The influence of cadmium precursors upon PdS/Zn1-XCXS photocatalysts efficiency in watersplitting reaction

Photocatalysts based on hexagonal cadmium sulfide have been hydrothermally synthesized using crystalline zinc sulfide as sulfide source, and metal nitrates, acetates, chlorides and sulfatesas cadmium sources. The powders have been characterized by X-Ray Diffraction (XRD), UV-VIS Diffuse Reflectance Spectroscopy (DSR)and Energy-Dispersive X-ray Spectroscopy (EDX). Further experiments of photocatalysis in aqueous solution of sulfide and sulfite for hydrogen evolution, were conducted. The samples were irradiated by monochromatic blue light, generated by an LED. From these experiments it was concluded that the presence of sulfate and acetate anions in the system results in more performantphotocatalysts than the presence of nitrate and especially chlorideanions

Photodegradation of rhodamine B by WO3/glass foam visible-light third generation photocatalyst

This work focused on the evaluation of the photocatalytic activity of the glass foam, a chemically and physical stable support, coated with WO3–visible-light photoactive compound for degradation of rhodamine B. In this way, the removal of the rhodamine B in aqueous solution by WO3/glass foam was compared with the removal of rhodamine B by uncoated glass foam during the experimental stages of the photocatalytic tests: adsorption and visible-light irradiation. The uncoated sample presented no photocatalytic activity, whereas WO3/glass foam removed approximately 33% of rhodamine B from aqueous solution. Physical and chemical characterization of the photocatalyst was carried out by 3D scanning microscopy and energy dispersive X-ray spectroscopy (EDAX) coupled with scanning electrone microscopy (SEM)

Analysis of the crystalline structure and morphological features of perovskite materials performed through different ways

Manganites are mixed oxides of manganese whose broad stoichiometric formula is ABO3, where A is a lanthanide element and B is manganese, with possible oxygen nonstoichiometry. Usually the manganite compounds crystallize within perovskite structure, with the following possible space groups: ideal cubic structure Pm3m, orthorhombic Pbnm or rhombohedral R3CH [1, 2]. The phase purity and physico-chemical properties of perovskites depends upon the preparation methods, thus a variety of chemical methods have been developed to prepare lanthanum manganite nanoparticles at low cost and lower processing temperature [3]. In order to analyze the crystalline structure and morphological properties, LaMnO3 materials were prepared by ultrasonic method with immersed sonotrode in the reaction medium (US) and the sol-gel technique (SG), followed by thermal treatment at low temperature. Structural characterization was performed by X-ray diffraction (XRD), Raman and Fourier transform infrared spectroscopy (FTIR), and morphological analysis was achieved using atomic force microscopy (AFM) and trasmission electron microscopy (TEM)

Studies on the physico-chemical properties of lanthanum manganite prepared by different synthesis methods

Perovskite LaMnO3 and related materials are technologically important for many possible applications due to their unique physical and chemical properties. It is well known that the properties of the materials depend on their synthesis processes, as have been already shown in the literature for a large class of materials [1, 2]. In this work, lanthanum manganite perovskite type materials prepared by ultrasonically method with immersed sonotrode in the reaction medium and sol-gel method, followed by heat treatment at 600°C, 6 h are reported. The asprepared samples were characterized by X-ray diffraction (XRD), thermal gravimetric analysis (TGA), surface area analysis (BET), scanning / transmission electron microscopy (SEM /HRTEM/EDX), and FT-IR spectroscopy. X-ray diffraction indicates that the synthesized materials are well crystallized, with perovskite structure and without any secondary phases

Hydrothermal crystallization of micrometric hydroxyapatite for biomedical applications

The paper presents the synthesis of hydroxyapatite by chemical reaction of calcium nitrate tetrahydrate and diammonium hydrogen phosphate, followed by hydrothermal crystallization at 200-230°C and 24/72 hours. The obtained white powders were characterized by X-Ray Diffraction, Scanning Electron Microscopy and Atomic Force Microscopy, revealing the formation of crystalline hydroxyapatite with microsized lamella shaped crystals, when the crystallization took place in acidic environment

Hydroxyapatite coatings on TI substrates by simultaneous precipitation and electrodeposition

This paper presents the results obtained by analyzing hydroxyapatite (HA) coatings electrodeposited onto titanium plates. Instead of using a solution containing both calcium and phosphorus ions, the present approach starts with just one precursor in the electrolysis cell, and the other precursor is being added while an electrochemical potential of -1500 mV is simultaneously applied. By alternating the order of precursor addition, the Ti substrate surface was modified and the differences were evidenced using XRD, SEM, Raman and AFM. For all samples, needle-like crystals of HA grouped as hemispheres on the substrate surface. There is no significant difference, regarding morphology and hemisphere size, between the samples prepared at 1h deposition time, regardless of the precursor addition order; by contrast, the sample deposited for 4h presented a higher density