(751d) Designing Hybrid Plasmonic Nanostructures for Photocatalysis

Plasmonic metal nanostructures (e.g. nanoparticles of Ag, Au, and Cu) are an emerging class of materials that can harvest light through the excitation of localized surface plasmon resonance (LSPR). The decay of LSPR results in the high rates of formation of charge carriers within the nanostructures which can potentially be extracted to perform excited state, nonequilibrium photochemical reactions. Unfortunately, both the extremely fast thermalization of these charge carriers (on the order of femtoseconds) within the plasmonic material and the low chemical reactivity of plasmonic metals have limited the applicability of plasmon-driven photocatalysis. In this contribution, we demonstrate that the efficient extraction of charge carriers from plasmonic materials is attainable by interfacing them with non-plasmonic, more catalytically active materials (e.g. a semiconductor, molecule, or another metal).^1-3 Through a systematic study of various well-defined core-shell nanostructures, we demonstrate that coating plasmonic nanostructures with thin layers of non-plasmonic metals can result in localized charge carrier formation at the surface layers of the nanoparticles (in the non-plasmonic component). We then reveal that the extent of this surface localization in the presence of the non-plasmonic material is governed by two factors: (1) the intensity of the plasmon-induced electric fields at the surface of the plasmonic nanostructure, and (2) the availability of direct, momentum conserved electronic excitations in the non-plasmonic material. We use these studies to propose a unifying physical framework that leads us towards molecular control of excited charge carrier generation in all hybrid plasmonic systems and to provide insights into how this physical framework can aid the rational design of hybrid plasmonic materials for photocatalysis.

References

1. Aslam, U., Chavez, S. & Linic, S., Nature Nanotechnol. 12, 1000–1005 (2017).
2. Chavez, S., Aslam, U., & Linic, S., ACS Energy Letters. 3, 1590-1596 (2018).
3. Chavez, S., Govind Rao, V., & Linic, S., Faraday Discussions. 214, 441-453 (2019).