Material, size and environment dependence of plasmon-induced hot carriers in metallic nanoparticles

TL;DR

This study explores how the material, size, and environment of metallic nanoparticles influence the generation and energy distribution of hot carriers from plasmon decay, with implications for energy conversion applications.

Contribution

It provides a comprehensive theoretical analysis of hot carrier generation across six plasmonic materials, sizes up to 40 nm, and various dielectric environments, highlighting optimal conditions for hot carrier production.

Findings

Small nanoparticles (≤16 nm) in high dielectric media produce most hot carriers.

Na, K, and Au generate the highest hot carrier rates among studied materials.

Metal nanoparticles can facilitate water splitting, with simple metals favoring hydrogen evolution and transition metals favoring oxygen evolution.

Abstract

Harnessing hot electrons and holes resulting from the decay of localized surface plasmons in nanomaterials has recently led to new devices for photovoltaics, photocatalysis and optoelectronics. Properties of hot carriers are highly tunable and in this work we investigate their dependence on the material, size and environment of spherical metallic nanoparticles. In particular, we carry out theoretical calculations of hot carrier generation rates and energy distributions for six different plasmonic materials (Na, K, Al, Cu, Ag and Au). The plasmon decay into hot electron-hole pairs is described via Fermi's Golden Rule using the quasistatic approximation for optical properties and a spherical well potential for the electronic structure. We present results for nanoparticles with diameters up to 40 nm, which are embedded in different dielectric media. We find that small nanoparticles with diameters of 16 nm or less in media with large dielectric constants produce most hot carriers. Among the different materials, Na, K and Au generate most hot carriers. We also investigate hot-carrier induced water splitting and find that simple-metal nanoparticles are useful for initiating the hydrogen evolution reaction, while transition-metal nanoparticles produce dominantly holes for the oxygen evolution reaction.