Se-Assisted Modulation of Electronic Structure of Ruthenium Phosphide Nanotubes for Efficient Alkaline Hydrogen Evolution Reaction.

Abstract

Anion-exchange membrane water electrolysis (AEMWE) holds immense promise for hydrogen (H₂) production yet faces challenges due to the sluggish kinetics of the hydrogen evolution reaction (HER). Highly efficient and durable catalysts for HER are crucial for the successful implementation of AEMWE to produce hydrogen gas reliably. Ruthenium phosphides (Ru _x P) have emerged as promising non-Pt catalysts for alkaline HER; however, they suffer from rapid degradation due to weak Ru-P bonding, which cannot protect the Ru center from further oxidation and subsequent dissolution. Herein, first-principles calculations indicate the enhanced stability of Ru-Se against oxidation compared to Ru-P, highlighting the importance of introducing Se into the Ru₂P phase. Electrochemical studies using the selenium (Se)-doped Ru₂P double-walled nanotubes (Ru₂(P_0.9Se_0.1) DWNTs) demonstrate significantly lower overpotentials (29 mV @ 10 mA cm^-2) and robust stability (>50 h) in 1.0 m KOH, surpassing those of Pt/C. In AEMWE, Ru₂(P_0.9Se_0.1) DWNTs exhibit an outstanding performance (10.31 A cm^-2 @ 80 °C, stable @ 1.0 A cm^-2 for ≈200 h), surpassing state-of-the-art catalysts. The findings of this study highlight the pivotal role of anion modification in enhancing the catalytic stability and performance for efficient hydrogen production in AEMWE systems.