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The Bi2O3/Bi2SiO5 heterostructures were obtained with various samples of silica as a precursor: on the basis of biogenic silica isolated from rice husk and rice straw and the silica of mineral origin. A mixture of Bi(NO3)3 and SiO2 with a mass content of 15% was used for synthesizing all the samples. Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscope (SEM), X-ray phase, X-ray fluorescence, and ultraviolet-visible diffused reflectance spectroscopy (UV-vis DRS) were used to systematically characterize as-obtained materials. Photodegradation of methyl orange in neutral aqueous solutions (pH = 6.8) under UV irradiation was studied to evaluate their photocatalytic activities. Morphology, bandgaps, the value of the zero charge point, and photocatalytic activity of the samples depended on the characteristics of the original silica. The degree of methyl orange degradation reached the maximum values (81%-85%) for samples based on precipitated silica from rice husks, straw, and the minimum value (16%) for a composite with thermal silica from rice straw. Composites based on thermal silica from rice husks and reagents from mineral raw materials did not statistically differ from each other in the degree of methyl orange degradation (67%-74%). [ABSTRACT FROM AUTHOR]

Herein, a method for the preparation of hard carbon via carbonization of chemically modified (molybdenum-doped) commercially available viscose fiber was developed. The effects of a molybdenum dopant on carbonization conditions were studied. The carbonization products retained the fibrous structure and flexibility. The structural features of the synthesized hard carbon materials were investigated, and their relationships to the carbonization temperature and the amount of the molybdenum dopant were analyzed. The texture of materials was studied, and correlations between the specific surface area and porosity, on the one hand, and the synthesis conditions, on the other, were discovered. The usefulness of the products as anode materials for sodium-ion batteries was evaluated. The electrochemical tests, together the extant relevant data, indicate that molybdenum induces the structural rearrangement of the carbon framework upon annealing, accompanied by the growth and ordering of graphite-like nanoclusters. The material prepared at 1050°C exhibited the best electrochemical performances among the synthesized products and the stable cyclability with a capacity of 290 (mA h)/g at a current density of 25 mA/g. [ABSTRACT FROM AUTHOR]

Manganese-doped anatase with a nanosized morphology (as spherically shaped nanoparticles) has been synthesized under hydrothermal conditions. It has been shown that manganese is incorporated into the titanium dioxide structure to form substitutional solid solutions. At high dopant concentrations, part of the introduced manganese goes to the formation of α-MnO2. A significant increase in the optical activity in the visible range and a decrease in the bandgap width down to ~2.4 eV are observed for manganese-doped anatase because of the appearance of extrinsic (multivalent Mn ions) and intrinsic compensating (oxygen vacancies) defects. It has been found that manganese-doped samples are diluted magnetic semiconductors, and the magnetic characteristics increase with increasing manganese content. All manganese-containing samples demonstrate photocatalytic activity in the degradation reaction of indigo carmine when irradiated with visible light. The degree of dye degradation depends on the content of manganese in the samples and reaches >90%. [ABSTRACT FROM AUTHOR]

Materials based on nickel- and zinc-doped TiO2(B), consisting of mesoporous nanorods, are produced via hydrothermal synthesis. Complementary methods are used to study the mechanism of doping and the physicochemical properties of the synthesized samples. According to the results of testing of materials in the cells of lithium- and sodium-ion batteries, it is found that the doping of TiO2(B) with nickel and zinc has a favorable effect. [ABSTRACT FROM AUTHOR]

In this study, TiO2(B) metastable β-TiO2 or bronze TiO2 was doped with Zr4+ (Zr/Ti = 0.03; 0.06) through hydrothermal approach. The materials were shown to be nanobelts (thickness: 10–l5 nm, width: 50–100 nm, length: several micrometers, and specific surface area: 72–76 m2/g). Doping the TiO2(B) structure with Zr4+ was found to be accompanied by the formation of Ti1−xZrxO2(B) (x = 0.03; 0.06) solid solutions, where the unit cell volume increases as the zirconium content rises. For doped TiO2(B), electrical conductivity increased by two order of magnitude, from 1.6 × 10−11 in an undoped sample to 8.2 × 10−10 S/cm for Zr/Ti = 0.06. After 90 charge/discharge cycles at the C/10-rate, Ti0.94Zr0.06O2(B) electrode had a capacity of 165 (mA h)/g. For undoped TiO2(B), this parameter was only 135 (mA h)/g. Moreover, Ti0.94Zr0.06O2(B) retained a reversible capacity of about 107 (mA h)/g even under an increased current load (5C). The major factors influencing the electrochemical behavior of Ti0.94Zr0.06O2(B) are the enhanced stability of the structure to lithiation/delithiation and an improved electrical conductivity. [ABSTRACT FROM AUTHOR]

Recent results of plasma electrolytic oxidation modification of the surfaces of Ti as well as NiTi alloy obtained by a joint effort of Institute of Chemistry FEB RAS, Institute of Strength Physics and Materials Science SB RAS, and Russian Ilizarov Scientific Center for Restorative Traumatology and Orthopedics are demonstrated in comparison with the literature ones. Conditions of coating synthesis determine their functional designation. It is presented that purposeful selection of the electrolyte composition used for coating formation has allowed to obtain layers containing Ca and P, whose bioactivity is confirmed both in vitro and in vivo. Prospects for the application of the plasma electrolytic oxidation method for the formation of the composite bioinert coatings at the titanium nickelide surface improving its morphological structure and electrochemical properties and significantly reducing the quantity of nickel ions releasing into the organism are demonstrated. [ABSTRACT FROM AUTHOR]

Nanostructured TiO and TiO-ZrO (4 wt % ZrO) in the anatase crystal modification have been synthesized through a template sol-gel route. Morphological and structural features of these compounds have been studied by scanning electron microscopy and Raman spectroscopy. The synthesized materials are porous nanostructured microtubes 10-300 μm in length and 3-5 μm in diameter. The size of nanoparticles forming tubes is 15-25 nm. Doping with zirconia (≤4 wt %) does not change the anatase crystal structure; at the same time, this is accompanied by an increase in the unit cell parameters and in the number of defects in the lattice. The availability of nanostructured TiO-ZrO as an anode material for a Li-ion battery has been evaluated by the galvanostatic discharge-charge method. After 20 cycles in the range 3-1 V, the reversible capacity of TiO-ZrO was 140 mA h/g, while the capacity of the undoped TiO was 65 mA h/g. The developed method for modification of titania is efficient from the standpoint of producing a promising anode material for Li-ion battery. [ABSTRACT FROM AUTHOR]

It has been demonstrated for the first time that an original method of pulsed high-voltage discharge is efficient for the preparing of nanostructures promising for application in Li-ion batteries. In particular, a nanostructured TiO-TiOF composite is synthesized as a result of destructing Ti electrodes and polytetrafluoroethylene in plasma. It is established that TiO-TiOF is a porous structure composed of TiO and TiOF nanocrystallites 40-200 nm in size. The diameter of pores varies from 3 to 5 nm. The discharge capacity of a Li/TiO-TiOF half-cell during a first cycle at a current density of 20 mA/g in voltage range from 3 to 0.005 V amounted to 1370 mA h/g, which exceeds (due to the presence of TiO) the theoretical capacity of TiOF. The cycling of Li/TiO-TiOF characterizes the stability of the capacity about 205 mA h/g after the 20th cycle. [ABSTRACT FROM AUTHOR]

The possibility of using hydrolysis lignin as a cathode material for primary lithium batteries has been demonstrated for the first time. The electroconductivity, morphology, and element composition of hydrolysis lignin have been investigated by means of the methods of impedance spectroscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The main parameters and the behavior of lignin-based lithium batteries were studied using two electrolyte systems: 1 M LiBF in γ-butyrolacton and 1 M LiClO in propylene carbonate. The chemical composition of cathode materials upon battery discharge down to 0.9 V was studied by the methods of X-ray photoelectron spectroscopy and infrared spectroscopy. The suggestions on possible electrochemical reactions occurring in the lithium/hydrolysis lignin system were made on the basis of the products composition analysis. [ABSTRACT FROM AUTHOR]