Visible-light-assisted electrocatalytic water splitting via plasmon enhancement and interfacial engineering of Ag/Fe nanoplates supported on Ni foam

Plasmon-enhanced electrocatalysis offers a promising route to improve water splitting efficiency, yet achieving optimal interfacial contact between plasmonic nanoparticles and catalytic supports remains challenging. Herein, we report a bifunctional Ag/Fe nanoplates/nickel foam (Ag/Fe nanoplates/NF) electrocatalyst fabricated via electrostatic self-assembly. The negatively charged Fe nanoplate scaffold, derived from selective alkaline etching of electrodeposited Fe–Al films, enables uniform embedding of positively charged Ag nanoparticles. The optimized Ag/Fe nanoplates/NF electrode achieves low overpotentials of 206 mV for the oxygen evolution reaction (OER) and 81 mV for the hydrogen evolution reaction (HER) at 10 mA/cm 2 under visible-light illumination (AM 1.5G simulator, λ ≤ 650 nm). When configured for overall water splitting, it requires a cell voltage of only 1.53 V to reach 10 mA/cm 2 and demonstrates outstanding stability exceeding 120 h. Density functional theory (DFT) calculations reveal that spontaneous electron transfer from Ag to Fe downshifts the Fe d-band center from −1.03 eV to −1.25 eV, which weakens the overly strong adsorption of *H and OER intermediates on pristine Fe and optimizes the adsorption thermodynamics for both OER and HER. This work establishes a general strategy for designing plasmon-enhanced electrocatalysts through rational interface engineering and charge-directed assembly.