Exceptionally Active and Stable Spinel Nickel Manganese Oxide Electrocatalysts for Urea Oxidation Reaction

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• 作者：Sivakumar Periyasamy ; Palaniappan Subramanian ; Elena Levi ; Doron Aurbach ; Aharon Gedanken ; Alex Schechter
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2016
• 出版时间：May 18, 2016
• 年：2016
• 卷：8
• 期：19
• 页码：12176-12185
• 全文大小：768K
• 年卷期：0
• ISSN：1944-8252

文摘

Spinel nickel manganese oxides, widely used materials in the lithium ion battery high voltage cathode, were studied in urea oxidation catalysis. NiMn₂O₄, Ni_1.5Mn_1.5O₄, 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-Ni_1.5Mn_1.5O₄ 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. Ni_1.5Mn_1.5O₄ 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 Ni_1.5Mn_1.5O₄modified 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 Ni_1.5Mn_1.5O₄ in alkaline solution is 7 times higher than that of nickel oxide and 4 times higher than that of NiMn₂O₄ and MnNi₂O₄, respectively.