Investigating the role of metals loaded on nitrogen-doped carbon-nanotube electrodes in electroenzymatic alcohol dehydrogenation

A new enzymatic biofuel cell (EBFC) is developed using conductive metal alloy nanoparticles with carbon cloth (CC) as an immobilization support for ethanol dehydrogenase (EtDH) and formolase (FLS). Ethanol (EtOH) dehydrogenation to acetaldehyde via direct electron transfer (DET) is pursued as the first step, followed by the condensation of acetaldehyde to acetoin. Metals are deposited onto novel three-dimensional jellyfish (JF)-shaped nanoparticles (SiO₂–NCNT–CoFe₂), where NCNT denotes “N-doped carbon nanotube”. The fabricated JF–metal–CC–EtDH bioelectrodes exhibit a variation in power generation with varying metals, with a value 37.6-fold higher than that of previously reported EBFC operations with DET for EtOH oxidation. The highest acetoin content is also found in JF-Os–CC–EtDH–FLS, attributable to faster electron uptake by the bioelectrode. First-principles calculations suggest that the d-state delocalization of metal-loaded JF particles is the cause of the enhanced catalytic activity, and it can be utilized in designing electrocatalysts.