Superhydrophilic Porous CoOOH Nano-Architecture with Abundant Oxygen Vacancies for Enhanced Urea Electrooxidation at Ampere-Level Current Densities

Abstract

The conversion of urea-containing wastewater into clean hydrogen energy has gained increasing attention. However, challenges remain, particularly with sluggish catalytic kinetics and limited long-term stability of urea oxidation reaction (UOR). Herein, we report the loosely porous CoOOH nano-architecture (CoOOH LPNAs) with hydrophilic surface and abundant oxygen vacancies (O_v) on carbon fiber paper (CFP) by electrochemical reconstruction of the CoP nanoneedles precursor. The resulting three-dimensional electrode exhibited an impressively low potential of 1.38 V at 1000 mA·cm⁻² and excellent durability for UOR. Furthermore, when tested in an anion exchange membrane (AEM) electrolyzer, it required only 1.53 V at 1000 mA·cm⁻² for industrial urea-assisted water splitting and operated stably for 100 h without degradation. Experimental and theoretical investigations revealed that rich oxygen vacancies effectively modulate the electronic structure of the CoOOH while creating unique Co₃-triangle sites with Co atoms close together. As a result, the adsorption and desorption processes of reactants and intermediates in UOR could be finely tuned, thereby significantly reducing thermodynamic barriers. Additionally, the superhydrophilic self-supported nanoarray structure facilitated rapid gas bubble release, improving the overall efficiency of the reaction and preventing potential catalyst detachment caused by bubble accumulation, thereby improving both catalytic activity and stability at high current densities.

Keywords

CoOOH / Electrochemical reconstruction / Oxygen vacancy / Superhydrophilic surface / Urea electrooxidation

Supporting Information

Supporting information for this article is available at https://jelectrochem.xmu.edu.cn/journal/.

Acknowledgements

This work was supported by the Applied Basic Research Program of Yunnan Province (202101BE070001-032), Yunnan Major Scientific and Technological Projects (No. 202202AG050001), Analysis and Testing Foundation of Kunming University of Science and Technology.

Conflicts of Interest

The authors declare no conflict of interest.

Data Availability

Data will be made available on request.

Author contributions

Wen-Jing Lv: Conceptualization (Equal), Data curation (Lead), Formal analysis (Lead), Investigation (Lead), Methodology (Equal), Visualization (Equal), Writing - original draft (Lead); Xiao-Man Tang: Formal analysis (Equal), Investigation (Equal), Software (Lead), Validation (Lead), Visualization (Lead); Xue-Tong Wang: Data curation (Equal), Investigation (Supporting), Validation (Equal), Visualization (Supporting); Wen-Cai Liu: Investigation (Supporting), Validation (Equal), Visualization (Equal); Jian-Wen Zhu: Data curation (Supporting), Formal analysis (Equal), Softwar (Supporting); Guo-Jing Wang: Conceptualization (Lead), Methodology (Lead), Supervision (Equal), Writing - review & editing (Equal); Yuan-Zhi Zhu: Funding acquisition (Lead), Project administration (Lead), Supervision (Lead), Writing - review & editing (Equal)

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