Distinguishing Inner and Outer-Sphere Hot Electron Transfer in Au/p-GaN Photocathodes

TL;DR

This study uncovers an inner-sphere electron transfer mechanism in Au/p-GaN photocathodes, enhancing understanding of hot electron injection processes crucial for plasmonic photocatalysis and optoelectronic device performance.

Contribution

It reveals a novel inner-sphere hot electron transfer mechanism in Au/p-GaN systems, combining experimental and ab initio methods to improve device efficiency.

Findings

Inner-sphere electron transfer enhances photocathode performance.

Experimental and computational methods reveal new injection pathways.

Mechanistic insights aid in designing better plasmonic devices.

Abstract

Exploring nonequilibrium hot carriers from plasmonic metal nanostructures is a dynamic field in optoelectronics, driving photochemical reactions such as solar fuel generation. The hot carrier injection mechanism and the reaction rate are highly impacted by the metal/molecule interaction. However, determining the primary type of the reaction and thus the injection mechanism of the hot carriers has remained elusive. In this work, we reveal an electron injection mechanism deviating from a purely outersphere process for the reduction of ferricyanide redox molecule in a gold/p-type gallium nitride (Au/p- GaN) photocathode system. Combining our experimental approach with ab initio simulations, we discover that the efficient inner-sphere transfer of low-energy electrons leads to a continuous enhancement in the photocathode device performance in the interband regime. These findings provide important mechanistic insights, showing our methodology as a powerful tool for analyzing and engineering hot-carrier-driven processes in plasmonic photocatalytic systems and optoelectronic devices.