Hydrogenation is a widely used reaction in the oil processing and industrial organic synthesis. UiO-66 is a prom-ising porous organic-inorganic material that can be used as a support for catalytically active particles. The key part in the application of highly porous UiO-66 is the search of a simple synthesis method that meets international environmental standards. In this study, a "rational" method for the synthesis of MOFs was used to produce UiO-66. The use of pre-synthesized multinuclear zirconia clusters facilitates the synthesis of the desired network to-pology, enabling the process to be conducted in an environmentally friendly aqueous solution. The effects of re-action temperature, linker volume concentration and solvent type on the specific surface area and thermal properties were also evaluated in this work. We studied the composition, structure and physicochemical properties of the obtained compounds by IR spectroscopy, TGA and XRD analysis. The proposed procedure has been shown to yield UiO-66 with high specific surface area (SBET = 885 m2/g) and to extend the thermal stability range up to 490 °C. The post-synthetic modification of the obtained UiO-66 with the introduction of catalytically active Pd (Pd/UiO-66) was carried out, and high selectivity (83,0 %) of the obtained Pd/UiO-66 exhibited high selectivity in the hydrogenation reaction of p-chloronitrobenzene into p-chloroaniline in comparison with the traditional Pd/Al2O3.

The present work focuses on the synthesis of Fe3O4 magnetite core@shell type nanoparticles modified with three types of ligands: Magnetite with activated carbon (MAC), Magnetite with silica (tetraethoxysilane, TEOS, and 3-aminopropyltriethoxysilane, APTES) (MTA) and Magnetite with silica, APTES and humic acids (MTAH). The MTAH sample shows greater porosity in comparison to MTA, and MAC samples. The band gap of MTAH is 4.08 eV, which is higher than MTA (2.92 eV), and MAC (2.80 eV). Rietveld quantitative phase analysis of all derivatives was performed and compared with all three samples. The LPG sensing at room temperature shows the highest sensor response of 9.42, in comparison to 3.87 sensor response for MAC, and 4.60 for MTA. This approximately double sensor response increment is justified with the help of band gap, porosity, and size of all 3 the samples. The MTAH sample shows the lowest response-recovery time of 9.33 and 10.78 s respectively in comparison to MAC and MTA samples. In conclusion, this manuscript describes the synthesis procedure of different derivatives of Fe3O4 core@shell materials along with the relation of LPG sensing with different parameters of the materials.

Bimetallic FeCo and FeNi nanoparticles attract much attention due to their promising magnetic properties and a wide range of practical applications as recording and storage media, catalytic systems in fuel cells, supercapacitors, lithium batteries, etc. In this paper, we propose an original approach to the preparation of FeCo- and FeNi/N-doped carbon nanocomposites by means of a coupled process of frontal polymerization and thermolysis of molecular co-crystallized acrylamide complexes. The phase composition, structure, and microstructure of the resulting nanocomposites are studied using XRD, IR spectroscopy, elemental and thermal analysis, and electron microscopy data. The main magnetic characteristics of the synthesized nanocomposites, including the field dependences and the ZFC-FC curves peculiarities, are studied. It is shown that the obtained FeCo/N-C nanocomposites exhibit exchange bias behavior at low temperatures. In turn, FeNi/N-C nanocomposites are ferromagnetically ordered.

The introduction of nanoparticles and their homogeneous distribution in the polymer matrix, as well as their size, can have a significant effect on the mechanical properties of composite materials. In this work, we studied the mechanical characteristics of TiO2/epoxy nanocomposites with different contents and sizes of nanoparticles. The preparation of nanocomposites was carried out by a stepwise curing (at 90 and 160 °C) of ED-20 dianic epoxy resin in the presence of an aromatic hardener with the addition of titanium (IV) dioxide nanoparticles preliminarily synthesized by the plasma-chemical method. Ultrasonic dispersion was used to achieve a uniform distribution of nanoparticles in the polymer matrix. The chemical and phase composition, the structure of the as-synthesized TiO2 nanoparticles, and the resulting epoxy nanocomposites were characterized by elemental analysis, X-ray diffraction, transmission and scanning electron microscopy, and infrared spectroscopy. The mechanical properties of the nanocomposites were determined by the static tensile test, and the impact toughness was determined by the Charpy method. The glass transition temperature and thermal stability of the TiO2/epoxy nanocomposites were studied by thermal analysis methods. The formation of an interfacial layer between the TiO2 nanoparticles and an epoxy matrix has been shown for the first time by spectral methods. It is shown that the mode of curing and ultrasonic dispersion used, as well as varying the content and dispersity of the TiO2 nanoparticles, make it possible to obtain epoxy nanocomposites with simultaneously improved deformation-strength characteristics and impact strength values.

The present article addresses the preparation of nanostructured scandium polyacrylamide deposited on borosilicate glass substrates of 1.0 cm × 1.0 cm × 0.2 cm dimensions to investigate the variations in the electrical parameters with adsorption/desorption of water in a controlled humidity glass chamber. Field emission scanning electron microscopy (FESEM) analysis showed that the material had spherically shaped clusters. X-ray diffraction (XRD) revealed the amorphous nature of the polymer whereas crystalline nature of the metal part in complex. Minimum particle size was reported as 2 nm by Zeta nanosizer which was further confirmed by high-resolution transmission electron microscopy (HRTEM). Energy band gap of the film was anticipated as 4.03 eV by UV–Vis spectrophotometer. Fourier transform infrared (FTIR) spectroscopy confirmed the presence of the amide group in the material’s chemistry. The film was employed as an electrical humidity sensor. Maximum sensitivity was calculated as 1.85 MΩ/%RH with ~ 96.76% reproducible results. This testing device showed the humidity response and recovery times as 24 s and 101 s, respectively.

In this work, using the advantages of Fe and Co nitrates acting as nucleation sites, we polymerized acrylamide (AAm) complexes using frontal polymerization to obtain FeCo alloy/N-doped carbon composites by converting its original precursor. The results of PAAm coating were found to be extremely useful in suppressing the collapse of the FeCo microstructure during pyrolysis, resulting in a unique hierarchical FeCo@C-N core-shell nanoparticle architecture encapsulated in PAAm-derived carbon nanocages. The thermal, mechanical and magnetic properties of the resulting FeCo/C-N filling polyethylene system have been investigated and presented.

Several approaches for producing metallopolymer hybrid nanocomposites were developed and analyzed. Among of them one-stage synthesis of metal nanoparticles and stabilizing polymer matrix – conjugated thermal (co)polymerization of metal-containing monomers and following thermolysis of forming polymers; in situ reduction of metal ions either in epoxy resins by curing agents or in thermoplastics by thermal decomposition of metal-containing precursor; and post synthetic modification of coordination polymers are considered. Thermal transformations of metal-containing monomers possess the unique way for preparation of nanocomposite materials when metal (or their oxides and carbides) nanoparticles and a stabilizing polymer matrix are formed simultaneously in situ. Molecular and supramolecular organization of nanocomposites obtained can be controlled during the thermal transformation of such monomers in inert or self-generated atmosphere. The main advantage of the synthesis of composites by thermal transformation of metal-containing precursors is in the possibility of formation of nanocomposites with a relatively high concentration of metal phase. Another advantage deals with technological simplicity and the ease to control the processes and the properties of material obtained. The process includes three stages: dehydration, solid-phase polymerization, and pyrolysis of the polymer products formed. The approach makes it possible to adjust the mean particle size in a given range by just choosing the appropriate reaction conditions. The composition of metal nanoparticles, their size and distribution on the size as well as the type and thickness of polymer shell can be controlled on the stage of nanocomposite formation. The nanocomposites obtained reveal ferromagnetic behavior at room temperature with high coercive force and magnetic anisotropy. With aim to control the composition and structure (for example, core–shell type) of ferromagnetic nanomaterials obtained as well as their properties, the reaction conditions such as temperature, ratio of starting compounds, the type of polymer matrix can be varied.

Nowadays, numerous researches are being performed to formulate nontoxic multifunctional magnetic materials possessing both high colloidal stability and magnetization, but there is a demand in the prediction of chemical and colloidal stability in water solutions. Herein, a series of silica-coated magnetite nanoparticles (MNPs) has been synthesized via the sol-gel method with and without establishing an inert atmosphere, and then it was tested in terms of humic acids (HA) loading applied as a multifunctional coating agent. The influence of ambient conditions on the microstructure, colloidal stability and HA loading of different silica-coated MNPs has been established. The XRD patterns show that the content of stoichiometric Fe3O4 decreases from 78.8% to 42.4% at inert and ambient atmosphere synthesis, respectively. The most striking observation was the shift of the MNPs isoelectric point from pH ~7 to 3, with an increasing HA reaching up to the reversal of the zeta potential sign as it was covered completely by HA molecules. The zeta potential data of MNPs can be used to predict the loading capacity for HA polyanions. The data help to understand the way for materials’ development with the complexation ability of humic acids and with the insolubility of silica gel to pave the way to develop a novel, efficient and magnetically separable adsorbent for contaminant removal.

Metal-organic frameworks (MOFs) are promising sacrificial templates for synthesis of carbon functional materials with a relatively high concentration of stabilized metallic species. In this work coordination polymers based on trans,trans-muconic acid and transition metals (Cu, Zn, Ni, Co) were prepared and selected as the precursors for supramolecular organization of nanocomposites. The coordination polymers and metal-containing thermolysis products obtained were characterized using a number of analytical techniques including powder X-ray diffraction, elemental analysis, thermal gravimetric analysis, scanning electron microscopy and volumetric nitrogen adsorption/desorption. This study extends the application of coordination polymers as precursors for designing of carbon materials incorporating metal nanoparticles. It is shown that appropriate choice of metal-organic precursors in solid-phase thermolysis allowed to get materials with determined morphologies.

Herein, the preparation of a Cu0.8Zn0.2Sb2AAm–polymer nanocomposite synthesizedviaa frontal polymerization technique is reported, together with its humidity sensing and photoconductive behaviour.

В статье приведены данные исследований моно и биметаллических наноструктурных композитов на основе Fe и Co, синтезированных методом фронтальной полимеризации с последующим термолизом. Проведена оценка состава, структуры и магнитных свойств нанокомпозитов.

Metal-organic frameworks (MOFs) are promising materials for a number of applications including gas storage and separation. In this work, coordination polymers based on copper and trimesic acid were prepared and characterized by physicochemical methods. Three different synthesis strategies were employed: precipitation at room temperature, hydrothermal method (at different temperatures) and using CO2 as SAS technique (Supercritical AntiSolvent). The obtaining samples was also tested on its capacity in CH4 adsorption at 1 bar and 296 К and 233K.

The present paper reports the investigation of transmitted power through the nanostructured zinc (II) nitrate polyacrylamide deposited substrate to investigate the adsorption/desorption of humidity at room temperature. For this purpose, the precursor of Zn(NO3)2·(AAm)4·2H2O was prepared and used for the deposition of films on borosilicate flat substrates. The film was then investigated using SEM, XRD and UV–Vis absorption techniques. Scanning Electron Microscope showed the macroporous nature of the film with multiple pores in situ. XRD revealed the nature of monomer and polymer. Energy band-gap of the film was estimated as 3.865 eV by UV–Vis spectrophotometer. SAED confirmed the crystalline nature of the material. From Zeta nanosizer, the minimum range of particles was found as 5–20 nm. The film was employed as transmission based opto-electronic humidity sensor. Maximum sensitivity was found as 1.831 µW/%RH. Response and recovery times of the sensor were found as 250 and 37 s respectively. Experiments were repeated time to time and found that the sensor was ~ 96% stable after a long run. Thus the investigated opto-electronic sensor being polymeric is flexible in nature.

Metal carboxylates are widely used in science and technology and have been the subject of intense studies due to the practical importance of their products. The present paper reports the synthesis of MnO2-CoO using metal carboxylates as precursors and the effect of humidity on the transmitted power through its thin film at room temperature. The refractive index of the material was found to be 1.445930 and the peak obtained from the photoluminescence spectra lies in the visible region. TEM reported a minimum grain size of ∼5.7 nm and SAED confirmed the crystalline nature of the material, which was further confirmed by XRD. Fluorescence characteristics also confirmed the low dimensionality of the material. The film was then investigated using SEM which exhibited the porous morphology. Through UV-Vis spectroscopy, it was found that the absorption of the film takes place in the UV region and the optical band-gap was observed to be 3.849 eV from the Tauc plot. The film was employed as a transmission based opto-electronic humidity sensor. Average sensitivity was found to be ∼2.225 μW/% RH with response and recovery times of 47 s and 59 s respectively. Experiments were repeated and the reproducibility of result was found to be ∼89%.

The present paper reports the effect of humidity on the transmitted power through the nanostructured copper (II) nitrate polyacrylamide (Mm) complex film at room temperature. For this purpose, the precursor of Cu(II) nitrate polyAAm was prepared and used for the deposition of a film on the substrates of borosilicate. The film was then investigated using SEM which revealed the uniform leaf-like structured morphology. By UV vis spectrophotometer, it was found that the absorption of light took place in UV region and the corresponding optical energy band-gap was observed as 4.02 eV. The diffraction pattern obtained from TEM showed the crystalline nature of the material. Powder XRD revealed the minimum crystallite size as 9 nm and average size as 13 nm which was further confirmed by the Zeta Nano-sizer. The film was employed as transmission based opto-electronic humidity sensor. Maximum sensitivity was found as similar to 0.838 mu W/%RH. Response and recovery times were found as 31 s and 76 s respectively. Experiments were repeated time to time and reproducibility was found similar to 96% with negligible ageing effect. The investigated sensor being optical in nature has the capability of multiplexing the information with the signal. (C) 2017 Elsevier B.V. All rights reserved.

The thermal behavior of Ni(II) chelates with bi-, tri-, and tetradentate azomethine ligands is examined by the methods of thermal analysis (DSC, TGA, and DTA) and kinetic analysis of weight loss. It is shown that the controlled isothermal thermolysis of azomethine complexes of Ni(II) in a self-generated atmosphere is an efficient method for obtaining nickel-containing nanoparticles. Products of thermal conversions of chelate complexes are characterized by the x-ray phase analysis and SEM. The magnetic properties of the nanocomposites obtained are studied.

The present paper reports the study of modulation in intensity of light transmitted through the thin films of nanostructured yttria stabilized zirconia (YSZ) with the exposure of moisture at room temperature. For this purpose the precursor of YSZ was prepared and used for the deposition of multilayered thin films on borosilicate substrates. The film was then investigated using SEM, XRD and UV-vis absorption techniques. The refractive index of the sensing material was found as 1.448829. SEM showed the macroporous nature of the film and XRD revealed the minimum crystallite size as 5 nm which was further confirmed using TEM and Zeta nanosizer. Energy band-gaps of one-, two-, three- and four- layered films were estimated as 3.927, 3.919, 3.873 and 3.830 eV respectively by UV-vis spectrophotometer. These films were employed as transmission based opto-electronic humidity sensor. Maximum sensitivity was found as similar to 1.937, 1.642, 1.393 and 1.143 mu W/%RH for one, two, three and four- layered films, respectively. Response and recovery times of the sensor were found as 28 s and 30 s respectively. Experiments were repeated time to time and found that the sensor was similar to 94% stable after long run. Thus the investigated opto-electronic sensor has excellent potential to replace an electrical humidity sensor. (C) 2016 Elsevier B.V. All rights reserved.

Metal–polymer nanocomposites, which can weaken the activity of a beta radiation source in undesirable directions at the minimum protection size, are developed. These nanocomposites are fabricated by dispersing metal-containing nanoparticles in thermoplastic matrices. Metal nanoparticles are synthesized by the polymerassisted thermolysis of metal-containing precursors. The composition and structure of the nanocomposites are characterized by elemental and X-ray diffraction analyses and transmission electron microscopy.

Surface functionalization methods of magnetic nanoparticles by photochromic ligands linking covalently with bifunctional alkoxysilanes as spacer bridges are developed. The epoxy nanocomposite films based on the mixture of epoxy oligomer ED-20 and aliphatic epoxy oligomer DEG-1 containing the modified magnetite nanoparticles are obtained via polycondensation. The polycarbonate nanocomposite films are obtained via evaporation of dichloromethane in which polycarbonate and nanoparticles were previously dispersed. The structure, composition, photochromic and magnetic properties of obtained nanocomposites are studied.