Thermal Activation of Molecularly-Wired Gold Nanoparticles on a Substrate as Catalyst

Abstract

The ability to prepare nanostructured metal catalysts requires the ability to control size and interparticle spatial and surface access properties. In this work, we report novel findings of an atomic force microscopic investigation of a controlled thermal activation strategy of gold catalysts nanostructured via molecular wiring or linking on a substrate surface. Gold nanocrystals of approximately 2 nm diameter capped by decanethiolate and wired by 1,9-nonanedithiolate on mica substrates were studied as a model system. By manipulating the activation temperature (200-250 degrees C), the capping/wiring molecules can be removed to produce controllable particle size and interparticle spatial morphology. The electrocatalytic activity of the activated nanostructures toward methanol oxidation, which is of fundamental importance to fuel cell catalysis, has been demonstrated. The novelty of the findings is the viability of a thermal activation strategy of core-shell nanostructured catalysts based on molecularly predefined interparticle spatial properties on a substrate, which upon further investigation may form the basis for spatially controllable nanostructured catalysts.

Sonogashira reactions catalyzed by water-soluble, β-cyclodextrin-capped palladium nanoparticles

“…Nanoparticle-based materials are increasingly investigated as new types of homogeneous or heterogeneous catalysts (also called nanocatalysts) for various reactions in different media [23][24][25][26][27][28]. Advantages of metal nanoparticles as homogeneous nanocatalysts (HomoNC) include the highly economic efficiency due to their large surface-to-volume ratio, and enhancement of the reaction rate through elimination of the diffusion barrier existing in typical heterogeneous catalytic systems [26].…”

Thiolate‐Protected Aun Nanoclusters as Catalysts for Selective Oxidation and Hydrogenation Processes

“…[1][2][3] Notable examples include lowtemperature oxidation of CO to CO 2 , aerobic oxidation of alcohol, selective oxidation of styrene to an aldehyde and epoxide, and partial oxidation of propene to epoxide. [4][5][6] Despite the ''less-is-more'' success, [7] the origin of the catalytic power of nanoscale gold is still unclear and under intense debate.…”

“…Although the crystal structures of both Au 38 (SR) 24 and Au 144 (SR) 60 have not been attained so far, theoretical predictions have been made recently. [22,23] The lowest-energy structure of Au 38 (SR) 24 is predicted to be composed of a face-fused bi-isocahedral Au 23 core protected by six Au 2 (SR) 3 extended motifs and three RSÀAuÀSR simple motifs; [22] among the motifs, the six Au 2 (SR) 3 are evenly distributed on the two icosahedral Au 13 subunits, while the three Au(SR) 2 motifs bridge the two icosahedral units. For the Au 144 (SR) 60 cluster, it is predicted to be composed of an icosahedral Au 114 core with 30 RSÀAuÀSR simple staples protecting the entire particle.…”

Nanocomposites of Carbon Nanotubes and Semiconductor Nanocrystals as Advanced Functional Material with Novel Optoelectronic Properties

“…Such nanostructures are known as CNT-NP (or CNT-QD) hybrids, or nanocomposites. These nanocomposite materials are potentially useful in a wide range of advanced applications, in the field of chemical sensors [13], biosensors [14], electrocatalysis [15], fuel cells [16], and nanoelectronics [17]. Semiconductor NPs of very small size are known as quantum dots (QDs), as they exhibit interesting size-dependent optical and electronic properties, due to quantum confinement effect.…”