  Dye-sensitized photocatalytic (DSP) approach is considered as one of the
promising approaches for developing visible light- and near-infrared
light-responsive photocatalysts. DSP systems are still affected by significant
drawbacks, such as low light absorption efficiency. Recently, it has been
demonstrated that the plasmonic metal nanostructures can be used to enhance the
light absorption efficiency and the overall dye-sensitization rate of DSP
systems through the plasmonic Mie resonance-enhanced dye-sensitization
approach. In this contribution, we report an alternate and novel approach,
dielectric Mie resonance-enhanced dye sensitization. Specifically, we
demonstrate that the dielectric Mie resonances in cuprous oxide (Cu2O)
spherical and cubical nanostructures can be used to enhance the
dye-sensitization rate of methylene blue dye. The Cu2O nanostructures
exhibiting dielectric Mie resonances exhibit up to an order of magnitude higher
dye-sensitization rate as compared to Cu2O nanostructures not exhibiting
dielectric Mie resonances. Our model system developed from finite-difference
time-domain simulation predicts a volcano-type relationship between the dye
sensitization rate and the size of Cu2O nanostructures. The predicted
structure-property-performance relationship is experimentally verified and the
optimal size ranges of Cu2O nanospheres and nanocubes are identified. Although
we demonstrate the dielectric Mie resonance-enhanced dye-sensitization approach
using Cu2O nanostructures, the proposed approach can be used to design a wide
range of DSP systems, including CeO2, {\alpha}-Fe2O3, and TiO2
nanostructures-based DSP systems.
