Joint Theoretical and Experimental Study of the Electronic, Magnetic, and Lattice Phonon Dynamics Properties of Ca _<i>x</i> Fe _<i>y</i> O _<i>z</i> Compounds Applied to CO ₂ Capture

Unleashing energy innovation ensures a resilient and reliable energy supply. There is a critical need for the development of new carbon dioxide (CO2) captors that have improved energy efficiency accompanied by lower capital and operational costs to ensure abundant, affordable, and secure energy. Among solid materials, CaO is a good CO2 sorbent for capture technology due to its wide availability and low cost. However, CaO also suffers from some disadvantages, such as high calcination temperature, decreasing capability due to sintering, attrition, and reaction with SOx and NOx. In this study, we employed an ab initio thermodynamic approach and experimental measurements to improve its CO2 capture performance during the cycles. To do so, we explored the electronic, magnetic, and lattice dynamic properties of a series of calcium ferrites (CaxFeyOz) and applied them for CO2 capture. Our results showed that all of them can thermodynamically react with CO2 to form CaCO3 and iron oxides. Compared to pure CaO capturing CO2, CaFe3O4, CaFe2O4, and Ca2Fe2O5 could shift the CO2 regeneration temperature to a lower range. The experimental measurements showed that CaFeO2 is a good CO2 captor with or without the presence of an O2 presence. The calculated thermodynamic properties of CaxFeyOz capturing the CO2 reactions can be used to find their operational temperature ranges for different CO2 capture technologies.