Photoinduced ultrafast carriers and thermal effects within metasurfaces for light-driven catalysis

Chemical transformations involve formation and breaking of bonds in molecules, and their rate is determined by the reaction pathway for converting reactants to products. The use of photoexcited plasmonic nanostructures to alter such pathways, hence improving the reaction economics, has recently emerged as a transformative solution to the extreme energy demands of traditional catalysis. Strong photothermal nanoheating and high-energy charge carriers can be optically induced in metal nanoparticles, creating a local environment where reactions occur at temperatures far below those of common catalysts and lowered energy barriers. Most plasmonic photocatalysts operate however in the steady state, which intrinsically restricts rates and photon usage, as the inherent dynamics of chemical bonds, catalyst surface, and light-matter interactions remain untapped. This project aims at introducing new theoretical approaches breaking the steady-state paradigm to drive reactions along thermal and nonthermal pathways with ultrashort pulses. A comprehensive numerical model will be developed to rationalise the dynamics at play and design metasurfaces (ordered nanostructure arrays) working as photocatalysts in the ultrafast regime. Pulsed (femto- to nanosecond) light will be used to induce transient localised heating and to enhance the photogeneration of hot carriers on timescales relevant to the chemical kinetics. The two effects will contribute to promote reactions with increased energy efficiencies: the intrinsic thermal nonlinearities of chemical processes will be leveraged to achieve rates out of reach in steady state, the dynamics of high-energy carriers will be tailored to unlock nonthermal channels with selectivity otherwise unattainable. The envisaged predictive time-resolved models will guide experimental efforts and provide data-comparable results to demonstrate new concepts for enhancing photocatalysis via ultrafast nanophotonics, opening routes in light-driven.