Synthesis and Catalytic Application of Ag₄₄ Clusters Supported on Mesoporous Carbon

Abstract

4-(Fluoro­phenyl)­thiolate-protected Ag44 clusters (Ph4P)4[Ag44(SC6H4F)30] were calcined on mesoporous carbon (MPC) under vacuum at 300–500 °C for 2 h. X-ray absorption spectroscopy, transmission electron microscopy, and thermal-desorption mass spectrometry revealed that sulfur-free Ag44 clusters were successfully produced by the calcination of [Ag44(SC6H4F)30]4– at 300 °C, in sharp contrast to the formation of silver sulfide nanoparticles by the calcination of dodecanethiolate-protected Ag nanoparticles (3.0 ± 0.6 nm). Ag44/MPC was applied in the catalytic dehydrogenation of ammonia–borane (NH3BH3) as a test reaction. It turned out that the Ag44/MPC catalysts produced 1 equiv of H2 from NH3BH3 but only in the presence of O2 (turnover frequency 1.9 × 103 h–1 Ag atom–1). Given that nanoparticles of other metals (Pt, Pd, Rh, Ni, or Ru) produced 3 equiv of H2 under an inert atmosphere, this result indicates that the Ag44/MPC-catalyzed dehydrogenation of NH3BH3 proceeds by a different mechanism from that on other nanoparticles.

Metal Nanoclusters: New Paradigm in Catalysis for Water Splitting, Solar and Chemical Energy Conversion

“…However, in this case, instead of capping, the porous carbonaceous materials are usually used to support the NCs during the in situ synthesis. Moreover, externally synthesized NCs can also be dispersed to prevent sintering/migration during pyrolysis . During catalysis the use of conducting materials, such as graphene and CNTs, as support for NCs is an effective strategy.…”

“…Moreover,e xternallys ynthesized NCs can also be dispersed to prevents intering/migration during pyrolysis. [160] During catalysis the use of conducting materials, such as graphene and CNTs, as support for NCs is an effective strategy.I na ddition to the extended p-p interactions throughout graphene andd opingo fh eteroatoms functionalizations can further increase the number of defective sites and their trapping ability for the stabilization of small NCs (Scheme 8d). [161] In addition to solution-based chemistry (wet chemistry), various sputtering and ionization methods were also developed and usually adopted for the atom-by-atomd eposition in gas phase.…”

Size‐Dependent Cytotoxicity of Thiolated Silver Nanoparticles Rapidly Probed by using Differential Pulse Voltammetry

“…Our work advances one step toward monitoring and understanding the cytotoxicity of thiolated silver nanoparticles.Silver nanoparticles (Ag NPs, including the ultrasmall nanoparticles, so-called nanoclusters, [1,2] and their larger counterparts, nanocrystals [3,4] )h ave been increasingly used for practical applicationsa nd research purposes, [5][6][7][8][9][10][11][12][13][14][15][16] owing to their relatively low cost (compared with Au, Pt, etc.) How to rapidly probe their cytotoxicity?, ands of orth.…”

“…It is found that the cytotoxicity of silver nanoparticles is size dependent in the investigated size range, that is, with increasing size, the cytotoxicityi ncreases. Our work advances one step toward monitoring and understanding the cytotoxicity of thiolated silver nanoparticles.Silver nanoparticles (Ag NPs, including the ultrasmall nanoparticles, so-called nanoclusters, [1,2] and their larger counterparts, nanocrystals [3,4] )h ave been increasingly used for practical applicationsa nd research purposes, [5][6][7][8][9][10][11][12][13][14][15][16] owing to their relatively low cost (compared with Au, Pt, etc.) andi ntriguing physicochemicalp roperties (enhanced Ramans cattering, [17,18] bright fluorescence, [19,20] antimicrobial property, [21][22][23] etc.).…”

Reducing Capsule Based on Electron Programming: Versatile Synthesizer for Size‐Controlled Ultra‐Small Metal Clusters

“…a) Illustration of the cluster fabrication process using RTDPAs with 24 reducinge lectrons. STEM images and size dispersionso fb ,d) Ag24 and c,e) Pt 6 .…”