Plasmonic nanoparticles (PNPs) present unique optoelectronic properties that depend on their size and shape and are not present in larger particles or the bulk material. Such properties arise from their localized surface plasmon resonances (LSPRs) . LSPRs are the light-induced coherent motion of electrons that produce dramatic enhancements of the electromagnetic field close to the surface of the particle (hot spots) as well as large scattering and absorption cross-sections . These properties have motivated the use of PNPs in many applications in the field of nanotechnology including ultra-sensitive sensing, light harvesting, imaging, photonics, catalysis, and medical and pharmaceutical therapies . Very recently, a previously unexplored feature of LSPRs opened a new perspective of these systems. Non-radiative decay of LSPRs can result in the excitation of electron-hole pairs with high, far-from-equilibrium energies known as hot carriers . These carriers can either dissipate their energy to the phonon lattice producing heat or – if they reach the surface fast enough without relaxing – can be injected into a nearby molecule causing its chemical transformation . Manipulating LSPRs allows for the fine control of the reactive properties of hot carriers, in a similar way in which it has enabled control of electromagnetic fields.
The advances in the fundamental understanding of plasmon-mediated chemical reactions could find applications in the design of alternative photocatalytic methods with improved efficiency and/or selectivity. This would contribute to European Union goals for energy and environment policies. For example, the outcome of this plan can lead to new materials for solar energy conversion.
However, determining the role of hot carriers in plasmon-mediated chemistry is a difficult task as it is usually masked by other catalytic properties (heat generation and field enhancement).
The main objective of this proposal is the implementation of an optical method for reactive-spot mapping, which will allow to create a map that highlights areas of low and high photochemical reactivity on single PNPs with high spatial resolution.
