash745 2005

[30] C-C Huang C-S Yeh and C-J Ho ldquoLaser ablation synthesisof spindle-like gallium oxide hydroxide nanoparticles withthe presence of cationic cetyltrimethylammonium bromiderdquoJournal of Physical Chemistry B vol 108 no 16 pp 4940ndash49452004

[31] L C Varanda M P Morales M Jafelicci Jr and C J SernaldquoMonodispersed spindle-type goethite nanoparticles fromFeIIIsolutionsrdquo Journal of Materials Chemistry vol 12 no 12 pp3649ndash3653 2002

[32] T Sugimoto K Okada and H Itoh ldquoFormation mechanismof uniform spindle-type titania particles in the gel-sol processrdquoJournal of Dispersion Science and Technology vol 19 no 2-3 pp143ndash161 1998

[33] Y Cudennec and A Lecerf ldquoThe transformation of Cu(OH)2

into CuO revisitedrdquo Solid State Sciences vol 5 no 11-12 pp1471ndash1474 2003

[34] R Rodrıguez-Clemente C J SernaMOcana and EMatijevicldquoThe relationship of particle morphology and structure of basiccopper(II) compounds obtained by homogeneous precipita-tionrdquo Journal of Crystal Growth vol 143 no 3-4 pp 277ndash2861994

[35] F J Opalko J H Adair and S R Khan ldquoHeterogeneousnucleation of calcium oxalate trihydrate in artificial urine byconstant compositionrdquo Journal of Crystal Growth vol 181 no4 pp 410ndash417 1997

[36] KNaka andYChujo ldquoControl of crystal nucleation and growthof calcium carbonate by synthetic substratesrdquo Chemistry ofMaterials vol 13 no 10 pp 3245ndash3259 2001

Submit your manuscripts athttpwwwhindawicom

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


Nano

materials


Journal ofNanomaterials


Cu(OH)2have been reported M Y Hanrsquos group reported the

3D nanoarchitectures of dendritic Cu(OH)2[23]The oxygen

from the atmosphere induced the spontaneous oxidationreaction of copper foil in the presence of formamide andCu2+ ions were released continuously from the copper foilinto the formamide solution while oxygen was reduced Thereleased copper ions can be captured by coordinating withformamide molecules to form copper complexions (Cu +12O2+ H2O + 4HCONH

2rarr [Cu(HCONH

2)4]2++

2OHminus) which transformed into 3D dendritic copper hydrox-ide on substrate in 10 days

The removal of tobacco-specific nitrosamines (TSNAs)N-nitrosonornicotine (NNN) 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) N-nitrosoanatabine (NAT)and N-nitrosoanabasine (NAB) from cigarette smoke hasattracted growing interest over the past years because ofthe potent carcinogens in animal studies of TSNAs [24ndash26]The design and preparation of new materials are crucial forremoving carcinogenic compounds from tobacco smokeHowever to the best of our knowledge the reduction ofTSNAs in cigarette smoke using the 3Dhierarchical Cu(OH)

2

frameworks has not been reported until nowIn this work a fast and template-free approach for the

progressive production of 3D hierarchical Cu(OH)2frame-

works was developed from the oxidation of copper metalunder a highly alkaline condition The high-order shell-ornamented self-assembled structures keep the frameworkin the foreground of research in natural biominerals orsynthetic materials This unexplored Cu(OH)

2frameworks

with interesting morphologies and high surface area are theextension of the work of 3D epitaxial scrolls on the Cu(OH)

2

ribbons on the copper foil [14] On the basis of a series ofcomparative experiments the formation mechanism and theTSNAs reduction rate of the 3DCu(OH)

2hierarchical frame-

works in cigarette smoke were proposed and thoroughlyinvestigated It is expected that the impressive 3D frameworksof Cu(OH)

2might bring new ways to reduce carcinogenic

compounds in cigarette smoke in the near future

2 Experimental Methods

A typical synthesis of 3D Cu(OH)2hierarchical frameworks

on copper foil was performed as follows an aqueous solu-tion was prepared in a 50mL glass bottle by mixing 84 gof NaOH (7mol Lminus1) 108 g of K

2S2O8(013mol Lminus1) and

30mL of water that were analytically pure A piece of 9999copper foil (5 times 25 times 025mm3) which was cleaned in 30nitric acid for 20 s rinsed in deionized water and ultrasoni-cally cleaned in acetone was immersed in the solution After30min the copper foil was taken out of the solution andrinsed with distilled water

The phase identification of the samples was carriedout using X-ray powder diffraction (XRD) patterns with aMAC Science Co Ltd MXP 18 AHF X-ray diffractometerwith Cu K120572 radiation (120582 = 154056 A) The morphologyof the products was in situ measured by scanning elec-tron microscopy (FE-SEM JEOL JSM-6700F FEI PHILIPSXL30 ESEM-TMP) and energy dispersive X-ray spectroscopy

10 20 30 40 50 60 70 80

110 111

200 220

2120579 (deg)

Inte

nsity

(au

)

111lowast

200lowast

220lowast

Figure 1 XRD pattern of the as-prepared sample with [NaOH] =7mol Lminus1 and [K

2S2O8] = 013mol Lminus1 for 30min (peaks marked

with ldquolowastrdquo correspond to the copper foil)

(EDS OXFORD INCA400) The nitrogen adsorption anddesorption isotherms at 77K were measured with a Micro-metrics ASAP 2020 analyzer Before measurement the sam-ples were degassed in vacuum at 140∘C for at least 6 h

The content of TSNAs in cigarette smoke was analyzedby liquid chromatography with tandem mass spectrometry(LC-MSMS API 5500 triple quadruple mass spectrometerApplied Biosystems Foster City CA USA) For the wetcut tobacco a certain amount of Cu(OH)

2hierarchical

frameworks was dispersed in water to form an emulsion witha concentration of 50 g Lminus1 Subsequently the cut tobaccowas sprayed with different volumes of emulsion to obtain10mg cigaretteminus1 The wet cut tobacco samples were driedat 40∘C until the moisture content was approximately 12The cut tobacco treated by this method was used to makecigarettes with an automated process and the final weight was850plusmn30mg Before smoking the cigarettes were conditionedat 295 plusmn 1K and 60 plusmn 2 relative humidity for 48 h and thensmoked by a Cerulean SM 450 smoking machine under thestandard ISO regime (ISO 4387)

3 Results and Discussion

The composition of the sample was examined by X-raydiffraction (XRD) A typical XRD pattern of the sample isshown in Figure 1 All of the diffraction peaks can be indexedto the orthorhombic phase Cu(OH)

2(space group Cmc2

1

JCPDS card No 13-420) except those marked with an ldquolowastrdquowhich were from the copper substrate

The panoramic morphology of the sample as examinedby scanning electron microscopy and shown in Figure 2(a)indicated that the hierarchical framework with spherulitictexture grew onto the copper surface Single particles hada round shape and a uniform size of 10 120583m and peanut-or dumbbell-like particles were formed when two particlesmerged together Other shapes were also produced whenthree or more particles fused together The structure and


10120583m

(a)

0

5

O

Cu

Cu

Cu

Cou

nts

0 2 4 6 8 10Energy (keV)

1120583m

(b)






2structures




2S2O8was


2S2O8was





2

+ Na2SO4+ K2SO4

(1)


2S2O8concentration





2mor-







2S2O8concen-











2120583m

(a)

1120583m

(b)

5120583m

(c)

500nm

(d)






2120583m

(a)

3120583m

(b)

5120583m

(c)

3120583m

(d)





20120583m

(a)

3120583m

(b)

120583m5

(c)

2120583m

(d)






2 The

















2structure





2


2



400nm

(a)

400nm

(b)

400nm

(c)

600nm

(d)

1120583m

(e)

5120583m

(f)












2





Nucleation

(d)

(c)(b)(a)





2


90

80

70

60

50

40

Volu

me a

dsor

bed

(cm

3g

)

00 02 04 06 08



10

0016

0012

0008

0004

0000Pore

vol

ume (

cm3g

)

0 10 20 30 40 50

(a)






2for












4 Conclusions


2hierarchi-











Acknowledgments


References









2































2and CuO from Cu

4SO4(OH)


63 no 5 pp 519ndash522 2009






















CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




10120583m

(a)

0

5

O

Cu

Cu

Cu

Cou

nts

0 2 4 6 8 10Energy (keV)

1120583m

(b)






2structures




2S2O8was


2S2O8was





2

+ Na2SO4+ K2SO4

(1)


2S2O8concentration





2mor-







2S2O8concen-











2120583m

(a)

1120583m

(b)

5120583m

(c)

500nm

(d)






2120583m

(a)

3120583m

(b)

5120583m

(c)

3120583m

(d)





20120583m

(a)

3120583m

(b)

120583m5

(c)

2120583m

(d)






2 The

















2structure





2


2



400nm

(a)

400nm

(b)

400nm

(c)

600nm

(d)

1120583m

(e)

5120583m

(f)












2





Nucleation

(d)

(c)(b)(a)





2


90

80

70

60

50

40

Volu

me a

dsor

bed

(cm

3g

)

00 02 04 06 08



10

0016

0012

0008

0004

0000Pore

vol

ume (

cm3g

)

0 10 20 30 40 50

(a)






2for












4 Conclusions


2hierarchi-











Acknowledgments


References









2































2and CuO from Cu

4SO4(OH)


63 no 5 pp 519ndash522 2009






















CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




2120583m

(a)

1120583m

(b)

5120583m

(c)

500nm

(d)






2120583m

(a)

3120583m

(b)

5120583m

(c)

3120583m

(d)





20120583m

(a)

3120583m

(b)

120583m5

(c)

2120583m

(d)






2 The

















2structure





2


2



400nm

(a)

400nm

(b)

400nm

(c)

600nm

(d)

1120583m

(e)

5120583m

(f)












2





Nucleation

(d)

(c)(b)(a)





2


90

80

70

60

50

40

Volu

me a

dsor

bed

(cm

3g

)

00 02 04 06 08



10

0016

0012

0008

0004

0000Pore

vol

ume (

cm3g

)

0 10 20 30 40 50

(a)






2for












4 Conclusions


2hierarchi-











Acknowledgments


References









2































2and CuO from Cu

4SO4(OH)


63 no 5 pp 519ndash522 2009






















CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




20120583m

(a)

3120583m

(b)

120583m5

(c)

2120583m

(d)






2 The

















2structure





2


2



400nm

(a)

400nm

(b)

400nm

(c)

600nm

(d)

1120583m

(e)

5120583m

(f)












2





Nucleation

(d)

(c)(b)(a)





2


90

80

70

60

50

40

Volu

me a

dsor

bed

(cm

3g

)

00 02 04 06 08



10

0016

0012

0008

0004

0000Pore

vol

ume (

cm3g

)

0 10 20 30 40 50

(a)






2for












4 Conclusions


2hierarchi-











Acknowledgments


References









2































2and CuO from Cu

4SO4(OH)


63 no 5 pp 519ndash522 2009






















CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




400nm

(a)

400nm

(b)

400nm

(c)

600nm

(d)

1120583m

(e)

5120583m

(f)












2





Nucleation

(d)

(c)(b)(a)





2


90

80

70

60

50

40

Volu

me a

dsor

bed

(cm

3g

)

00 02 04 06 08



10

0016

0012

0008

0004

0000Pore

vol

ume (

cm3g

)

0 10 20 30 40 50

(a)






2for












4 Conclusions


2hierarchi-











Acknowledgments


References









2































2and CuO from Cu

4SO4(OH)


63 no 5 pp 519ndash522 2009






















CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials





Nucleation

(d)

(c)(b)(a)





2


90

80

70

60

50

40

Volu

me a

dsor

bed

(cm

3g

)

00 02 04 06 08



10

0016

0012

0008

0004

0000Pore

vol

ume (

cm3g

)

0 10 20 30 40 50

(a)






2for












4 Conclusions


2hierarchi-











Acknowledgments


References









2































2and CuO from Cu

4SO4(OH)


63 no 5 pp 519ndash522 2009






















CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials





2































2and CuO from Cu

4SO4(OH)


63 no 5 pp 519ndash522 2009






















CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials










CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials



research article 3d cu(oh) hierarchical frameworks: self

Documents