Composition-Dependent Catalytic Activity of Bimetallic Nanocrystals: AgPd-Catalyzed Hydrodechlorination of 4‑Chlorophenol

Ag–Pd bimetallic nanocrystals (NCs) with tunable compositions and narrow size distributions were produced by a one-pot synthesis. The NC growth process was investigated by time-dependent TEM, XRD, and UV–vis studies. In the hydrodechlorination of 4-chlorophenol, the AgPd_<i>x</i> (<i>x</i> = 2, 4, 6, 9, 19) showed pronounced composition-dependent catalytic activities, leading to the AgPd₉ catalyst with excellent activity

Single-Crystalline Octahedral Au–Ag Nanoframes

We report the formation of single-crystalline octahedral Au–Ag nanoframes by a modified galvanic replacement reaction. Upon sequential addition of AgNO₃, CuCl, and HAuCl₄ to octadecylamine solution, truncated polyhedral silver nanoparticles formed first and then changed into octahedral Au–Ag nanoframes, without requiring a conventional Ag removal step with additional oxidation etchant. The nanoframes have 12 sides, and all of the eight {111} faces are empty. The side grows along the [110] direction, and the diameter is less than 10 nm. The selective gold deposition on the high-energy (110) surface, the diffusion, and the selective redeposition of Au and Ag atoms are the key reasons for the formation of octahedral nanoframes

Syntheses of Water-Soluble Octahedral, Truncated Octahedral, and Cubic Pt–Ni Nanocrystals and Their Structure–Activity Study in Model Hydrogenation Reactions

We developed a facile strategy to synthesize a series of water-soluble Pt, Pt_<i>x</i>Ni_1‑<i>x</i> (0 < <i>x </i>< 1), and Ni nanocrystals. The octahedral, truncated octahedral, and cubic shapes were uniformly controlled by varying crystal growth inhibition agents such as benzoic acid, aniline, and carbon monoxide. The compositions of the Pt_<i>x</i>Ni_1‑<i>x</i> nanocrystals were effectively controlled by choice of ratios between the Pt and Ni precursors. In a preliminary study to probe their structure–activity dependence, we found that the shapes, compositions, and capping agents strongly influence the catalyst performances in three model heterogeneous hydrogenation reactions

Molybdenum Disulfide Nanoparticles as Multifunctional Inhibitors against Alzheimer’s Disease

The complex pathogenic mechanisms of Alzheimer’s disease (AD) include the aggregation of β-amyloid peptides (Aβ) into oligomers or fibrils as well as Aβ-mediated oxidative stress, which require comprehensive treatment. Therefore, the inhibition of Aβ aggregation and free-radical scavenging are essential for the treatment of AD. Nanoparticles (NPs) have been found to influence Aβ aggregation process in vitro. Herein, we report the inhibition effects of molybdenum disulfide (MoS₂) NPs on Aβ aggregation. Polyvinylpyrrolidone-functionalized MoS₂ NPs were fabricated by a pulsed laser ablation method. We find that MoS₂ NPs exhibit multifunctional effects on Aβ peptides: inhibiting Aβ aggregation, destabilizing Aβ fibrils, alleviating Aβ-induced oxidative stress, as well as Aβ-mediated cell toxicity. Moreover, we show that MoS₂ NPs can block the formation of the Ca²⁺ channel induced by Aβ fibrils in the cell membrane for the first time. Thus, these observations suggest that MoS₂ NPs have great potential for a multifunctional therapeutic agent against amyloid-related diseases

Highly Active and Selective Catalysis of Bimetallic Rh₃Ni₁ Nanoparticles in the Hydrogenation of Nitroarenes

Because of the requirements of sustainable development as well as the desirability of using molecular hydrogen as a chemical reagent, it is of paramount importance and great challenge to develop highly active and selective catalysts for the hydrogenation of organic molecules, including substituted nitroarenes. We approach this question by probing unsupported bimetallic nanoparticles. A series of novel bimetallic Rh_<i>x</i>Ni_<i>y</i> (<i>x</i>, <i>y</i> = 1, 2, 3) nanoparticles were successfully prepared using our “noble metal-induced reduction” strategy. Unsupported Rh₃Ni₁ nanoparticles were subsequently identified to be a highly active and exceedingly selective catalyst for the hydrogenation of nitroarenes under ambient conditions, underscoring a remarkable synergistic effect of the two metals. Further experiments showed that the Rh₃Ni₁ catalyst could be a highly efficient, selective, and recyclable catalyst for a range of nitroarene substrates. This work showcased the value of bimetallic nanoparticles in catalysts development for sustainable chemistry

Room Temperature Activation of Oxygen by Monodispersed Metal Nanoparticles: Oxidative Dehydrogenative Coupling of Anilines for Azobenzene Syntheses

It is highly challenging but desirable to develop efficient catalysts for the activation of oxygen under mild conditions. Here, we report that various monodispersed metal nanoparticles (Ag, Pt, Co, Cu, Ni, Pd, and Au) efficiently activated molecular oxygen under mild conditions, illustrated by the aerobic oxidation of anilines to form either symmetric or asymmetric aromatic azo compounds. This discovery indicates that exploiting the catalytic power of nanoparticles could enable sustainable chemistry suitable for important oxidation reactions

Direct Syntheses of Styryl Ethers from Benzyl Alcohols via Ag Nanoparticle-Catalyzed Tandem Aerobic Oxidation

Ag nanoparticle-catalyzed aerobic oxidation of benzyl alcohols in basic DMSO gave efficient formation of styryl ethers, featuring single carbon transfer and CC and C–O bond formation. A deuterium labeling experiment established that DMSO was the carbon source. Further experiments showed the reaction proceeded through a styryl sulfoxide intermediate originating from basic DMSO and transient benzaldehyde. Control reactions in the absence of the Ag NPs or air indicated that oxidation of the styryl sulfoxide was required for the final C–O bond formation. This work demonstrated that metal nanoparticles could be applied to tandem heterogeneous catalysis in organic chemistry