Review-Origin and Promotional Effects of Plasmonics in Photocatalysis

Plasmonic effects including near-field coupling, light scattering, guided mode through surface plasmon polaritons (SPPs), Forster resonant energy transfer (FRET), and thermoplasmonics are extensively used for harnessing inexhaustible solar energy for photovoltaics and photocatalysis. Recently, plasmonic hot carrier-driven photocatalysis has received additional attention thanks to its specific selectivity in the catalytic conversion of gas molecules and organic compounds, resulting from the direct injection of hot carriers into the lowest unoccupied molecular orbital of the adsorbate molecule. The excellent light trapping property and high efficiency of hot charge-carrier generation through electromagnetic surface plasmon decay have been identified as the dominant mechanisms that promote energy-intensive chemical reactions at room temperature and atmospheric pressure. However, understanding the electromagnetic effects of plasmonics and distinguishing them from chemical effects in photocatalysis is challenging. While there exist several reviews underlining the experimental observations of plasmonic effects, this critical review addresses the physical origin of the various plasmon-related phenomena and how they can promote photocatalysis. The conditions under which each plasmonic effect dominates and how to distinguish one from another is also discussed, together with the analysis of the photoconversion efficiency. Finally, future research directions are proposed with the aim to accelerate progress in this field at the interface between chemistry and physics.