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, (La0.76Sr0.24)3(Fe0.22Co0.21Ni0.18Cu0.17Mn0.22)2O7 achieved robust seawater oxidation for over 1200 h at 200 mA cm−2, showing competitive performance. The anion exchange membrane electrolyzer coupling with (La0.76Sr0.24)3(Fe0.22Co0.21Ni0.18Cu0.17Mn0.22)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. Designing efficient high entropy catalysts is highly desired but remains challenging. Here, the authors report the spin state engineering to develop high-entropy Ruddlesden Popper perovskite oxides for efficient seawater splitting, with the strategy applicable to other high entropy catalysts.