Bioelectrocatalytic CO2 reduction to formate by Candida boidinii formate dehydrogenase overcoming NADH dependence with tailored amino-viologen redox polymers

CO 2 reduction to formate through enzymatic systems represents a sustainable pathway for carbon utilization but is often limited by the cost and irreversibility of cofactors like NADH. In this study, we introduce a novel biocathode integrating NAD-dependent formate dehydrogenase ( cb FDH) and an amino-viologen redox polymer (NH 2 Et-PVI) to act as a mediating artificial cofactor, enabling continuous formate production without re-supply of exogenous cofactors. This bioelectrode achieves a faradaic efficiency of 95.4 % and a 43-fold increase in formate yield over traditional NADH-dependent biocatalytic systems, which highlights the cb FDH/NH 2 Et-PVI bioelectrode as a promising advancement for economically viable CO 2 conversion. • CO 2 reduction with NAD-dependent FDH and an amino-viologen redox polymer acting as a mediating artificial cofactor. • The bioelectrode achieved faradaic efficiency of 95.4 %. • The cb FDH/NH 2 Et-PVI bioelectrode achieved a 43-fold increase in formate yield over NADH-dependent biocatalytic systems.