The pH and Potential Dependence of Pb-Catalyzed Electrochemical CO Reduction to Methyl Formate in a Dual Methanol/Water Electrolyte.

The conversion of waste CO to value-added chemicals through electrochemical reduction is a promising technology for mitigating climate change while simultaneously providing economic opportunities. The use of non-aqueous solvents like methanol allows for higher CO availability and novel products. In this work, the electrochemistry of CO reduction in acidic methanol catholyte at a Pb working electrode was investigated while using a separate aqueous anolyte to promote a sustainable water oxidation half-reaction. The selectivity among methyl formate (a product unique to reduction of CO in methanol), formic acid, and formate was critically dependent on the catholyte pH, with higher pH conditions leading to formate and low pH favoring methyl formate. The potential dependence of the product distribution in acidic catholyte was also investigated, with a faradaic efficiency for methyl formate as high as 75 % measured at -2.0 V vs. Ag/AgCl.