Driving energetically-unfavorable dehydrogenation dynamics with plasmonics

TL;DR

This study demonstrates how plasmonic optical excitation can control and enable chemical reactions at energetically unfavorable sites on nanoparticle catalysts, revealing new pathways for catalytic activity.

Contribution

The paper introduces a plasmonic approach to activate and control chemical transformations at sites that are normally energetically inaccessible, using a novel Au-PdHx antenna-reactor system.

Findings

Plasmonic excitation enables hydrogen dissociation at nanorod faces.

Optical control allows access to energetically unfavorable catalytic sites.

In situ microscopy confirms plasmon-induced formation of new reaction sites.

Abstract

Nanoparticle surface structure and geometry generally dictate where chemical transformations occur, with the low-coordination-number, high-radius-of-curvature sites being energetically-preferred. Here, we show how optical excitation of plasmons enables spatially-controlled chemical transformations, including access to sites which, without illumination, would be energetically-unfavorable. We design a crossed-bar Au-PdHx antenna-reactor system that localizes electromagnetic enhancement away from the innately reactive PdHx nanorod tips. Using optically-coupled in situ environmental transmission electron microscopy, we track the dehydrogenation of individual antenna-reactor pairs with varying optical illumination intensity, wavelength, and hydrogen pressure. Our in situ experiments show that plasmons enable new catalytic sites, including hydrogenation dissociation at the nanorod faces. Molecular dynamics simulations confirm that these new nucleation sites are energetically unfavorable in equilibrium and only accessible via tailored plasmonic excitation.