Reviving Oxygen Evolution Electrocatalysis of Bulk La-Ni Intermetallics via Gaseous Hydrogen Engineering.

Herein a hydrogen processing strategy has been developed to enable bulk LaNi 5 to attain high activity and long-term stability towards electrocatalytic oxygen evolution reaction (OER). By a combination of in situ Raman and quasi in situ X-ray absorption (XAS) spectra, secondary electron-excited scanning transmission electron microscopic (STEM) patterns as well as the Rietveld method and density functional theory (DFT) calculations, it was discovered that hydrogen-induced lattice distortion, grain refinement, and particle cracks dictated the effective reconstruction of LaNi 5 surface into porous hetero-nanoarchitecture composed of uniformly confined active γ-NiOOH nanocrystals by La(OH) 3 layer in alkaline OER process. This significantly optimizes the charge transfer, structural integrity, active site exposure, and adsorption energy towards the reaction intermediates. Benefiting from these merits, the overpotential (322 mV) at 100 mA cm -2 for the hydrogen-processed OER catalyst deposited on nickel foam was reduced by 104 mV as compared to the original phase. Notably, it exhibited remarkable stability for 10 days at an industrial-grade current density of more than 560 mA cm -2 in alkaline media. This article is protected by copyright. All rights reserved.