ABSTRACT
Bismuth oxychloride photocatalysts were obtained using solvothermal synthesis and different additives (CTAB-cetyltrimethylammonium bromide, CTAC-cetyltrimethylammonium chloride, PVP-polyvinylpyrrolidone, SDS-sodium dodecylsulphate, U-urea and TU-thiourea). The effect of the previously mentioned compounds was analyzed applying structural (primary crystallite size, crystal phase composition, etc.), morphological (particle geometry), optical (band gap energy) parameters, surface related properties (surface atoms' oxidation states), and the resulted photocatalytic activity. A strong dependency was found between the surface tension of the synthesis solutions and the overall morpho-structural parameters. The main finding was that the characteristics of the semiconductors can be tuned by modifying the surface tension of the synthesis mixture. It was observed after the photocatalytic degradation, that the white semiconductor turned to grey. Furthermore, we attempted to explain the gray color of BiOCl catalysts after the photocatalytic decompositions by Raman and XPS studies.
ABSTRACT
In the present work, shape tailored Cu2O microparticles were synthesized by changing the nature of the reducing agent and studied subsequently. d-(+)-glucose, d-(+)-fructose, d-(+)xylose, d-(+)-galactose, and d-(+)-arabinose were chosen as reducing agents due to their different reducing abilities. The morpho-structural characteristics were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), and diffuse reflectance spectroscopy (DRS), while their photocatalytic activity was evaluated by methyl orange degradation under visible light (120 min). The results show that the number of carbon atoms in the sugars affect the morphology and particle size (from 250 nm to 1.2 µm), and differences in their degree of crystallinity and photocatalytic activity were also found. The highest activity was observed when glucose was used as the reducing agent.
Subject(s)
Copper/chemistry , Light , Reducing Agents/chemistry , Sugars/chemistry , Catalysis , Particle Size , Photochemical Processes , Surface PropertiesABSTRACT
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.
ABSTRACT
Talent identification based on multiple criteria is a common way of considering students for gifted education services. As part of a nationwide talent identification program led by UNK (New Generation Centre, Hungary of Talents Program, 2016-2020), we developed an online rating tool with which teachers could indicate the talent areas of their 5th grade students. Through several iterations-involving the translation, application, and analysis of Renzulli's Scales for Rating the Behavioral Characteristics of Superior Students questionnaire and a custom-made normative questionnaire-we developed a matrix-style competency rating instrument called TalentTiles. The primary aim of the instrument is to collect more realistic and reliable teacher-ratings on students. The instrument takes a very short time-less than 2 minutes per student-to complete, focuses on the behavioral characteristics, measures school-related areas, addresses general competencies (e.g., ability, motivation) in a domain-specific way and has low average inter-item correlations. After the first pilot test TalentTiles seems to be an innovative and user friendly way of collecting teachers' opinions about school-related gifted behavior.
