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

Abstract

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. −0.55V vs. Ag/AgCl (3M 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 ≤200mV 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.