Reaction–Transport Coupling in a Nanostructured Porous Electrode

The
function of nanoporous electrodes involves chemical reactions coupled
to transport of reactants and products into and out of the solid matrix.
To understand how this coupling can depend on electrode structure
and chemistry, a general multiscale, molecular-level computational
framework is introduced and applied to a model system containing a
nanoporous photoanode, the dye-sensitized solar cell. The pore structure
and electrolyte composition are systematically varied to probe this
coupling, revealing that in most cases the photocurrent density depends
on dye coverage within the anode matrix, the specific architecture
of an individual pore, and electrolyte gradients in between the anode
and cathode. The large electrolyte gradients that develop in the anode
are not kinetically controlling. The computational framework demonstrated
is general and can be applied to other electrochemical, photochemical,
and thermally driven nanoporous systems to evaluate the fundamental
characteristics of their function.