Issue 17, 2017

MnO2/MnCo2O4/Ni heterostructure with quadruple hierarchy: a bifunctional electrode architecture for overall urea oxidation

Abstract

A three-dimensional MnO2/MnCo2O4/Ni core–shell heterostructured electrode has been fabricated through a facile method. This electrode architecture consists of four levels of interconnected hierarchy: a primary macroporous Ni foam scaffold (≥500 μm), an intermediate vertically-aligned MnCo2O4 core-nanoflake array (50–100 nm), topmost ultra-thin MnO2 nanosheets (∼10 nm) and short-range ordered mesopores (∼5 nm) on the MnO2 nanosheets. This freestanding, hierarchical porous electrode has advantages in enhancing electroactive surface area, enabling efficient mass transport through the porous structure. The heterostructured electrode exhibits a low onset potential (1.33 V vs. RHE), a high anodic peak current density (1000 mA cm−2 g−1 at 1.7 V vs. RHE) and long-term catalytic stability for urea oxidation, which surpasses previous reported electrode materials for urea electrolysis. Remarkably, the MnO2/MnCo2O4/Ni electrode possesses bifunctional catalytic activity for both urea oxidation and hydrogen evolution. A urea electrolytic cell with both anode and cathode using the heterostructured electrodes has been fabricated and a current density of 10 mA cm−2 has been achieved at a cell voltage of 1.55 V. This noble metal-free quadruple hierarchy electrode shows potential as a new platform for multi-purpose applications.

Graphical abstract: MnO2/MnCo2O4/Ni heterostructure with quadruple hierarchy: a bifunctional electrode architecture for overall urea oxidation

Supplementary files

Article information

Article type
Paper
Submitted
31 Jan 2017
Accepted
01 Mar 2017
First published
02 Mar 2017

J. Mater. Chem. A, 2017,5, 7825-7832

MnO2/MnCo2O4/Ni heterostructure with quadruple hierarchy: a bifunctional electrode architecture for overall urea oxidation

C. Xiao, S. Li, X. Zhang and D. R. MacFarlane, J. Mater. Chem. A, 2017, 5, 7825 DOI: 10.1039/C7TA00980A

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