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An effort to prepare different non-stoichiometric Cu

CuFeS

CuFeS2/TiO2 nanocomposite has been prepared by a simple, low-cost mechanochemical route to assess its visible-light-driven photocatalytic efficiency in Methyl Orange azo dye decolorization. The structural and microstructural characterization was studied using X-ray diffraction and high-resolution transmission electron microscopy. The presence of both components in the composite and a partial anatase-to-rutile phase transformation was proven by X-ray diffraction. Both components exhibit crystallite size below 10 nm. The crystallite size of both phases in the range of 10–20 nm was found and confirmed by TEM. Surface and morphological properties were characterized by scanning electron microscopy and nitrogen adsorption measurement. Scanning electron microscopy has shown that the nanoparticles are agglomerated into larger grains. The specific surface area of the nanocomposite was determined to be 21.2 m2·g−1. Optical properties using UV-Vis and photoluminescence spectroscopy were also investigated. CuFeS2/TiO2 nanocomposite exhibits strong absorption with the determined optical band gap 2.75 eV. Electron paramagnetic resonance analysis has found two types of paramagnetic ions in the nanocomposite. Mössbauer spectra showed the existence of antiferromagnetic and paramagnetic spin structure in the nanocomposite. The CuFeS2/TiO2 nanocomposite showed the highest discoloration activity with a MO conversion of ~ 74% after 120 min irradiation. This study has shown the possibility to prepare nanocomposite material with enhanced photocatalytic activity of decoloration of MO in the visible range by an environmentally friendly manner

Photocatalysts composed of graphitic carbon nitride (g-CN) and TiO2 were efficiently prepared by thermolysis of the MIL-125(Ti) metal organic framework deposited on g-CN. The heterojunction between the 12 nm-sized TiO2 nanoparticles and g-CN was well established and the highest photocatalytic activity was observed for the g-CN/TiO2 (3:1) material. The g-CN/TiO2 (3:1) composite exhibits high visible light performances both for the degradation of pollutants like the Orange II dye or tetracycline but also for the production of hydrogen (hydrogen evolution rate (HER) up to 1330 μmolh−1g−1 and apparent quantum yield of 0.22% using NiS as a cocatalyst). The improved visible light performances originate from the high specific surface area of the photocatalyst (86 m2g−1) and from the efficient charge carriers separation as demonstrated by photoluminescence, photocurrent measurements, and electrochemical impedance spectroscopy. The synthetic process developed in this work is based on the thermal decomposition of metal organic framework deposited on a graphitic material and holds huge promise for the preparation of porous heterostructured photocatalysts.

Elemental sulfur nanoparticles (nanosulfur, S 0 ) have been obtained in a matrix consisting of sodium sulfite (diluent and a final reaction product) and succinic acid (catalyst) by mechanochemical syntheses via the reaction Na2S2O3 · 5H2O + H2(C4H4O4) + zNa2SO3 = (z + 1)Na2SO3 + H2(C4H4O4) + 5H2O+ S 0 , at z = 19.6. It has been shown that free nanodispersed sulfur can be obtained by dissolving the matrix in water. The prepared samples have been characterized using a set of physical and physicochemical methods.

International audience; A facile two-step method was developed to prepare core/shell ZnO/rGO particles from ZIF-8/rGO composites. ZIF-8 particles were first grown at the surface of rGO sheets. Next, ZIF-8 particles were transformed into ZnO particles by thermal decomposition under air at 500 °C. All materials were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Raman spectroscopy, thermogravimetric analysis, and Brunauer−Emmett−Teller analyses. Results obtained show that ZIF-8 particles strongly associate with rGO sheets and that the calcination of this material produces porous core/shell ZnO/rGO particles with an average diameter of ca. 40 nm. The wt % of rGO associated with ZIF-8 particles was varied from 5 to 20%. The ZnO/rGO (10%) particles exhibit the highest photocatalytic activity for the degradation of the Orange II dye under simulated solar light irradiation of weak intensity (5 mW/cm2). This high photocatalytic activity was demonstrated to originate from superoxide O2•− radicals due to the efficient trapping of photogenerated electrons in ZnO by rGO.

Реализацией обменной механохимической реакции NH4Cl + AgNO3 + z NH4NO3 = (z+1) NH4 NO3 + AgCl при z = z1 = 7.22 и z = z2 = 3.64 получены наночастицы хлорида серебра в матрице нитрата аммония - разбавителя и одного из конечных продуктов реакции. Показано образование двойной соли NH4Ag(NO3)2 - промежуточного продукта механической активации. Рассмотрены возможности получения свободных наночастиц AgCl, обусловленные высокой термической стабильностью хлорида серебра по сравнению с другими компонентами системы.