Synthesis optimization, adsorption properties and spectroscopic investigation of a NH2-tagged Cu-based MOF with open metal sites

Boudjema, Lotfi; Dahiya, Anil Kumar; da Silva, Ivan; Gianolio, Diego; Nduka, Izuchika; Schuster, Manfred Erwin; Theodora van de Kerkhof, Gea; Kalinowska, Paulina; Borrego-Marin, Emilio; Navarro, Jorge A R; Colombo, Valentina; McCorquodale, June; Grinter, David C.; Ferrer, Pilar; Held, G.; Catlow, C. Richard A.; Arrigo, Rosa

Abstract

We investigate the rapid microwave-assisted solvothermal synthesis of a Cu-MOF (Metal-Organic Framework) with open metal sites, with a focus on understanding its CO2 capture properties in relation to phase purity and stability. A combined experimental and theoretical approach is used to identify the MOF structural features involved in the adsorption process. Specifically, Cu(I) defects are found playing an important role in the CO2 adsorption process, with the Cu-1 sample, synthesized using an optimized ligand/Cu precursor ratio for highest phase purity, exhibiting more abundant Cu(I) defects as well as highest adsorption capacity. Grand Canonical Monte Carlo simulations show that the Cu(I) sites exhibit a greater affinity for CO2 adsorption compared to the Cu(II) sites. In situ spectroscopic soft and hard X-ray absorption fine structure spectroscopy confirm the conversion of Cu(I) to Cu(II) upon CO2 chemisorption, with this conversion being more pronounced in the core of the particles. The simulations are used to estimate the fraction of Cu(I) defects and Cu(II) sites present within the Cu-1 MOF and to validate the experimental isotherm. Overall, this study provides insights into the CO2 capture properties of GIF-KUC Cu-MOFs and highlights the importance of phase purity for achieving high adsorption performance.

• Journal Article Type: Article
• Acceptance Date: Jan 31, 2025
• Deposit Date: Jul 10, 2025
• Publicly Available Date: Jul 10, 2025
• Journal: Materials Advances
• Electronic ISSN: 2633-5409
• Peer Reviewed: Peer Reviewed
• DOI: https://doi.org/10.1039/d5ma00666j