Improved Catalytic Reaction of Biotemplated Palladium Nanoparticles through Immobilized Metal Affinity Purification

To investigate the effect purification plays on nanoparticle (NP) synthesis and catalytic activity, three copies of Pd4 (TSNAVHPTLRHL) fused to the N-terminus of Green Fluorescent Protein (GFP) was produced recombinantly and its characteristics pre and post purification was assessed. An E. coli expression system was employed, and purification was performed with Immobilized Metal Affinity Column (IMAC). Transmission electron microscopy (TEM) was utilized to examine the morphology of NPs synthesized with an enriched protein sample and ImageJ was used to determine the average size to be 2.44 nm. The turnover frequency of fabricated NP from the purified protein was analyzed by a model Suzuki-Miyaura coupling reactions and determined to be 33,000 hr-1. This value is three times higher than the turnover frequency when crude lysate containing (Pd4)3-GFP was used during NP synthesis. This result shows that enrichment enhanced the catalytic activity of NP.

Stable Silver Nanoparticles Synthesis by Citrus Sinensis(Orange) and Assessing Activity Against Food Poisoning Microbes

Silver nanoparticles are considerecl as good antimicrobial agent. AgNPs were synthesized by mixing silver nitrate solution with citrus sinesb extract for 2 h at 37 and analyzed by UV-visible spectra, SEM, XRD, and FTIR. AgNPs were tested against B. subtilis, Shigello, S. oureus, ond E. coli. Minimum inhibitory concentration of AgNPs was 20 I^g/mL for B. subtilis and Shigello and 30 I^g/mL for S. oureus and E. coll. Antibiofilm activity （80% to 90%） was observed at 25 IJg/mL. AgNPs were stable for five months with sustained an＇timicrobial activity. Biosynthesized AgNPs can bE： used to inhibit food poisoning microbial growth.

Facile Synthesis of Rose-Like NiO Nanoparticles and Their Ethanol Gas-Sensing Property

In this study, rose-like nickel oxide （NiO） nanoparticles with diameters of 400-500 nm are prepared on ITO glass substrates by simple electrodeposition in NiSO46H20 solution at room temperature followed by oxidation in air. Scanning electron microscopy, x-ray diffraction and a transmission electron microscope are used for analyses of the NiO nanoparticles. The ethanol gas sensitivity of these nanoparticles is studied. The results indicate that the rose-like NiO nanoparticles could be used for the fabrication of ethanol gas sensors to monitor the low concentration of ethanol gas in air. Furthermore, at 5 ppm, the NiO nanorose-based sensors show a high response to ethanol （Rg/Ra = 8.4）.

Controlled Synthesis of CuO Nanoparticles by TritonX-100-based Microemulsions

CuO nanoparticles were synthesized by using microreactors made of Triton X-100/n-hextnol/cyclohexane/water W/O microemulsion system. Basic synthesis parameters were determined. The results of thermo gravimetric/differential thermal analysis（TG/DTA） of the precursor products indicated that the proper calcination temperature was about 500 ℃. The nanoparticles were characterized by X-ray diffraction（XRD）, transmission electron microscopy（TEM） and UV-visible spectra. It was indicated that the grain size was highly dependent on the ratio of water to surfactant（R）. With the R value increasing, the particles size became larger.

Microwave hydrothermal synthesis and characterization of rare-earth stannate nanoparticles

Rare-earth stannate（Ln_2Sn_2O_7（Ln = Y, La–Lu）） nanocrystals with an average diameter of 50 nm were prepared through a facile microwave hydrothermal method at 200°C within 60 min. The products were well characterized. The effect of reaction parameters such as temperature, reaction time, p H value, and alkali source on the preparation was investigated. The results revealed that the p H value plays an important role in the formation process of gadolinium stannate（Gd_2Sn_2O_7） nanoparticles. By contrast, the alkali source had no effect on the phase composition or morphology of the final product. Uniform and sphere-like nanoparticles with an average size of approximately 50 nm were obtained at the p H value of 11.5. A possible formation mechanism was briefly proposed. Gd_2Sn_2O_7：Eu^（3＋） nanoparticles displayed strong orange-red emission. Magnetic measurements revealed that Gd_2Sn_2O_7 nanoparticles were paramagnetic. The other rare-earth stannate Ln_2Sn_2O_7（Ln = Y, La–Lu） nanocrystals were prepared by similar approaches.

Coercivity Ageing Effect on FePt Nanoparticles in Mesoporous Silica via Stepwise Synthesis Strategy

FePt nanoparticles in mesoporous silica are fabricated by a simple stepwise synthesis strategy.A pre-annealing temperature-dependent coercivity-ageing effect in FePt nanoparticles is observed at room temperature.For facecentered cubic（fcc）structured FePt nanoparticles,the ageing effect is sensitive to the pre-annealing temperature,especially when the temperature is close to the phase-transition.The special magnetic behavior of FePt nanoparticles reveals that the physical properties gradually change between fee and face-centered tetragonal structures,and will deepen our understanding of the mechanism of such magnetism in FePt nanoparticles.

Seed-mediated synthesis of dendritic platinum nanostructures with high catalytic activity for aqueous-phase hydrogenation of acetophenone

This work reports a facile and efficient seed-mediated method for the synthesis of dendritic platinum （Pt） nanoparticles （NPs） at low temperatures of 55-60 ℃ in water, using L-ascorbic acid as a reducing agent and sodium citrate as a capping agent. It is found that the dendritic Pt NPs （10-150 nm） are composed of tiny Pt nanocrystals, which nucleate and grow through the introduced smaller Pt seeds with diameters of 3-5 nm. Further investigation shows that the dendritic Pt nanostructures display excellent catalytic performance in an aqueous-phase aromatic ketone hydrogenation reaction, including： （i） acetophenone conversion rate of 〉 90%, with smaller dendritic Pt NPs （10-46 nm） offering a higher conversion efficiency; （ii） high chemoselectivity toward carbonyl group （90.6%-91.5%）, e.g., the selectivity to l-phenylethanol is -90.1% with nearly 100% acetophenone conversion for 10 nm dendritic Pt NPs within 60 rain, under mild reaction conditions （20 ℃, 1.5 bar H2 pressure, and 1.5 tool% catalyst）. The high catalytic activity, selectivity and stability of the dendritic Pt nanostructures under the organic solvent-free conditions make them promising for many potential applications in green catalytic conversion of hydrophilic biomass derived compounds.

Role of size and pretreatment of Pd particles on their behaviour in the direct synthesis of H_2O_2

Two families of catalysts, based on Pd nanoparticles supported on ceramic asymmetric tubular alumina membranes, are studies in the direct synthesis of H2O2. They are prepared by depositing Pd in two ways：（i） reduction with N2H4 in an ultrasonic bath and（ii） by impregnation-deposition. The first preparation leads to larger particles, with average size of around 11 nm, while the second preparation leads to smaller particles, with average size around 4 nm. The catalytic membranes were tested as prepared, after thermal treatment in air and after further pre-reduction with H2 in mild（100 ℃） conditions. Samples were characterized by TEM, CO-chemisorption monitored by DRIFTS method and TPR, while catalytic tests have been performed in a semi-batch recirculation membrane reactor. Experimental catalytic results were analysed using two kinetics models to derive the reaction constants for the parallel and consecutive reactions of the kinetic network. Smaller particles of Pd show lower selectivity due to the higher rate of parallel combustion, even if the better dispersion of Pd and thus higher metal surface area in the sample lead to a productivity in H2O2 similar or even higher than the sample with the larger Pd particles. Independently on the presence of smaller or larger Pd nanoparticles, an oxidation treatment leads to a significant enhancement in the productivity, although the catalyst progressively reduces during the catalytic process. The inhibition of the parallel combustion reaction（to water） induced from the calcination treatment remains after the in-situ reduction of the oxidized Pd species formed during the pre-treatment.This is likely due to the elimination of defect sites which dissociatively activate oxygen, and tentatively attributed to Pd sites able to give three- and four-fold coordination of CO.

Plasma Syntheses of Carbon Nanotube-Supported Pt-Pd Nanoparticles

It is reported that the highly dispersed Pt nanoparticles on carbon nanotubes can be synthesized under mild conditions by in situ plasma treatment.The carbon nanotube was pretreated by O_2 plasma to transform into oxide carbon nanotubes（O-CNTs）,and then it was mixed with the precursors（the mixture of H_2 PtCl_6and PdCl_6）.After that,the O-CNTs and the precursors were simultaneously treated by H_2 plasma.The precursors were transformed into Pt-Pd nanoparticles（NPs）and the O-CNTs transformed into CNT.The synthesized CNT-based Pt-Pd nanoparticles were characterized by scanning electron microscopy,transmission electron microscopy,X-ray diffraction and X-ray photoelectron spectroscopy.All the analysis showed that the Pt-Pd nanoparticles were deposited on CNT as a form of face-centered cubical structure.

Seasoning Chinese cooking pans: The nanoscience behind the Kitchen God's blessing

The Chinese iron pan can function as a nonstick pan even without a polytetrafluoroethylene(PTFE)coating after a“Kitchen God blessing”seasoning process.We simulate this process and disclose the science behind the“Kitchen God blessing,”finding that through repeated oil-coating and heating,the reversible insertion and extraction of oxygen atoms split the surface of the iron pan,gradually producing Fe 3 O 4 nanoballs.These balls give the iron pan a conditional hydrophobicity property,meaning the pan would be hydrophilic when the ingredients contain much water and hydrophobic when they contain less water.The former enables heat to be transferred rapidly through the nanoballs while the latter slows down the heat transference and prevents the pan from sticking.This discovery provides an approach of generating nanoballs on the surface of the metal and also discloses the secret of the fantastic taste produced by cooking with a Chinese iron pan.

A Facile Synthesis of Monodisperse Au Nanoparticles and Their Catalysis of CO Oxidation

Monodisperse Au nanoparticles(NPs)have been synthesized at room temperature via a burst nucleation of Au upon injection of the reducing agent t-butylamine-borane complex into a 1,2,3,4-tetrahydronaphthalene solution of HAuCl4·3H2O in the presence of oleylamine.The as-synthesized Au NPs show size-dependent surface plasmonic properties between 520 and 530 nm.They adopt an icosahedral shape and are polycrystalline with multiple-twinned structures.When deposited on a graphitized porous carbon support,the NPs are highly active for CO oxidation,showing 100%CO conversion at-45°C.

Synthesis of cobalt, palladium, and rhenium nanoparticles

Over the past decade,metal nanoparticles(MNPs)have attracted extensive attention due to their unique physiochemical properties that make them highly applicable in various fields such as chemical sensing,energy storage,catalysis,medicine,and environmental engineering.Their physiochemical properties depend drastically on the MNP size and morphology,which are largely determined by their synthesis methods.Research on MNPs predominantly focused on coinage metals(Au,Ag and Cu),but in the last decade research on metals with a relatively high melting temperature such as Pd,Co,and Re has seen rapid increases,mainly driven by their potential applications as catalysts.This paper presents the recent advances on different synthesis techniques of Co,Pd,and Re nanoparticles,their resulting nanostructures,as well as existing and potential applications.

Chitosan-based Nanosystems as Drug Carriers

The formation and application of polymeric nanomaterials is great demand in science,industry,biotechnology,and medicine due to the possibility of achieving a significant improvement in the physicochemical,mechanical,and barrier properties of polymers and using them as drug carriers and fillers,which is especially promising for biodegradable polymers such as chitosan and their derivatives.The article presents methods for creating polymer nanostructures based on polysaccharides and,in particular,chitosan.Obtaining nanostructured samples of chitosan using the approaches of chemical transformation and modification of polysaccharides is an urgent scientific problem,the solution of which makes it possible to obtain new polymer systems of great practical interest.The medical aspects of the use of polymer carriers based on chitosan for the treatment of various diseases are discussed.The unique specificity of the properties of chitosan and nanomaterials derived from it,with the properties inherent in this natural polymer,can serve as a promising future,especially in the field of medicine.

Rapid high-temperature synthesis of SAPO-34 nanoparticles

Decreasing particle size results in larger increase of external surface area and shorter diffusion path, both reducing mass and heat transfer resistances in catalysis and sorption. A rapid high-temperature hydrothermal synthesis method was developed to synthesize uniform nanoparticles of SAPO-34 zeolite with high crystallinity. To investigate the effects of temperature and synthesis time on purity and crys- tallinity of the final products, the crystallization temperature was increased from 468 to 673 K while the synthesis time was decreased from 24h to 45 rain. The products were characterized by XRD and SEM techniques. It was found that high temperature and short synthesis time reduce the particle size and change the morphology of the SAPO-34 final product.

THERMODYNAMIC AND PARTICLE-DYNAMIC STUDY FOR COMBUSTION SYNTHESIS OF TITANIA NANOPARTICLES

Recent referential studies on combustion synthesis of titania nanoparticles were briefly reviewed. Com-putations based on the minimization of Gibbs free energy were conducted to find the equilibrium compositions, the op-timal reaction temperature, the suitable mole ratio of oxygen to titanium tetrachloride, and the best inlet positions of tita-nium tetrachloride. The mean particle diameter was obtained from particle-dynamic simulation. A combustion apparatus was setup to synthesize titania nanoparticles by the oxidation and hydrolysis of titanium tetrachloride at high tempera-tures. Experimental investigation verified some results obtained from thermodynamic and particle-dynamic computations.

Understanding bottom-up continuous hydrothermal synthesis of nanoparticles using empirical measurement and computational simulation

Continuous hydrothermal synthesis was highlighted in a recent review as an enabling technology for the production of nanoparticles. In recent years, it has been shown to be a suitable reaction medium for the synthesis of a wide range of nanomaterials. Many single and complex nanomaterials such as metals, metal oxides, doped oxides, carbonates, sulfides, hydroxides, phosphates, and metal organic frameworks can be formed using continuous hydrothermal synthesis techniques. This work presents a methodology to characterize continuous hydrothermal flow systems both experimentally and numerically, and to determine the scalability of a counter current supercritical water reactor for the large scale production （〉1,000 T-year-1） of nanomaterials. Experiments were performed using a purpose-built continuous flow rig, featuring an injection loop on a metal salt feed line, which allowed the injection of a chromophoric tracer. At the system outlet, the tracer was detected using UV/Vis absorption, which could be used to measure the residence time distribution within the reactor volume. Computational fluid dynamics （CFD） calculations were also conducted using a modeled geometry to represent the experimental apparatus. The performance of the CFD model was tested against experimental data, verifying that the CFD model accurately predicted the nucleation and growth of the nanomaterials inside the reactor.

Amine facilitates the synthesis of silica-supported ultrasmall bimetallic nanoparticles

Supported catalysts based on metal nanoparticles are a class of widely used heterogeneous catalysts in industry.The catalytic performances of supported metal catalysts are highly determined by many parameters of metal nanoparticles such as their particle size,composition,surface structure and also interfacial interaction with supports[1].Supported metal catalysts are

Study of Photocatalytic Activity of a Nanostructured Composite of ZnS and Carbon Dots

Environmental pollution jeopardizes our existence. For this purpose, research is moving more and more towards the search for economic means and green chemistry to curb this phenomenon. In this context, the photocatalytic activity of zinc sulfide nanoparticles (ZnS NPs) and nanostructured composite ZnS/carbon dots (ZnS/CDs) was evaluated after their synthesis. The results of X-ray diffraction (XRD) analysis indicate that the crystal structure of ZnS/CDs is identical to that of the cubic phase structure of ZnS, revealing that the cubic phase structure of ZnS was not altered in the presence of CDs. Indeed, there is no additional peak in the crystal structure of ZnS/CDs, revealing that the crystalline structure of ZnS is not responsible for the difference in photocatalytic activity between ZnS/CDs and ZnS NPs. Moreover, analysis performed by transmission electron microscopy (TEM) shows aggregation of the synthesized ZnS and ZnS/CDs nanoparticles with an average size estimated around 10 nm and 12 nm, respectively. In addition, the reflectance study in the visible range shows a reduction in the sunlight reflection intensity using ZnS/CDs compared to the capability of ZnS NPs. Photocatalytic degradation tests reveal that ZnS/CDs have the best methylene blue (MB) degradation rate. Indeed, under the optimal conditions, the photocatalytic activity can reach 100% efficiency within 100 min and 240 min of sunlight exposure for the degradation of 7.5 mg/L MB using ZnS/CDs and ZnS, respectively. This improvement in photocatalytic activity of ZnS/CDs may be due to the presence of CDs which can permit to undergo a reduction of reflection properties of ZnS NPs in the visible range. These results show that CDs can play a key role in enhancing the photocatalytic activity of ZnS, and suggest that ZnS/CDs could be used as eco-friendly composite materials for the degradation of organic pollutants of similar structures in the aquatic environment under solar irradiation.

Synthesis and opto-electrical properties of Cu2NiSnS4 nanoparticles using a facile solid-phase process at low temperature

Cu_2NiSnS_4 nanoparticles were prepared for the first time using a facile solid-phase process at a temperature of 180 °C. The crystalline structure, morphology and optical properties of the Cu_2NiSnS_4 nanoparticles were characterized by means of X-ray diffraction(XRD), field emission scanning electron microscopy(FESEM), transmission electron microscope(TEM) and ultraviolet-visible(UV-vis) spectrophotometer. The band gap and conversion efficiency of Cu_2NiSnS_4 nanoparticles were studied at various temperature. The results showed that the Cu_2NiSnS_4 nanoparticles exhibited an optimum band gap of 1.58 e V and a conversion efficiency of 0.64% at 180 °C, indicating that it maybe be useful in low-cost thin film solar cells.

Gold nanoparticles functionalized with supramolecular macrocycles

Gold nanoparticles （AuNPs） functionalized with supramolecular macrocycles are versatile and diverse hybrid nanomaterials, which combine and enhance the characteristics of the two components. In this mini-review, we summarize the recent research progress on the synthesis and assembly of AuNPs functionalized with different supramolecular macrocyclic compounds, i.e., crown ethers, cyclophanes, cyclodextrins （CDs）, cucurbit[n]urils （CB[n]）, calix[n]arenes, and pillar[n]arenes （PIn]A）. Meanwhile, applications of these supramolecular hybrid nanomaterials in the fields of sensors, biomedicine and plasmonic devices are also presented.