Toward High Corrosion Resistivity and High Efficiency in Seawater Oxygen Evolution: The Synergy of Fe and Ni Dopants in Co Layered Double Hydroxide Ultrathin Nanosheets

The development of efficient, robust, and cheap electrocatalysts for the seawater oxygen evolution reaction (OER) is of great significance but still faces huge challenges. Herein, Fe and Ni synergistically substituted Co layered double hydroxide (LDH) ultrathin nanosheets (Co0.24Ni0.50Fe0.26 LDH, 1.2 nm thickness) have been rationally designed and successfully prepared by the etching and precipitation method. The electronic structure of CoxNiyFez LDH could be regulated by both Fe/Co/Ni cations and sulfate anions. The as-obtained Co0.24Ni0.50Fe0.26 LDH exhibits significant OER activity and stability in alkaline simulated seawater, requiring overpotentials of only 214 and 265 mV to drive current densities of 10 and 100 mA cm–2, respectively, along with a small Tafel slope of 53.34 mV dec–1. The as-optimized Co0.24Ni0.50Fe0.26 LDH catalyst with rationally selected cations (Fe2+ or Ni2+) and intercalated anions (SO42–) could be continuously stable for 72 h at an ultrahigh current density of 500 mA cm–2, suggesting its strong corrosion resistance. Theoretical calculations indicate that the LDH catalyst with Fe/Co/Ni ternary elements can optimize the adsorption capacity of *O intermediates, ultimately reducing the energy barrier of the rate-determining step of the OER. The excellent activity and stability could be attributed to the synergistic effect of Fe/Co/Ni, more catalytic sites of ultrathin nanosheets, and chlorine repulsion of intercalated polysulfate anions. The present study provides a novel strategy to design robust OER electrocatalysts for industrial seawater electrolysis.