Defects trigger redox reactivities between metal and lattice oxygen in high-entropy layered double hydroxide for...

The oxygen evolution reaction (OER) at the anode undergoes a sluggish multi-step process, thereby impeding overall water splitting. As the classical adsorbate evolution mechanism (AEM) involves multiple oxygen-containing intermediates, such as *OH, *O and *OOH, breaking the linear relationship of the adsorption energies between *OH and *OOH is the key to efficient oxygen evolution. Herein, we report a high-entropy FeCoNiAlZn layered double hydroxide decorated with defects (E-FeCoNiAlZn LDH) for boosting oxygen evolution in alkaline. The product exhibits high OER activity with a low overpotential of 220 at 10 mA cm^-2 and outstanding stability with negligible decline after 100 h operation. The defects in E-FeCoNiAlZn LDH not only enhance the adsorption of *OH by metal sites but also foster the release of oxygen from lattice, which triggers the coupled oxygen evolution mechanism (COM). This mechanism has only *OH and *OO intermediates, perfectly avoiding the obstacles of linear relationship between *OH and *OOH. Theoretical calculations demonstrate that the introduction of defects enhances the adsorption of *OH due to the presence of unsaturated bonds. Additionally, it is evidence that the O 2p band is elevated, leading to a weakening of the metal-O bond and a reduction of the energy barrier for OO coupling.