Enzymatic Flow Electrolyzer for CO2 and Waste Comproportionation to Formate and Its Use in Photocatalytic Alkene Hydrocarboxylation

Abstract

Paired electrolysis enables the simultaneous coupling of CO2 reduction with anodic waste upcycling to form valuable products. However, achieving selective, efficient, and stable product formation and coupling to downstream valorization remains a challenge. In this study, W-containing formate dehydrogenase from Nitratidesulfovibrio vulgaris Hildenborough is immobilized onto a cathode made from carbon felt coated with porous TiO2 and paired with a commercial Ni foam anode to assemble a semiartificial flow electrolyzer for the simultaneous conversion of CO2 and waste (plastic and biomass) to the single product formate. The enzymatic flow electrolyzer achieved an initial cell faradaic efficiency toward formate of almost 200%, a maximum CO2 conversion yield of 18% and can operate at a low full-cell voltage of −1.5 V for 122 h, which allows for bias-free operation with a silicon photovoltaic cell. The aqueous formate produced in the enzymatic electrolyzer was subsequently utilized downstream as a C1 building block in the photocatalytic hydrocarboxylation of alkenes, providing a path for the domino valorization of CO2 and waste toward bulk and fine chemical synthesis.