Revealing Substituent Effects in CO to CH₃OH Conversion on a Cobalt Phthalocyanine Catalyst Using DFT Method

The electrochemical transformation of carbon monoxide (CO), which is a primary one-carbon result of the carbon dioxide (CO2) reduction reaction (CO2RR), into useful chemical compounds is a promising method for achieving carbon neutrality. Here, we use density functional theory (DFT) to study the detailed mechanism for the CO reduction reaction (CORR) to methanol (CH3OH) on cobalt phthalocyanine (CoPc) catalyst and the effect of the substituents on the overpotential (η). For all considered complexes, the rate-determining step (RDS) is found to be the transformation of the *CHO intermediate to the *OCH2 intermediate. According to our DFT calculations, the most favorable pathway for the CO to CH3OH formation for all the complexes is *CO → *CHO → *OCH2 → *CH2OH → CH3OH. Moreover, our results suggest that substitutions of electron-donating groups on the phthalocyanine ligand increase the η values, whereas substitutions of electron-withdrawing groups decrease the η values. Our results suggest that appropriate substitutions on the macrocycle ligands can be used to design an efficient electrocatalyst with excellent product selectivity, and a minimum overpotential, motivating further experimental and theoretical investigations of molecular catalysts for CO2RR or CORR into valuable products.