Ultrafast Room-Temperature Synthesis of Phosphate-Intercalated NiFe Layered Double Hydroxides for High-Performance...

Quick and easy synthetic methods and highly efficient catalytic performance are equally important to anodic oxygen evolution reaction (OER) electrocatalysts for alkaline seawater electrolysis. Herein, we report a facile one-step route to in situ growing PO₄^3- intercalated NiFe layered double hydroxides (NiFe-LDH) on Ni foam (denoted as NiFe-P/NF) by a room-temperature immersion for several minutes. This ultrafast approach transforms the NF surface into a rough PO₄^3- intercalated NiFe-LDH overlayer, which demonstrates outstanding OER performance in both alkaline simulated and natural seawaters owing to good hydrophilic interface and the electrostatic repulsion of PO₄^3- against Cl^- anions. Density functional theory calculations reveal that the intercalated PO₄^3- can not only promote electron transfer but also prevent Cl^- from entering the interlayer and simultaneously inhibit the migration of Cl^- over the NiFe-LDH surface. In alkaline simulated and natural seawater electrolytes, NiFe-P/NF needs low overpotentials of 248 and 298 mV to achieve a current density of 100 mA cm^-2, respectively. NiFe-P/NF can stably run over 42 h in an alkaline high-salty electrolyte (1 M KOH + 2.5 M NaCl) at 250 mA cm^-2, more than 70 times that of NiFe/NF (0.6 h), emphasizing the critical role of the intercalated PO₄^3- anions on the excellent durability. This study offers a new strategy to modify commercial NF to prepare efficient and stable OER catalysts for seawater electrolysis.