Modeling
Dioxygen Reduction at Multicopper Oxidase
Cathodes
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Abstract
We
report a general kinetics model for catalytic dioxygen reduction
on multicopper oxidase (MCO) cathodes. Our rate equation combines
Butler–Volmer (BV) electrode kinetics and the Michaelis–Menten
(MM) formalism for enzymatic catalysis, with the BV model accounting
for interfacial electron transfer (ET) between the electrode surface
and the MCO type 1 copper site. Extending the principles of MM kinetics
to this system produced an analytical expression incorporating the
effects of subsequent intramolecular ET and dioxygen binding to the
trinuclear copper cluster into the cumulative model. We employed experimental
electrochemical data on Thermus thermophilus laccase as benchmarks to validate our model, which we suggest will
aid in the design of more efficient MCO cathodes. In addition, we
demonstrate the model’s utility in determining estimates for
both the electronic coupling and average distance between the laccase
type-1 active site and the cathode substrate