Preparation of copper nanoparticles with low sintering temperature

This paper describes a simple and convenient method for the preparation of copper nanoparticles in aqueous solution at room temperature. The synthesis of copper nanoparticles from different types of copper salt was studied, with hydrazine and sodium hypophosphite as reducing reagent and lactic acid as capping agents. The stable copper nanoparticles with diameter less than 10 nm and a narrow size distribution were prepared with copper acetate as the precursor and hydrazine as reducing reagent. The obtained copper nanoparticles were capped by the carboxylic acids that can be completely removed at about 200°C. The copper nanoparticles were characterized by TEM, UV-Vis, SEM and XRD. Copper films were prepared from the copper nanoparticles by drop coating and sintered at 150 and 200°C for 60 min. in nitrogen.