Direct electrochemical regeneration of enzymatic cofactor 1,4‐NADH on a cathode composed of multi‐walled carbon nanotubes decorated with nickel nanoparticles

Abstract

Abstract Multi‐walled carbon nanotubes (MWCNTs) were grown on a stainless steel mesh and decorated with nickel nanoparticles (Ni NPs). The developed Ni NP‐MWCNT material was then used as a cathode in an electrochemical batch reactor to electrocatalytically convert NAD + to enzymatically‐active 1,4‐NADH. The regeneration of 1,4‐NADH was studied at various electrode potentials. At electrode potential of −1.6 V, a very high recovery (relative amount of 1,4‐NADH in the product mixture) was obtained, 98 ± 1 %. In comparison, to achieve the same recovery on a non‐decorated MWCNT cathode, a much higher cathodic potential was needed (−2.3 V), establishing the importance of Ni NPs on the electrocatalytic activity in reducing NAD + to 1,4‐NADH. It was postulated that hydrogen adsorbs on Ni NPs immobilized on MWCNTs to form Ni‐H ads , and this activated hydrogen rapidly reacts with neighbouring NAD‐radicals, preventing the dimerization of the latter species, ultimately yielding 1,4‐NADH.