Control of CO₂ Capture Process on Transition-Metal-Porphyrin-like Graphene with Mechanical Strain

Nanomaterials, such as zeolites and metal-organic frameworks, have been studied for CO₂ capture and sequestration. However, this application of nanomaterials has been limited largely due to their poor selectivity for flue gases as well as low capture capacity under low pressures. The first-principle density-functional theory calculations for porphyrin-like graphene decorated with a transition metal were performed to investigate the effects of mechanical strain on its CO₂ capture capacity. We found that Sc- and V-decorated porphyrin-like graphenes could capture CO₂ molecules selectively from gaseous mixtures under low CO₂ pressure with compressive strain and release them with tensional strain at room temperatures. The CO₂ binding to these transition metals was understood to be mostly due to the Dewar interaction involving hybridization of the metal d orbitals with π orbitals of CO₂. These results elucidate a novel approach to the CO₂ capture process with the application of the mechanical strain to nanomaterials.