Understanding the formation mechanism of crystalline hydrated polymorphs of carbonic acid from CO2 clathrate hydrate

Year: 2025

Authors: Berni S., Scelta D., Romi S., Fanetti S., Alabarse F., Wehinger B., Bini R.

Autors Affiliation: European Lab Nonlinear Spect, LENS, Via N Carrara 1, I-50019 Florence, Italy; Natl Res Council Italy, Inst Chem Organo Metall Cpds, ICCOM CNR, Via Madonna Piano 10, I-50019 Florence, Italy; Univ Firenze, Dipartimento Chim Ugo Schiff, Via Lastruccia 3, I-50019 Florence, Italy; Elettra Sincrotrone Trieste SCpA, ELETTRA, AREA Sci Pk,Basovizza, I-34149 Trieste, Italy; European Synchrotron Radiat Facil, ESRF, 71 Ave Martyrs,CS40220, F-38043 Grenoble 9, France; INO CNR, Ist Nazl Ott, Via N Carrara 1, I-50019 Florence, Italy.

Abstract: Carbon dioxide (CO2) and water (H2O) icy mixtures, together with a few other simple molecules, have a prominent role in astrochemical processes. The formation of the solid 1 : 1 CO2 : H2O adduct, carbonic acid (H2CO3), has been long studied because of its importance in the biological and geochemical domains. Our recent discovery of a novel, highly reproducible synthetic path to obtain crystalline hydrated H2CO3 polymorphs from low temperature compression of CO2 clathrate hydrate highlighted the role of pressure in the chemistry of crystal ices. Herein, we report an extensive study about the reaction mechanism leading to this synthesis, unveiling a multi-step temperature-governed process that involves the formation of carbonic acid molecules starting from about 200 K and their organisation in a crystalline lattice at temperatures close to 270 K. In addition, the essential role played by the clathrate in the formation of crystalline carbonic acids is clearly highlighted, while the entire process meticulously mimics what can occur during the subduction of icy materials.

Journal/Review: CHEMICAL SCIENCE

More Information: The authors acknowledge the funding provided by the project IPHOQS, CUP: B53C22001750006. The authors also acknowledge the financial support provided under the National Recovery and Resilience Plan (NRRP), Mission 4, Component 2, Investment 1.1, Call for tender no. 104 published on 2/2/2022 by the Italian Ministry of University and Research (MUR), funded by the European Union-NextGenerationEU, Project Title: Pressure induced photoreduction of CO2 inside inorganic and metal organic porous materials, CUP B53D23025660001, Grant Assignment Decree No. 1384 adopted on 01/09/2023 by the Italian Ministry of Ministry of University and Research (MUR). This research has also been funded by the European Union-NextGeneration EU, within PRIN 2022, PNRR M4C2, Project E-ICES, Project Title: Probing the exotic properties of gas and ions filled ICES under extreme conditions: from planetary interiors modelling to hydrogen storage and green energy applications 2022NRBLPT, CUP B53D23004390006. This study was further supported by the Deep Carbon Observatory (DCO) initiative under the project Physics and Chemistry of Carbon at Extreme Conditions and by the Italian Ministero dell’Istruzione, dell’Universita e della Ricerca (MIUR). The authors acknowledge the ESRF synchrotron for the provision of synchrotron radiation facilities (proposal CH-7025, https://doi.org/10.15151/ESRF-ES-1554170001) and thank B. Wehinger for his assistance in using beamline ID-27 (ESRF, Grenoble). The authors acknowledge the Elettra Sincrotrone Trieste for the provision of synchrotron radiation facilities (proposal 20245138) and thank F. Alabarse for his assistance in using beamline XPress. S. B. thanks the project CNR-FOE-LENS.
KeyWords: Proton-irradiated H2o+co2; Neutron-diffraction; Amino-acids; Gas-phase; Ice; Pressure; Chemistry; System; Transitions; Photolysis
DOI: 10.1039/d5sc02241j