Turing-type high-entropy oxide nanosheets for efficient seawater electrolysis

Owing to the merit of twin boundaries, Turing-type nanostructures have received increasing attention in electrocatalysis. Integrating high-entropy design holds great promise for further improved activities due to compositional flexibility and high-entropy effects. Here, Turing-type high-entropy oxide nanosheets of spinel (Co_0.19Mn_0.21Cu_0.20Ni_0.20Zn_0.20)₃O₄ are designed for seawater electrolysis. The high density of twin boundaries causes severe distortion and compressive strain. The compressive strain weakened metal-ligand interaction and induced a spin transition of active cobalt(III) ion from low-spin (LS) to high-spin (HS) configuration, which favors hydroxide ion adsorption, deprotonation, and strong repulsion toward chloride ions during seawater oxidation. Consequently, the optimized Turing HEO-300 achieves an overpotential of 340 millivolts at 100 milliampere per square centimeter for over 350 hours, outperforming the Turing-type low-entropy oxides, non-Turing high-entropy oxides, and most of reported oxide-based catalysts. Moreover, a seawater electrolyzer with Turing HEO-300 anode maintains 1 ampere per square centimeter at 1.80 volts for over 100 hours. This work paves the way for designing Turing-type high-entropy catalysts.