Transient Laser‐Shocked Synthesis of Amorphous Layer‐Supported Metal Nanocrystals for Efficient Nitrate Reduction

ABSTRACT Metal‐support interactions provide a powerful tool to tailor the catalytic activities of metallic catalysts. Amorphous materials can serve as an effective support matrix to form unique crystalline‐amorphous interfaces and modulate the electronic structure of active metals. However, robust synthetic strategies for precise structural control remain underdeveloped. Here, we report the laser‐shocked synthesis of heterostructures including bimetallic CuNi, CuFe, CuCo, and medium‐entropy CuFeCoNi heterostructures, where crystalline metal nanoparticles are anchored on amorphous hydroxide supports. The heterostructures are characterized by an interfacial electronic distribution that improves catalytic activities. With CuNi as an example for nitrate reduction reaction, the laser‐engineered heterophase CuNi achieves an NH 3 production rate of 92.18 mg/h/mg cat with 98.6% Faradaic efficiency (FE), substantially superior to standalone crystalline CuNi or amorphous CuNi hydroxide. The CuNi heterostructure maintains a stable FE(NH 3 ) of ∼90% up to 80 h while improving current density from 75 to 120 mA/cm 2 due to the robust amorphous layer and dynamic amorphous/crystalline reconstruction. In situ characterization and theoretical calculations reveal that the amorphous/crystalline interface regulates the balance between reactive hydrogen species and reaction intermediates, effectively suppressing the competing hydrogen evolution and promoting cascade nitrate‐to‐nitrite and nitrite‐to ammonia conversion. This work provides a general and viable strategy for producing high‐performance supported catalysts.