Conversion of CO₂ into Formic Acid on Transition Metal-Porphyrin-like Graphene: First Principles Calculations

Recently, transition metal (TM)-porphyrin-like graphene has been predicted to be a promising material for CO₂ capturing under favorable conditions. Such materials can capture CO₂ at 300 K and release it at 450 K. However, the captured CO₂ gas is mostly stored in oceans. With the aid of first principles calculations, we herein propose a method in which the captured CO₂ is converted into an environmentally friendly product, formic acid. Addition of H₂ to CO₂ molecules adsorbed on Sc- and Ti-porphyrin-like graphene was found to catalyze this conversion. We also performed nudged elastic band calculations and thermodynamic analysis using the first-order Polanyi-Wigner equation and equilibrium statistical mechanics to investigate the chemical reactions involved in this conversion. In addition, we performed Bader charge analysis to obtain insights into the mechanism of charge transfer and adsorption throughout the conversion. Our study presents a novel method in which the captured CO₂ is treated by converting it into an environmentally friendly product. Since this method does not require CO₂ storage, it is expected to be an effective strategy to manage the rising CO₂ level in the environment.