Superhydrophilicity boron-doped cobalt phosphide nanosheets decorated carbon nanotube arrays self-supported electrode for overall water splitting

Ruiqi Guo; Jialun Shi; Kaiwen Ma; Wenxiang Zhu; Haiwei Yang; Minqi Sheng

doi:10.1016/j.jcis.2023.07.176

Superhydrophilicity boron-doped cobalt phosphide nanosheets decorated carbon nanotube arrays self-supported electrode for overall water splitting

J Colloid Interface Sci. 2023 Dec:651:172-181. doi: 10.1016/j.jcis.2023.07.176. Epub 2023 Jul 28.

Authors

Ruiqi Guo¹, Jialun Shi¹, Kaiwen Ma¹, Wenxiang Zhu², Haiwei Yang², Minqi Sheng³

Affiliations

¹ School of Iron and Steel, Soochow University, 215137 Suzhou, China.
² Institue of Functional Nano & Soft Materials (FUNSOM), Soochow University, 215123 Suzhou, China.
³ School of Iron and Steel, Soochow University, 215137 Suzhou, China; State Key Laboratory of Advanced Special Steel, Shanghai Key Laboratory of Advanced Ferrometallurgy, Shanghai University, 200072 Shanghai, China. Electronic address: shengminqi@suda.edu.cn.

PMID: 37542892
DOI: 10.1016/j.jcis.2023.07.176

Abstract

Transition metal borides (TMBs) or phosphides (TMPs) have attracted great attention to the design of bifunctional electrocatalysts for energy storage. The superaerophobicity and superhydrophilicity of the catalytic electrode surface are crucial factors to determine the reaction process of the gas electrode. Herein, we report a self-supported electrode of carbon nanotube (CNTs) array grown on carbon cloth (CC) modulated together by boron-doped cobalt phosphide (CoP-B/CNTs/CC). The electrode requires the overpotential of 73.8 mV and 189.5 mV at the current density of ±10 mA cm^-2 for hydrogen and oxygen evolution reactions in an alkaline electrolyte (1.0 M KOH), respectively, meanwhile maintaining outstanding long-term durability for more than 300 h. The excellent activity of CoP-B/CNTs/CC is attributed to boron doping regulating its electronic structure and further enriching active sites. The attractive stability of CoP-B/CNTs/CC is due to the unique geometric structure of the self-supported electrode. Furthermore, the superaerophobicity and superhydrophilicity of the electrode surface also accelerate the reaction process of the gas electrode. Expectedly, water splitting cells assembled using CoP-B/CNTs/CC electrodes as cathode and anode, respectively, require a cell voltage of 1.54 V at 10 mA cm^-2, which is lower than that of the Pt/C/CC||RuO₂/CC couple (1.69 V at 10 mA cm^-2). Importantly, CoP-B/CNTs/CC||CoP-B/CNTs/CC achieve stable cell voltage under the step current changes (10 mA cm^-2, 50 mA cm^-2, and 100 mA cm^-2) over 300 h. This work highlights a new path to understanding the effects of the static and dynamic behavior of bubbles on the surface of self-supporting electrodes on catalytic performance.

Keywords: Boron-doped cobalt phosphide; Bubble escape behavior; Carbon nanotube; Electrocatalytic water splitting; Self-supported electrode.