Synthesis of iron-doped TiO2 nanoparticles by ball-milling process : the influence of process parameters on the structural, optical, magnetic, and photocatalytic properties

Titanium dioxide (TiO2) absorbs only a small fraction of incoming sunlight in the visible region thus limiting its photocatalytic efficiency and concomitant photocatalytic ability. The large-scale application of TiO2 nanoparticles has been limited due to the need of using an ultraviolet excitation source to achieve high photocatalytic activity. The inclusion of foreign chemical elements in the TiO2 lattice can tune its band gap resulting in an absorption edge red-shifted to lower energies enhancing the photocatalytic performance in the visible region of the electromagnetic spectrum. In this research work, TiO2 nanoparticles were doped with iron powder in a planetary ball-milling system using stainless steel balls. The correlation between milling rotation speeds with structural and morphologic characteristics, optical and magnetic properties, and photocatalytic abilities of bare and Fedoped TiO2 powders was studied and discussed.This work was partially financed by FCT-Fundacao para a Ciencia e Tecnologia-under the project PTDC/FIS/120412/2010: "Nanobased concepts for Innovative & Eco-sustainable constructive material's surfaces.

High rate capabilities Fe3O4-based Cu nano-architectured electrodes for lithium-ion battery applications

All battery technologies are known to suffer from kinetic problems linked to the solid-state diffusion of Li in intercalation electrodes, the conductivity of the electrolyte in some cases and the quality of interfaces. For Li-ion technology the latter effect is especially acute when conversion rather than intercalation electrodes are used. Nano-architectured electrodes are usually suggested to enhance kinetics, although their realization is cumbersome. To tackle this issue for the conversion electrode material Fe3O4, we have used a two-step electrode design consisting of the electrochemically assisted template growth of Cu nanorods onto a current collector followed by electrochemical plating of Fe3O4. Using such electrodes, we demonstrate a factor of six improvement in power density over planar electrodes while maintaining the same total discharge time. The capacity at the 8C rate was 80% of the total capacity and was sustained over 100 cycles. The origin of the large hysteresis between charge and discharge, intrinsic to conversion reactions, is discussed and approaches to reduce it are proposed. We hope that such findings will help pave the way for the use of conversion reaction electrodes in future-generation Li-ion batteries

The flora and vegetation of rocky outcrops in three municipalities in the northern region of Ceará, Brazil: phytosociological characterization

Veja material suplementar em <https://doi.org/10.6084/m9.figshare.5915233.v2O presente estudo teve como objetivo identificar a flora e a vegetação dos afloramentos rochosos isolados e de baixa altitude (lajedos), na vegetação de Caatinga Arbustiva Aberta, que se encontram nos municípios de Sobral, Groaíras e Santa Quitéria, no estado do Ceará, Brasil e propor uma classificação fitossociológica para estas comunidades xerófilas. Foram definidas cinco áreas de coleta de dados com elevada proporção de rochas expostas (> 80%) onde as excursões de campo decorreram em março de 2014 e 2015 (3º56’S e 40º23’W, 4º01’S e 40º05’W, 4º07’S e 40º08’W, 4º09’S e 40º09’W e 4º03’S e 40º00’W). No estudo da vegetação aplicou-se os métodos TWINSPAN (two-way indicator species analysis) e o clássico sigmatista de Braun-Blanquet. As áreas mínimas dos inventários fitossociológicos variaram de 8 a 16 m2. Foram coletadas as espécies vegetais que crescem em fissuras, fendas e ilhas de vegetação que se encontram em afloramentos rochosos. Foram registradas 88 espécies, distribuídas em 59 gêneros e 30 famílias botânicas. Fabaceae foi a família que se destacou em riqueza específica (20 spp.), seguida por Poaceae (dez spp.), Euphorbiaceae (sete spp.) e Convolvulaceae (seis spp.). Quanto ao endemismo foram registradas, em vegetação rupestre, 19 espécies endêmicas para o Brasil. Na análise fitossociológica da vegetação propôs-se estudar a comunidade de Pilosocereus gounellei (FA.C.Weber) Byles & Rowley e Encholirium spectabile Mart. ex Schult. & Schult.f. e a de Crateva tapia L. e Combretum leprosum Martinfo:eu-repo/semantics/publishedVersio