Electrochemical reactivities of pyridinium in solution: Consequences for CO₂reduction mechanisms

One of the most promising CO₂reduction processes presently known suffers from a lack of fundamental understanding of its reaction mechanism. Using first principles quantum chemistry, we report thermodynamical energies of various pyridine-derived intermediates as well as barrier heights for key homogeneous reaction mechanisms. From this work, we predict that the actual form of the co-catalyst involved in pyridinium-based CO₂reduction is not the long-proposed pyridinyl radical in solution, but is more probably a surface-bound dihydropyridine species.