CO₂ adsorption and desorption across the Fe-doped Ca-based composites in the presence of H₂O: A DFT approach

This work explores the adsorption and desorption of CO2 in the presence of H2O on Fe-doped Ca-based composites through an investigation of structural changes, electron density, adsorption energy and transitional states. The results show that Fe atoms bind O atoms to form a solid solution dispersed in CaO. This solid solution inhibits the transition of CO2 from a gas state to an adsorbed state while facilitating the chemical adsorption and desorption of CO2. The presence of H2O promotes the activity of O atoms around the solid solution and accelerates the rate of CO2 adsorption. Once CO2 has transitioned to the adsorbed state, the addition of H2O activates O atoms on the surface of both pure CaO and Fe-doped CaO, promoting CO2 adsorption. During desorption, the addition of H2O promotes the interaction between Fe and O-2 in CO32-, which further accelerates the desorption of CO2.