Nanorods of transition metal oxalates: A versatile route to the oxide nanoparticles

Abstract

A versatile route has been explored for the synthesis of nanorods of transition metal (Cu, Ni, Mn, Zn, Co and Fe) oxalates using reverse micelles. Transmission electron microscopy shows that the as-prepared nanorods of nickel and copper oxalates have diameter of 250nm and 130nm while the length is of the order of 2.5μm and 480nm, respectively. The aspect ratio of the nanorods of copper oxalate could be modified by changing the solvent. The average dimensions of manganese, zinc and cobalt oxalate nanorods were 100μm, 120μm and 300nm, respectively, in diameter and 2.5μm, 600nm and 6.5μm, respectively, in length. The aspect ratio of the cobalt oxalate nanorods could be modified by controlling the temperature.The nanorods of metal (Cu, Ni, Mn, Zn, Co and Fe) oxalates were found to be suitable precursors to obtain a variety of transition metal oxide nanoparticles. Our studies show that the grain size of CuO nanoparticles is highly dependent on the nature of non-polar solvent used to initially synthesize the oxalate rods. All the commonly known manganese oxides could be obtained as pure phases from the single manganese oxalate precursor by decomposing in different atmospheres (air, vacuum or nitrogen). The ZnO nanoparticles obtained from zinc oxalate rods are ∼55nm in diameter. Oxides with different morphology, Fe3O4 nanoparticles faceted (cuboidal) and Fe2O3 nanoparticles (spherical) could be obtained.