The electrochemical reduction of carbon dioxide (CO₂) to methanol in the presence of pyridoxine (vitamin B₆)

Experiments aimed at ameliorating carbon dioxide (CO₂) into methanol were explored using pyridoxine, a member of the vitamin B₆ family, to enhance the reduction process. At a platinum electrode, an aqueous solution (pH ≈ 5) of pyridoxine showed a quasi-reversible redox couple with the cathodic peak detected at ca. - 0.55 V vs. Ag/AgCl (3 M KCl) in the presence of CO₂ and argon. An increase in the corresponding cathodic peak current was observed following saturation of the solution with CO₂ using a Pt electrode, but with no detectable reduction current recorded at a glassy carbon electrode for the same system. Confirmation of methanol formation during the pyridoxine-assisted CO₂ reduction was conducted by using gas chromatography analysis of the electrolyzed solutions and faradic yields of ca. 5% were afforded. A combination of the results from the cyclic voltammetry and constant current chronopotentiometry experiments revealed an overpotential of ≤ 200 mV was required. The results indicate a potential utility of pyridoxine as an alternative reagent to the more toxic pyridine during the electrochemical reduction of CO₂.