Stabilizing Gold Nanoparticles by Solid Supports

Abstract

Catalysis by supported gold nanocatalysts has attracted much attention recently. However, gold nanoparticles tend to sinter under realistic conditions (e.g., under elevated temperatures or in reaction media), leading to degraded activity. Although there are many excellent reviews covering various aspects of gold catalysis, few have focused on the stabilization of gold nanoparticles on solid supports. Here we summarize several synthesis strategies for the stabilization of gold nanoparticles on solid supports, including: (1) pre-modification of supports before loading gold; (2) post-modification of supported gold catalysts; (3) dispersion of gold oxide dumbbell structures on supports; (4) in situ transformation of supported alloy catalysts into metal oxide modified supported gold catalysts; and (5) development of Au@oxide core-shell or yolk-shell structures. These synthesis strategies not only help develop new gold catalysts with tailored structures and better catalytic performance, but also furnish some ideas for the development of other supported metal catalysts. In addition, the observations on the enhanced thermal stability of these new gold catalysts provide new opportunities for future fundamental research.

Thermal stability of oxide-supported gold nanoparticles

“…There are a few reports on the growth of Au nanoparticles supported on TiO 2 upon high-temperature treatment and under oxidizing atmosphere [7]. Akita et al reported that Au nanoparticles of 2.1 nm on TiO 2 grew to 9.7-nm particles upon calcination in air at 600°C for 4 h [32].…”

“…Gold is the most active catalyst for CO oxidation at room temperature which makes Au catalysts very interesting for this application [2][3][4][5][6]. However, when the engine becomes hot, it reaches the temperatures as high as 700°C, and high-temperature treatment often causes growth of Au nanoparticles [7][8][9][10][11][12][13][14]. For bulk Au, the melting point is 1064°C, and the Hüttig temperature at which surface atoms become mobile is 319°C.…”

“…For instance, Au nanoparticles on Al 2 O 3 have shown excellent stability upon treatment at 650°C under oxidizing conditions [2,26,27]. However, Au/TiO 2 catalyst, which is the most studied type of Au catalyst, is known to grow during CO oxidation [28][29][30] as well as during high-temperature treatment under oxidizing atmosphere [7], though the exact conditions that cause the growth are under discussion [29,30]. Au/TiO 2 catalysts are known to deteriorate during storage, as they are light and moisture sensitive [31,32].…”

Impacts of oxygen vacancies on the electrocatalytic activity of AuTiO2 nanocomposites towards oxygen reduction

“…In these earlier studies, it is generally difficult to control the deposition and dispersion of metal nanoparticles on the oxide surfaces [13][14][15]. Horvath et al [16] employed two different methods to mitigate such an issue.…”

Microstructure Characterization of Noble Metal-Silica Nanocomposites

“…A wellknown is the fact that unique properties of nanoparticles are related with their stability. One method for stabilization the metallic nanoparticles is their deposition on a solid support [11]. The specific properties of solid material may determine the final properties of the nanoparticles.…”