Magnetic Fe3O4-Ag0 nanocomposites for effective mercury removal from water

In this study, magnetic Fe3O4 particles and Fe3O4-Ag0 nanocomposites were prepared by a facile and green method, fully characterized and used for the removal of Hg2+ from water. Characterizations showed that the Fe3O4 particles are quasi-spherical with an average diameter of 217 nm and metallic silver nanoparticles formed on the surface with a size of 23-41 nm. The initial Hg2+ removal rate was very fast followed by a slow increase and the maximum solid phase loading was 71.3 mg/g for the Fe3O4-Ag0 and 28 mg/g for the bare Fe3O4. The removal mechanism is complex, involving Hg2+ adsorption and reduction, Fe2+ and Ag0 oxidation accompanied with reactions of Cl- with Hg+ and Ag+. The facile and green synthesis process, the fast kinetics and high removal capacity and the possibility of magnetic separation make Fe3O4-Ag0 nanocomposites attractive materials for the removal of Hg2+ from wate

UV LIGHT BLOCKING AND CONVERSION BY POROUS EUROPIUM-DOPED TITANIUM DIOXIDE (TIO2-EU) THIN FILMS FOR POTENTIAL PROTECTION OF PHOTOVOLTAIC DEVICES

In recent years, transparent thin films capable of screening and converting ultraviolet (UV) photons into visible spectrum gained significant interest in the protection of photovoltaic devices.We investigated the optical properties and UV screening capability of europium-doped titanium oxide (TiO2 Eu) thin films deposited by the spin-coating method from a solution precursor for the first time in this study. We showed that TiO2-Eu thin films demonstrate europium concentration-dependent optical properties, and the quantum yield of the optimized sample was found to be ~10.2%. Transmittance and photoluminescence measurements suggested that TiO2 Eu thin film can effectively block UV photons (~30.5% at 320 nm) at glass substrate and convert them to the red emission thanks to 5D0/7Fj (j ¼ 0, 1, 2, 3, and 4) Eu (III) electronic transitions. Photodegradation experiments with methylene blue dye revealed that TiO2 Eu thin films offer better UV protection compared to uncoated samples. We strongly believe that porous TiO2 Eu thin films can be effectively utilized as a UV blocking and light conversion coating

A new step in the development of Zn/LiFePO4 aqueous battery

Abstract In recent years, aqueous batteries have gained much attention due to their low production cost and exceptional safety compared to commercial Li-ion battery systems. Three-dimensional (3D) structure could be promising to enhance these batteries energy capacity. In this work, the electrochemical performance of 3D Zn electrode, developed for aqueous rechargeable Zn/LiFePO4 (Zn/LFP) battery system, was studied. Formation of uniformly coated Zn metal on the three-dimensionally organized carbon fibers was verified by field emission scanning electron microscopy (FE-SEM). The electrochemical performance of the battery with this anode was tested for over 50 cycles, where the initial capacity decayed by 11%. Further, poly(methyl methacrylate) (PMMA) and poly(p-phenylene oxide) (PPO) polymer coatings were extensively investigated as a potential separator for the 3D aqueous battery system. Cyclability of PMMA-coated Zn anode was better than that of “plane” Zn; however, the initial capacity of 3D Zn anode was lower than that for the counterpart system

Development of a novel SiO2 based composite anode material for Li-ion batteries

Abstract Research interest towards Li-ion batteries (LIBs) has been significantly increased over decades as high power energy storage systems for renewable energy generators and electrical vehicles emerged. One of the most representative anode materials for LIBs is silica (SiO2) thanks to its high theoretical capacity of 1965 mAh·g-1. However, low coulombic efficiency and irreversible capacity losses during cycling of silica-based anodes are critical issues that need to be addressed nowadays. In this work, a novel three-dimensional SiO2/carbon nanotube/graphene ternary composite was developed as an anode material for LIBs to improve electrochemical performances and to make significant advances as a potential candidate for high-energy applications. The novel ternary composite with weight ratio of 50:25:25 exhibited initial discharge and charge capacities of 732 mAh·g-1 and 260 mAh·g-1 respectively, with initial coulombic efficiency of 82%. Nevertheless, further investigations are necessary for attaining higher specific capacities, enhanced cyclic stability and better rate capability

How xerogel carbonization conditions affect the reactivity of highly disperse SiO2–C composites in the sol–gel synthesis of nanocrystalline silicon carbide

A transparent silicon polymer gel was prepared by sol–gel technology to serve as the base in the preparation of highly disperse SiO2–C composites at various temperatures (400, 600, 800, and 1000°C) and various exposure times (1, 3, and 6 h) via pyrolysis under a dynamic vacuum (at residual pressures of ~1 × 10–1 to 1 × 10–2 mmHg). These composites were X-ray amorphous; their thermal behavior in flowing air in the range 20–1200°C was studied. The encapsulation of nascent carbon, which kept it from oxidizing in air and reduced the reactivity of the system in SiC synthesis, was enhanced as the carbonization temperature and exposure time increased. How xerogel carbonization conditions affect the micro- and mesostructure of the xerogel was studied by ultra-small-angle neutron scattering (USANS). Both the carbonization temperature and the exposure time were found to considerably influence structure formation in highly disperse SiO2–C composites. Dynamic DSC/DTA/TG experiments in an inert gas flow showed that the increasing xerogel pyrolysis temperatures significantly reduced silicon carbide yields upon subsequent heating of SiO2–C sys- tems to 1500°C, from 35–39 (400°C) to 10–21% (1000°C)