Durable Ru Nanocrystal with HfO2 Modification for Acidic Overall Water Splitting

Xiangkai Kong; Jie Xu; Zhicheng Ju; Changle Chen

doi:10.1007/s40820-024-01384-7

Durable Ru Nanocrystal with HfO₂ Modification for Acidic Overall Water Splitting

Nanomicro Lett. 2024 Apr 30;16(1):185. doi: 10.1007/s40820-024-01384-7.

Authors

Xiangkai Kong^{1

2}, Jie Xu^{3

4}, Zhicheng Ju⁵, Changle Chen⁶

Affiliations

¹ School of Materials and Physics, China University of Mining and Technology, Xuzhou, 221116, Jiangsu, People's Republic of China. xkong@cumt.edu.cn.
² Anhui Province Key Laboratory of Pollutant Sensitive Materials and Environmental Remediation, Huaibei Normal University, Huaibei, 235000, Anhui, People's Republic of China. xkong@cumt.edu.cn.
³ Anhui Province Key Laboratory of Pollutant Sensitive Materials and Environmental Remediation, Huaibei Normal University, Huaibei, 235000, Anhui, People's Republic of China.
⁴ School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210023, Jiangsu, People's Republic of China.
⁵ School of Materials and Physics, China University of Mining and Technology, Xuzhou, 221116, Jiangsu, People's Republic of China. juzc@cumt.edu.cn.
⁶ School of Chemistry and Materials Science, University of Science and Technology of China, Hefei, 230026, Anhui, People's Republic of China. changle@ustc.edu.cn.

Abstract

Durable and efficient bi-functional catalyst, that is capable of both oxygen evolution reaction and hydrogen evolution reaction under acidic condition, are highly desired for the commercialization of proton exchange membrane water electrolysis. Herein, we report a robust L-Ru/HfO₂ heterostructure constructed via confining crystalline Ru nanodomains by HfO₂ matrix. When assembled with a proton exchange membrane, the bi-functional L-Ru/HfO₂ catalyst-based electrolyzer presents a voltage of 1.57 and 1.67 V to reach 100 and 300 mA cm^-2 current density, prevailing most of previously reported Ru-based materials as well as commercial Pt/C||RuO₂ electrolyzer. It is revealed that the synergistic effect of HfO₂ modification and small crystalline domain formation significantly alleviates the over-oxidation of Ru. More importantly, this synergistic effect facilitates a dual-site oxide path during the oxygen evolution procedure via optimization of the binding configurations of oxygenated adsorbates. As a result, the Ru active sites maintain the metallic state along with reduced energy barrier for the rate-determining step (*O→*OOH). Both of water adsorption and dissociation (Volmer step) are strengthened, while a moderate hydrogen binding is achieved to accelerate the hydrogen desorption procedure (Tafel step). Consequently, the activity and stability of acidic overall water splitting are simultaneously enhanced.

Keywords: Anti-oxidation; Hafnium dioxide; Oxygen evolution catalysis; Ruthenium.