Synthesis and characterization of Co-Ni colloids prepared in nonaqueous solvents

摘要

The synthesis of Co-Ni bimetallic colloids nanoparticles by the CLD method were obtained. The metals were melted and evaporated in a metal atom reactor and cocondensed with ethanol, 2-propanol and 2-methoxyethanol at 77 K. The colloids were characterized by transmission electron microscopy (TEM), ultraviolet spectroscopy (UV-VIS), EDX and electrophoresis. The stability at room temperature was also measured. The higher stability dispersion (> 40 days) was Co-Ni/ ethanol, Co-Ni/ 2-methoxyethanol and Co-Ni/ 2-propanol (< 10 days). The electrophoresis showed that particles are positively charged for the alcohols (62 mV for ethanol and 1.4x 10(-1) mV for 2-propanol) and 9.64 mV negatively charged for 2-methoxyethanol. The particles size of the bimetal colloids ranges from 5.7 to 9.8 nm. The active solids were obtained by solvent evaporation from the colloids dispersion. The microanalysis showed the presence of C, H between 5 to 13% which is indicative that the solvent is incorporated in the solid. The thermogravimetric analysis (TGA) reveals the thermal stability of the active solids. The Co-Ni/ ethanol and Co-Ni/ 2-propanol exhibit a weight loss of 20% w/w, while the Co-Ni/ 2- methoxyethanol shows a weight loss of 42% being the less stable solid. The FTIR of the active solids in KBr pellets exhibit the presence of the solvents incorporated in the active solid.