title: Exceptionally Active and Stable Spinel Nickel Manganese Oxide Electrocatalysts for Urea Oxidation Reaction.
abstract: Spinel nickel manganese oxides, widely used materials in the lithium ion battery high voltage cathode, were studied in urea oxidation catalysis. NiMn2O4, Ni1.5Mn1.5O4, and MnNi2O4 were synthesized by a simple template-free hydrothermal route followed by a thermal treatment in air at 800 °C. Rietveld analysis performed on nonstoichiometric nickel manganese oxide-Ni1.5Mn1.5O4 revealed the presence of three mixed phases: two spinel phases with different lattice parameters and NiO unlike the other two spinels NiMn2O4 and MnNi2O4. The electroactivity of nickel manganese oxide materials toward the oxidation of urea in alkaline solution is evaluated using cyclic voltammetric measurements. Ni1.5Mn1.5O4 exhibits excellent redox characteristics and lower charge transfer resistances in comparison with other compositions of nickel manganese oxides and nickel oxide prepared under similar conditions.The Ni1.5Mn1.5O4modified electrode oxidizes urea at 0.29 V versus Ag/AgCl with a corresponding current density of 6.9 mA cm(-2). At a low catalyst loading of 50 μg cm(-2), the urea oxidation current density of Ni1.5Mn1.5O4 in alkaline solution is 7 times higher than that of nickel oxide and 4 times higher than that of NiMn2O4 and MnNi2O4, respectively.
authors.affiliation: Department of Chemistry, Bar-Ilan Institute of Nanotechnology and Advanced Materials (BINA), Bar-Ilan University , Ramat-Gan 52900, Israel.
authors.forename: Sivakumar
authors.initials: S
authors.lastname: Periyasamy
authors.affiliation: Department of Biological Chemistry, Ariel University , Ariel 40700, Israel.
authors.forename: Palaniappan
authors.initials: P
authors.lastname: Subramanian
authors.affiliation: Department of Chemistry, Bar-Ilan Institute of Nanotechnology and Advanced Materials (BINA), Bar-Ilan University , Ramat-Gan 52900, Israel.
authors.forename: Elena
authors.initials: E
authors.lastname: Levi
authors.affiliation: Department of Chemistry, Bar-Ilan Institute of Nanotechnology and Advanced Materials (BINA), Bar-Ilan University , Ramat-Gan 52900, Israel.
authors.forename: Doron
authors.initials: D
authors.lastname: Aurbach
authors.affiliation: Department of Chemistry, Bar-Ilan Institute of Nanotechnology and Advanced Materials (BINA), Bar-Ilan University , Ramat-Gan 52900, Israel.
authors.forename: Aharon
authors.initials: A
authors.lastname: Gedanken
authors.affiliation: Department of Biological Chemistry, Ariel University , Ariel 40700, Israel.
authors.forename: Alex
authors.initials: A
authors.lastname: Schechter
keywords: cyclic voltammetry; electrochemical impedance spectroscopy; hydrothermal synthesis; nickel manganese oxide; urea oxidation