Engineering oxygen nonbonding states in high entropy hydroxides for scalable water oxidation.

The lattice oxygen oxidation mechanism typically requires the removal of electrons from the metal-oxygen band, which may cause structural instability due to a decrease in the metal-oxygen bond order. To address this challenge, we introduce low-valence, non-catalytically active Na to construct oxygen non-bonding bands on high-entropy hydroxides, allowing electrons to be removed from the oxygen non-bonding band rather than the metal-oxygen bonds, thereby improving the stability of the catalyst. Na doped high-entropy layered double hydroxide (Na-HE LDH) with a low overpotential of 176 mV@10 mA cm⁻² under alkaline conditions. Furthermore, the Pt/C | |Na-HE LDH electrode pair operates continuously for 2000 h at ~500 mA cm⁻² in an anion-exchange membrane electrolyzer (30 wt% KOH, 60 °C). In-situ spectroscopic and density functional theory calculations identify that the introduction of Na facilitates the formation of oxygen non-bonding band thereby mitigating structural instability. This study offers a strategy for designing efficient and stable lattice oxygen catalysts and provides valuable insights for developing catalysts capable of withstanding the rigorous demands of industrial hydrogen production environments.