Synthesis and characterization of Copper nanoparticles by chemical reduction method

 

Satyanarayana Thodeti¹, Dr. S. Sudhakar Reddy¹, Srikanth Vemula²

¹Department of Physics, Sreyas Institute of Engineering and Technology, Hyderabad, Telangana, India

²Department of CNST, JNTUH, Hyderabad, Telangana, India

 

Abstract:

Chemical reduction technique is employed to synthesis copper nanoparticles. This method involves simple operation, low cost and faster reaction rate with low energy consumption. Copper nanoparticles are playing key role in the application of optics, electronics, biosensors, antimicrobial and electrochemical sensor fields. In this method Copper acetate monohydrate Cu (CH₃COO)₂ used as a precursor, Hydrazine hydrate (N₂H₆O) as a reducing agent and Poly vinyl Pyrrolidone (PVP K-40) as a capping agent. These nanoparticles are characterized by XRD, PSA.UV-V Spectroscopy, SEM, and EDAX.

 

 

 

 

1. INTRODUCTION:

The properties of nanomaterials are differing from bulk material of the same composition, nanomaterials are being applied in more and more fields within engineering and technology. Copper is an  element with atomic number 29, Block D and  Period 4 in Periodic table, There are many industrial uses of copper, due to its characteristics like high ductility, malleability, thermal conductivity and resistance to corrosion. Copper is one of the metals whose nanoparticles find wide practical applications [1]. Copper nanoparticles are extremely small and have a high surface area to volume ratio and they shows unique properties including catalytic, anti bacterial activities that are not observed in bulk copper [13]. Copper nanoparticles with great catalytic activities can be applied to biosensors and electrochemical sensors. These copper nanoparticles also act as an anti-biotic anti-microbial and anti-fungal agent when added to plastics, coatings and textiles [2]. The property of copper nanoparticles mainly depends on the synthesis route and their process parameters. However, copper nanoparticles have major limitations, which include rapid oxidation on exposure to air [4]. Copper oxidizes to CuO and Cu₂O and converts to Cu²⁺ during preparation and storage, so it is difficult to synthesize copper nanoparticles in an ambient environment. There are several methods to synthesize copper nanoparticles which include chemical reduction method [11], electro chemical techniques, sol-gel method, thermal decomposition, laser ablation electron beam irradiation etc. There are so many synthesis processes to produce the copper nanoparticles like Top-down and Bottom- up approaches [6], in which chemical reduction method is a simple technique for the preparation of copper nanoparticles. The chemicals used in chemical reduction method are Copper acetate monohydrate Cu (CH₃COO)₂ ,Hydrazine hydrate (N₂H₄, H₂O) ,Poly vinyl Pyrrolidone or Polyvidone (PVP K-40) [(C₆H₉NO)_n] ,Millipore distilled water and methanol.

 

2. EXPERIMENTAL:

The process Chemical reduction method involves in synthesis of Cu nanostructures, in this initially N₂H₄, H₂O  is heated up to 80°C- 90°C to evaporate the water content and then cooled up to room temperature. Cu (CH₃COO)₂  used as a precursor, N₂H₄ H₂O as a reducing agent and PVP K-40 as a capping agent. The ratio of precursor and PVP K-40 is 2:1. Then make up a 0.2 M of Cu (CH₃COO)₂ and  dissolve in 50ml Millipore distilled water in a beaker the color turns to blue under constant mechanical stirring about 10-15 min. Add PVP K-40 to the solution under mechanical stirring for about 10 minutes to dissolve. Then the prepared anhydrous N₂H₄, H₂O added drop wise to the solution, then the blue color turns to change yellow is observed at the time of reduction, then raise the temperature up to 65°C -75°C, in 30-40 minutes the total solution color changes from yellow to brown and finally it becomes reddish brown. Allow this solution to cool up to the room temperature then we observe that the Cu nanoparticles begin to condense on the inner walls of the beaker in the form of a thin film [3]. After allowing one day the whole copper nanoparticles settles at the bottom of the beaker. The deposited copper nanoparticles are filtered and washed several times with methanol to remove the unnecessary components in the solution and dried at room temperature to get Cu nano particle powder.

 

3.RESULTS AND DISCUSSIONS:

3.1 Phase Analysis and Particle Size Of Powders

The structural properties like crystallite size, packing fraction and surface to the volume ratio of the nano particles were determined using Bragg’s equation where λ be the wave length of X-ray. ‘d’ be the spacing between the planes in the atomic lattice, and be the angle between the incident ray and the scattering planes by x-ray diffractometer D8 ADVANCE OF BROKER AXS.

 

XRD analysis was carried out for Copper nano material. The synthesized nano material is matched with the JCPDF card no 89-2838, where the lattice constants for this material is         a = 3.60A^o, b=3.51A^o, c=3.61A^o; α = β = γ = 90^o, the structure is Face Centered Cube, molecular weight is 63.546 g/mol, Average crystalline size (D) is 21.32 nm, d-spacing is calculated  to be  0.36 nm. Packing fraction 74.5%, void space volume is 25.5% and surface to volume ratio is 2.35.

 

Fig.1. X-ray diffraction patterns of Cu nanoparticle.

 

Table.1.  XRD data of copper nanoparticle.

S.No	Theta (2θ) (Degrees)	Theta (θ) (Degrees)	Theta(θ) (Radians)	FWHM (β in degrees)	FWHM (β in radians)	Cos(θ) (radians)	Crystallite    size D =
1	43.37	21.69	0.38	0.32	0.005588	0.999978	26.61
2	50.50	25.25	0.44	0.46	0.008004	0.999970	19.09
3	74.15	37.08	0.65	0.55	0.009499	0.999934	18.26
						Total	63.96
						Average	21.32

 

Fig.2.  Micro-strain plot for copper nanoprticles.

 

Micro-strain and average crystal size can be determined from Williamson-Hall plot using the equation.

 

β_hkl(cosθ) =(  )+ (4εsinθ)

The W-H plot gives micro-strain value and is observed to be 9.09409E-4.

3.2 Particle Size Analyzer (PSA):

Synthesized Copper nanoparticles were characterized by PSA for particle size distribution. 

 

 

 

Fig. 3. Particle distribution in the Particle Size Analyzer of Copper nanoparticle.

The measurement of particle size distribution of Copper nano particle was done by Particle Size Analyzer. In the prepared sample it was observed that, particles have a wide size distribution, but the majority of them were dispersed within a narrow range, as shown in Fig. The average particle size of Copper nanoparticle from the histogram was found to be 46.9 nm.

 

3.3 Ultraviolet-Visible Spectroscopy:

The copper nanoparticles were successfully prepared in the presence of a protective polymer PVP. The color of copper nano particles appeared as reddish brown. It depends up the PVP concentration. When the PVP concentration increased the copper nano particle under goes to copper oxides.

 

 

Fig. 4. UV-Visible image of Copper nanoparticle.

 

The 0.001 g of copper nano particle dissolved in ethanol as a media and sanitation for10 min. for total dispersion, after that give to UV-Visible spectroscopic analysis. From the UV- Spectroscopic analysis gives characterization graph, in which the peak is observation at 592 nm.

 

3.4. Scanning Electron Microscopy (SEM):

The surface morphology of Copper nanoparticle was investigated by using SEM (ZEISS-EVO18 Special Edition) and morphology images are shown in the following Figs. These figures show the morphology of Copper nano particles with different scales 100 μm, and 2 μm. From the SEM images, we can infer that the obtained Copper nano particles are porous in nature.

 

 

(A)

 

(B)

Fig.5 (A) and (B). SEM micrographs of Copper nano particles.

 

3.5. Energy Dispersive Analysis of X-Ray (EDAX):

EDAX ((ZEISS-EVO18 Special Edition)) studies are generally carried out to test the purity of the sample and give the details of all the elements present in the given sample. The following figures show EDAX results of synthesized copper nano particles. The elements present in the material are clearly known and whether the obtained material has any contamination can be known by EDAX results. 

 

 

Fig. 6. EDAX image of Copper nanoparticle.

 

Table-2. EDAX result of Copper nanoparticles

 

The EDAX analysis shows that the samples of copper nanomaterial contains atomic percentages of Copper 96.88 and Oxygen 03.12, element in its composition i.e., the energy-dispersive spectroscopy (EDAX) of the presence of these compounds clarified that the component is Copper nanoparticle.

 

4. CONCLUSIONS:

The chemical reduction method is a simple technique for the preparation of copper nanoparticles; this method also takes less time to synthesis nanoparticles. XRD analysis was carried out for Copper nano material. The synthesized nano material is matched with the JCPDF card no. 89-2838, where the average crystallite size is 21.32nm. From Williamson-Hall plot, micro-strain value is observed to be 9.094E-4. The measurement of particle size distribution of Copper nano particle was done by Particle Size Analyzer and the average particle size of copper nanoparticle from the histogram was found to be 46.9 nm. The UV- Spectroscopic analysis gives characterization graph, in which the peak is observed at 592 nm. The surface morphology of Copper nanoparticle was investigated by using SEM, which shows the morphology of Copper nanoparticles with different scales of 100 μm and 2 μm, From the SEM images we can infer that the obtained Copper nano particles are porous in nature.

 

5. REFERENCES:

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Received on 03.12.2017       Modified on 28.12.2017 Accepted on 08.01.2018      ©A V Publications All right reserved Research J. Science and Tech. 2018; 10(1):52-57 DOI: 10.5958/2349-2988.2018.00007.4