Concurrent Mechanisms of Hot Electrons and Interfacial Water Molecule Ordering in Plasmon‐Enhanced Nitrogen Fixation

Abstract The participation of high‐energy hot electrons generated from the non‐radiative decay of localized surface plasmons is an important mechanism for promoting catalytic processes. Herein, another vital mechanism associated with the localized surface plasmon resonance (LSPR) effect, significantly contributing to the nitrogen reduction reaction (NRR), is found. That is to say, the LSPR‐induced strong localized electric fields can weaken the intermolecular hydrogen bonds and regulate the arrangement of water molecules at the solid–liquid interface. The AuCu pentacle nanoparticles with excellent light absorption ability and the capability to generate strong localized electric fields are chosen to demonstrate this effect. The in situ Raman spectra and theoretical calculations are employed to verify the mechanism at the molecular scale in a nitrogen fixation process. Meanwhile, due to the promoted electron transfer at the interface by the well‐ordered interfacial water, as well as the participation of high‐energy hot electrons, the optimal catalyst exhibits excellent performance with an NH₃ yield of 52.09 µg h⁻¹ cm⁻² and Faradaic efficiency (FE) of 45.82% at ─0.20 V versus RHE. The results are significant for understanding the LSPR effect in catalysis and provide a new approach for regulating the reaction process.