Direct Electrochemical Regeneration of NADH on Au, Cu and Pt-Au Electrodes

The regeneration of a reduced form of nicotinamide adenine dinucleotide (NADH) in a batch electrochemical reactor employing Au, Cu and Pt-Au electrodes was investigated. The yield of enzymatically active NADH regenerated was found to depend on the electrolysis potential and the electrode material used. At low negative potentials the yield of active NADH regenerated is similar on both Au and Cu, and relatively high (75 % and 71 %, respectively), but the NAD+ reduction rate and the corresponding conversion degree is low. At high (industrially relevant) negative potentials the NAD+ reduction rate and the corresponding conversion degree is high, while the yield of active NADH formed on Au is low (28 %) and intermediate on Cu (52 %). In order to increase the yield of enzymatically active NADH formed at high (industrially relevant) potentials, the Au surface was modified with Pt. This resulted in an increase in the yield of active NADH from 29.6 % to 63 %. A reaction mechanism taking into account the influence of Pt is proposed.