Promoting Mn 3+ Spin-State Transitions from t 2g to e g through Ni Doping in Antiperovskite CuNMn 3 for Highly Efficient Ammonia Synthesis

作者：Yuxiang Yan, Jinyu Zhou, Hengdong Ren, Linze Li, Ka Wang, Lei Feng, Siying Ma, Qifan Wu, Di Wang, Yurong Yang, Chunlan Ma, Xiaobing Xu, Xinglong Wu · 发表于：The Journal of Physical Chemistry Letters · 年份：2025 · DOI：10.1021/acs.jpclett.5c00563 · 被引用次数：1 · 研究领域：Ammonia Synthesis and Nitrogen Reduction、Inorganic Chemistry and Materials、Hydrogen Storage and Materials

The electrochemical nitrogen reduction reaction (e-NRR) offers a sustainable approach to ammonia synthesis under ambient conditions, with the potential to replace the energy-intensive Haber–Bosch process. Despite significant progress in this promising field, the low NH 3 yield rate and limited Faradaic efficiency (FE) remain formidable challenges. Here, we introduce antiperovskite Cu 1– x Ni x NMn 3, where partial substitution of Cu by Ni in CuNMn 3 is developed as an effective and robust e-NRR electrocatalyst. Notably, Cu 0.7 Ni 0.3 NMn 3 demonstrates outstanding e-NRR performance, achieving an NH 3 yield rate of 33.9 ± 1.1 μg h –1 mg –1, an FE of 19.2 ± 0.62% at −0.4 V versus RHE, and excellent long-term stability over 50 h of electrolysis. In-depth mechanistic studies reveal that the Ni/Cu exchange process in Cu 1– x Ni x NMn 3 maintains structural integrity and stabilizes the valence states. Ni atoms at the corner sites interact with adjacent Mn atoms at the face centers via antiferromagnetic interactions, altering the original magnetic exchange interactions. This modification triggers a spin-state transition of some Mn 3+ ions from a low-spin (t 2g 4 e g 0 ) to a high-spin (t 2g 3 e g 1 ) configuration. Density functional theory (DFT) calculations confirm that the improved e g orbital electronic configuration enhances N 2 adsorption energy at Mn catalytic sites and promotes the hydrogenation of N 2 to form *NNH intermediates, thereby accounting for the high activity of C...