Catalytic Performance in Nitroarene Reduction of Nanocatalyst Based on Noble Metal Nanoparticles Supported on Polymer/s-Layer Protein Hybrids

We present a novel bionanocatalyst fabricated by the adsorption-reduction of metal ions on a polyurethane/S-layer protein biotemplate. The bioinspired support was obtained by the adsorption of S-layer proteins (isolated from Lentilactobacillus kefiri) on polyurethane particles. Silver and platinum nanoparticles were well-loaded on the surface of the support after the combination with metallic salts and reduction with H2 at room temperature. Transmission electron microscopy analysis revealed the strawberry-like morphology of the bionanocatalysts with a particle size, dn, of 2.39 nm for platinum and 9.60 nm for silver. Both systems catalyzed the hydrogenation of p-nitrophenol to p-aminophenol with high efficiency in water at mild conditions in the presence of NaBH4. Three different amounts of bionanocatalyst were tested, and in all cases, conversions between 97 and 99% were observed. The catalysts displayed excellent recyclability over ten cycles, and no extensive damage in their nanostructure was noted after them. The bionanocatalysts were stable during their production, storage, and use, thanks to the fact that the biosupport provides an effective driving force in the formation and stabilization of the metallic nanoparticles. The successful bioinspired production strategy and the good catalytic ability of the systems are encouraging in the search for nontoxic, simple, clean, and eco-friendly procedures for the synthesis and exploitation of nanostructures.

Pt@Metal-Organic Framework (ZIF-8) Thin Films Obtained at a Liquid/Liquid Interface as Anode Electrocatalysts for Methanol Fuel Cells: Different Approaches in the Synthesis

Smart membranes, nanodevices, chemical sensors, and catalytic coatings are some of the applications that make the metal-organic framework (MOF) thin films very important. Encapsulation of nanoparticles in the porous structure of MOFs can lead to the formation of effective catalysts with new unique properties and wide range of applications that may not be obtained by MOFs individually. Three main strategies, ship-in-a-bottle, bottle-around-the-ship, and in situ synthesis including the simultaneous formation of the two components, were applied for the synthesis of Pt(0)@zeolitic imidazolate framework-8 (ZIF-8) thin films at the toluene/water interface. The effects of platinum precursor transfer directions toward the interface on the properties of the films were investigated by using the [PtCl₂(cod)] (where cod = cis,cis-1,5-cyclooctadiene) complex soluble in toluene as the upper phase and K₂PtCl₄ soluble in water as the lower phase. The six obtained films with different morphologies were applied as electrocatalysts for the methanol oxidation reaction. Considerable current density, mass activity, catalyst stability, activation energy, exchange current density, maximum power, and long-term poisoning rate are some of the advantages of the Pt(0)@ZIF-8 catalysts synthesized using the in situ strategy and K₂PtCl₄ as the platinum precursor. Furthermore, we report the formation of Pt@ZIF-8 nanorods at the interfaces without using any stabilizer or template. Our results suggest that the in situ strategy at the liquid/liquid interface is one of the best procedures for the synthesis of Pt(0)@ZIF-8 thin films as a suitable anode electrocatalyst for methanol fuel cells.

Catalytic applications of β-cyclodextrin/palladium nanoparticle thin film obtained from oil/water interface in the reduction of toxic nitrophenol compounds and the degradation of azo dyes

A supramolecular catalyst of Pd/β-cyclodextrin thin film is synthesized via a facile and one-pot procedure at an oil–water interface and applied for the reduction of toxic nitrophenol compounds and the degradation of harmful azo dyes.

ZIF-8 nanoparticles thin film at an oil–water interface as an electrocatalyst for the methanol oxidation reaction without the application of noble metals

Monodispersed and nano-sized ZIF-8 was synthesized at an oil–water interface for the first time and applied as an electrocatalyst for the methanol oxidation reaction in an alkaline medium.

Facile Fabrication of Highly Active Magnetic Aminoclay Supported Palladium Nanoparticles for the Room Temperature Catalytic Reduction of Nitrophenol and Nitroanilines

Magnetically recyclable nanocatalysts with excellent performance are urgent need in heterogeneous catalysis, due to their magnetic nature, which allows for convenient and efficient separation with the help of an external magnetic field. In this research, we developed a simple and rapid method to fabricate a magnetic aminoclay (AC) based an AC@Fe₃O₄@Pd nanocatalyst by depositing palladium nanoparticles (Pd NPs) on the surface of the magnetic aminoclay nanocomposite. The microstructure and the magnetic properties of as-prepared AC@Fe₃O₄@Pd were tested using transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and vibrating sample magnetometry (VSM) analyses. The resultant AC@Fe₃O₄@Pd nanocatalyst with the magnetic Fe-based inner shell, catalytically activate the outer noble metal shell, which when combined with ultrafine Pd NPs, synergistically enhanced the catalytic activity and recyclability in organocatalysis. As the aminoclay displayed good water dispersibility, the nanocatalyst indicated satisfactory catalytic performance in the reaction of reducing nitrophenol and nitroanilines to the corresponding aminobenzene derivatives. Meanwhile, the AC@Fe₃O₄@Pd nanocatalyst exhibited excellent reusability, while still maintaining good activity after several catalytic cycles.

Synthesis and characterization of graphene oxide sheets integrated with gold nanoparticles and their applications to adsorptive removal and catalytic reduction of water contaminants

Here, we report the facile synthesis of graphene oxide-gold (GO-Au) nanocomposites and their use as adsorbents for the removal of toxic industrial dyes from water and as catalysts for the individual and simultaneous reduction of a dye and a nitro compound in aqueous medium. GO sheets were prepared using a modified Hummers method while Au nanoparticles were integrated on GO sheets by reducing Au(iii) ions on the surfaces of GO sheets using sodium citrate as a reducing agent. The prepared composite was characterized with field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), elemental dispersive X-ray analysis (EDX), X-ray diffraction (XRD), Fourier transform infra-red (FT-IR) spectroscopy and thermal gravimetric analysis (TGA). The GO-Au nanocomposite demonstrated efficient adsorption capacities and recyclability for malachite green (MG) and ethyl violet (EV) dyes. The effects of various experimental parameters including temperature, pH, contact time, and adsorbent dose were studied. From the simulation of experimental data with different adsorption isotherms and kinetic models it was found that the adsorption of both the dyes followed the Freundlich adsorption model and a pseudo-second order kinetic model, respectively. Moreover, the adsorbent showed better recyclability for both dyes without any compromise on the removal efficiency. Similarly, the catalytic performance for the reduction of 2-nitroaniline (2-NA) has been investigated in detail by using the prepared nanocomposite as a catalyst. Most importantly, we reported the simultaneous adsorption of cationic and anionic dyes from water using the prepared nanocomposite as well as the simultaneous catalytic reduction of a mixture of EV and 2-NA. So, considering the facile synthesis process and the efficient removal of a variety of dyes and the catalytic performance this work opens up a tremendous opportunity to bring GO based nanocomposites from experimental research to practically applied materials for wastewater treatment.

Ultrasonic assisted synthesis of palladium-nickel/iron oxide core-shell nanoalloys as effective catalyst for Suzuki-Miyaura and p-nitrophenol reduction reactions

In this study, ultrasonic assisted synthesis of Pd-Ni/Fe₃O₄ core-shell nanoalloys is reported. Unique reaction condition was prepared by ultrasonic irradiation, releasing the stored energy in the collapsed bubbles and heats the bubble contents that leads to Pd(II) and Ni(II) reduction. Co-precipitation method was applied for the synthesis of Fe₃O₄ nanoparticles (NPs). Immobilized solution was produced by sonicating the aqueous mixture of Fe₃O₄ and mercaptosuccinic acid to obtain Pd-Ni alloys on Fe₃O₄ magnetic NP cores. The catalytic activity of the synthesized Pd-Ni/Fe₃O₄ core-shells was investigated in the Suzuki-Miyaura CC coupling reaction and 4-nitrophenol reduction, which exhibited a high catalytic activity in both reactions. These magnetic NPs can be separated from the reaction mixture by external magnetic field. This strategy is simple, economical and promising for industrial applications.

Sb2Se3 assembling Sb2O3@ attapulgite as an emerging composites for catalytic hydrogenation of p-nitrophenol

The construction and application of a new type of composite material are achieved more and more attention. However, expected Sb2Se3/attapulgite composites aim to use the low price, and high adsorption of attapulgite in assembling Sb2Se3 is quite difficult to be acquired by a facile and benign environmental hydrothermal method. In this manuscript, we developed a new way for preparation of an emerging composite by means of Sb2O3 as a media linking Sb2Se3 and attapulgite together, and finally won an emerging composite Sb2Se3/Sb2O3@attapulgite, which presented an excellent catalytic properties for catalytic hydrogenation of p-nitrophenol. It was noted that the Sb2Se3/Sb2O3@attapulgite composites exhibited a high conversion rate for the hydrogenation of p-nitrophenol that was up to 90.7% within 15 min, which was far more than the 61.5% of Sb2Se3 sample. The excellent catalytic performance was attributed to the highly dispersion Sb2Se3 microbelts and Sb2Se3@Sb2O3@attapulgite rods, which would improve the adsorption of the reactant species and facility electronic transfer process of the catalytic hydrogenation of p-nitrophenol.

One step photochemical synthesis of clean surfaced sponge-like porous platinum with high catalytic performances

HYPOTHESIS

Template-free and surfactant-free strategies are highly desirable, which might be used for high efficient platinum catalyst developments.

EXPERIMENTS

In this work, a facile one step photochemical synthesis method was developed to prepare sponge-like porous platinum. The present synthesis was performed via ultraviolet light irradiation on a K₂PtCl₄ aqueous solution at ambient condition. The final pore sizes were in the range of 1-3nm. The walls of the pores were formed with platinum nanoparticles of 3-5nm average diameters. For comparisons, pluronic F127 was introduced into the reaction solutions as a surfactant, and sponge-like and dendritic-like platinum nanostructures were obtained. The catalytic activities of these platinum nanomaterials were studied with both menthol oxidation and 4-nitrophenol reduction.

FINDINGS

The sponge-like platinum synthesized without surfactant exhibited higher catalytic activities than the porous platinum with surfactant and the commercial platinum black.

A water-soluble fluorescent hybrid material based on aminoclay and its bioimaging application

A water soluble fluorescent hybrid material by functionalization of aminoclay as an efficient biological stain for bio-imaging.

Sucrose-mediated mechanical exfoliation of graphite: a green method for the large scale production of graphene and its application in catalytic reduction of 4-nitrophenol

A simple and green method for the large scale production of graphene by ball-milling of graphite with sucrose is exploited here.

Room temperature complete reduction of nitroarenes over a novel Cu/SiO2@NiFe2O4 nano-catalyst in an aqueous medium – a kinetic and mechanistic study

The current investigation reports the preparation of a novel system, Cu/SiO₂@NiFe₂O₄, as characterised by XRD, XPS, IR, SEM-EDS, TEM, ICP-AES and VSM data.

Formation of nanoneedle Cu(0)/CuS nanohybrid thin film by the disproportionation of a copper(i) complex at an oil–water interface and its application for dye degradation

A toluene–water planar interface has been used as an ideal template for the self-assembly of a nanoneedle Cu(0)/CuS nanohybrid thin film and Cu(0)/CuS nanoneedles as efficient catalysts for dye degradation.

Effect of metal alloying on morphology and catalytic activity of platinum-based nanostructured thin films in methanol oxidation reaction

In this paper, alloy thin films with a high degree of alloying were synthesized through a liquid–liquid interface method showing remarkable electrocatalytic activity for the methanol oxidation reaction.

The catalytic evaluation of in situ grown Pd nanoparticles on the surface of Fe3O4@dextran particles in the p-nitrophenol reduction reaction

We report the catalytic activity evaluation of in situ grown Pd nanoparticles on the surface of superparamagnetic Fe₃O₄ particles coated with the natural polymer dextran, in the reduction of p-nitrophenol (Nip), in water, by sodium borohydride.

Covalent attachment of 3-(aminomethyl)pyridine to graphene oxide: a new stabilizer for the synthesis of a palladium thin film at the oil–water interface as an effective catalyst for the Suzuki–Miyaura reaction

A toluene–water planar interface has been used as an ideal template for the self-assembly of a Pd/3-(aminomethyl) pyridine-reduced graphene oxide nanohybrid.