Main-group metal-nonmetal dynamic proton bridges enhance ammonia electrosynthesis

• Main Authors: Sun, Yuntong, Dai, Liming, Dong, Kai, Sui, Nicole L. D., Li, Yinghao, Sun, Jingwen, Zeng, Jianrong, Fan, Wenjun, Tian, Meng, Zhu, Junwu, Lee, Jong-Min
• Other Authors: School of Chemistry, Chemical Engineering and Biotechnology
• Format: Article
• Language: English
• Published: 2025
• Subjects: Chemistry; Asymmetric dual-sites; Dynamic proton bridge
• Online Access: https://hdl.handle.net/10356/182371
• Institution: Nanyang Technological University

The electrochemical nitrogen reduction reaction (eNRR) is a crucial process for the sustainable production of ammonia (NH3) for energy and agriculture applications. However, the reaction's efficiency is highly dependent on the activation of the inert N≡N bond, which is hindered by the electron back-donation to the π* orbitals of the N≡N bond, resulting in low eNRR capacity. Herein, we report a main-group metal-nonmetal (O-In-S) eNRR catalyst featuring a dynamic proton bridge, with In-S serving as the polarization pair and O functioning as the dynamic electron pool. In situ spectroscopic analysis and theoretical calculations reveal that the In-S polarization pair acts as asymmetric dual-sites, polarizing the N≡N bond by concurrently back-donating electrons to both the πx* and πy* orbitals of N2, thereby overcoming the significant band gap limitations, while inhibiting the competitive hydrogen evolution reaction. Meanwhile, the O dynamic electron pool acts as a "repository" for electron storage and donation to the In-S polarization pair. As a result, the O-In-S dynamic proton bridge exhibits exceptional NH3 yield rates and Faradaic efficiencies (FEs) across a wide potential window of 0.3 V, with an optimal NH3 yield rate of 80.07±4.25 μg h-1 mg-1 and an FE of 38.01±2.02 %, outperforming most previously reported catalysts.