A rational design of manganese electrocatalysts for Lewis acid-assisted carbon dioxide reduction

Abstract

Herein, the mechanisms of Brønsted acid- and Lewis acid-assisted CO₂ electroreduction by Mn(mesbpy)(CO)₃Br (1) were investigated by density functional theory calculations. Our results indicate that for the Lewis acid-assisted cycle, an energy sink (13) is present owing to the interaction between Mg(OTf)₂ and activated CO₂, which is disadvantageous to the apparent activation energy (ΔG^≠). Moreover, a series of substituted 13 counterparts were investigated to reduce the energy sink and decrease ΔG^≠. Based on our study on the substituent effect, an excellent linear relationship was found between 2e reduction potentials and LUMO energies of substituted 1, and a moderate linear relationship was observed between ΔG of substituted 13 and the 2e reduction potential of substituted 1 counterparts. Moreover, for the CO₂ reduction assisted by a Lewis acid, the formyl-substituted complex R8 has been predicted to be a more effective catalyst with lower overpotential and higher catalytic activity than its parent complex 1.