Bimetallic Au@Pd‐Au Tadpole‐Shaped Asymmetric Nanostructures by a Combination of Precursor Reduction and Ostwald Ripening

Abstract

Bimetallic and asymmetrich eterostructures represent an emerging class of nanomaterials. They allow for the combination of distinctc ompositions, shapes, and physicochemical features within as ingle particle, thus leading to intriguing properties. We demonstrate herein the synthesis of asymmetric Au@Pd-Au tadpoles having at ail comprising as ingle Au nanorod and as pherical head composed of core@shell Au@Pd decorated with small Au NPs. This material was produced by ac ombination of Au deposition and Ostwald ripening at the surface of Au@Pd core-shell NPs. The overall morphologyc ould be tailored both by controlling the amount of AuCl 4 À employed as precursor and by altering the reactiont ime, leading to shape-dependent optical and catalytic properties. We believe that theser esults mayh ave important implications for the synthesis nanomaterials having novel morphologies and complex functionalities that can combine properties from their different components.The synthesis of bimetallic nanoparticles (NPs) based on gold (Au) and palladium (Pd) has attracted tremendous attention due to their many applications in heterogeneousc atalysis.

Nanocatalysis by noble metal nanoparticles: controlled synthesis for the optimization and understanding of activities

“…It has been demonstrated that there is a strong dependence between performance (both activity and selectivity) and shape, which have been demonstrated by both computational and experimental studies. [64][65][66][67] There is a consensus that catalytic activity and selectivity is dependent on the atomic arrangement of the surface, which in turn can regulate adsorption energies and geometries of substrate molecules and intermediates during a molecular transformation. [64][65][66][67] It is noteworthy that geometric effects that are important in nanocatalysis also include (in addition to the surface arrangement) the presence of steps, kinks, and atoms with low coordination numbers relative to atoms with high coordination numbers.…”

“…[64][65][66][67] There is a consensus that catalytic activity and selectivity is dependent on the atomic arrangement of the surface, which in turn can regulate adsorption energies and geometries of substrate molecules and intermediates during a molecular transformation. [64][65][66][67] It is noteworthy that geometric effects that are important in nanocatalysis also include (in addition to the surface arrangement) the presence of steps, kinks, and atoms with low coordination numbers relative to atoms with high coordination numbers. 68 As a notable example for demonstrating how shape can affect the catalytic activity (geometric effects), we highlight the formic acid electrooxidation in the presence of Pd nanomaterials having different proportions of {100} and {111} facets exposed at their surfaces, as depicted in Fig.…”

“…77 It is clear that composition strongly affects catalytic activities in noble-metal NPs. 27,38,64,[78][79][80] Considering the large applicability of catalysis, it can be stated that even slight changes in the composition of a catalyst (reducing the loading of a more expensive metal, for example) can have large economic and environmental impacts. In this context, the substitution of noble metals (Pt, Pd, Ru, Rh, and Ir) by less expensive ones (Cu, Fe, Ni, Co, etc.)…”

Metallic nanoparticles for electrocatalytic reduction of halogenated organic compounds: A review

“…Recently, increasing attention has been paid to bi-and tri-metallic NPs to obtain higher electrocatalytic property, resulting from the synergistic reaction between metals [98][99][100].…”