title: Facile synthesis of mesoporous spinel NiCo₂O₄ nanostructures as highly efficient electrocatalysts for urea electro-oxidation.
abstract: Mesoporous spinel nickel cobaltite (NiCo2O4) nanostructures were synthesized via a facile chemical deposition method coupled with a simple post-annealing process. The physicochemical properties were characterized via X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectra (XPS) and nitrogen sorption measurements. The electrocatalytic performances were investigated by cyclic voltammetry (CV), chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS) tests. The obtained NiCo₂O₄ materials exhibit typical agglomerate mesoporous nanostructures with a large surface area (190.1 m(2) g(-1)) and high mesopore volume (0.943 cm(3) g(-1)). Remarkably, the NiCo₂O₄ shows much higher catalytic activity, lower overpotential, better stability and greater tolerance towards urea electro-oxidation compared to those of cobalt oxide (Co₃O₄) synthesized by the same procedure. The NiCo₂O₄ electrode delivers a current density of 136 mA cm(-2) mg(-1) at 0.7 V (vs. Hg/HgO) in 1 M KOH and 0.33 M urea electrolytes accompanied with a desirable stability. The impressive electrocatalytic activity is largely ascribed to the high intrinsic electronic conductivity, superior mesoporous nanostructures and rich surface Ni active species of the NiCo₂O₄ materials, which can largely boost the interfacial electroactive sites and charge transfer rates for urea electro-oxidation, indicating promising applications in future wastewater remediation, hydrogen production and fuel cells.
authors.affiliation: State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun 130022, China. dingrui@ciac.ac.cn hongyuwang@ciac.ac.cn drm8122@163.com.
authors.forename: Rui
authors.initials: R
authors.lastname: Ding
authors.forename: Li
authors.initials: L
authors.lastname: Qi
authors.forename: Mingjun
authors.initials: M
authors.lastname: Jia
authors.forename: Hongyu
authors.initials: H
authors.lastname: Wang