Investigation of the electrocatalytic mechanisms of urea oxidation reaction on the surface of transition metal oxides

Jianhua Ge; Zhongfei Liu; Minghui Guan; Juner Kuang; Yuhua Xiao; Yang Yang; Chi Him Tsang; Xiaoying Lu; Chunzhen Yang

doi:10.1016/j.jcis.2022.03.152

Investigation of the electrocatalytic mechanisms of urea oxidation reaction on the surface of transition metal oxides

J Colloid Interface Sci. 2022 Aug 15:620:442-453. doi: 10.1016/j.jcis.2022.03.152. Epub 2022 Apr 2.

Authors

Jianhua Ge¹, Zhongfei Liu¹, Minghui Guan¹, Juner Kuang¹, Yuhua Xiao¹, Yang Yang¹, Chi Him Tsang², Xiaoying Lu³, Chunzhen Yang⁴

Affiliations

¹ School of Materials, Sun Yat-Sen University, Guangzhou 510275, PR China.
² Faculty of Science and Technology, Technological and Higher Education Institute of Hong Kong, Hong Kong, PR China.
³ Faculty of Science and Technology, Technological and Higher Education Institute of Hong Kong, Hong Kong, PR China. Electronic address: xylu@thei.edu.hk.
⁴ School of Materials, Sun Yat-Sen University, Guangzhou 510275, PR China. Electronic address: yangchzh6@mail.sysu.edu.cn.

PMID: 35439695
DOI: 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.

Keywords: Operando Raman spectroscopy; Solid–liquid Interfaces; Surface adsorption energy; urea oxidation reaction (UOR).