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

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

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)

Influence of ceramic separator’s characteristics on microbial fuel cell performance

This study aimed at evaluating the influence of clay properties on the performance of microbial fuel cell made using ceramic separators. Performance of two clayware microbial fuel cells (CMFCs) made from red soil (CMFC-1) typically rich in aluminum and silica and black soil (CMFC-2) with calcium, iron and magnesium predominant was evaluated. These MFCs were operated under batch mode using synthetic wastewater. Maximum sustainable volumetric power density of 1.49 W m-3 and 1.12 W m-3 was generated in CMFC-1 and CMFC-2, respectively. During polarization, the maximum power densities normalized to anode surface area of 51.65 mW m-2 and 31.20 mW m-2 were obtained for CMFC-1 and CMFC-2, respectively. Exchange current densities at cathodes of CMFC-1 and CMFC-2 are 3.38 and 2.05 times more than that of respective anodes, clearly indicating that the cathodes supported much faster reaction than the anode. Results of laboratory analysis support the presence of more number of exchangeable cations in red soil, representing higher proton exchange capacity of CMFC-1 than CMFC-2. Higher power generation was observed for CMFC-1 with separator made of red soil. Hence, separators made of red soil were more suitable for fabrication of MFC to generate higher power