Entropy‐Engineered Catalysts for Electrochemical Nitrate Reduction to Ammonia

Medium‐entropy alloys (MEAs) and high‐entropy alloys (HEAs) have recently emerged as promising electrocatalysts, owing to their compositional complexity, electronic tunability, and configurational entropy. They offer a diverse array of active sites, favorable adsorption energies, and enhanced structural stability, enabling efficient and selective multielectron nitrate reduction. Herein, we critically examine the recent advances in MEA/HEA‐based electrocatalysts for nitrate reduction reaction (NO 3 RR), detailing their synthetic strategies, phase behaviors, structure and property relationships, and mechanistic pathways. Mechanistic insights into NO 3 RR, with emphasis on proton‐coupled electron transfer, intermediate stabilization, and hydrogen evolution suppression, are also discussed. A comparative assessment with monometallic and bimetallic systems is presented to highlight the advantages conferred by entropy‐driven design. Moreover, recent developments in operando characterization, density functional theory modeling, and alloy microstructure optimization are reviewed to provide a comprehensive understanding of catalyst behavior. This work outlines key challenges, such as atomic‐scale surface control and long‐term durability, and proposes future directions to advance entropy‐engineered catalysts in sustainable nitrogen chemistry. The review bridges the gap between fundamental alloy theory and practical applications, positioning MEAs and HEAs as next‐generation electrocatalysts for green NH 3 synthesis.