Non‐Thermal Plasma‐Activated Ammonia Decomposition for Hydrogen Production: Tuning CeO ₂ Catalyst Nanomorphology to Enhance Performance

ABSTRACT Non‐thermal plasma coupled with catalysts offers a promising route to improve ammonia‐to‐hydrogen conversion efficiency. This study integrates plasma discharge with morphology‐controlled CeO 2 nanocrystals (fiber, cuboids‐S, cuboids‐L, nano‐rod, and pyramid) to enhance ammonia decomposition. Among them, CeO 2 fiber achieves outstanding ammonia conversion exceeding 99.9% (SIE = 19.8 kJ L −1 ) without metal additives or external heating, while also demonstrating remarkable long‐term stability. Through combined microscopic, electrical, and Mass Spectrometry‐based transient analysis, it is revealed that the fibrous CeO 2 structure increases the surface Ce 3+ and oxygen vacancy concentration and provides balanced NH 3 adsorption, boosting catalytic activity. Additionally, its favorable dielectric properties enhance plasma discharge and plasma−catalyst interactions. These results demonstrate that tuning catalyst nanostructure is an effective alternative to noble metal doping for efficient plasma‐driven catalysis.