Gallate-based metal–organic frameworks for the selective removal of trace ammonia via hydrogen bond engineering

Wu, Peng; Shao, Zai-Dong; Chen, George Z.; He, Jun; Zheng, Yu-Ming

Abstract

Ammonia (NH3) is a prevalent indoor pollutant, particularly in semiconductor cleanrooms, where it is essential to adhere to stringent regulations that maintain concentration levels below parts per million (ppm). The development of sustainable adsorbents exhibiting high selectivity and adsorption capacity for NH3 at low partial pressures constitutes a critical yet challenging endeavor within this field. Herein, we introduce a class of isostructural gallate-based metal–organic frameworks (M−GA MOFs, M = Co, Mg, and Mn) endowed with abundant hydrogen bond donors within the pore channels. Notably, the Co-GA MOF exhibits an exceptionally high NH3 uptake of 3mmol g−1 at an ultralow pressure of 0.001 mbar, surpassing all previously reported MOFs. Density-functional theory (DFT), independent gradient model based on Hirshfeld partition (IGMH), and quantum theory of atoms in molecules (QTAIM) analyses reveal the presence of strong O-H···N and N-H···O hydrogen bonds between NH3 and the MOF framework. These interactions, combined with van der Waals forces, contributed to exceptional NH3 selectivity over CO2 and N2, with selectivity exceeding 104 for NH3/CO2 = 0.1 %:99.9 %. Breakthrough experiments validate the exceptional removal performance of Co-GA MOFs for trace amounts of NH3, with a breakthrough point observed at 14 d·g−1 for a concentration of 10 ppm NH3. This work not only advances our understanding of ultralow-pressure gas separation mechanisms but also offers a scalable solution for efficient separation and purification of trace contaminants in environmentally relevant settings.

Citation

Wu, P., Shao, Z.-D., Chen, G. Z., He, J., & Zheng, Y.-M. (2025). Gallate-based metal–organic frameworks for the selective removal of trace ammonia via hydrogen bond engineering. Separation and Purification Technology, 373, Article 133529. https://doi.org/10.1016/j.seppur.2025.133529

• Journal Article Type: Article
• Acceptance Date: May 12, 2025
• Online Publication Date: May 13, 2025
• Publication Date: Nov 18, 2025
• Deposit Date: May 19, 2025
• Publicly Available Date: May 14, 2026
• Journal: Separation and Purification Technology
• Print ISSN: 1383-5866
• Electronic ISSN: 1873-3794
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 373
• Article Number: 133529
• DOI: https://doi.org/10.1016/j.seppur.2025.133529
• Public URL: https://nottingham-repository.worktribe.com/output/49264470
• Publisher URL: https://www.sciencedirect.com/science/article/abs/pii/S1383586625021264?via%3Dihub