Abstrakt

In contrast to their molybdenum dependent relatives, tungsten enzymes, which operate at significantly lower redox potentials, have received little attention regarding their ability to participate in electrochemical catalysis. The bacterial tungsten enzyme aldehyde oxidoreductase from Aromatoleum aromaticum (AOR) has been immobilised on a glassy carbon working electrode to generate a functional system that can electrochemically oxidise a wide variety of aromatic and aliphatic aldehydes in the presence of any of the electron transfer mediators benzyl viologen, methylene blue or dichlorophenol indophenol. Simulation of the cyclic voltammetry has enabled a thorough kinetic analysis of the system, which reveals that methylene blue acts as a two-electron acceptor. In contrast, the other two mediators act as single electron oxidants. The different electrochemical driving forces imparted by these mediators also lead to significantly different outer sphere electron transfer rates with AOR. This work shows that electrocatalytic aldehyde oxidation can be achieved at a low applied electrochemical potential leading to an extremely energy efficient process