Aluminium/iron mixed oxides obtained by co-precipitation method

In last years, various synthesis methods have been used for production of nanomaterials, composites/nanocomposites. For preparation of catalysts are used different methods such as hydrothermal, sol-gel and co-precipitation. Because Fe2O3 -Al2O3 mixed oxide system offer many advantages, its important to know if the combination of two transition metal oxides can affect their stoichiometry, surface, catalytic properties and textural structure. The aim of this study is represented by mixed of oxides who was obtained from the synthesis of aluminum nitrate and iron nitrate who was prepared by the co-precipitation method. Then, the characterization studies about the compounds obtained such as hematite, magnetite and the alumina were performed by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and UV-Vis spectrophotometry

THERMAL BEHAVIOR REGARDING THE THERMOELECTRIC Zn4Sb3 OBTAINED BY MELTING AND QUENCHING METHOD

The present paper is focused on studying the thermal behaviour of the Zn4Sb3 material. The thermal behavior of Zn4Sb3 was investigated using differential thermal analysis which was taken on the temperature range 300 -1073K. The melting point and the solidification temperature of Zn4Sb3 were determined. Also, a characterization of the Zn4Sb3 material from an electrical point of view was done. It was shown the semiconducting behavior of the material as a function of temperature, and also as function of material electrical resistivity and electrical conductivity. Also, the optical and the electrical band gap were estimated

Electrochemical oxygen uptake/release process over Ca-112 electrodes in aqueous solutions

This paper presents the electrochemical study of Y3+ substitution with Ca2+ ions on intake/release of oxygen. These studies were performed using alkaline solution (1 mol L-1 KOH) and also neutral solution (0.5 mol L-1 Na2SO4). All electrochemical behavior presented in this paper has been studied by cyclic voltammetry

Investigation of Cu2O as photocathode for P-type dye-sensitized solar cells

In p-type dye-sensitized solar cells (p-DSSCs), NiO is the most commonly used p-type semiconductor [1]. Considering the drawbacks of NiO, alternative p-type semiconductors with better optical transparency, lower VB edge position and higher hole mobility are desired for p-DSSCs [2]. The cuprous oxide (Cu2O) is a natively p-type semiconductor with a direct band gap of about 1.9–2.2 eV [3]. Non-toxic nature, the stability, natural abundance, low cost production, good electrical properties and a good absorption coefficient for visible light prompted to investigate the cuprous oxide as a material suitable for the realization of low cost and large scale p-DSSCs [4]. the nanoparticles have been intensively studied as photocathodes materials for DSSCs because of their larger specific surface areas to absorb more dye molecules. At the same time, the small-sized particles have shown that the inefficient ability to scatter the solar radiation which reduces the light-harvesting efficiency. Based on these premises, we propose to investigate the effect of micrometer-size structures on the photovoltaic performance of p-DSSCs based on cuprous oxide. In this work, 3D hierarchical structure built of the micrometer dendritic rods and the porous truncated octahedrons have been successfully synthesized via a facile one-step hydrothermal methods using copper (II) acetate and ethyl cellulose as reactants. The DSSC based on the porous structure exhibits approximately 15% increase in JSC and VOC than 3D hierarchical structure. XRD patterns of the Cu2O_1 and Cu2O_2 compound, obtained from hydrothermal method are shown in figure 1. All the diffraction peaks could be indexed as Cu2O (cuprite) with cubic structure (space group: Pn-3m; JCPDS Nr. 01-074-1230), only a small amount of CuO is detected as impurity in Cu2O_2 sample. The formation of CuO phase is determined by the time reaction which in the case of Cu2O_2 is still small to establish completely Cu+1 oxidation state

Mining activity: Environmental impact in the West area of Romania

Pollution is a major problem updated in every corner of the world. The sources of pollution are diverse, from the natural pollution to the anthropogenic pollution. Anthropogenic pollution has a significant impact. Industrial activity, with all its fields, represents one of the most important sources of anthropic pollution. Also, the mining activities can be a source of pollution worth considering. Even if the mining activity has been completed, the possibility of pollution exists. Mining activity is the major source of industrial waste. At present, the mining units can fall into three categories: active mining, where the activity continues; in conservation mining, where the closing and greening program has not yet been applied; closed mining, which are in the Closing and Greening Program. The most affected environmental factors can be the sources of water, soil, but also air

Electrochemical oxygen uptake/release process on Ca doped Y-114 electrodes in aqueous solutions

In present study, the electrochemical characterization of Y0.5Ca0.5BaCo4O7 compound in aqueous solution: alkaline (1 molL-1 KOH) and neutral (0.5 mol L-1 Na2SO4) was followed, correlated with the study of oxygen intake/release process. The use of neutral aqueous solutions is an element of originality in electrochemical studies performed on this family of layered cobalt perovskites. Electrochemical behavior has been studied by cyclic voltammetry and chronoelectrochemical methods: chronoamperometry and chronocoulometry

Three-dimensional graphene nanosheets as cathode catalysts in standard and supercapacitive microbial fuel cell

© 2017 The Authors Three-dimensional graphene nanosheets (3D-GNS) were used as cathode catalysts for microbial fuel cells (MFCs) operating in neutral conditions. 3D-GNS catalysts showed high performance towards oxygen electroreduction in neutral media with high current densities and low hydrogen peroxide generation compared to activated carbon (AC). 3D-GNS was incorporated into air-breathing cathodes based on AC with three different loadings (2, 6 and 10mgcm−2). Performances in MFCs showed that 3D-GNS had the highest performances with power densities of 2.059±0.003Wm-2, 1.855±0.007Wm-2 and 1.503±0.005Wm-2 for loading of 10, 6 and 2mgcm−2 respectively. Plain AC had the lowest performances (1.017±0.009Wm-2). The different cathodes were also investigated in supercapacitive MFCs (SC-MFCs). The addition of 3D-GNS decreased the ohmic losses by 14–25%. The decrease in ohmic losses allowed the SC-MFC with 3D-GNS (loading 10mgcm−2) to have the maximum power (Pmax) of 5.746±0.186Wm-2. At 5mA, the SC-MFC featured an “apparent” capacitive response that increased from 0.027±0.007F with AC to 0.213±0.026F with 3D-GNS (loading 2mgcm−2) and further to 1.817±0.040F with 3D-GNS (loading 10mgcm−2)