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1.
Interest in the photocatalytic oxidation of formaldehyde from contaminated wastewater is growing rapidly. The photocatalytic activity of the nanocrystalline Fe 3+/F ? co-doped TiO 2–SiO 2 composite film for the degradation of formaldehyde solution under visible light was discussed in this study. The films were characterised by field emission scanning electron microscopy (FE-SEM) equipped with energy-dispersive spectroscopy, X-ray diffraction (XRD), BET surface area, UV–Vis absorption spectroscopy, and photoluminescence spectroscopy. The FE-SEM results revealed that the Fe 3+/F ? co-doped TiO 2–SiO 2 film was composed of uniform round-like nanoparticles or aggregates with the size range of 5–10 nm. The XRD results indicated that only the anatase phase was observed in the film. Compared with a pure TiO 2 film and a singly modified TiO 2 film, the Fe 3+/F ? co-doped TiO 2–SiO 2 composite film showed the best photocatalytic properties due to its strong visible light adsorption and diminished electrons-holes recombination. 相似文献
2.
An efficient visible light photocatalyst has been prepared from TiO 2 nanoparticles and a partly conjugated polymer derived from polyvinyl chloride (PVC). It was characterized by transmission
electron microscopy (TEM), X-ray diffraction (XRD), UV–visible diffuse reflectance spectroscopy (UV–Vis DRS), Fourier-transform
infrared spectroscopy (FT-IR), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). The visible light photocatalytic
activity of the as-prepared photocatalyst was evaluated by the photocatalytic degradation of Rhodamine B (RhB) under visible
light irradiation. The XPS, FT-IR, and Raman spectra show that the partly conjugated polymer derived from PVC exists on the
surface of the TiO 2 nanoparticles. The UV–Vis DRS, XRD, and TEM results reveal that the modification of the partly conjugated polymer can obviously
improve the absorbance of the TiO 2 nanoparticles in the range of visible light and hardly affect their size and crystallinity. The visible light photocatalytic
activity of the as-prepared TiO 2 nanocomposites is higher than that of commercial TiO 2 (Degussa P25) and comparable with those of visible light photocatalysts reported in the literature. Their visible light photocatalytic
stability is also good. The reasons for their excellent visible light photocatalytic activity and the major factors affecting
their photocatalytic activity are discussed. 相似文献
3.
Highly efficient visible light TiO 2 photocatalyst was prepared by the sol-gel method at lower temperature (≤300 °C), and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), UV-vis diffuse reflectance spectroscopy (UV-vis DRS), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and differential scanning calorimetry-thermogravimetric analysis (DSC-TGA). The effects of the heat treatment temperature and time of the as-prepared TiO 2 on its visible light photocatalytic activity were investigated by monitoring the degradation of methyl orange solution under visible light irradiation (wavelength ≥ 400 nm). Results show that the as-prepared TiO 2 nanoparticles possess an anatase phase and mesoporous structure with carbon self-doping and visible photosensitive organic groups. The visible light photocatalytic activity of the as-prepared TiO 2 is greatly higher than those of the commercial TiO 2 (P-25) and other visible photocatalysts reported in literature (such as PPy/TiO 2, P3HT/TiO 2, PANI/TiO 2, N-TiO 2 and Fe 3+-TiO 2) and its photocatalytic stability is excellent. The reasons for improving the visible light photocatalytic activity of the as-prepared TiO 2 can be explained by carbon self-doping and a large amount of visible photosensitive groups existing in the as-prepared TiO 2. The apparent optical thickness ( τapp), local volumetric rate of photo absorption (LVRPA) and kinetic constant ( kT) of the photodegradation system were calculated. 相似文献
4.
Nanoporous TiO 2 films were fabricated by thermal rapid treatment (TRT) of the TiO 2 film which was previously deposited on a substrate by liquid phase deposition. The TiO 2 films were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and UV-VIS diffuse reflectance spectroscopy (UV-VIS DRS). Photocatalytic activity of nanoporous TiO 2 coating was assessed by the photocatalytic degradation of methylene blue aqueous solution. 相似文献
5.
Nanocrystalline photocatalysts of TiO 2 codoped with yttrium and nitrogen were prepared by the sol–gel method and investigated by X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM), the Brunauer–Emmett–Teller (BET) surface area measurement, X-ray photoelectron spectroscopy (XPS) and ultraviolet–visible diffuse reflectance spectroscopy (UV–vis DRS), respectively. Slight red-shifts of the Raman peak at 144 cm ?1 were observed in the doped samples after the incorporation of Y 3+ and N 3? into the lattice of TiO 2. The N doping caused the improvement of visible light absorption because of the formation of the N 2p states isolated above the valence band maximum of TiO 2. Whereas, the absorption property of the pure or N doped TiO 2 was depressed after the introduction of Y. The photocatalytic activities of the samples were evaluated by monitoring the degradation of methylene blue (MB) solution. The codoped sample with N and 0.05 at.% Y exhibited an enhanced photocatalytic efficiency. It is suggested that the charge trapping due to the Y doping and the visible light response due to the N doping are responsible for the enhanced photocatalytic performance in this sample. However, the photocatalytic activity of the codoped TiO 2 was suppressed step by step as the Y doping level increased, which could be attributed to the formation of photogenerated charge carriers recombination centers at the Y substituting sites. 相似文献
6.
SnO 2 semiconductor is a new-typed promising photocatalyst, but wide application of SnO 2-based photocatalytic technology has been restricted by low visible light utilization efficiency and rapid recombination of photogenerated electrons–holes. To overcome these drawbacks, we prepared B/Fe codoped SnO 2–ZnO thin films on glass substrates through a simple sol–gel method. The photocatalytic activities of the films were evaluated by degradation of organic pollutants including acid naphthol red (ANR) and formaldehyde. UV–Vis absorption spectroscopy and photoluminescence (PL) spectra results revealed that the B/Fe codoped SnO 2–ZnO film not only enhanced optical absorption properties but also improved lifetime of the charge carriers. X-ray diffraction (XRD) results indicated that the nanocrystalline SnO 2 was a single crystal type of rutile. Field emission scanning electron microscopy (FE-SEM) results showed that the B/Fe codoped SnO2–ZnO film without cracks was composed of smaller nanoparticles or aggregates compared to pure SnO2 film. Brunauer–Emmett–Teller (BET) surface area results showed that the specific surface area of the B/Fe codoped SnO 2–ZnO was 85.2 m 2 g ?1, while that of the pure SnO 2 was 20.7 m 2 g ?1. Experimental results exhibited that the B/Fe codoped SnO 2–ZnO film had the best photocatalytic activity compared to a pure SnO 2 or singly-modified SnO 2 film. 相似文献
7.
The photocatalytic oxidation of the azo dye Orange-II (Or-II) using Fe loaded TiO 2 (Fe–TiO 2) was studied under ultraviolet (UV), visible (vis) and simultaneous UV–vis irradiations using a solar light simulator. Photocatalysts were characterized by means of XRD, SEM-EDX, FTIR and DRS. Fe 3+ species, identified in XPS analyses, were responsible of the increased absorption of visible light. Moreover, DRS analyses showed a decrease in the bandgap due to Fe 3+ loading. Photocatalystic tests proved that Fe modification enhanced the TiO 2 photocatalytic activity towards Or-II photodegradation under simultaneous UV–vis irradiation. Even so, the performance of the Fe–TiO 2 samples towards the photodegradation of phenol, under UV irradiation, was lower than TiO 2 suggesting the recombination of the UV photogenerated electron–hole pair. Therefore, results evidence a Fe 3+ promotion of the electron caption in the photosensitization process of TiO 2 by Or-II acting as a sensitizer. Such process leads to the Or-II photooxidation under UV–vis irradiation by losing energy in electron transferring processes to sensitize TiO 2, and, the formation of reactive oxygen species promoted by the injected electron to the TiO 2 conduction band. 相似文献
8.
Bi-doped TiO 2 catalyst was prepared by sol–gel method and was characterized by thermo gravimetric analysis (TGA), X-ray diffraction spectra (XRD), X-ray photo electronic spectroscopy (XPS), UV–Vis diffused reflectance spectra (DRS), photoluminescence spectra (PLS), transmission electron microscopy (TEM), energy dispersive analysis of X-rays (EDAX) and BET surface area. The photocatalytic activity of the catalysts were evaluated for the degradation of isoproturon herbicide under solar light irradiation. The UV–Visible DRS of Bi-doped TiO 2 showed red shift in optical absorption. The presence of Bi 3+δ+ species are playing a vital role in minimizing the electron hole recombination resulting higher activity compared to bare TiO 2. 相似文献
9.
Highly active photocatalytic Fe-doped nano TiO 2 was successfully synthesised by chemical vapour deposition (CVD) method using FeCl 3 as Fe source. CVD was carried out by evaporating FeCl 3 at 350°C in nitrogen flow during 30–90?min. The amount of Fe incorporated into TiO 2 framework is adjusted by the amount of FeCl 3 used and the evaporation time. The obtained sample was characterised by X-ray diffraction (XRD), atomic absorption spectroscopy (AAS), energy dispersive X-ray spectroscopy (EDS), UV-Vis, Fourier transform-infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS). Photocatalytic activities of the samples were tested in photocatalytic decomposition of 2-propanol in liquid phase using visible light instead of UV light irradiation. Non-doped TiO 2 and high Fe loading TiO 2 samples showed very low photocatalytic activity, whereas the low Fe loading TiO 2 sample exhibited high photocatalytic activity under visible light. The high photocatalytic activity of this sample was rationalised by the existence of defects (Ti–OH groups) as the active sites. 相似文献
10.
Synthesis of single phase cobalt-orthotitanate inverse spinel nano particles is reported for the first time via a novel solvothermal method at low calcination temperature at 400?°C. The pure phase cobalt-orthotitanate spinel nano particles were prepared using cobalt nitrate and titanium tetraisopropoxide (1:1 molar ratio) as cobalt and titanium sources. The synthesised Co 2TiO 4 nanoparticles were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), fourier transform infrared spectroscopy, energy dispersive X-ray spectroscopy, surface area analyses (Brauner–Emmett–Teller) (BET) and UV–Vis diffuse reflectance spectroscopy. The XRD results proved the formation of a single phase cobalt-orthotitanate (Co 2TiO 4) nanoparticles by calcination temperature of 400?°C. The FE-SEM results showed that nano particles possess a uniform spherical morphology with an average size of 51 nm. Porosity and specific surface area of cobalt-orthotitanate nano particles was measured by nitrogen adsorption using BET and the results showed surface area of 44.47 m 2/g. DRS results showed an optical band gap value of 1.802 eV for cobalt-orthotitanate nano powder. An excellent performance as a nano photo-catalyst toward the degradation of Remazol Red RB 133 (RR133) as a single azo textile dye with excellent efficiency. Mineralization of RR133 by highly active cobalt-orthotitanate nano-catalyst coated on glass surface was applied and 97% TOC removal was observed. This is due to high electron–hole charge separation and high surface area of nano-catalyst. 相似文献
11.
The structural, morphological, and optical properties of the sol–gel derived TiO 2 nanoparticles at different pH and calcination temperature were investigated in the present study. X-ray diffraction (XRD), Thermogravimetric analysis (TGA), Field emission scanning electron microscopy (FE-SEM), Transmission electron microscopy (TEM), UV–Visible(Vis) spectroscopy, energy dispersive studies (EDS), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray photoluminescence (PL) spectroscopy, BET surface area analysis, and Barrett-Joyner-Halenda (BJH) pore size distribution and pore volume analysis were used to characterize the prepared TiO 2 photocatalyst. The range of crystallite size and band gap of the synthesized TiO 2 samples were in the range of 20–80?nm and 2.5–3.2?eV respectively. The photocatalytic performance of prepared TiO 2 photocatalysts was evaluated by photodegradation of Methylene Blue (MB) solution under simulated solar irradiation. Results illustrate that the synthesized TiO 2 exhibits visible light activity at higher calcination temperature. Crystallinity and surface area plays a vital role in the overall performance of the prepared TiO 2 photocatalyst. 相似文献
12.
Visible light response and superior dispersed S 6+-doped TiO 2 nanoparticle catalysts (S-TiO 2) were prepared via ionic liquid of 1-butyl-3-methylimidazolium hexafluorophosphate. The phenol was used for the evaluation of the S-TiO 2 photocatalytic activity. S-TiO 2 was characterized by XPS, UV–vis DRS, FE-SEM, TEM, XRD, TG/DSC, FTIR, and BET. The results showed that S-TiO 2 with appropriate S doping prepared via ionic liquid had smaller particle size, better dispersion, higher activity, and higher surface area ( SBET) than that prepared in water. Cationic S 6+ incorporation into TiO 2 lattice substitutes for Ti 4+ lattice site, generates Ti–O–S bonds in TiO 2, and leads to the formation of donor defect levels in band gap, so that the photocatalytic sensitization of TiO 2 has been extended to visible light region. The optimal content in S doping for the better photocatalytic performance can optimize electrical properties of the intrinsic n-type TiO 2 by adding the adequate amount of donor defect of S Ti2+ for considering the lifetime of the photo-induced charge pairs. 相似文献
13.
Sm 3+-doped TiO 2 nanocrystalline was synthesized by a sol–gel auto-combustion method and characterized by X-ray diffraction, Brunauer-Emmett-Teller
method (BET), UV–vis diffuse reflectance spectroscopy (DRS), and also photoluminescence (PL) emission spectroscopy. The photocatalytic
activity of Sm 3+–TiO 2 catalyst was evaluated by measuring degradation rates of methylene blue (MB) under either UV or visible light. The results
showed that doping with the samarium ions significantly enhanced the photocatalytic activity for MB degradation under UV or
visible light irradiation. This was ascribed to the fact that a small amount of samarium dopant simultaneously increased MB
adsorption capacity and separation efficiency of electron-hole pairs. The results of DRS showed that Sm 3+-doped TiO 2 had significant absorption between 400 nm and 500 nm, which increased with the increase of samarium ion content. The adsorption
experimental demonstrated that Sm 3+–TiO 2 had a higher MB adsorption capacity than undoped TiO 2 and adsorption capacity of MB increased with the increase of samarium ion content. It is found that the stronger the PL intensity,
the higher the photocatalytic activity. This could be explained by the points that PL spectra mainly resulted from surface
oxygen vacancies and defects during the process of PL, while surface oxygen vacancies and defects could be favorable in capturing
the photoinduced electrons during the process of photocatalytic reactions, so that the recombination of photoinduced electrons
and holes could be effectively inhibited. 相似文献
14.
CuO-VO2/TiO2 as a new nanocomposite was synthesized through hydrothermal method and identified by various spectroscopic techniques including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), energy dispersive X-ray analysis (EDX), UV–visible, differential reflectance spectroscopy (DRS), and Mott–Schottky. The presence of nanotubes/nanosheets in the synthesized nanocomposite was confirmed by HR-TEM. The anatase and rutile crystalline forms of TiO2 were detected by Raman spectroscopy and X-ray diffraction (XRD). XPS analysis confirmed the presence of CuO and VO2 in the nanocomposite. The surface area and the band-gap energy of the nanocomposite were determined via N2 adsorption–desorption analysis and DRS. The presence of a p–n junction between TiO2 (n-type) and CuO/VO2 (p-type) was confirmed by the Mott–Schottky analysis. The photocatalytic activity of the nanocomposite against methylene blue (MB), methyl orange (MO), and cango red (CR) was studied under visible-light irradiation. The times of degradation for the decomposition of the dyes were 10–25 min. The rate constants of degradation for MB, MO, and CR were calculated as 0.34, 0.090, and 0.155 min?1, respectively. The catalyst was recovered four times. In addition, the mineralization of the dyes was investigated by chemical oxygen demand (COD). The reaction was performed in the presence of different radical scavengers, and the ·OH was found to be the predominantly active species in the photodegradation of the dyes. 相似文献
15.
N–I co-doped TiO 2 nanoparticles were prepared by hydrolysis method, using ammonia and iodic acid as the doping sources and Ti(OBu) 4 as the titanium source. The prepared catalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and ultraviolet–visible diffuse reflection spectroscopy (UV–vis DRS). XRD spectra show that N–I–TiO 2 samples calcined at 673 K for 3 h are of anatase structure. XPS analysis of N–I–TiO 2samples indicates that some N atoms replace O atoms in TiO 2 lattice, and I exist in I 7+, I − and I 5+ chemical states in the samples. UV–vis DRS results reveal that N–I–TiO 2 had significant optical absorption in the region of 400–600 nm. The photocatalytic activity of catalysts was evaluated by monitoring the photocatalytic degradation of methyl orange (MO). Compared with P25 and mono-doped TiO 2, N–I–TiO 2 powder shows higher photocatalytic activity under both visible-light ( λ > 420 nm) and UV–vis light irradiation. Furthermore, N–I–TiO 2 also displays higher COD removal rate under UV–vis light irradiation. 相似文献
16.
The nanocrystalline S doped titanium dioxide films were successfully prepared by the improved sol-gel process. Here TiO(C 4H 9O) 4 and CS(NH 2) 2 were used as precursors of titania and sulfur, respectively. The as-prepared specimens were characterized using x-ray diffraction (XRD), x-ray energy dispersive spectroscopy (EDS), high-resolution field emission scanning electron microscopy (FE-SEM), Brunauer-Emmett-Teller (BET) surface area, and ultraviolet-visible diffuse reflectance spectroscopy. The photocatalytic activities of the films were evaluated by degradation of organic dyes in aqueous solution. The results of XRD, FE-SEM, and BET analyses indicated that the TiO 2 films were composed of nanoparticles. S doping could obviously not only suppress the formation of brookite phase but also inhibit the transformation of anatase to rutile at high temperature. Compared with pure TiO 2 film, S doped TiO 2 film exhibited excellent photocatalytic activity. It is believed that the surface microstructure of the modified films is responsible for improving the photocatalytic activity. 相似文献
17.
Mo-N-codoped TiO 2 was synthesized by using ammonium molybdate tetrahydrate and ammonia water as the sources of Mo and N, respectively. The resulting materials were characterized by X-ray diffraction (XRD), X-photoelectron spectroscopy (XPS) and UV–vis light diffuse reflection spectroscopy (DRS). Furthermore, the activity enhanced-mechanism was proposed. XRD results indicated that codoping favored the formation of anatase and improved the anatase crystallinity. XPS analysis revealed that N was incorporated into the lattice of TiO 2 through substituting lattice O and coexisted in the substitutional forms. Meanwhile, Mo was incorporated into the lattice of TiO 2 through substituting Ti and coexisted in the forms of Mo 6+ and Mo 5+. DRS showed that the light absorption in visible region was improved by co-doping, leading to a narrower band gap and higher visible activity for the degradation of phenol than that of others. The enhanced activity was attributed to the high anatase crystallinity, large amount of surface oxygen vacancies, intense light absorption and narrow band gap. 相似文献
18.
In the present study, TiO 2 films were deposited on the surface of cenosphere particles using the modified magnetron sputtering equipment under different working conditions. The resulting films were characterized by field emission scanning electron microscopy (FE-SEM), Atomic Force Microscopy (AFM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The FE-SEM and AFM results show that the grain sizes and root-mean-square (RMS) roughness values of the TiO 2 films increase with the increase in deposition time and film thickness. The XRD results indicate that the film was TiO 2 film and sputtering time is an importance condition to influence the films crystal. With the increasing of sputtering time, the crystallization of the TiO 2 film was increased. The XPS results show that only TiO 2 films existed on the surface of cenosphere particles. In addition, the photocatalytic activities of these films were investigated by degrading methyl orange under UV irradiation. The results suggest that the photocatalytic activity of cenosphere particles with anatase TiO 2 films is remarkable and this catalyst can be applicable for the photocatalytic degradation of other organic compounds under UV lights. 相似文献
19.
The nano-crystalline B 3+ and F ? co-doped titanium dioxide films were successfully prepared by the improved sol–gel process. The as-prepared specimens were characterised using X-ray diffraction (XRD), high-resolution field emission scanning electron microscopy (FE-SEM), the Brunauer–Emmett–Teller (BET) surface area, X-ray photo-electron spectroscopy, photoluminescence spectra and UV–Vis diffuse reflectance spectroscopy. The photo-catalytic activities of the films were evaluated by degradation of an organic dye in aqueous solution. The results of XRD, FE-SEM and BET analysis indicated that the TiO 2 films were composed of nano-particles. B 3+ and F ? co-doping could obviously not only suppress the formation of brookite phase but also inhibit the transformation of anatase to rutile at high temperature. Diffuse reflectance measurements showed that co-doping could clearly extend the absorbance spectra of TiO 2 into visible region. Compared with pure TiO 2, B 3+ doped or F ? doped TiO 2 film, the B 3+ and F ? co-doped TiO 2 film exhibited excellent photo-catalytic activity. It is believed that the surface microstructure of the films and the doping methods of the two ions are responsible for improving the photo-catalytic activity. 相似文献
20.
Providing novel photocatalysts with high photocatalytic efficiency is of great significance. In the present work, hydrogen peroxide and carbon dots (C-Dots) were utilized to enhance the photocatalytic performance of TiO 2 under visible light. The fabricated TiO 2-peroxo/C-Dots photocatalysts were analyzed by XRD, HRTEM, SEM, EDX, BET, FT-IR, XPS, PL, UV–Vis DRS, EIS, and photocurrent density. Photocatalytic abilities of the nanocomposites were evaluated by photocatalytic removal of RhB, MO, MB, fuchsine, and Cr (VI) upon visible-light illumination. The results demonstrated that the binary nanocomposites exhibited remarkably enhanced photocatalytic activity compared with the TiO 2 and TiO 2-peroxo photocatalysts. The best photocatalytic performance was obtained using 0.75?mL of C-Dots, which was approximately 79.2, 17.1, 71.4, and 40.5 times higher than the pure TiO 2 for degradations of RhB, MO, MB, and fuchsine, respectively. Furthermore, the TiO 2-peroxo/C-Dots nanocomposites exhibited high stability in consecutive photocatalytic processes. Based on the results, the TiO 2-peroxo/C-Dots photocatalyst is expected to become a promising photocatalyst for practical applications in water purification. 相似文献
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