Toward Monodispersed Silver Nanoparticles with Unusual Thermal Stability

Sun, Junming; Ma, Ding; Zhang, He; Liu, Xiumei; Han, Xiuwen; Bao, Xinhe; Weinberg, Gisela; Pfänder, Norbert; Su, Dang Sheng

doi:10.1021/ja064884j

Cited by 241 publications

(223 citation statements)

References 47 publications

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“…According to the research of Sun et al [38], HCHO was used to get metallic Ag from Ag(NH 3 ) 2 NO 3 precursor at relatively low temperature, which led to diverse distribution of silver nanoparticles in the channels of SBA-15. In the preparation of Au/SBA-15 in this paper, using HCHO can get diverse dispersion of gold pseudospherical nanoparticles (refer to TEM image as Fig.…”

Section: Catalyst Synthesis and Characterizationmentioning

confidence: 99%

Catalytic oxidation of benzyl alcohol on Au or Au–Pd nanoparticles confined in mesoporous silica

Yan

Dou

et al. 2009

Applied Catalysis B: Environmental

144

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Section: Catalyst Synthesis and Characterizationmentioning

confidence: 99%

Catalytic oxidation of benzyl alcohol on Au or Au–Pd nanoparticles confined in mesoporous silica

Yan

Dou

et al. 2009

Applied Catalysis B: Environmental

144

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“…Earlier theoretical studies modelled the effect of support pore size on the kinetics of metal particle migration and coalescence [39]. In addition, the impact of pore size on the growth-stability of Ni/Al 2 O 3 [40], Au/SiO 2 [41] and Ag/SiO 2 [42] catalysts has been experimentally assessed. Generally, narrow pores were found to enhance metal particle stability, which was ascribed to partial confinement of the metal particles by the pore walls leading to impeded particle mobility.…”

Section: Introductionmentioning

confidence: 99%

Interplay between pore size and nanoparticle spatial distribution: Consequences for the stability of CuZn/SiO2 methanol synthesis catalysts

Prieto

Meeldijk

Jong

et al. 2013

Journal of Catalysis

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Particle growth is a major deactivation mechanism for supported metal catalysts. This study reveals that the impact of pore size on catalyst stability is very sensitive to the nanoscale metal distribution. A set of ex-nitrate CuZn/SiO 2 catalysts was synthesised using SiO 2 -gel supports (pore size 5-23 nm). The catalyst compositions were adjusted to attain series of catalysts with either constant pore volumetric (1.6 Cu nm -3 ) or surface (2.0 Cu nm -2 ) overall metal loading. The procedures of thermal decomposition of the metal nitrate precursors were adjusted to achieve < 10 nm Cu particles displaying markedly different nanospatial distributions, i.e either gathered in high-metaldensity domains with small interparticle spacings or evenly distributed over the support with maximum interparticle spacings. Under industrially relevant methanol synthesis conditions, a strong increase of the deactivation rate with the support pore size is observed for catalysts with high-density domains of Cu particles. For these samples the local, nanoscale Cu surface loading is determined by pore size rather than by the overall metal content, as ascertained by HAADF-STEM/EDX.Conversely, Cu nanoparticles evenly spaced on the surface of the SiO 2 carrier show improved stability, being the deactivation rate chiefly independent of the support pore size. The differences in catalyst stability are ascribed to the dominance of different particle growth mechanisms. Our study highlights the significance of local, nanoscale properties for rationalizing the relevance of structural parameters such as pore size for catalyst stability.

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“…30,31 An attractive alternative would be to find a way to create intrinsic reducing sites that are an integral part of the as-synthesized mesoporous silica, thereby simplifying the overall system. This is the focus of the present study.…”

mentioning

confidence: 99%

Spatially Confined Redox Chemistry in Periodic Mesoporous Hydridosilica–Nanosilver Grown in Reducing Nanopores

et al. 2011

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Since the discovery of surfactant-templated periodic mesoporous silica (PMS), 1 nearly two decades of research has yielded a vast array of differently functionalized periodic mesoporous materials, including the periodic mesoporous organosilicas (PMOs), 2 hybrid periodic mesoporous organosilicas (HPMOs), 3 bifunctional periodic mesoporous organosilicas (BPMOs), 4 and recently molecularly imprinted mesoporous organosilicas (MIMOs).5 A common motivating force in the synthesis of these materials has been the search for new functionality and improved applications, whether derived from their form exemplified by fibers, spheres, tubes, films, monoliths, and lithographic patterns, physical properties such as dielectric constant, mechanical strength, or hydrophobicity, pore morphology including hexagonal, cubic, worm, or lamellar, chemical properties of functional groups anchored within the mesopores, and hostÀguest interactions that can be tailored via the chemical composition of the host. One particularly interesting area of application of PMS and PMO materials is as solid supports for nanoscale metals such as silver nanoclusters and nanoparticles important in (photo)catalytic, optical, and biological applications.7À19 Although metallic nanoparticles are not usually known for their efficient emission properties due to quenching by conduction electrons, the highly efficient photoluminescence (PL) observed from molecular silver nanoclusters is exceptional and makes them attractive for optical and biomedical devices.11À17 By contrast, bulk and nanocrystalline forms of silver are only weakly photoluminescent with very low quantum efficiencies of 10 À8 % and 10 À2 %, respectively. 20,21 The development of synthetic methodologies for accessing highly emissive metallic nanoclusters is essential to fully study and exploit their optical properties.Creating few-atom silver clusters and stabilizing them in matrices such as rare gas solids, polymers, and zeolites has a long history and is an ongoing challenge. 22 Mesoporous silica materials in many forms have been functionalized with silver nanoparticles using various methods.23À29 These include direct incorporation of silver ions into the channels of mesoporous silica by simple impregnation, pore surface modification by creating silver ion binding sites, and liquid crystalline templating. 23À29 In all of these synthesis methods, Ag + ions are encapsulated in the pores and then transformed to Ag(0) by a reducing agent or a thermal post treatment. There have also been many attempts to create mesoporous materials with reducing agents that are chemically anchored to the channel walls.30 While modifying mesoporous silica with such tethered reducing agents requires tedious steps, it has been shown to produce uniform Ag nanoparticles and nanowires in the channels. 30,31 An attractive alternative would be to find a way to create intrinsic reducing sites that are an integral part of the as-synthesized mesoporous silica, thereby simplifying the overall system. This is the focus of the pr...

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Toward Monodispersed Silver Nanoparticles with Unusual Thermal Stability

Cited by 241 publications

References 47 publications

Catalytic oxidation of benzyl alcohol on Au or Au–Pd nanoparticles confined in mesoporous silica

Catalytic oxidation of benzyl alcohol on Au or Au–Pd nanoparticles confined in mesoporous silica

Interplay between pore size and nanoparticle spatial distribution: Consequences for the stability of CuZn/SiO2 methanol synthesis catalysts

Spatially Confined Redox Chemistry in Periodic Mesoporous Hydridosilica–Nanosilver Grown in Reducing Nanopores

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