Transition Metal Embedded Boron Doped Graphene for Reduction of CO2 to HCOOH

Abstract

Electro-chemical conversion of carbon dioxide stands out as an excellent strategy to alleviate the greenhouse effect. Lately, single atom catalysts have gained notable attention as emerging candidates for CO₂ reduction reaction, owing to their remarkable cost-efficiency and unprecedented atomic utilization. Applying density functional theory (DFT), our work examines the first couple of proton coupled electron transfer steps of CO₂RR, on 3d transition metal-doped B-Gr and compares the activity observed with previously studied supports. Since CO₂ activation is the 1st step of CO₂RR, we thoroughly investigated the capability of the TM SAs in effectively activating CO₂ in both dry phase and in presence of water. According to our calculation, except Ti, Cu and Zn, all other TM@B-Gr systems are able to activate the CO₂ molecule. CO₂ activation on selected SACs is further attributed to the transfer of charges from the TM SA to the CO₂ molecule, as revealed by our Bader charge calculations. In addition, the Gibbs free energy changes for all the reaction intermediates have been calculated to determine the most preferred pathway of the reaction. Our results indicate the preference for OCHO over COOH in the first protonation step, indicating the production of HCOOH as the preferred end product. The same trend has also been observed in presence of H₂O. Our DFT based analysis presented in this work, unravels the crucial role a support plays in determining the activity of a single atom catalyst and paves a way forward to the efficient design of 2D catalyst for CO₂ reduction reaction.