Pt‐Optimized NiFe Layered Double Hydroxide for Overall Water Splitting Reaction at High Current Densities

Noble metal catalysts are essential for overcoming the kinetic barriers of hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), but their high cost and scarcity hinder large‐scale applications. Herein, Pt and NiFe layered double hydroxide (LDH) heterojunction catalysts (Pt 14.57 @NiFe LDH/NF) with strong electronic metal–support interactions (EMSI) have been developed by a one‐step hydrothermal method. Heterojunction engineering optimizes the electronic structure at the Pt‐NiFe LDH interface, adjusting the d‐band center of Pt to balance the adsorption/desorption kinetics of intermediates in HER and OER. Electrochemical measurements show that Pt 14.57 @NiFe LDH/NF exhibits exceptional bifunctional performance in alkaline media, requiring ultralow overpotentials of 89 mV (HER, 500 mA cm −2 ) and 276 mV (OER, 500 mA cm −2 ), significantly outperforming state‐of‐the‐art catalyst. The catalyst also demonstrates excellent stability, maintaining performance without degradation after 200 h of testing under HER and OER conditions. When applied to an overall water splitting (OWS) system, it achieves cell voltages of 1.329 V (10 mA cm −2 ) and 1.715 V (1000 mA cm −2 ) with a Faradaic efficiency approaching 100%, and can stably catalyze for at least 200 h at high current densities. Physical characterizations confirm the formation of a robust heterojunction with enhanced active site density and electron transfer kinetics.