Dear

Heba Mohamed Fahmy

Please, find in attach a paper on:Synthesis and optical properties of copper nanoparticles prepared by a chemical reduction method Thi My Dung Dang1, Thi Tuyet Thu Le1, Eric Fribourg-Blanc2 and Mau Chien Dang1

Synthesis of copper nanoparticles

The four-step preparation scheme for copper nanoparticles starts with dissolving copper (II) sulfate pentahydrate salt, CuSO4 5H2O (0.01 M), in deionized water to obtain a blue solution. Next, polyethylene glycol 6000, PEG 6000 (0.02 M) was dissolved in water and added to the aqueous solution containing the copper salt while vigorously stirring. In this step, the solution changed from blue to white. In the third step, ascorbic acid (0.02 M) and sodium hydroxide (0.1 M) were dissolved in water and added to the synthesis solution. Color change occurred in the aqueous phase from white to yellow. Finally, a solution of NaBH4 (0.1 M) in deionized water was prepared and added to the solution under continuous rapid stirring. An instant color change occurred in the aqueous phase from yellow to black/red. The appearance of this dark color indicated that the reduction reaction had started. The source of electrons for the reaction was BH−4. The mixture was further stirred rapidly for around 10 min in ambient atmosphere, to allow the reaction to complete.

There is this one as well...

(Tian, 2012 - In situ synthesis of copper nanoparticles/polystyrene compositeI)

"Poly(N-vinylpyrrolidone) (PVP, 0.09 mmol) and cetyltrimethyl

ammonium bromide (CTAB, 3.0 mmol) were added to an aqueous

solution of cupric sulfate (0.02 M, 40 ml) in a round-bottom flask.

The pH of the reaction solution was adjusted to 9–11 with ammonia

solution. The reaction mixture was heated to 50 ◦C and stirred for

2 h. Then, an aqueous solution of hydrazine hydrate (0.3 M, 20 ml)

was dropped slowly into the reaction solution at 70 ◦C. The resulting

mixture was stirred at 70 ◦C for 1 h, giving a red CuNPs colloid."

But to store... Is important to you purge inert gas after to open the flask, cause the oxygen from the air diffuses through water.

http://dx.doi.org/10.1016/j.colsurfa.2012.01.019

If you have access to a Power Laser (e.g. a pulsed Nd:YAG Lab laser with ns pulses), you may produce Cu NPs n a non-oxidizing liquid environment (e.g. ethanol) via Pulsed Laser Ablation of a clean and high-purity target immersed in that liquid. No need of any other chemicals,

Power Laser with (n pulses) is valuable also in this concern.