A Highly-Efficient Boron Interstitially Inserted Ru Anode Catalyst for Anion Exchange Membrane Fuel Cells.

Han, Pengyu; Yang, Xinyi; Wu, Liqing; Jia, Hongnan; Chen, Jingchao; Shi, Wenwen; Cheng, Gongzhen; Luo, Wei · Adv Mater · 2024

basic_science · Level V

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Abstract

Developing high-performance electrocatalysts for alkaline hydrogen oxidation reaction (HOR) is crucial for the commercialization of anion exchange membrane fuel cells (AEMFCs). Here, boron interstitially inserted ruthenium (B-Ru/C) is synthesized and used as an anode catalyst for AEMFC, achieving a peak power density of 1.37 W cm<sup>-2</sup> , close to the state-of-the-art commercial PtRu catalyst. Unexpectedly, instead of the monotonous decline of HOR kinetics with pH as generally believed, an inflection point behavior in the pH-dependent HOR kinetics on B-Ru/C is observed, showing an anomalous behavior that the HOR activity under alkaline electrolyte surpasses acidic electrolyte. Experimental results and density functional theory calculations reveal that the upshifted d-band center of Ru after the intervention of interstitial boron can lead to enhanced adsorption ability of OH and H<sub>2</sub> O, which together with the reduced energy barrier of water formation, contributes to the outstanding alkaline HOR performance with a mass activity of 1.716 mA µg<sub>PGM</sub> <sup>-1</sup> , which is 13.4-fold and 5.2-fold higher than that of Ru/C and commercial Pt/C, respectively.