Mechanism of hydrogen adsorption on gold nanoparticles and charge transfer probed by anisotropic surface plasmon resonance

TL;DR

This study investigates hydrogen adsorption on 10 nm gold nanoparticles using anisotropic surface plasmon resonance, revealing charge transfer and diffusion of hydrogen atoms on nanoparticle facets with high sensitivity.

Contribution

It introduces a sensitive optical technique to measure tiny LSPR shifts, demonstrating hydrogen diffusion and charge transfer on gold nanoparticles.

Findings

Hydrogen adsorption causes measurable LSPR shifts.

Hydrogen atoms diffuse across nanoparticle facets.

Negative charge transfer from gold to hydrogen is observed.

Abstract

The adsorption of hydrogen on Au nanoparticles (NPs) of size of the order of 10 nm has been investigated by use of localised surface plasmon resonances (LSPR) in the NPs. The samples, formed by Au NPs obtained by oblique angle deposition on glass substrates, display a strong optical dichroism due to two different plasmon resonances dependent on the polarisation of light. This ensured the use of Transmittance Anisotropy Spectroscopy, a sensitive derivative optical technique, which permitted one to measure shifts of the LSPR as small as 0.02 nm upon H adsorption, which is not accessible by conventional plasmonic methods. The measured signal is proportional to the area of the NPs, which shows that H atoms diffuse on their facets. A negative charge transfer from Au to H is clearly demonstrated