In this work, we apply for the first time ambient pressure operando soft X-ray absorption spectroscopy (XAS) to investigate the location, structural properties, and reactivity of the defective sites present in the prototypical metal-organic framework HKUST-1. We obtained direct evidence that Cu+ defective sites form upon temperature treatment of the powdered form of HKUST-1 at 160 °C and that they are largely distributed on the material surface. Further, a thorough structural characterization of the Cu+/Cu2+ dimeric complexes arising from the temperature-induced dehydration/decarboxylation of the pristine Cu2+/Cu2+ paddlewheel units is reported. In addition to characterizing the surface defects, we demonstrate that CO2 may be reversibly adsorbed and desorbed from the surface defective Cu+/Cu2+ sites. These findings show that ambient pressure soft-XAS, combined with state-of-the-art theoretical calculations, allowed us to shed light on the mechanism involving the decarboxylation of the paddlewheel units on the surface to yield Cu+/Cu2+ complexes and their reversible restoration upon exposure to gaseous CO2.

Catching the Reversible Formation and Reactivity of Surface Defective Sites in Metal-Organic Frameworks: An Operando Ambient Pressure-NEXAFS Investigation / L. Braglia, F. Tavani, S. Mauri, R. Edla, D. Krizmancic, A. Tofoni, V. Colombo, P. D'Angelo, P. Torelli. - In: THE JOURNAL OF PHYSICAL CHEMISTRY LETTERS. - ISSN 1948-7185. - 12:37(2021 Sep 23), pp. 9182-9187. [10.1021/acs.jpclett.1c02585]

Catching the Reversible Formation and Reactivity of Surface Defective Sites in Metal-Organic Frameworks: An Operando Ambient Pressure-NEXAFS Investigation

V. Colombo;
2021

Abstract

In this work, we apply for the first time ambient pressure operando soft X-ray absorption spectroscopy (XAS) to investigate the location, structural properties, and reactivity of the defective sites present in the prototypical metal-organic framework HKUST-1. We obtained direct evidence that Cu+ defective sites form upon temperature treatment of the powdered form of HKUST-1 at 160 °C and that they are largely distributed on the material surface. Further, a thorough structural characterization of the Cu+/Cu2+ dimeric complexes arising from the temperature-induced dehydration/decarboxylation of the pristine Cu2+/Cu2+ paddlewheel units is reported. In addition to characterizing the surface defects, we demonstrate that CO2 may be reversibly adsorbed and desorbed from the surface defective Cu+/Cu2+ sites. These findings show that ambient pressure soft-XAS, combined with state-of-the-art theoretical calculations, allowed us to shed light on the mechanism involving the decarboxylation of the paddlewheel units on the surface to yield Cu+/Cu2+ complexes and their reversible restoration upon exposure to gaseous CO2.
Settore CHIM/03 - Chimica Generale e Inorganica
Settore CHIM/02 - Chimica Fisica
PSR2015-1715FDEMA_M - PIANO DI SOSTEGNO ALLA RICERCA 2015-2017 - LINEA 2 "DOTAZIONE ANNUALE PER ATTIVITA' ISTITUZIONALE" - DEMARTIN, FRANCESCO - PSR2015-17 - Piano di sviluppo di ricerca 2015-17 - 2015
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/873199
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