In situ oxidation of carbon support stabilizes ultrafine NiFe-LDH for industrial alkaline seawater electrolysis

Alkaline seawater oxidation has attracted significant attention for hydrogen production via water splitting. However, the high concentration of Cl - and the corrosive intermediates from Cl - oxidation reaction pose serious challenges to the activity and durability of oxygen evolution reaction (OER) catalysts. Here, ultrafine NiFe-LDH supported on defect-rich graphite nanosheets is synthesized via a spatial confinement strategy. During the OER process, carbon defects of the graphite support undergo in situ oxidation to generate CO 3 2- species, which adsorb onto the ultrafine NiFe-LDH surface, forming an electrostatic repulsion network that effectively blocks Cl - access to active sites. Theoretical calculations further confirm that CO 3 2- adsorption modulates the electronic structure of catalytic active centers, enhancing their intrinsic activity. Consequently, the catalyst achieves a low overpotential of only 320 mV under a current density of 1 A cm −2 in simulated seawater and an outstanding selectivity with a Faradaic efficiency of 99.8 %. Under practical alkaline seawater, it maintains stable operation for over 1000 h at 0.5 A cm −2 . This work offers a promising route for designing high-performance and durable electrocatalysts for alkaline seawater electrolysis.