Efficient hot carrier dynamics in near-infrared photocatalytic metals

TL;DR

This study uses ab initio methods to analyze hot carrier dynamics in Pd and Pt metals, revealing their potential for near-infrared photocatalytic applications and providing detailed insights into their relaxation times and generation efficiencies.

Contribution

It provides the first microscopic characterization of hot carrier dynamics in Pd and Pt in the near-infrared range using many-body perturbation theory.

Findings

Hot carriers are mainly generated in the near-infrared range.

Pt has a 16% higher electron-phonon mass enhancement than Pd.

Pd hot electrons have relaxation times up to 35 fs at 0.5 eV above Fermi energy.

Abstract

Photoexcited metals can produce highly-energetic hot carriers whose controlled generation and extraction is a promising avenue for technological applications. While hot carrier dynamics in Au-group metals have been widely investigated, a microscopic description of the dynamics of photoexcited carriers in the mid-infrared and near-infrared Pt-group metals range is still scarce. Since these materials are widely used in catalysis and, more recently, in plasmonic catalysis, their microscopic carrier dynamics characterization is crucial. We employ \emph{ab initio} many-body perturbation theory to investigate the hot carrier generation, relaxation times, and mean free path in bulk Pd and Pt. We show that the direct optical transitions of photoexcited carriers in this metals are mainly generated in the near-infrared range. We also find that the electron-phonon mass enhancement parameter for Pt is 16 $\%$ higher than Pd, a result that help explains several experimental results showing diverse trends. Moreover, we predict that Pd (Pt) hot electrons possess total relaxation times of up to 35 fs (24 fs), taking place at approximately 0.5 eV (1.0 eV) above the Fermi energy. Finally, an efficient hot electron generation and extraction can be achieved in nanofilms of Pd (110) and Pd (100) when subject to excitation energies ranging from 0.4 to 1.6 eV.