Activating lattice oxygen based on energy band engineering in oxides for industrial water/saline oxidation

Abstract

The lattice-oxygen oxidation mechanism can bypass certain limitations in the adsorbate evolution mechanism to lower the energy barrier. Herein, we propose the regulation of energy band levels by introducing Fe and F-stabilized oxygen vacancies. A series of ex situ and in situ spectroscopy techniques combined with theoretical calculations revealed that such a strategy results in compressive strain and electron redistribution, which induces an upshift of the O 2p band and a downshift of the Ni 3d orbital, allowing lattice oxygen to be more likely to participate in the OER cycle, and reducing the reaction energy barrier. Consequently, the F-doped NiFe (oxy)hydroxide (F-NiFeO) exhibited high intrinsic OER activity, with a turnover frequency (TOF) of 3.86 s⁻¹ at 1.5 V vs. RHE, and its structure and performance remained stable for long periods of water/saline water oxidation at 1 A cm⁻². Furthermore, the F-NiFeO||Pt/C pair can reach 1 A cm⁻² at 1.71 V and operate stably for more than 140 h in an anion exchange membrane electrolyzer. Obviously, the current work provides a route for activating the lattice oxygen of metal oxide electrocatalysts, thereby having significant implications for large-scale hydrogen production.