Synthesis of highly stable dispersions of copper nanoparticles using sodium hypophosphite

Abstract

Highly stable dispersions of copper nanoparticles with an average diameter of 80 nm were synthesized using a straightforward and cost-effective method in the presence of polyvinylpyrrolidone (PVP) as a stabilizer and without any inert gas protection. Sodium hypophosphite was used as the reducing agent in low pH value aqueous medium. The copper nanoparticles were characterized by ultraviolet-visible spectroscopy and scanning electron microscopy. The mechanism of the PVP on the stabilization of copper nanoparticles is also discussed.

Preparation of stable sub 10 nm copper nanopowders redispersible in polar and non-polar solvents

“…Use of two protective ligands seems to be beneficial for forming small stable particles [24]. We also used similar strategy, but a pair of polymers, PVP-PEG has been used instead of polymer-surfactant pair to obtain small stable particles at a copper salt concentration of 0.02 M. The concentrations of polymers were maintained at the same level as reported by other investigators [26][27][28].…”

Cu nanoparticles: synthesis, crystallographic characterization, and stability

“…In order to prepare a stable prefect transparent copper sols, CTABr and NaOH were introduced into the reaction mixture. Interestingly, an initial precursor solution with light blue color changed to wine red colloidal slurry, indicating the formation of metallic Cu nanoparticles without any inert gas protection [5]. The resulting color was stable for several months under our experimental conditions.…”

“…The intensities of the two peaks, 425 and 590 nm, increased with time and reached steady state after about 1 h. As can be seen, the new nanoparticles were not formed after the first 60 min of the reaction; absorbance remained nearly constant for each variation, indicating that the nucleation might be finished. The first absorption peaks of different curves were all at around 305 nm corresponding to the oxidation product of ascorbic acid, i.e., dehydroascorbic acid [5]. The second broad weak band might be due to the hydrolysis of copper hydrosols.…”

“…have been the interest of various researchers owing their wide applications (biological devices, catalysis, electronics, lubricants, mechanical, optical, sensors, and thermal transfer nanofluids) in bionanotechnology, nanotechnology, and nanotoxicology [1][2][3][4][5]. The colloidal solutions of noble metals (silver, gold, and copper) strongly absorb light in the visible region due to surface plasma resonance [6].…”

“…Due to the tendency of copper to rapidly oxidize (low redox potential of couple CuO/Cu 2+ =0.34 V and oxidation of the nanoparticles at ambient conditions), the synthesis of stable copper nanoparticles having desired and controlled morphology has become very difficult [10]. Generally, ascorbic acid [11], ethylene glycol [12], hydrazine [13], sodium borohydride [14], and sodium hypophosphite [5] were used for the synthesis of copper nanoparticles in absence and presence of stabilizers such as surfactants and polymers. Hydrothermal method has been reported by Zhang and his coworkers for the synthesis of copper nanorods using ascorbic acid and poly(vinylpyrrolidone) as a reducing and stabilizing agents, respectively, at 120°C for 4 h [15].…”