Photo-assisted flavin mediated electro-oxidation of NADH model compound using photogalvanic cell

The electrochemical conversion of NADH to NAD+ is a key process for enzymatic biofuel cells in order to obtain a high performance. However, the direct electrochemical oxidation of NADH requires an extremely high overpotential (about 1.2 V). To promote this electrochemical conversion, an indirect electrochemical oxidation was performed by utilizing a photogalvanic cell. 1-Benzyl-1,4-dihydronicotinamide (BNAH) was used as a model compound of NADH, and riboflavin (RF) was selected as the current mediator. The anodic cell reaction is the oxidation of reduced riboflavin (RFH−) produced by the photocatalyzed redox reaction with BNAH, and the cathodic cell reaction is the reduction of the hydronium ion. The highly-efficient electrochemical conversion of BNAH to BNA+ provides both electricity and dihydrogen as by-products.