Heat generation by branched Au/Pd nanocrystals: influence of morphology and composition.

Marta Quintanilla,Joshua D Smith,Luis M Liz-Marzán,Andreas Seifert,Sara E Skrabalak,Christian Kuttner

doi:10.1039/c9nr05679c

Marta Quintanilla, Joshua D Smith + Show 4 more

Open Access

https://doi.org/10.1039/c9nr05679c

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Abstract

Bimetallic gold-palladium particles were originally proposed as catalysts with tunable reaction rates. Following the development of synthesis routes that offer better control on the morphology and composition of the particles, novel optical sensing functionalities were more recently proposed. Since temperature is a fundamental parameter that interplays with every other proposed application, we studied the light-to-heat conversion ability of Au/Pd bimetallic nanoparticles with a regular octapodal shape. Both compositional (Au-to-Pd ratio) and structural (diagonal tip-to-tip distance and tip width) characteristics were screened and found to be essential control parameters to promote light absorption and efficient conversion into heat. Electromagnetic simulations reveal that the Pd content, and specifically its distribution inside the branched particle geometry, has a profound impact on the optical properties and is an essential criterion for efficient heating. Notably, the optical and photothermal responses are shown to remain stable throughout extended illumination, with no noticeable structural changes to the branched nanocrystals due to heat generation.

Highlights

The microscopic characteristics of a material, such as lattice parameters or the presence of defects, are fundamentally connected to its physicochemical properties
Under the idea that nanomaterials with catalytic and heating properties may lead to local control of chemical reactions,[23] we investigate the lightto-heat conversion abilities of stellated gold–palladium structures dispersed in aqueous media
On account of the synthetic method, the final octopods consist of an inner octahedral gold core from the seed and a branched outer layer of Au/Pd alloy that is enriched with Pd at the tips.[15]

Summary

Introduction

The microscopic characteristics of a material, such as lattice parameters or the presence of defects, are fundamentally connected to its physicochemical properties. To study the effect of the geometry of the particles on their light-to-heat conversion, we prepared a set of five samples with different characteristics (see Fig. 1 and Table 1).

Results

Conclusion