Computational Design of Defect-engineered Ca(OH)₂ Monolayer for CO₂ Capture

Greenhouse gas emissions originating from fossil fuel combustion contribute significantly to global warming, and therefore the design of novel materials that efficiently capture CO₂ play a crucial role in solving this challenge. Here, we show that reducing the dimensionality of bulk crystalline portlandite results in a monolayer material, named portlandene, that is highly effective at capturing CO₂. Based on theoretical analysis comprised of ab-initio calculations and force-field molecular dynamics simulations, we show that this single-layer phase is robust and maintains its stability at high temperatures. The chemical activity of portlandene further increases upon defect engineering its surface. Defect-containing portlandene is capable of separating CO and CO₂ from a syngas stream, yet is inert to water. This selective behavior and the associated mechanisms have been elucidated by examining the electronic structure, local charge distribution and bonding orbitals of portlandene. Unlike conventional capturing technologies, the regeneration process of portlandene does not require heat treatment since it can release CO₂ by application of a mild external electric field, making portlandene an ideal CO₂ capturing material both in pre- and post-combustion processes.