Defect Engineering via Ultrasonic Vibration for Activating High‐Valent Nickel Sites Toward Enhanced Seawater Urea Oxidation Reaction

ABSTRACT Developing high‐efficiency catalysts for the seawater urea oxidation reaction (UOR) is pivotal to advancing hydrogen production via seawater electrolysis. Defect engineering has established itself as a core strategy for regulating catalytic activity. However, conventional defect regulation technologies are predominantly hindered by inherent drawbacks such as high energy consumption, substantial costs, and environmental contamination. Herein, we introduce high‐frequency ultrasonic vibration cold‐manufacture (HUVCM) as a novel, eco‐friendly, and highly efficient defect engineering approach to fabricate high‐performance Ni‐based catalysts for seawater UOR. Our findings demonstrate that HUVCM induces the formation of high‐density dislocation defects on the surface of Ni‐based alloys, which subsequently initiate the in situ construction of ultra‐fine nanocrystalline structures with an average grain size of ∼ 5 nm. The Ni‐based alloys modified by HUVCM exhibit remarkably enhanced catalytic activity toward both the hydrogen evolution reaction and UOR. Notably, for UOR, the catalyst shows excellent activity with merely 1.4 V at 100 mA cm −2 , placing the catalyst among the state‐of‐the‐art Ni‐based seawater UOR electrocatalysts. We further reveal that the superior catalytic performance stems directly from the elevated valence states of constituent elements, which are effectively modulated by the high‐density dislocation defects introduced via HUVCM. This work proposes an efficient and facile defect‐engineering strategy for electrocatalysts, while establishing a pivotal foundation for the industrial‐scale production of hydrogen via seawater electrolysis.