Preparation of Ag nanoparticle loaded mesoporous γ-alumina catalyst and its catalytic activity for reduction of 4-nitrophenol

Fabrication of silver nanoparticles decorated on sodium alginate microbeads enriched with keratin and investigation of its catalytic and antioxidant activity

In this study, an environmentally friendly, effective, easily synthesizable and recoverable nano-sized catalyst system (Ag@NaAlg-keratin) was designed by decorating Ag nanoparticles on microbeads containing sodium alginate (NaAlg) and keratin obtained from goose feathers. The structure, morphology and crystallinity of the Ag@NaAlg-keratin nanocatalyst were evaluated by XRD, FT-IR, FE-SEM, EDS/EDS mapping and TEM analyses. Catalytic ability of designed Ag@NaAlg-keratin nanocatalyst was then investigated against 4-nitrophenol (4-NP) and methyl orange (MO) reductions. Ag@NaAlg-keratin nanocatalyst effectively reduced 4-NP in 6 min and MO in 5 min, with rate constants of 0.17 min-1 and 0.16 min-1, respectively. Additionally, activation energies (Ea) were found as 39.8 kJ/mol for 4-NP and 37.9 kJ/mol for MO. Performed recyclability tests showed that the Ag@NaAlg-keratin nanocatalyst was easily recovered due to its microbead form and successfully reused five times, maintaining both its activity and structure. Furthermore, antioxidant activity of Ag@NaAlg-keratin nanocatalyst was the highest (73.16 %).

CoFe2O4 Nanoparticles Grown within Porous Al2O3 and Immobilized on Graphene Nanosheets: A Hierarchical Nanocomposite for Broadband Microwave Absorption

Demands to develop efficient microwave-absorbing materials are increasing with the advancement of information technology and the exponential rise in the usage of electromagnetic devices. To reduce electromagnetic interference and to overcome the adverse effects caused by microwave exposure resulting from the excessive usage of electromagnetic devices, microwave absorbers are very necessary. In addition, radar-absorbing materials are essential for stealth technology in military applications. Herein, we report a nanocomposite in which CoFe₂O₄ (CF) nanoparticles were grown within the porous structure of Al₂O₃ (PA), and this CoFe₂O₄-loaded Al₂O₃ (PA-CF) nanocomposite was immobilized on the surface of nanometer-thin graphene sheets (Gr). Owing to the hierarchical structure created by the constituents, the (60PA-40CF)₉₀-Gr₁₀ nanocomposite exhibited excellent microwave-absorption properties in the X-band region with a reflection loss (RL) value of ∼-30.68 dB (∼99.9% absorption) at 10.71 and 9.04 GHz when thicknesses were 2.0 and 2.3 mm, respectively. This nanocomposite demonstrated its competence as a lightweight, high-performance microwave absorber in the X-band region, which can be utilized in the applications of pioneering stealth technology.

An exclusive deposition method of silver nanoparticles on TiO2 particles via low-temperature decomposition of silver-alkyldiamine complexes in aqueous media

The low-temperature decomposition of Ag(i)–dmpda complexes catalytically occurs on TiO₂ surfaces in water.

Chemoselective reduction of nitro and nitrile compounds using an Fe3O4-MWCNTs@PEI-Ag nanocomposite as a reusable catalyst

Chemoselective reductions by an Fe₃O₄-MWCNTs@PEI-Ag nanocomposite.

Fabrication and microstructure of quartz ceramics with orderly-arranged carbon filler

Ceramics with tailored pore structure are showing potential applications in some special fields. For fabricating quartz ceramics with orderly–arranged carbon filler, a combination of 3D printing, vacuum suction filtration and sintering was explored to fabricate quartz ceramics with highly–ordered and well–connected big pore channels. The spatial lattice structure in the polylactic acid (PLA) template fabricated by 3D printing together with raw material ratio and sintering temperature has great effect on the properties and pore structure of the porous quartz ceramics. To demonstrate the technical feasibility for fabricating quartz ceramics with orderly–arranged filler, carbon powder was taken as an example and fully filled in the big pore channels of the porous quartz ceramics via vacuum impregnation method. By choosing the quartz ceramics with only highly–ordered and well–connected big pore channels as substrate, quartz ceramics with orderly–arranged carbon filler were successfully obtained.

Palladium immobilized on in situ cross-linked chitosan superfine fibers for catalytic application in an aqueous medium

Chitosan composite superfine fibers with a diameter of 321 ± 99 nm were prepared by electrospinning with PEO as the co-spinning polymer and itaconic acid as the in situ cross-linking agent.

Gold, silver and nickel nanoparticle anchored cellulose nanofiber composites as highly active catalysts for the rapid and selective reduction of nitrophenols in water

Highly active metal nanoparticle (MNP) supported cellulose nanofiber (CNF) composites (Au/CNF, Ni/CNF and Ag/CNF) were prepared for the reduction of 4- and 2-nitrophenols (4-NP and 2-NP) in water. Transmission electron microscopy (TEM) images showed that the ultrafine nanoparticles (Au, Ni and Ag NPs) were uniformly deposited on CNFs surface. The content of Au (9.7 wt%), Ni (21.5 wt%) and Ag (22.6 wt%) in Au/CNF, Ni/CNF and Ag/CNF respectively was determined by energy dispersive spectroscopy (EDS) and inductive coupled plasma-mass spectroscopy (ICP-MS) analysis. The chemical state of the MNPs in Au/CNF, Ni/CNF and Ag/CNF was determined by X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). The significant metal-support interaction was studied by means of XPS. The Au/CNF, Ni/CNF and Ag/CNF demonstrated excellent catalytic activity towards the reduction of nitrophenols to aminophenols in water. To our delight, even a very low amount of catalyst was also found to be good enough to achieve 100% reduction of 4- and 2-NP with a higher reaction rate (within 5 min). The best rate constant (k_app) values were determined for the cellulose nanocomposites. To the best our knowledge, Au/CNF, Ni/CNF and Ag/CNF are the most efficient nanocatalysts for the reduction of 4- and 2-NP reported to date. The catalytic performance of Au/CNF, Ni/CNF and Ag/CNF was compared with previously reported results. A possible mechanism has been proposed for these catalytic systems.

Metal nanoparticles supported cellulose nanofiber composites (Au/CNF, Ni/CNF and Ag/CNF) were found to be highly efficient nanocatalysts for the rapid and selective reduction of nitrophenols in water.

Preparation of a magnetically separable CoFe2O4supported Ag nanocatalyst and its catalytic reaction towards the decolorization of a variety of dyes

CoFe₂O₄supported Ag nanoparticles were investigated as a catalyst for the decolorization of 4-nitrophenol, Congo red, rhodamine B and dye mixtures.

Micro/nano-structured polyaniline/silver catalyzed borohydride reduction of 4-nitrophenol

Micro/nano-structured polyaniline/Ag composites with different morphologies were prepared. The composites were applied as a catalyst in the borohydride reduction reaction of 4-nitrophenol and showed comparable catalytic performance.