Document Type

Journal Article

Publication Date

2022

Keywords

urea oxidation reaction (UOR), Solid–liquid Interfaces, Operando Raman spectroscopy, Surface adsorption energy

DOI

https://doi.org/10.1016/j.jcis.2022.03.152

Abstract

Urea oxidation reaction (UOR) has been widely considered as an alternative anodic reaction to water oxidation for the green production of hydrogen fuel. Due to the high catalytic activity of transition metal oxides towards UOR, various strategies have been developed to improve their syntheses and catalytic properties. However, little is known about the underlying mechanisms of UOR on catalyst surface. In this work, three transition metal oxides, including NiO, Co3O4, and Fe2O3 are investigated as model catalysts. Through analyzing the electrochemical properties by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and operando Raman spectroscopy, it is revealed that NiO has a unique high catalytic activity towards UOR due to simultaneous formation of a thin layer of oxyhydroxide species above 1.40 V vs. RHE in alkaline media. In addition, density functional theory (DFT) calculations further suggest that the adsorption of urea molecules is largely affected by surface interactions resulting in different space configurations, which impose large influences on the consecutive deprotonation and NN formation processes. Overall, results of this work point to the subtle adsorption − kinetics relationship in UOR and highlight the importance of the interfacial electronic interactions on catalyst surface.

Source Publication

Journal of Colloid and Interface Science

Volume Number

620

First Page

442

Last Page

453

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