While our research efforts in plasmonic nanoparticles largely focus on the chemistry of metal nanoparticles, there are also significant opportunities to understand the impact of optical resonances in dielectric materials. A dielectric material is a poor conductor of electricity but an efficient supporter of electrostatic fields. Some common examples include silicon or titanium dioxide. When dielectric materials are properly engineered with nanoscale features, they can also strongly interact with electromagnetic fields in the visible and near-infrared through Mie resonances.

Our recent research on Mie resonant metal oxide nanospheres has demonstrated that the optical properties of dielectric nanoparticles can significantly impact photonic energy transfer and photon utilization. For example, a co-solvent hydrolysis synthesis of titanium isopropoxide followed by an annealing procedure allowed us to synthesize a series of size-controlled Mie resonant TiO2 nanospheres. Unlike standard TiO2, our nanoparticles have carbon inclusion in their structure from the annealing step that produces structural colors. These materials exhibit broadband multipolar scattering features that contribute to the broadband enhancement of CO oxidation as a model reaction when the TiO2 is decorated with 5nm goal particles. This research is an important step in demonstrating how engineering optical resonances into catalyst supports amplifies photocatalysts’ activity.