title: Synthesis of highly stable, water-dispersible copper nanoparticles as catalysts for nitrobenzene reduction.
abstract: We report an aqueous-phase synthetic route to copper nanoparticles (CuNPs) using a copper-surfactant complex and tests of their catalytic efficiency for a simple nitrophenol reduction reaction under atmospheric conditions. Highly stable, water-dispersed CuNPs were obtained with the aid of polyacrylic acid (PAA), but not with other dispersants like surfactants or polymethacrylic acid (PMAA). The diameter of the CuNPs could be controlled in the range of approximately 30-85 nm by modifying the ratio of the metal precursor to PAA. The catalytic reduction of p-nitrophenol to p-aminophenol takes place at the surface of CuNPs at room temperature and was accurately monitored by UV/Vis spectroscopy. The catalytic efficiency was found to be remarkably high for these PAA-capped CuNPs, given the fact that at the same time PAA is efficiently preventing their oxidation as well. The activity was found to increase as the size of the CuNPs decreased. It can therefore be concluded that the synthesized CuNPs are catalytically highly efficient in spite of the presence of a protective PAA coating, which provides them with a long shelf life and thereby enhances the application potential of these CuNPs.
authors.affiliation: Department of Chemistry and Centre for Advanced Studies in Chemistry, Panjab University, Chandigarh-160014 (India), Fax: (+91) 172-2545074; Stranski-Laboratorium für Physikalische und Theoretische Chemie, Institut für Chemie, Technische Universität Berlin, Strasse des 17. Juni 124, Sekr. TC7, 10623 Berlin (Germany), Fax: (+49) 30-314-26602.
authors.forename: Ravneet
authors.initials: R
authors.lastname: Kaur
authors.forename: Cristina
authors.initials: C
authors.lastname: Giordano
authors.forename: Michael
authors.initials: M
authors.lastname: Gradzielski
authors.forename: Surinder K
authors.initials: SK
authors.lastname: Mehta
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry; D000627:Aminophenols / Q000138:chemical synthesis* / Q000737:chemistry; D002384:Catalysis; D003300:Copper / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry*; D015394:Molecular Structure; D009596:Nitrophenols / Q000737:chemistry*; D010084:Oxidation-Reduction; D010316:Particle Size; D013499:Surface Properties; D014867:Water / Q000737:chemistry
chemical_list: D000180:Acrylic Resins; D000627:Aminophenols; D009596:Nitrophenols; D014867:Water; C006903:carbopol 940; D003300:Copper; C026729:4-aminophenol; C024836:4-nitrophenol
keywords: catalysis; copper; nanoparticles; reduction; surfactants