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.