Urea electro-oxidation efficiently catalyzed by nickel-molybdenum oxide nanorods

• Published in: Electrochimica acta Vol. 295; pp. 524 - 531
• Main Authors: Yang, Dawen, Yang, Liting, Zhong, Lei, Yu, Xu, Feng, Ligang
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.02.2019; Elsevier BV
• Subjects: Catalysis; Catalysts; Charge transfer; Chemical reactions; Crystal structure; Electro-catalysis; Electrochemical impedance spectroscopy; Electrochemical oxidation; Energy storage; Molybdates; Molybdenum; Molybdenum oxides; Morphology; Nanorods; Nickel compounds; Nickel-molybdenum oxide; Organic chemistry; Oxidation; Photoelectrons; Precursors; Reaction kinetics; Reaction mechanisms; Spectrum analysis; Urea oxidation; Ureas; Wastewater treatment; X-ray diffraction; Urea oxidation; Catalysts; Electro-catalysis; Nickel-molybdenum oxide
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2018.10.190

Electrochemical oxidation of urea plays a significant role in electrochemical removal urea in the waste-water and energy conversation and storage. Here we demonstrated that nickel-molybdenum oxide nanorods were efficient catalysts for urea electro-oxidation. Nickel-molybdenum oxide nanorods were prepared with various Ni/Mo molar ratios in the precursors and the crystal structure, morphology and surface elements compositions of the nickel-molybdenum oxide nanorods were characterized by X-ray diffraction, Raman spectrum, scanning electron microscope, transmission electron microscope and X-ray photoelectron spectroscopy. The catalytic performance of urea oxidation and kinetics analysis were measured by cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy; the process of urea catalyzed by nickel-molybdenum oxide was proposed to follow an electrochemical-chemical reaction mechanism in which urea oxidation happened accompanying the redox of NiOOH/Ni(OH)2 at high potentials. The catalytic ability for urea oxidation was varied by changing the ratio of Ni/Mo in the precursors, and the rapid kinetics, small charge transfer resistance and low Tafel slope consistently supported NiMoO4-C (Ni/Mo = 2) materials as the best catalyst for urea electro-oxidation. The desirable electrocatalytic activity, stability and tolerance towards urea oxidation indicated its promising applications in sustainable energy techniques and alleviating water contamination. •Nickel-molybdenum oxide nanorods are efficient catalysts for urea electro-oxidation.•Catalytic ability is varied by changing Ni/Mo ratio in the precursors.•NiMoO4-2-C (Ni/Mo = 2) is best for urea electro-oxidation.•Redox of NiOOH/Ni(OH)2 is significant to urea electro-oxidation.