Water-Enhanced Direct Air Capture of Carbon Dioxide in Metal–Organic Frameworks Chen, Oscar Iu-Fan Liu, Cheng-Hsin Wang, Kaiyu Borrego-Marin, Emilio Li, Haozhe Alawadhi, Ali H. Rodríguez Navarro, Jorge Andrés Yaghi, Omar M. Adsorption Amines Functionalization Metal organic framework This work was financially supported by the Department of Energy under Award DE-FE0031956. The authors thank Ephraim Neumann from the Yaghi research group for his help with SEM–EDS measurement. They also thank Zihui Zhou from the Yaghi research group for helpful discussions with material characterizations; Dr. Mark D. Doherty, Dr. David R. Moore, and their colleagues at GE Research for insightful discussions regarding material synthesis and characterizations; and Drs. Hasan Celik, Raynald Giovine, and UC Berkeley’s NMR facility in the College of Chemistry (CoC-NMR) for spectroscopic assistance. The instrument used in this work was supported by the National Science Foundation under Grant No. 2018784. J.A.R.N. is grateful to the financial support from Spanish Ministerio de Universidades for a Salvador Madariaga-Fulbright grant (PRX21/00093) and from Ministerio de Ciencia e Innovación Agencia Estatal de Investigació (MCIN/AEI/10.13039/501100011033, Project PID2020-113608RB-I00; TED2021-129886B-C41). O.I.-F.C. acknowledges financial support from the Taiwan Ministry of Education. E.B.-M. acknowledges Plan Propio de Investigación-Universidad de Granada for a predoctoral fellowship. In this work, we have developed two distinct amine-functionalization series for a zirconium-based metal-organic framework (MOF), MOF-808. These strategies involved the direct coordination of amino acids with zirconium metal ions and the covalent incorporation of polyamines The MOF variants underwent thorough characterization and testing for their suitability in direct air capture (DAC) of CO2. Multiple analytical techniques, encompassing liquid-state 1H nuclear magnetic resonance (NMR) measurements, potentiometric acid-base titration, and with energy-dispersive X-ray spectroscopy was comprehensively employed to assess the loading quantity of the amine functionalities. Following amine functionalization, improved CO2 capture performance was investigated using single-component sorption isotherms and dynamic breakthrough measurements. In dry conditions, the L-lysine- and tris(3-aminopropyl)amine-functionalized variants, termed as MOF-808-Lys and MOF-808-TAPA, exhibited the highest CO2 uptakes at 400 ppm, measuring 0.612 and 0.498 mmol g-1. Further capacity enhancement was achieved by introducing 50% relative humidity, resulting in a remarkable 97% and 75% increase compared to the dry uptakes, respectively. The enhanced uptake efficiency was demonstrated by 13C solid-state NMR, revealing the formation of bicarbonate species. This research indicates a broader potential for advancing MOF materials through judicious post-synthetic amine functionalization for DAC applications. 2025-10-29T11:36:10Z 2025-10-29T11:36:10Z 2024 journal article Published version: Chen, Oscar Iu-Fan et al. Water-Enhanced Direct Air Capture of Carbon Dioxide in Metal–Organic Frameworks. J. Am. Chem. Soc. 2024, 146, 4, 2835–2844. https://doi.org/10.1021/jacs.3c14125 https://hdl.handle.net/10481/107570 10.1021/jacs.3c14125 eng http://creativecommons.org/licenses/by-nc-nd/4.0/ open access Attribution-NonCommercial-NoDerivatives 4.0 Internacional American Chemical Society