Detailed Spectroscopic and Structural Analysis of TiO2/WO3 Composite Semiconductors

WO3-TiO2 composite materials were obtained using commercial titania (Evonik Aeroxide P25) and hydrothermally crystallized WO3. Different ratios of TiO2/WO3 were investigated, starting at 1 wt.% of WO3 to 50 wt.%. The morphology of WO3 was of the star-like type, and its structure is basically composed of monoclinic crystalline phase. All spectroscopic characteristics of the composites and their derived data (band-gap energy value, light absorption threshold, and IR specific bands) directly varied with the increase of the WO3 content. However, the oxalic acid photodegradation achieved under UV light reached the highest yield for 24 wt.% WO3 content, a result that was attributed to the charge separation efficiency and the surface hydrophilicity. The latter mentioned reason points out the crucial importance of the surface quality of the investigated structure in photocatalytic tests

Kuprit ásványok lehetséges alkalmazásai a kémiában - anyagtudományi jellemzés: Cuprite minerals – investigation of material properties and possible applications in chemistry

Synthetic copper (I) oxide is widely used in industry and research as a pigment, fungicide, antimicrobial agent, solar cell, catalyst, photocatalyst, gas sensor etc. As with many other synthetic materials, the process of producing Cu2O can require high chemical, thermal, and electrical energy. Therefore, exploiting the characteristics of minerals found in nature promises to be a more cost-effective and environmentally friendly way to obtain Cu2O. The present work focuses on the naturally occurring mineral equivalent of copper (I) oxide, cuprite. It is presented a possible processing method of the mineral, a wide range investigation of the material characteristics and based on the found structural, morphological and optical properties, the potential applicability. Kivonat A szintetikus réz(I)-oxid széles körű felhasználásnak örvend az iparban és a kutatásban egyaránt, mint pigment, gombaölő szer, antimikrobiális szer, napelem alkotó, katalizátor, fotokatalizátor, gáz szenzor stb. Mint sok más szintetikus anyag esetében, a Cu2O előállításakor is a folyamat magas vegyianyag, hő- és elektromos energia ígényű lehet. Ahhoz, hogy költséghatékonyabb és környezetbarátabb úton tegyünk szert rá, jó alternatívának ígérkezik a természetben megtalálható ásványok jellemzőinek kiaknázása. Jelen munka középpontjában a réz(I)-oxid természetben megtalálható, ásványi eredetű megfelelője áll, a kuprit. Az ásvány lehetséges feldolgozási módszere, széles körű anyagjellemzése és a megismert szerkezeti, morfológiai és optikai tulajdonságok alapján a potenciális felhasználhatóság kerül bemutatásra

Controlled Synthesis of Visible Light Active CuxS Photocatalyst: The Effect of Heat Treatment on Their Adsorption Capacity and Photoactivity

The effects of different precursor salts, stabilizing agents, and heat treatment parameters are already known to have an influence on the synthesis of nano-sized semiconductors in heterogenous photocatalysis. In the present work, CuxS materials were prepared by using different precursors (copper (II) chloride dihydrate or copper (II) acetate monohydrate) and shape tailoring/stabilizing agents, such as ethylenediaminetetraacetic acid/polyvinylpyrrolidone, and thiourea as the sulfur source. The polyvinylpyrrolidone (PVP) kinetically controlled the growth rate of the nanoplates, while ethylenediaminetetraacetic acid (EDTA) adjusted the nucleation process through the complexation of copper. A one-step hydrothermal method was used for the synthesis, and the materials were characterized by means of morphological and structural complementary investigation methods. Furthermore, the adsorption capacity and photocatalytic activity were also measured for these materials. It was found that the vacancy sites formed by changing the precursor salt, as confirmed by Raman measurements, affect the photocatalytic activity. The rise of the specific surface area was achieved by heat treatment, and concomitantly, the adsorption capacity of the treated samples was found to increase likewise

Synthesis of Shape-Tailored WO3 Micro-/Nanocrystals and the Photocatalytic Activity of WO3/TiO2 Composites

A traditional semiconductor (WO3) was synthesized from different precursors via hydrothermal crystallization targeting the achievement of three different crystal shapes (nanoplates, nanorods and nanostars). The obtained WO3 microcrystals were analyzed by the means of X-ray diffraction (XRD), scanning electron microscopy (SEM) and diffuse reflectance spectroscopy (DRS). These methods contributed to the detailed analysis of the crystal morphology and structural features. The synthesized bare WO3 photocatalysts were totally inactive, while the P25/WO3 composites were efficient under UV light radiation. Furthermore, the maximum achieved activity was even higher than the bare P25's photocatalytic performance. A correlation was established between the shape of the WO3 crystallites and the observed photocatalytic activity registered during the degradation of different substrates by using P25/WO3 composites

Application of TiO2-Cu Composites in Photocatalytic Degradation Different Pollutants and Hydrogen Production

In the present work, copper nanoparticles were deposited onto the surface of two different commercial titanias (Evonik Aeroxide P25 and Aldrich anatase). During the synthesis, the concentration of copper was systematically varied (0.5%, 1.0%, 1.5%, 5.0%, and 10 wt.%) to optimize the composite-composition. The photocatalytic activity was evaluated under UV-light, using methyl orange and Rhodamine B as model and ketoprofen as real pollutant. For the hydrogen production capacity, oxalic acid was used as the sacrificial agent. The morpho-structural properties were investigated by using XRD (X-ray diffraction), TEM (Transmission Electron Microscopy) DRS (Diffuse Reflectance Spectroscopy), XPS (X-ray Photoelectron Spectroscopy), and SEM-EDX methods (Scanning Electron Microscopy-Energy Dispersive X-ray Analysis). Increasing the copper concentration enhanced the photocatalytic activity for methyl orange degradation in the case of Aldrich anatase-based composites. When the P25-based composites were considered, there was no correlation between the Cu concentration and the activity; but, independently of the base photocatalyst, the composites containing 10% Cu were the best performing materials. Contrarily, for the ketoprofen degradation, increasing the copper concentration deteriorated the photoactivity. For both Aldrich anatase and P25, the best photocatalytic activity was shown by the composites containing 0.5% Cu. For the degradation of Rhodamine B solution, 1.5% of copper nanoparticles was the most suitable. When the hydrogen production capacity was evaluated, the P25-based composites showed higher performance (produced more hydrogen) than the Aldrich anatase-based ones. It was found that Cu was present in four different forms, including belloite (Cu(OH)Cl), metallic Cu, and presumably amorphous Cu(I)- and Cu(II)-based compounds, which were easily convertible among themselves during the photocatalytic processes

Bizmut-vanadát fotokatalizátorok előállítása és stabilitásvizsgálata

In this study, bismuth vanadate with different cube-like structured morphologies were crystalized by one-step hydrothermal method with pH modulation without additives. The asprepared BiVO4 products were systematically characterized with various techniques to prove their crystallographic, morphological, chemical and optical properties. The photocatalytic activities of the synthetized BiVO4 were assessed by the photodegradation of rhodamine B (RhB) and oxalic acid under UV and visible light irradiation. The recyclability was investigated as well and found that the bismuth vanadate microcrystals were transformed