Hot electron and thermal effects in plasmonic photocatalysis
Luca Mascaretti, Alberto Naldoni
Abstract
Surface plasmons have shown increasingly widespread applications in the last decade, especially in the field of solar energy conversion, recently leading to the use of metal nanoparticles as plasmonic photocatalysts. The latter offers great potential in overcoming traditional catalysts by providing localized heating and unconventional reaction pathways leading to improved product selectivity. A complete understanding of the underlying mechanisms remains, however, elusive due to the close resemblance between thermal and non-thermal effects, both leading to enhanced reaction rates. In this tutorial, we will introduce the basic physics of surface plasmons and the interaction mechanisms with surrounding molecules. We will then discuss the main strategies to evaluate photothermal effects and the main signatures of hot electron-driven processes. These aspects will be covered in specific examples of plasmonic photocatalysis for energy-relevant chemical reactions in the case of colloidal suspensions and at the solid/gas interphase in solid pellets, which involve different thermal constraints and thus different experimental strategies to reveal the effects of localized heating and hot electrons.