A “doping–interfacing” strategy enables efficient alkaline freshwater and seawater oxidation by NiFe-layered double hydroxides

Seawater electrolysis is a promising approach to large-scale hydrogen production, offering a sustainable path toward a greener energy landscape, yet requires a highly active, stable, and selective electrocatalyst. We present the modification of NiFe-LDH by Li-ion doping and hybridization with g-C₃N₄ and demonstrate enhanced catalytic activity and selectivity toward oxygen evolution reaction (OER). Li-ion doping increases surficial Ni³⁺ sites and oxygen defects, facilitating the formation of a built-in electric field at the interface with g-C₃N₄ and preferential absorption of OH⁻. The Li-doped NiFe-LDH/g-C₃N₄ achieves a current density of 100 mA cm⁻² at low overpotentials of 276 and 319 mV in 1 M KOH and 1 M KOH seawater, respectively, with high OER selectivity (Faradaic efficiency = 96.7 %) and durability (100 h at 200 mA cm⁻²). This work demonstrates the effective combination of alkaline cation doping and heterointerface for designing low-cost, stable, and efficient catalysts with good selectivity for seawater electrolysis.