Multifunctional Electrochemical Properties of Synthesized Non-Precious Iron Oxide Nanostructures

Magnetic Fe3O4 nanostructures for electrochemical water splitting and supercapacitor applications were synthesized by low temperature simple wet-chemical route. The crystal structure and morphology of as-acquired nanostructures were examined by powder X-ray diffraction and transmission electron microscopy. Magnetic measurements indicate that the as-synthesized Fe3O4 nanostructures are ferromagnetic at room temperature. The synthesized nanostructures have a high-specific surface area of 268 m2/g, which affects the electrocatalytic activity of the electrode materials. The purity of the as-synthesized nanostructures was affirmed by Raman and X-ray Photoelectron studies. The electrochemical activity of the magnetic iron oxide nanoparticles (MIONPs) for the hydrogen evolution reaction (HER) and supercapacitors were investigated in alkaline medium (0.5 M KOH) versus Ag/AgCl at room temperature. The electrocatalysts show low onset potential (~0.18 V) and Tafel slope (~440 mV/dec) for HER. Additionally, the specific capacitance of MIONPs was investigated, which is to be ~135 ± 5 F/g at 5 mV/s in 1 M KOH

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

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 250 nm and 130 nm while the length is of the order of 2.5 μm and 480 nm, 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 100 μm, 120 μm and 300 nm, respectively, in diameter and 2.5 μm, 600 nm and 6.5 μm, 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 ~55 nm in diameter. Oxides with different morphology, Fe<SUB>3</SUB>O<SUB>4</SUB> nanoparticles faceted (cuboidal) and Fe<SUB>2</SUB>O<SUB>3</SUB> nanoparticles (spherical) could be obtained

Silver nanoparticles: large scale solvothermal synthesis and optical properties

Silver nanoparticles have been successfully synthesized by a simple and modified solvothermal method at large scale using ethanol as the refluxing solvent and NaBH<SUB>4</SUB> as reducing agent. The nanopowder was investigated by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), dynamic light scattering (DLS), UV-visible and BET surface area studies. XRD studies reveal the monophasic nature of these highly crystalline silver nanoparticles. Transmission electron microscopic studies show the monodisperse and highly uniform nanoparticles of silver of the particle size of 5 nm, however, the size is found to be 7 nm using dynamic light scattering which is in good agreement with the TEM and X-ray line broadening studies. The surface area was found to be 34.5 m<SUP>2</SUP>/g. UV-visible studies show the absorption band at ~425 nm due to surface plasmon resonance. The percentage yield of silver nanoparticles was found to be as high as 98.5%