Search results for "Photocatalyst"
showing 10 items of 45 documents
Synthesis of ZnO–Ag2CO3–Fe3O4@rGO core–shell structure: magnetically separable photocatalyst for degradation of MB using the Box–Behnken design
2020
In this work, a simple microwave method was utilized to prepare ZnO sheet linked with Fe3O4@rGO core–shell and of Ag2CO3 through formation of the quadri-photocatalytic with high activity. The microstructure, morphology, spectroscopic, and magnetic characteristics of the prepared samples were assessed using XRD, SEM, PL, TEM, FT-IR, DLS, and VSM analysis. The photocatalytic activity of the material was evaluated for photodegradation of methylene blue dye under the UV and visible light with home-made photoreactor. The response surface method in a Box–Behnken design was utilized to design the experiments. The parameters affecting the efficiency of the degradation including, pH (5–9), photocata…
Microscopic Revelation of Charge-Trapping Sites in Polymeric Carbon Nitrides for Enhanced Photocatalytic Activity by Correlating with Chemical and El…
2019
The influences of chemical and electronic structures on the photophysical properties of polymeric carbon nitrides (PCNs) photocatalysts, which govern the microscopic mechanisms of the superior photocatalytic activity under visible-light irradiation, have been resolved in this work. Time-resolved photoluminescence and in situ electron paramagnetic resonance measurements indicate that the photoexcited electrons in the fractured PCNs swiftly transfer to the C2p-localized states where the trapped photoelectrons exhibit longer lifetime compared to those in the ordinary PCNs. Moreover, the structure deviation at the carbon (Cb) atoms around the bridging sites of heptazine ring units, where trappe…
Comparison of activity in the 2-propanol dehydration of supported heteropolyacid (photo)catalysts at the gas-solid interface
2015
Catalytic and photocatalytic tests for 2-propanol dehydration to propene were successfully carried out by using binary materials obtained by supporting a Keggin heteropolyacid H3PW12O40 (PW12) via impregnation method and/or solvothermal treatment. The supports used were commercial SiO2 (Mallinckrodt), TiO2 (Evonik P25) and multiwall carbon nanotubes (Sunnano) or home solvothermically prepared SiO2 and TiO2. (Photo)catalytic 2-propanol dehydration was studied in gas-solid regime by using a continuous (photo)reactor working at atmospheric pressure and 80 °C. the reaction was also studied by performing FTIR spectra of the gas-phase over the HPA-support composites, where the 2-propanol had been…
Hybrid TiO2 @ phthalocyanine catalysts in photooxidation of 4-nitrophenol: Effect of the matrix and sensitizer type
2020
Abstract Microcrystalline and nanocrystalline anatase (TiO2) based hybrid photocatalysts including selected phthalocyanine sensitizers were explored in photooxidation of 4-nitrophenol (4-NP) in water. Composites obtained with the homemade pure nano-anatase displayed a very poor catalytic performance compared to the other ones prepared from the commercial Tioxide-Huntsman (micro) and Evonik P25 (nano) products. In particular, the microcrystalline anatase impregnated with sandwich phthalocyanines of Gd or Yb showed excellent results both in photooxidation of 4-NP and hydroquinone, and proved the only ones which completely removed these two compounds from the system during the same reaction cy…
Activity of phthalocyanine-sensitized TiO2-anatase in photooxidation of sulfite ions
2015
Abstract Hybrid catalysts based on the TiO2 matrix impregnated with Nd, Eu and Yb diphthalocyanines proved effective in oxidation of sulfite ions under irradiation with light from the UV-visible range. Micro- and nano-crystalline anatase powders were used in preparation of the photocatalysts, which were applied in the form of a suspension in the water phase. The reaction yield was found to depend on the phthalocyanine sensitizer used and the conditions of TiO2 impregnation. The best results were obtained when micro-anatase impregnated with Yb-diphthalocyanine was used.
Photocatalytic oxidation of gaseous toluene on anatase TiO2 catalyst: Mechanistic aspects and FT-IR investigation
1999
Abstract Photo-oxidation of toluene has been carried out in gas–solid regime by using polycrystalline anatase TiO2 as the catalyst. The reacting gaseous mixture was toluene, air and water in various molar ratios. A pyrex fixed-bed continuous photoreactor irradiated by a medium pressure Hg lamp was used for performing the photoreactivity experiments. The main oxidation product was benzaldehyde but benzene, benzyl alcohol and traces of benzoic acid, phenol and unidentified compounds were also detected. The molar conversion to benzaldehyde with respect to the initial amount of toluene was ca. 20% in the best experimental conditions. Benzene was produced only as a transient product during the f…
Photoassisted Oxidation of the Recalcitrant Cyanuric Acid Substrate in Aqueous ZnO Suspensions
2007
The photoassisted oxidative transformation of the highly recalcitrant cyanuric acid was examined in the liquid−solid regime at pH 3 and natural pH 7.5 under UV irradiation in oxygen- and ozone-saturated ZnO suspensions using ZnO as a photomediator. Loss of cyanuric acid was assayed by HPLC UV absorption spectroscopy, whereas intermediates and final products were determined by HPLC ion chromatography (IC), by MS techniques using an electrospray ionization mass spectrometer operated in the negative-ion mode, and by FT-IR spectroscopy. Final reaction products were CO2 gas and NO3- ions. The measure of nitrate in solution quantified the degree of mineralization of the substrate; its concentrati…
Preparation of photocatalysts by physical methodologies
2021
The synthesis of photocatalytic materials is an important task for obtaining better results in terms of activity and/or selectivity in photocatalysis. This chapter reports an overview of the main methodologies using physical techniques to obtain bulky, supported powders or films and coatings to be used as heterogeneous photocatalysts. The classical chemical methodologies for the preparation of photocatalytic materials are presented in the previous chapter, so the information presented here complements the aforementioned one. Materials scientists and engineers have made significant progresses in the improvement of methods of synthesis of nanomaterial solids by developing different apparatuse…
Preparation of photocatalytic brookite thin films
2007
Pure brookite films were deposited from a brookite dispersion obtained by peptizing a mixture brookite–rutile prepared by thermolysis of TiCl4 in a HCl solution. The films were characterised by X-ray diffraction and Raman spectroscopy. The photoactivity of the samples was tested by using the photo-oxidation of 2-propanol in gas–solid regime as a probe reaction. The brookite films efficiently degraded 2-propanol under UV illumination.
Study of the annealing conditions and photoelectrochemical characterization of a new iron oxide bi-layered nanostructure for water splitting
2016
Iron oxide nanostructures have emerged as promising materials for being used as photocatalysts for hydrogen production due to their advantageous properties. However, their low carrier mobility and short hole diffusion length limit their efficiency in water splitting. To overcome these drawbacks, in the present study, we synthetized a new hematite (alpha-Fe2O3) bi-layered nanostructure consisting of a top nanosphere layer and a nanotubular underneath one by electrochemical anodization. Annealing parameters such as temperature, heating rate and atmosphere were studied in detail in order to determine the optimum annealing conditions for the synthetized nanostructure. The obtained new bi-layere…