Title: Catalyzed bimolecular reactions in responsive nanoreactors,
Abstract: We describe a general theory for surface-catalyzed bimolecular reactions in
responsive nanoreactors, catalytically active nanoparticles coated by a
stimuli-responsive 'gating' shell, whose permeability controls the activity of
the process. We address two archetypal scenarios encountered in this system:
The first, where two species diffusing from a bulk solution react at the
catalyst's surface; the second where only one of the reactants diffuses from
the bulk while the other one is produced at the nanoparticle surface, e.g., by
light conversion. We find that in both scenarios the total catalytic rate has
the same mathematical structure, once diffusion rates are properly redefined.
Moreover, the diffusional fluxes of the different reactants are strongly
coupled, providing a richer behavior than that arising in unimolecular
reactions. We also show that in stark contrast to bulk reactions, the
identification of a limiting reactant is not simply determined by the relative
bulk concentrations but controlled by the nanoreactor shell permeability.
Finally, we describe an application of our theory by analyzing experimental
data on the reaction between hexacyanoferrate (III) and borohydride ions in
responsive hydrogel-based core-shell nanoreactors.