Molecular modelling of electrocatalytic CO₂ conversion

The conversion and long-term storage of renewable energy are crucial to building a sustainable society, and electrocatalysis, which converts electrical energy into chemical energy through electrolysis, is dedicated to addressing this challenge. This thesis employs density functional theory (DFT) and ab initio molecular dynamics (AIMD) simulations to investigate cation and solvent effects in the electrocatalytic CO₂ reduction reaction (CO2RR) on cobalt-based molecular catalysts. We systematically compare a confined cobalt porphyrin-cage (Co-Cage) catalyst with a planar cobalt porphyrin (Co-TPP). Micro-solvated and fully explicit solvation models reveal that the Co-Cage structure enhances selectivity for CO2RR over the competing hydrogen evolution reaction (HER) by stabilizing a confined water network and dynamically interacting with cations. While alkali cations facilitate CO2RR in the Co-Cage by stabilizing key intermediates, their effect on the proton transfer kinetics in Co-TPP is less pronounced. Extending the study to multi-electron reduction, we examine cobalt phthalocyanine (CoPc) for the conversion of CO₂/CO to methanol. The simulations elucidate how cations and applied potential govern proton-coupled electron transfer (PCET) mechanisms, stabilizing critical intermediates like formaldehyde. Collectively, this work underscores the necessity of explicit solvation and dynamic cation modeling for an accurate mechanistic understanding of selectivity and activity in electrocatalysis.