Synthesis and characterization of metal oxide nanoparticles

Abstract

Nanoparticles of CuO, Co3O4 and Mn5O8 were prepared via sol-gel chemical routes. Thermal treatments of the gels were used to obtain particles of different sizes, as determined by the widths of the Bragg lines in x-ray diffraction. To prepare CuO nanoparticles, a Cu(OH)2 gel was first produced by reacting copper nitrate with sodium hydroxide, followed by annealing the gel at temperatures between 160 degrees C to 1,000 degrees C to produce particles in the 6 to 36 nm range. Nanoparticles of Co3O4 in the size range of 9 to 45 nm were prepared in an analogous manner by reacting cobalt nitrate and sodium hydroxide. Similar procedures to produce nanoparticles of MnO resulted only in the synthesis of Mn3O4. Annealing Mn3O4 at 400 degrees C for three hours produced nanoscale Mn5O8 (14nm), a difficult-to-prepare oxide. Using an electrochemical route, 30nm particles of NiO were also synthesized. Thermogravimetric measurements were used to identify the thermally-induced phase transformations and x-ray diffraction was used to identify the phases and determine the average particle sizes of the phases.