Self-activation-driven in-situ growth of nickel‑iron layered double hydroxides on vacancy-rich nanoporous Ni foam for high-efficiency oxygen evolution reaction

Nickel‑iron layered double hydroxides (NiFe-LDH) have been recognized as a promising oxygen evolution reaction (OER) electrode, but their practical fabrication is bottlenecked by harsh synthesis conditions and the poor scalability of existing strategies. Herein, we address these challenges via a room-temperature and scalable route to fabricate self-supported NiFe-LDH on nanoporous Ni foam (NPNF) by utilizing the intrinsic self-activation effect of NPNF in the hydrolysis reaction of NaBH₄. The NPNF is prepared through a gaseous oxidation-reduction approach for commercial Ni foam, serving as a highly active and scalable substrate for NiFe-LDH growth. The nanopores within the NPNF significantly increase the nucleation sites for NiFe-LDH. Furthermore, experimental characterizations combined with density functional theory calculations demonstrate that the high concentration of Ni vacancies of NPNF enhances the adsorption of H₂O and *BH₄, thereby accelerating the hydrolysis of NaBH₄. The localized microenvironment established by the rapid hydrolysis favors the in-situ nucleation and growth of NiFe-LDH. Consequently, the designed NiFe-LDH/NPNF electrode demonstrates exceptional OER performance, exhibiting a low overpotential of 270 mV at 100 mA cm⁻² and excellent durability of over 2200 h. Combined with its feasibility for large-area fabrication (>1000 cm²), this electrode holds practical potential for application as an industrial electrode in alkaline water electrolysis.