Plasmonic photocatalytic reactions enhanced by hot electrons in a one-dimensional quantum well

Hung Ji Huang ,Bo-Heng Liu ,Chun-Ting Lin ,Wan-Sheng Su

doi:10.1063/1.4935950

Abstract

The plasmonic endothermic oxidation of ammonium ions in a spinning disk reactor resulted in light energy transformation through quantum hot charge carriers (QHC), or quantum hot electrons, during a chemical reaction. It is demonstrated with a simple model that light of various intensities enhance the chemical oxidization of ammonium ions in water. It was further observed that light illumination, which induces the formation of plasmons on a platinum (Pt) thin film, provided higher processing efficiency compared with the reaction on a bare glass disk. These induced plasmons generate quantum hot electrons with increasing momentum and energy in the one-dimensional quantum well of a Pt thin film. The energy carried by the quantum hot electrons provided the energy needed to catalyze the chemical reaction. The results indicate that one-dimensional confinement in spherical coordinates (i.e., nanoparticles) is not necessary to provide an extra excited state for QHC generation; an 8 nm Pt thin film for one-dimensional confinement in Cartesian coordinates can also provide the extra excited state for the generation of QHC.

Highlights

A plasmon[1,2,3,4,5,6,7] is the quantized collective motion of free electrons induced in metals under external light illumination
The plasmonic endothermic oxidation of ammonium ions in a spinning disk reactor resulted in light energy transformation through quantum hot charge carriers (QHC), or quantum hot electrons, during a chemical reaction
The results indicate that one-dimensional confinement in spherical coordinates is not necessary to provide an extra excited state for QHC generation; an 8 nm Pt thin film for one-dimensional confinement in Cartesian coordinates can provide the extra excited state for the generation of QHC

Summary

Introduction

A plasmon[1,2,3,4,5,6,7] is the quantized collective motion of free electrons induced in metals under external light illumination. Plasmons can generate giant electromagnetic field and high-density free electrons localized in a small, limited space. Many studies have been conducted on the enhancement of photocatalytic reactions by generated plasmons, and these enhancements have been explained using various physical models.[8,9,10,11,12,13,14,15,16,17] Recently, quantum hot charge carriers (QHC), or hot electrons, generated by the decay of a plasmon were demonstrated to greatly enhance photocatalytic reactions.[2,3,4,5,18] In this study, the plasmonic enhancement of the chemical oxidization of ammonium ions in water is presented. The Arrhenius equation expresses the relationship between the chemical reaction rate constant k and the absolute temperature T:

Methods

Results

Conclusion