High Entropy Oxynitride for Anti‐Poisoning Electrocatalytic Nitrogen Reduction
Yiwen Su, Xinzhong Wang, Jinjin Wu, Shurong Li, Jiashu Chen, Mingcong Tang, Yongbiao Mu, Wenyi Guo, Yongwei Wang, Sida Zhang, Fujing Xu, Gang Liu, Jing Yang, Xiucheng Zheng, Junye Cheng, Jingyu Sun, Shixue Dou, Guangping ZhengABSTRACT
Electrocatalytic nitrogen reduction reaction (eNRR) under ambient conditions is a promising route for sustainable ammonia synthesis, yet its progress is fundamentally limited by the inertness of N≡N bonds and the lack of robust, selective catalysts. Here, we report the first synthesis of a rutile‐structured high‐entropy oxynitride (HEON, CoFeTiVSnON). By leveraging the mixing entropy of five metal elements and dual anion regulation, HEON achieves dynamically regenerable nitrogen vacancies, and a tunable electronic structure. Operando spectroscopic investigations and density functional theory (DFT) calculations reveal that HEON uniquely activates N 2 via a stabilized vacancy‐mediated quasi Mars‐van Krevelen (MvK) mechanism, wherein nitrogen vacancies directly participate in the catalytic cycle, enabling continuous vacancy formation and healing. Correspondingly, the NH 3 poisoning and vacancy depletion issues that plague conventional binary nitrides have been circumvented whilst breaking linear scaling relationship of intermediate adsorption. The HEON catalyst delivers a high NH 3 yield rate of 159.2 µg h −1 mg cat. −1 and a Faradaic efficiency of 46.6% at −0.5 V vs. RHE, with good structural stability over extended operation. Our work establishes high‐entropy oxynitrides as a transformative platform for multi‐step electrocatalysis, and provides mechanistic insights for the rational design of catalysts stabilized by high entropy effects.