Multiscale modelling of diffusion and enzymatic reaction in porous electrodes in Direct Electron Transfer mode
Résumé
This work is dedicated to a multi-scale modelling of diffusion and reaction coupled problem in a porous micro-electrode operating in the Direct Electron Transfer mode. The physicoelectrochemical unsteady model at the pore-scale is developed considering the oxygen reduction, catalyzed by an enzyme coating the pores of the electrode, coupled to the diffusion of oxygen and mass balance of enzymes. This model is formally upscaled to obtain an original closed unsteady macroscopic model operating at the electrode scale, together with the associated closure providing the effective diffusivity tensor. A validation of this model is carried out from a comparison with the solution of the initial 3D pore-scale governing equations considering the bilirubin oxydase as the catalyst. The relevance and accuracy of the macroscale model are proved allowing a considerable simulation speedup. It is further employed to successfully predict experimental voltammetry results obtained with porous gold electrodes functionnalized with a bilirubin oxidase mutant (BOD S362C).
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