High entropy engineering promoted active sites in layered double hydroxide for seawater oxygen evolution reaction

Efficient oxygen-evolving electrodes that can operate under high-current-density alkaline water/seawater electrolysis are essential for practical hydrogen production, yet the simultaneous achievement of high activity, chloride tolerance, and long-term durability remains difficult for non-precious-metal catalysts. In this work, a binder-free high-entropy layered double hydroxide electrode has been successfully constructed by directly growing multimetal LDH nanosheets on nickel foam through a facile one-step hydrothermal process. The optimized quinary LDH, composed of five non-noble transition metals, namely Fe, Ni, Co, Zn, and Cr, is denoted as CoNiFeZnCr LDH@NF. Benefiting from the high-entropy multimetal coordination environment, this electrode exhibits superior OER performance compared with the corresponding binary, ternary, and quaternary LDH counterparts. In alkaline seawater, CoNiFeZnCr LDH@NF requires a low OER overpotential of 250 mV to reach 100 mA cm −2 and shows a Tafel slope of 66.93 mV dec −1 . The electrode also maintains stable operation for 200 h at 100 mA cm −2 , indicating strong resistance to seawater-induced degradation. Density functional theory calculations further reveal that the quinary high-entropy configuration optimizes the adsorption behavior of *O intermediates and lowers the energy barrier of the rate-determining OER step. The improved activity and durability are therefore attributed to the synergistic electronic and structural effects arising from the incorporation of Fe, Ni, Co, Zn, and Cr into the LDH framework. This study demonstrates a practical high-entropy engineering strategy for developing robust non-precious-metal OER electrodes toward seawater-relevant hydrogen production.