Hybrid Au nanoparticles on Fe3O4@polymer as efficient catalyst for reduction of 4-nitrophenol

Design and synthesis of a new magnetic metal organic framework as a versatile platform for immobilization of acidic catalysts and CO2 fixation reaction

The first report of the use of an acidic magnetic metal organic framework for the chemical fixation of CO2 as an environmentally friendly reaction.

Thermoresponsive Amphiphilic Block Copolymer-Stablilized Gold Nanoparticles: Synthesis and High Catalytic Properties

A series of novel well-defined 8-hydroxyquinoline (HQ)-containing thermoresponsive amphiphilic diblock copolymers {poly(styrene- co-5-(2-methacryloylethyloxy-methyl)-8-quinolinol)- b-poly( N-isopropylacrylamide) P(St- co-MQ)- b-PNIPAm (P1,2), P(NIPAm- co-MQ)- b-PSt (P3,4)} and triblock copolymer poly( N-isopropylacrylamide)- b-poly(methyl-methacrylate- co-5-(2-methacryloylethyloxymethyl)-8-quinolinol)- b-polystyrene PNIPAm- b-P(MMA- co-MQ)- b-PSt (P5) were prepared by reversible addition-fragmentation chain-transfer (RAFT) polymerization, and their self-assembly behaviors were studied. Block copolymer P1-P5-stabilized gold nanoparticles (Au@P1-Au@P5) with a small size and a narrow distribution were obtained through the in situ reduction of gold precursors in an aqueous solution of polymer micelles with HQ as the coordination groups. The resulting Au@P nanohybrids possessed excellent catalytic activity for the reduction of nitrophenols using NaBH₄. The size, morphology, and surface chemistry of Au NPs could be controlled by adjusting the structure of block polymers with HQ in different block positions, which plays an important role in the catalytic properties. It was found that longer chain lengths of hydrophilic or hydrophobic segments of block copolymers were beneficial to elevating the catalytic activity of Au NPs for the reduction of nitrophenols, and the spherical nanoparticles (Au@P5) stabilized with triblock copolymers exhibit higher catalytic performance. Surprisingly, the gold nanowires (Au@P4) produced with P4 have the highest catalytic activity due to a large abundance of grain boundaries. Excellent thermoresponsive behavior for catalytic reaction makes the as-prepared Au@P hybrids an environmentally responsive nanocatalytic material.

Tailored Macroporous Hydrogels with Nanoparticles Display Enhanced and Tunable Catalytic Activity

This work demonstrates that a model system of poly( N-isopropylacrylamide) (PNIPAam) macroporous hydrogels, with tailored microstructures and comprising gold (Au) or silver (Ag) nanoparticles, display enhanced and tunable catalytic activity. These nanocomposites are prepared using polymer templates obtained from melt-processed cocontinuous polymer blends. The reaction rate, controlled by both hydrogel porosity and the PNIPAam lower critical solution temperature, increases by more than an order of magnitude as compared to nonporous gels, and is comparable to micro- or nanocarrier-based systems, with easier catalyst recovery. The fabrication process is scalable, and is compatible with broad choices of polymer blend, gel, and nanoparticle chemistries.

Mussel inspired green synthesis of silver nanoparticles-decorated halloysite nanotube using dopamine: characterization and evaluation of its catalytic activity

Naturally occurring ceramic tubular clay, Halloysite nanotubes (HNTs), having a significant amount of surface hydroxyls has been coated by self-polymerized dopamine in this work. The polydopamine-coated HNTs acts as a self-reducing agent for Ag+ ion to Ag0 in nanometer abundance. Herein, nano size Ag0 deposited on solid support catalyst has been used to mitigate water pollution within 10 min. To establish the versatility of the catalyst, nitroaryl (4-nitrophenol) and synthetic dye (methylene blue) have been chosen as model pollutant. The degradation/reduction of the aforementioned pollutants was confirmed after taking UV–visible spectra of the respective compounds. All the study can make sure that the catalyst is green and the rate constant value for catalytic reduction of 4-nitrophenol and methylene blue was calculated to be 4.45 × 10−3 and 1.13 × 10−3 s−1, respectively, which is found to be more efficient in comparison to other nanostructure and commercial Pt/C nanocatalyst (1.00 × 10−3 s−1).

In situ formation of gold nanoparticles on magnetic halloysite nanotubes via polydopamine chemistry for highly effective and recyclable catalysis

A simple and green approach to fabricate magnetic halloysite nanotubes supported Au nanoparticles composite from bio-inspired polydopamine chemistry was demonstrated for highly effective and recyclable catalysis.

Microbial synthesis of Pd/Fe3O4, Au/Fe3O4 and PdAu/Fe3O4 nanocomposites for catalytic reduction of nitroaromatic compounds

Magnetically recoverable noble metal nanoparticles are promising catalysts for chemical reactions. However, the chemical synthesis of these nanocatalysts generally causes environmental concern due to usage of toxic chemicals under extreme conditions. Here, Pd/Fe3O4, Au/Fe3O4 and PdAu/Fe3O4 nanocomposites are biosynthesized under ambient and physiological conditions by Shewanella oneidensis MR-1. Microbial cells firstly transform akaganeite into magnetite, which then serves as support for the further synthesis of Pd, Au and PdAu nanoparticles from respective precursor salts. Surface-bound cellular components and exopolysaccharides not only function as shape-directing agent to convert some Fe3O4 nanoparticles to nanorods, but also participate in the formation of PdAu alloy nanoparticles on magnetite. All these three kinds of magnetic nanocomposites can catalyze the reduction of 4-nitrophenol and some other nitroaromatic compounds by NaBH4. PdAu/Fe3O4 demonstrates higher catalytic activity than Pd/Fe3O4 and Au/Fe3O4. Moreover, the magnetic nanocomposites can be easily recovered through magnetic decantation after catalysis reaction. PdAu/Fe3O4 can be reused in at least eight successive cycles of 4-nitrophenol reduction. The biosynthesis approach presented here does not require harmful agents or rigorous conditions and thus provides facile and environmentally benign choice for the preparation of magnetic noble metal nanocatalysts.

Rose-like Pd-Fe3O4 hybrid nanocomposite-supported Au nanocatalysts for tandem synthesis of 2-phenylindoles

A facile synthesis of rose-like Pd-Fe3O4 nanocomposites via controlled thermal decomposition of Fe(CO)5 and reduction of Pd(OAc)2, followed by the immobilization of Au nanoparticles (NPs) onto the Pd-Fe3O4 supports, is reported. The morphology of these hybrid nanostructures could be easily controlled by varying the amount of Fe(CO)5 and the reaction temperature. Moreover, the synthesized Au/Pd-Fe3O4 catalyst exhibited high catalytic activity for the tandem synthesis of 2-phenylindoles and demonstrated magnetic recyclability.

Parts per Million Level, Green, and Magnetically-recoverable Triazole Ligand-stabilized Au and Pd Nanoparticle Catalysts

A nano gold or palladium catalyst is encapsulated into a nano reactor via triazole and recovered by an external magnetic field.

Synthesis and characterization of gold complexes with pyridine-based SNS ligands and as homogeneous catalysts for reduction of 4-nitrophenol

Three gold complexes efficiently catalyze 4-nitrophenol reduction to 4-nitroaniline in the presence of NaBH₄ under homogeneous conditions in water.

Triazole-stabilized gold and related noble metal nanoparticles for 4-nitrophenol reduction

The preparation of N-substituted triazole–polyethylene glycol-stabilized metal nanoparticles and their high catalytic activities for 4-nitrophenol reduction.