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Journal of Physics and Chemistry of Solids 69 (2008) 1718–1727

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Synthesis of quasi-1D cuprous oxide nanostructureand its structural characterizations

Poonam Sharma�, H.S. Bhatti

Department of Physics, Punjabi University, Patiala 147 002, Punjab, India

Received 19 July 2007; received in revised form 13 December 2007; accepted 14 December 2007

Abstract

A wealth of superfine polycrystalline cuprous oxide (Cu2O) nanowires have been synthesized with hydrazine hydrated (N2H4 �H2O),

act as the reducing agent, and Cu(OH)2 nanowires, act as a soft template and surfactant, at room temperature. Two methods were

employed for the synthesis of these nanowires, i.e. with and without capping agent (polyethylene glycol Mw 8000). Techniques of powder

X-ray diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED) pattern, electron

diffraction X-ray (EDX) spectroscopy, and UV–visible (UV–vis) spectroscopy have been used to characterize the morphology, structure,

crystallinity, purity, and composition of nanowires. The average diameters of Cu2O nanowires, prepared with and without capping

agent, were observed to be 8–10 and 12–15 nm and lengths of several microns, respectively. It is found that capping agent (PEG) confines

the dimensions of synthesized nanowires. In addition, the observed optical band gap of products show blue-shift effect compared to the

bulk Cu2O (Eg ¼ 2.17 eV), which ascribe it as a promising material for the conversion between solar energy and electrical or chemical

energy.

r 2007 Elsevier Ltd. All rights reserved.

Keywords: A. Nanostructures; B. Chemical synthesis; C. Electron microscopy; C. X-ray diffraction; C. XRD

1. Introduction

Inorganic nanoparticles of uniform size and shape are ofspecial interest from both theoretical as well as practicalperspectives due to their potential applications. Fieldswhich would be greatly benefited from advances in thesynthesis of well-defined nanostructures include photonics[1], nanoelectronics [2], information storage, catalysis [3],biological diagnosis [4], magnetic recording, magnetic fluid,precursor for high strength materials, etc. Many above-stated applications of nanomaterials depend upon the size,shape, and crystallinity of the particles [5]. These propertiesare commonly controlled in solution-phase nanoscalesynthesis via nucleation and growth mechanism in thepresence of surfactant under high-temperature reactioncondition [6]. Two general strategies have been employedfor ‘‘bottom up’’ chemical synthesis of nanomaterials:(i) the use of hard templates, which physically confine the

front matter r 2007 Elsevier Ltd. All rights reserved.

s.2007.12.013

ng author.

ss: poonam.vats@gmail.com (P. Sharma).

size and shape of growing nanoparticles and (ii) the use ofcapping agents during nanoparticles growth to control itsdirection and dimension [7]. Nanomaterials have beenfabricated in many shapes like prism, cages [8], pyramids,cones, cubes [7,9–11], boxes [12], spheres [13], ribbon [14],tree [15], rods [16], belts [17], plates [18], etc. Dimension-ality plays an important role in determining the propertiesof materials due to interaction of electron in three-dimensional (3D), two-dimensional (2D) and one-dimen-sional (1D) structures [19]. Nowadays, 1D nanoscalematerials are of current interest because of their funda-mental importance and wide range of unique electronic,magnetic, thermal, surface, mechanical, and optical prop-erties [20,21]. Consequently, many 1D nanoscale materialssuch as carbon nanotubes/rods [22] as well as otherinorganic nanotubes/rod/wires [23–26] have been synthe-sized by the variety of methods. These methods usuallyinvolves conventional lithography [27], surfactant-inducedanisotropic growth [28], electrolysis [29], coordinationchemistry method [30], and technique based on templatesof ‘‘Track-Etch’’ polycarbonate membranes [31], alumina

ARTICLE IN PRESSP. Sharma, H.S. Bhatti / Journal of Physics and Chemistry of Solids 69 (2008) 1718–1727 1719

membranes [32], zeolites [33], mica [34], DNA [35], andcalix[4]hydroquinone nanotubes [36]. However, the fabri-cation of 1D material is a very difficult task because of itsextreme small size and their anisotropy. The control ofnucleation and growth of 1D nanostructural materials isbecoming critical [37]. One-dimensional nanostructurehave many potential applications, which includes nano-electronics, superstrong and tough composites, functionalnanostructured materials, and novel probe microscopy tips[38,39].

Copper(I)oxide, [Cu2O], is an important p-type semi-conductor material having a direct band gap of 2.17 eV. Ithas important applications in hydrogen production, assolar cell [40] material and as superconductor. Uponphotoexcitation, the long-lived excitons in Cu2O exhibitcoherent propagation analogous to that of photons in alaser [4]. Cu2O has a high-symmetry and a lower anion/cation ratio [41]. Recent investigations [42] indicate that theCu2O submicrosphere can be used as a negative electrodematerial for lithium ion batteries. Furthermore, Cu2O actas a stable photocatalyst for photochemical decompositionof water into O2 and H2 under visible light irradiation [43].Cu2O is expected to have full Cu 3d orbital, band theoryexpected to provide a good description about the electronicstructures [44].

In the present context, quasi-1D cuprous oxide (Cu2O)nanowires were synthesized by the reduction route methodwith [45] and without [46] using capping agent polyethyleneglycol (PEG) at room temperature. The influence ofcapping agent on the morphology of Cu2O nanowires hasalso been investigated. The fabrication of Cu2O nanowiresstart with a sequence of reactions by first fabricateprecursor Cu(OH)2 nanowires. The obtained nanowireswere reduced by hydrazine hydrated, acts as reducingagent, which results in formation of Cu2O nanowires. Thissynthesis technique is very simple, easy and requires veryshort time to get completed. Cu2O nanowires wereprepared according to Wang et al. [45,46] with slightmodifications.

2. Experimental details

2.1. Materials and equipments

PEG (Mw 8000) (H(OCH2CH2)nOH) (analytic reagent,AR), copper chloride dihydrated (Cu(II)Cl2 � 2H2O)(99.99%), sodium hydroxide (NaOH) (AR), ammoniumhydroxide (NH4OH) (AR), hydrazine hydrated (N2H4 �

H2O) (AR), all aqueous solutions were prepared in triplydeionized water with high purity. The crystallographicinformation of the prepared samples were investigated byPW1710-powder X-ray diffractometer with Cu Ka radia-tion (l=0.154187 nm) and equipped with a secondarypyrolytic graphite monochromator. The step scan coveredthe angular range of 201–801 in step of 0.061. Morpholo-gical characterizations were carried out with HitachiH-6000 transmission electron microscope, in bright field

image mode operating at an accelerating voltage of 120 kV.Samples for transmission electron microscopy (TEM) wereprepared by drying a drop of the colloidal suspension on acarbon coated copper grid in the air. UV–visible (UV–vis)spectrums of the dispersions were obtained from ELICO-SL 164 PC-coupled UV-spectrophotometer.

2.2. Synthesis method for Cu2O nanowires using capping

agent PEG (Cu2OPEG)

In this synthesis process, copper(II)chloride was used asa starting material and PEG as capping agent. Firstly,400mg of PEG (Mw 8000) and 200mg of Cu(II)Cl2 � 2H2Owere dissolved in 200ml of distilled water and stirred withmagnetic stirrer for 10–15min to ensure that PEG andCuCl2 dissolves completely. Then, 2.0ml of 6M NaOHsolution was added drop-wise in the reaction mixture,under constant stirring. A deep blue color precipitates ofCu(OH)2 were soon produced. After continuous stirringfor next 15min, 1.5ml of 13.7M N2H4 �H2O solution wasadded drop-wise into blue Cu(OH)2 precipitated solution.The blue color precipitates gradually turn into a red color.The stirring was continued for next 2 h to ensure thatCu(OH)2 nanowires were completely reduced by N2H4 �

H2O solution. As, Cu(OH)2 precipitates were completelyreduced, the obtained red color precipitates of Cu2O wasfiltered out, washed with distilled water several times, anddried in desigator for 24 h.Basic chemical equations involved in the synthesis

process of Cu2O nanowires by the reduction of Cu(OH)2nanowires are as follows:

CuCl2! Cu2þ þ Cl�; (1)

Cu2þ þ 2NaOH! CuðOHÞ2 þ 2Na2þ; (2)

4CuðOHÞ2 þN2H4! 2Cu2Oþ 6H2OþN2: (3)

N2H4 �H2O in basic aqueous solution acts as a strongreducing agent and reduces copper hydroxide to cuprousoxide:

N2 þH4 þ 4e� ! N2H4 þ 4OH�: (4)

2.3. Synthesis method for Cu2O nanowires without using

capping agent PEG (Cu2Owo)

In this reduction route process, 1.14 g of CuCl2 � 2H2Owas dissolved in 100ml distilled water and the solution wasstirred for 20min. A 0.15M of NH4OH aqueous solution(20ml) was added under constant stirring into the CuCl2 �2H2O solution. After being stirred for next 15min, 5.0mlof 1.2M NaOH solution was added drop-wise to theabove-described solution. Blue precipitates of Cu(OH)2were soon produced, and stirring was continued foranother 15min. After that, 2.5ml of 10M N2H4 �H2Osolution was added drop-wise into blue Cu(OH)2 pre-cipitated solution with constant stirring for another 2 h.

ARTICLE IN PRESSP. Sharma, H.S. Bhatti / Journal of Physics and Chemistry of Solids 69 (2008) 1718–17271720

The blue color precipitates gradually turn into yellow thenorange and finally turn into red. The red color precipitatesof Cu2O were filtered out and washed with distilled waterseveral times, and dried in desigator for 24 h.

Basic chemical equations involved in the fabrication ofprecursor Cu(OH)2 nanowires are as follows:

2Cu2þ þ 2NH4ðOHÞ ! Cu2ðOHÞ2þ þ ðNH4Þ2þ; (5)

Cu2ðOHÞ2þ þ 8NH3! 2½CuðNH3Þ4�2þ þ 2OH�; (6)

½CuðNH3Þ4�2þ þ 4NH3; (7)

2Cu2þ þ 2OH� ! CuðOHÞ2: (8)

In both of the synthesis processes, cuprous hydroxide(Cu(OH)2) nanowires act as a reactant for growth of Cu2Onanowires as well as soft templates for controlling thedimensions of the resulting nanowires. Cu2O nanowireswere formed by the redox reaction of cuprous hydroxide

Fig. 1. Diagrammatic illustration of synthetic route of Cu2O nanowires pr

(Cu(OH)2) with hydrazine hydrated (N2H4 �H2O), whereN2H4 �H2O acts as a reducing agent. The chemical reactioninvolved will be given as

CuðOHÞ2 þN2H4! 2Cu2OþN2 þ 6H2O: (9)

The synthesis routes for the fabrication of Cu2Onanowires prepared with, (Cu2OPEG) and without,(Cu2OWO), capping agent is shown schematically in Fig. 1.

3. Results and discussions

3.1. X-ray diffraction (XRD)

Fig. 2(a) and (b) shows a typical X-ray diffractogramcollected from an as prepared samples. The crystalstructure of cuprous oxide lattice has been determinedfrom the observed ‘‘d’’ values by using an analytic method[47,48]. This analysis shows that all observed peaks can be

epared with (Cu2OPEG) and without (Cu2OWO) capping agent (PEG).

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Fig. 2. XRD pattern for Cu2O nanowires: (a) with, i.e.Cu2OPEG and (b) without capping agent (PEG), i.e. Cu2OWO.

P. Sharma, H.S. Bhatti / Journal of Physics and Chemistry of Solids 69 (2008) 1718–1727 1721

readily indexed to the polycrystalline pure cubic structureand belongs to Pn3m phase. Cu2OPEG and Cu2OWO

nanowires having lattice parameters of a=0.4234and 0.4249 nm, respectively. The diffraction pattern ofCu2OPEG nanowires shown in Fig. 2(a) contains five distin-guishable peaks, i.e. /1 1 0S, /1 1 1S, /2 0 0S, /2 2 0S,and /3 1 1S while Cu2OWO nanowires in Fig. 2(b) containseven distinguishable peaks, i.e. /1 1 0S, /1 1 1S, /2 0 0S,/2 1 1S, /2 2 0S, /3 1 1S, and /2 2 2S. /1 1 1S peak has100% intensities in both the cases. Corresponding, 2yvalues were 36.584 and 36.720 for Cu2OPEG and Cu2OWO

nanowires, respectively. These peaks were very clear and ingood agreement with those for Cu2O powder (JCPDS file(No. 05-0667)). No characteristic peaks for CuO and Cuwere observed in both of the cases. Diffraction pattern ofCu2OPEG samples shows only five peaks, whereas Cu2OWO

samples show seven diffraction peaks. This suggests thattwo peaks were suppressed when the capping agent wasused. Table 1(a) and (b) summarizes the crystallographicparameters of samples prepared with (Cu2OPEG) andwithout (Cu2OWO) capping agent, respectively. Table 1(c)shows the standard crystallographic parameters obtainedfrom [27] and it shows the standard lattice constant(a-value) value that corresponds to /1 1 1S peak.

3.2. Transmission electron microscopy (TEM)

TEM studies of the products obtained after reductionroute confirmed these predictions and showed that primarily

wire-like structure with (Cu2OPEG) and without (Cu2OWO)capping agent remarkably having average diameters of theorder of 8–10 and 12–16nm with lengths of 2.1 and 2.5mm,respectively, were produced by this approach. The typicalelectron micrograph images of the nanowires fabricatedwith, (Cu2OPEG), and without, (Cu2OWO), using cappingagent are illustrated in Fig. 3(a)–(d), respectively. TheTEM images recorded on individual wires further show thatall nanowires are highly crystalline. The length of allsynthesized wires are too long but there were variablediameters. This confirms that capping agent helps inreducing the dimensions of nanowires during the growth,by forming layer of micelles over the surface of wires. Byrecording selected area electron diffraction (SAED) patternsof both the wires, i.e. (Cu2OPEG) and (Cu2OWO), grownpreferably in /1 1 1S direction. Chemical compositions ofall the wires were checked by electron diffraction X-ray(EDX) observation. Fig. 4(a) and (b) obtained fromnanowires indicate that the final products were mostlycomposed of copper (Cu) and oxygen (O). In this growthprocess, first the nucleated particle grows then these existedparticles linked together by strong bonding to form longassembled packed structure.

3.3. UV–Vis spectrum

The UV–Vis spectra, for understanding the properties ofatomic coupling within such prepared nanowires, havebeen shown in Fig. 5. These optical absorption spectra

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Table 1

Crystallographic parameters of sample prepared: (a) with capping agent

(PEG), (Cu2OPEG); (b) without capping agent (PEG), (Cu2OWO); (c)

standard crystallographic parameters [27], i.e. lattice parameter (a-value)corresponding to /1 1 1S peak and shortest distance ‘‘d’’ between Cu–O,

O–O, and Cu–Cu

Plane d-Spacing (A) 2y a-Value (A)

(a)

110 3.002 29.712 4.246

111 2.453 36.583 4.249

200 2.129 42.782 4.258

220 1.516 61.023 4.288

311 1.288 73.425 4.271

(b)

110 2.980 29.945 4.214

111 2.445 36.720 4.234

200 2.121 42.585 4.241

211 1.795 50.815 4.396

220 1.504 61.595 4.254

311 1.281 73.855 4.250

222 1.224 77.980 4.239

(c)

Cu2O

Lattice parameter Cubic

a ¼ 4.27 A

Shortest distance

dCu–O 1.84 A

dO–O 3.68 A

dCu–Cu 3.02 A

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were taken from different Cu2O nanowires dispersed inaqueous media. A broad band ranging from 450 to 750 nm,having maxima at 529 nm (Eg ¼ 2.33 eV) and 536 nm(Eg ¼ 2.30 eV) for samples prepared with and withoutusing capping agent, respectively, have been observed. Theband gaps of Cu2OPEG and Cu2OWO calculated were 2.33and 2.30 eV, respectively, which was larger than thereported value for the bulk Cu2O (Eg ¼ 2.17 eV). It is wellknown that the optical absorption would be affectedconsiderably by the morphology and crystallinity of Cu2Onanowires. A blue-shift effect will be achieved due to thedecrease in overall crystal size. Thus, the observation onthe optical absorption of the Cu2O nanowires can berationalized by considering that capping agent made morepronounced effect on the optical absorption.

3.4. Synthesis discussion

This research work had summarized that, in the firstsynthesis process, capping agent PEG and chloride saltwere used as starting materials. While, in second synthesismethod, both ammonium hydroxide and sodium hydroxidesolutions were required to obtain the Cu(OH)2 nanowiresand no capping agent was used. Chloride salt was used asstarting material. It is well known that Cu2+ ions complexwith anions and its corresponding ligands present in theprecipitate solution, the bond strength of which follows the

order: OH�4NH34Cl�. The bond strength of chlorides(Cl�) with their corresponding cations/ligands is stronger.Also, the chlorides are more ionic because of morepolarization of electron clouds in solvent. The electronicclouds of chlorides are less dense; as a result it gets readilyionized in solvent.

3.4.1. Nanowire growth mechanism

The growth mechanism of Cu2O nanowires can be bestdescribed on the basis of coordination assembly growth. Inthe field of coordination chemistry, many complexes havestable infinite ordered structure, because of rigidity ofbridging ligands. Metal cations in some complexes arrangethemselves on long chains and bridges together by certainligands [26]. The growth of metal and metal oxidenanowires in suitable reaction will be provided by theorientation. Moreover, complexes having infinite structurewere stable and their ligands were difficult to leave frommetal cations, whereas small complex units were highlyunstable and their ligands can easily leave their metalcations. Figs. 6 and 7 illustrate the possible mechanisminvolved in the synthesis of Cu2O nanowires, with andwithout capping agent (PEG), respectively.The basic equations involved in the formation of Cu2O

nanowires using capping agent proceeds as follows:

Cu2þ þ ðHðOCH2CH2ÞnOHÞ ! Cu2þ � ðHðOCH2CH2ÞnOHÞ

! Cu2þ � ðHðOCH2CH2ÞnOHÞ þOH�

! ½CuðOHÞn�ðn�2Þ� ! CuðOHÞ2ðnanowiresÞ; (10)

CuðOHÞ2ðnanowiresÞ

! Cu2OðnanowiresÞ ½after reduced by N2H4 �H2O�:(11)

In the first synthesis process, the capping agent PEG wasused and these PEG molecules within the aqueous solutionform a monolayer structure. This monolayer structurechanges progressively into micelles with the passage oftime. These Cu2+ ions present within the solution to formcoordination bonding with PEG molecules. These PEGmicelles enwraps whole surface of wires, which may behydrophilic or hydrophobic, as whole reaction occurs inwater phase. It was proposed that the Cu2+ ionscoordinate loosely to the oxygen atoms of PEG initiallyin water to causes isotropic capping of the Cu2O nanowiressurfaces [10]. It is plausible, that the nucleation of Cu(OH)2starts from localized regions. Once the nucleus is formed,the assembled Cu(OH)2 nanowires grow within the surfaceof micelles and this continues till the addition of NaOHsolution. Then, Cu(OH)2 nanowires grow faster along/1 0 0S direction because of lesser dhkl values, which isbased on the assembly of olated chains of /Cu(OH)2CuS.The nanowire layers were connected together through H-bonding between tetra-coordinated OH� groups and twoneighboring bi-coordinated hydroxyls [40]. The obtainedCu(OH)2 nanowires will be reduced by using hydrazinehydrated (N2H4 �H2O) solution causes removal of OH�

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Fig. 3. (a,b) TEM images of Cu2O nanowires prepared using capping agent (PEG), i.e.Cu2OPEG. Inset in Fig. 3(a) shows the SAED pattern of

nanowires.(c,d) TEM images of Cu2O nanowires prepared without capping agent (PEG), i.e.Cu2OWO. Inset shows the SAED pattern of the wires.

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ions by O� ions. These growing Cu(OH)2 nanowires act asboth template and surfactant for the synthesis of Cu2Onanowires. This bond structure leads to the formation ofquasi-1D nanostructure, which is joined together by strongbonds. Thus, PEG directs the final product fabrication bycontrolling the direction and dimensions of nanowires andalso confines its diameter [25].

The reaction equations involved in the formation ofCu2O nanowires in the second synthesis method, i.e.without using capping agent (PEG) probably proceeds asfollows:

Cu2þ þNH3! ½CuðNH3Þn�2þ; (12)

½CuðNH3Þn�2þ þOH� ! ½CuðNH3Þn�mðOHÞm�

þ

! ½CuðOHÞn�ðn�2Þ� ! CuðOHÞ2ðnanowiresÞ; (13)

CuðOHÞ2ðnanowiresÞ ! Cu2OðnanowiresÞ

½after reduced by N2H4 �H2O�: (14)

The additional ammonia and NaOH solutions were usedto obtain the Cu(OH)2 nanowires and no capping agent

was used. First of all, the Cu2+ cations form square planar[Cu(NH3)4]

2+ complex in the presence of NH3 [32]. Underthe basic condition of pH value, the hydroxyl group (OH�)replaces the NH3 in the [Cu(NH3)n]

2+ complex, which wasthe stable complex before the addition of NaOH solution.It gives rise to a square planar [Cu(OH)4]

2� units. Additionof NaOH solution causes increase in the pH value andbasicity of the solution. As a result, the amine grouppresent in [Cu(NH3)n]

2+ complex is becoming less stablethan hydroxyl group. It follows the bond strength order:OH�4NH3. This complex finally breaks to form[Cu(OH)4]

2� complex. Note that, the nucleation ofCu(OH)2 starts from localized regions with the relativehigh concentrations of [Cu(NH3)n]

2+. Once the nucleusformed, the assembled Cu(OH)2 nanowires start growing[40]. The growth rate of wires along different direction isdifferent. According to the Bravais–Donnay–Harker(BDH) law, crystal planes with larger dhkl values growslowly, hence the growth rate of Cu(OH)2 nanowires along/1 0 0S direction is much faster. The growth of Cu(OH)2nanowires along /1 0 0S direction can be understood onthe basis of assembly of olated chains of /Cu(OH)2CuS,

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Fig. 4. (a) EDX pattern of Cu2O nanowires with capping agent (PEG), i.e.Cu2OPEG. (b) EDX pattern of Cu2O nanowires without capping agent (PEG),

i.e.Cu2OWO.

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which is the characteristics of square-planar coordinates ofCu2+-ions and sx

2–y2 bonds [40]. The effect of NH3 is

perhaps to absorb on the /0 1 0S surface, hinders theformation of hydrogen bond bridges, and thus slows downthe growth along /0 1 0S. As a result, wire like structuretakes shape. Finally, a long Cu(OH)2 nanowires preferablygrow along /1 0 0S direction, and enclosed with the

/0 1 0S and /0 0 1S direction [48,49]. Thus, Cu(OH)2nanowires are formed, which act as a template for thefurther growth of Cu2O nanowires. Then, freshly preparedhydrazine hydrated (N2H4 �H2O) was added to the reactionsolution. Thus, hydroxyl ions were reduced to oxide ions.Therefore, growth of Cu2O nanowires start by reductionof Cu(OH)2 nanowires. This leads to the formation of

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Fig. 5. UV–visible spectrum of Cu2O nanowires prepared: (a) with (PEG), i.e.Cu2OPEG and (b) without capping agent (PEG), i.e. Cu2OWO.

Fig. 6. Schematic diagram of coordination assembly growth of Cu2O nanowires obtained from Cu(OH)2 nanowires prepared in the presence of capping

agent polyethylene glycol (PEG) (Cu2OPEG).‘‘Considering the schematic space, the drawing cannot describe the size of nanowire’’.

P. Sharma, H.S. Bhatti / Journal of Physics and Chemistry of Solids 69 (2008) 1718–1727 1725

quasi-1D structure packed together by strong bonding ofO2� anions. Here, redox reaction happened.

An other important factor involved in the preparationof nanowires is temperature of reaction mixture as thewhole experiment was carried out at room temperature,i.e. 300K, but as reaction temperature is increased, the

reaction becomes much faster and the resultant nano-wires formed were aggregated [12]. Also, the above-defined synthesis processes are advantageous overother known methods as it provides good quality oflonger nanowires, yielding large quantity (90%) of endproduct.

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Fig. 7. Coordination assembly growth of Cu2O nanowires obtained from

Cu(OH)2 nanowires prepared without using capping agent (Cu2OWO).

P. Sharma, H.S. Bhatti / Journal of Physics and Chemistry of Solids 69 (2008) 1718–17271726

4. Conclusions

Cu2O nanowires were successfully synthesized with(Cu2OPEG) and without using capping agent PEG(Cu2OWO) at room temperature. The synthesis of nano-wires was carried out via first fabrication of precursorCu(OH)2 nanowires, then reduced via freshly preparedhydrazine hydrated (N2H4 �H2O), which acts as a strongreducing agent. Cu(OH)2 nanowires are very loosestructure and act as reactant as well as template for thesynthesis of many Cu-based quasi-1D nanostructures.Capping agent PEG acts as a surfactant for the synthesisof nanowires and confines the diameter of nanowires. Theeffectiveness and function of PEG and other polarmolecules, as surfactant, for growth of Cu2O was veryuseful for the future. XRD and TEM investigationssuggested that the nanowires were highly crystalline havingpure cubic structure belongs to Pn3m phase. While a largevariation in optical absorption band and shift towardslower wavelengths have been observed, i.e. it shows blue-shift effect compared to the bulk Cu2O. This method isadvantageous as whole synthesis process occurs at roomtemperature with nominal reaction conditions, yieldinglarge quantity of end product. This quasi-1D nanomaterialpromises many useful applications, such as photocatalyst,negative-electrode for batteries, and sensory devices.

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