Spin-state regulation of high-entropy Ruddlesden-Popper perovskite oxides for efficient seawater electrolysis

High-entropy oxides have emerged as a promising group of candidates for various catalytic fields, including seawater electrolysis. However, without rational understanding and guidance, designing multielement compositions for high-entropy systems and elucidating the synergistic effect of diverse elements in catalysis remain significant challenges. Herein, we report spin-state regulation of a high-entropy Ruddlesden-Popper perovskite oxide for efficient seawater electrolysis. The Cu²⁺ and Mn³⁺ with Jahn-Teller effect induced a transition of Fe³⁺/Co³⁺ spin state from low spin to high spin configuration. The high spin Fe³⁺/Co³⁺ favor OH^- adsorption and deprotonation during seawater oxidation. Besides, the oxygen intermediates adsorbed on high spin active sites repel the Cl^- ions. Consequently, (La_0.76Sr_0.24)₃(Fe_0.22Co_0.21Ni_0.18Cu_0.17Mn_0.22)₂O₇ achieved robust seawater oxidation for over 1200 h at 200 mA cm^-2, showing competitive performance. The anion exchange membrane electrolyzer coupling with (La_0.76Sr_0.24)₃(Fe_0.22Co_0.21Ni_0.18Cu_0.17Mn_0.22)₂O₇ anode and Pt/C cathode could maintain the seawater splitting performance of 1 A cm^-2 at 1.76 V and incessantly operate for 800 h. This spin-engineered strategy is universal to other high-entropy perovskite oxides and spinel oxides, offering promising way for designing efficient high-entropy catalysts.