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1.
Nanometric V-doped particles with vanadium concentration varying from 0 to 10% were prepared using the polyol method. The influence of the doping on the textural, structural and optical properties was studied by various methods of characterization. X-ray diffraction (XRD) patterns disclose that nanocrystallites of cassiterite, i.e. rutile-like tetragonal structure SnO2 and the absence of a new vanadium phase in the XRD pattern in the different concentration of doping were formed after annealing, the ordinary crystallite size decreased from 20.6 to 12.3 when the doping concentration increased from 0 to 10%, respectively. Moreover, the N2 sorption porosimetry and transmission electron microscopic show that all samples synthesized were constituted of an aggregated network of almost spherical nanoparticles, which sizes changed with the altitude in the doping concentration to 10%. In accordance with UV–visible absorption measurements, this diminution of nanoparticles sizes was followed by a decrease in the band gap value from 3.25 eV, for undoped SnO2, to 2.75 eV, for SnO2 doped at 10%. On the other part, the photocatalytic activity of undoped and V-doped SnO2 nanoparticles was studied using methylene blue (MB) as model organic pollutants. The SnO2 nanoparticles doped at 10% of vanadium disclosed that the discoloration of MB reached 97.4% after irradiation of 120 min, with an apparent constant rate of the degradation reaching 0.035 min?1 for MB degradation that was about 2.5 times more than that of pure SnO2 (0.014 min?1).  相似文献   

2.
SnO2 semiconductor is a new-typed promising photocatalyst, but wide application of SnO2-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 SnO2–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 SnO2–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 SnO2 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 SnO2–ZnO was 85.2 m2 g?1, while that of the pure SnO2 was 20.7 m2 g?1. Experimental results exhibited that the B/Fe codoped SnO2–ZnO film had the best photocatalytic activity compared to a pure SnO2 or singly-modified SnO2 film.  相似文献   

3.
Here novel photocatalysts, SnO2/CuO and CuO/SnO2 nanocomposites were successfully synthesized by chemical method at room temperature. X-ray Diffraction (XRD), transmission electron microscopy (TEM), Fourier transform Infrared (FT-IR), UV–Visible (UV–Vis) and photoluminescence (PL) spectroscopy were utilized for characterization of the nanocomposites. The photocatalytic activity of the nanocomposites was investigated. The hybrid nanocomposites exhibited high photocatalytic activity as evident from the degradation of methylene blue (MB) dye. The result revealed substantial degradation of the MB dye (92 and 69.5% degradation of SnO2/CuO and CuO/SnO2, respectively) under visible light illumination with short period of 30 min. Their large conduction band potential difference and the inner electrostatic field formed in the p–n heterojunction provide a strong driving force for the photogenerated electrons to move from Cu2O to SnO2 under visible light illumination. The excellent photodegradation of methylene blue suggested that the heterostructured SnO2/CuO nanocomposite possessed higher charge separation and photodegradation abilities than CuO/SnO2 nanocomposite under visible light irradiation.  相似文献   

4.
This paper reports the comparison of photoluminescence and afterglow behavior of Dy3+ in CaSnO3 and Ca2SnO4 phosphors. The samples containing CaSnO3 and Ca2SnO4 were prepared via solid-state reaction. The properties have been characterized and analyzed by utilizing X-ray diffraction (XRD), photoluminescence spectroscope (PLS), X-ray photoelectron spectroscopy (XPS), afterglow spectroscopy (AS) and thermal luminescence spectroscope (TLS). The emission spectra revealed that CaSnO3:Dy3+ and Ca2SnO4:Dy3+ phosphors showed different photoluminescence. The Ca2SnO4:Dy3+ phosphor showed a typical 4F9/2 to 6Hj energy transition of Dy3+ ions, with three significant emissions centering around 482, 572 and 670 nm. However, the CaSnO3:Dy3+ phosphor revealed a broad T1 → S0 transitions of Sn2+ ions. The XPS demonstrate the existence of Sn2+ ions in CaSnO3 phosphor caused by the doping of Dy3+ ions. Both the CaSnO3:Dy3+ and Ca2SnO4:Dy3+ phosphors showed a typical triple-exponential afterglow when the UV source switched off. Thermal simulated luminescence study indicated that the persistent afterglow of CaSnO3:Dy3+ and Ca2SnO4:Dy3+ phosphors was generated by the suitable electron or hole traps which were resulted from the doping the calcium stannate host with rare-earth ions (Dy3+).  相似文献   

5.
Zirconium doped tin oxide (SnO2:Zr) nanopowders were synthesized by a simple soft chemical route adding various concentrations of zirconyl chloride (0, 5, 10 and 15 wt%). The samples were characterized by techniques like XRD, SEM, TEM, EDX, FTIR spectroscopy, UV–Vis-NIR spectroscopy and photoluminescence spectroscopy. XRD studies confirm that all the samples exhibit rutile tetragonal crystal structure with a strong (1 0 1) preferential growth texture. Hexagonal shaped grains were evinced from the SEM images. Nanosized grains are evinced from the TEM images and EDX spectra confirm the presence of Zr in the doped samples. The bands at 523 and 583 cm?1 observed in the FTIR spectra which are attributed as the characteristics of γ (Sn–OH) terminal bond of the SnO2 crystalline phase confirm the presence of Sn–O in the synthesized samples. The doped samples exhibit ferromagnetic behavior. Enhanced antibacterial activity was observed for the doped samples. The obtained results show that zirconium strongly influenced the structural, morphological, optical, magnetic and antibacterial properties of pure SnO2 nanopowders.  相似文献   

6.
In this paper, g-C3N4/SnO2:Sb composite photocatalysts were fabricated by in situ loading Sb-doped SnO2 (SnO2:Sb) nanoparticles on graphitic carbon nitride (g-C3N4) nanosheets via a facile hydrothermal method. The synthesized g-C3N4/SnO2:Sb composites delivered enhanced visible light photocatalytic performance for degradation of rhodamine B in comparison with g-C3N4/SnO2 composites without doping Sb. Various techniques including XRD, SEM, TEM, FTIR, XPS, PL and electrochemical method were employed to demonstrate the successful fabrication of g-C3N4/SnO2:Sb composite and to investigate the enhanced mechanism of photocatalytic activity. The improvement of visible light absorption and the promotion of separation efficiency and interfacial transfer of photogenerated carriers induced by Sb doping were responsible for the enhancement of photocatalytic activity. This study provides a simple and convenient method to synthesize a visible light responsive catalyst with promising performance for the potential application in environmental protection.  相似文献   

7.
In this paper we report doping induced enhanced sensor response of SnO2 based sensor towards ethanol at a working temperature of 200 °C. Undoped and dysprosium-doped (Dy-doped) SnO2 nanoparticles were characterized by X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). XRD and Raman results verified tetragonal rutile structure of the prepared samples. It has been observed that crystallite size reduced with increase in dopant concentration. In addition, the particle size has been calculated from Raman spectroscopy using phonon confinement model and the values match very well with results obtained from TEM and X-ray diffraction investigations. Dy-doped SnO2 sensors exhibited significantly enhanced response towards ethanol as compared to undoped sensor. The optimum operating temperature of doped sensor reduced to 200 °C as compared to 320 °C for that of undoped sensor. Moreover, sensor fabricated from Dy-doped SnO2 nanostructures was highly selective toward ethanol which signifies its potential use for commercial applications. The gas sensing mechanism of SnO2 and possible origin of enhanced sensor response has been discussed.  相似文献   

8.
Sn4+ and La3+ co-doped TiO2 photocatalytic material with nanoparticle structure have been successfully prepared using SnCl2·2H2O and La(NO3)3·6H2O as precursors. Scanning electron microscopy, X-ray diffraction, transmission electron microscopy and UV–visible spectroscopy have been used to for the characterization of the morphology, crystal structure, particle size and optical properties of the samples. The photocatalytic properties of sample with various amount of La doped TiO2 have been studied by photo degradation of methyl orange (MO) in water under visible light. XRD patterns showed both rutile and anatase phases for 5 mol% of Sn and 5–10 mol% of La. But anatase phase with a little rutile phase was formed for 5 mol%Sn and 10 mol%La. The prepared Sn and La co doped TiO2 photo-catalyst showed optical absorption edge in the visible light area and exhibited excellent photo-catalytic ability for degradation of MO solution under visible irradiation. Antibacterial behavior towards E. coli was then studied under visible irradiation. The synthesized T-5%Sn-10%La powder exhibited superior antibacterial activity under visible irradiation compared to the pure TiO2.  相似文献   

9.
A convenient method for synthesizing highly photocatalytic activity PANI/TiO2–Fe3+ nanocomposite was developed. The effect of calcination temperature on the phase composition of TiO2 nanopowder was investigated. It was found that higher temperature could promote the formation of rutile phase. The nanocomposite was characterized by atomic force microscopy (AFM), transmission electron microscopy (TEM), infrared spectroscopy (IR) and X-ray diffraction (XRD). The results indicated that the nanohybrid was composed of TiO2, Fe3+ and PANI. The photocatalytic property of the nanocomposite was evaluated by the degradation of methyl orange. In the presence of this catalyst, the degradation rate of methyl orange of 95.2% and 70.3% could be obtained under the UV and sunlight irradiation within 30 min, respectively. The apparent rate constant was 5.64 × 10−2 which is better than that of the Degussa P25.  相似文献   

10.
Silver doped tin oxide (SnO2:Ag) nanopowders were synthesized by a simple soft chemical route with 0, 5, 10 and 15 wt% concentrations of Ag. The structural, morphological, optical, photoluminescence and photocatalytic properties of the synthesized samples were studied and the results obtained are reported in this paper. XRD studies confirm the polycrystalline nature of the synthesized samples. The undoped and doped samples exhibit a strong (1 0 1) preferential growth. Decreased crystallite size is observed with Ag doping. Nanosized grains were observed for the doped samples. Peak related to Sn–O–Sn lattice vibration is observed for both the undoped and doped samples in the FTIR spectra. Peaks related to oxygen vacancies were observed at 362 and 499 nm for all the samples in the PL spectra. Enhanced photocatalytic activity was observed for the doped samples and the SnO2:Ag nanopowder with 10 wt% Ag doping concentration exhibited maximum photodegradation efficiency against the degradation of methyl orange dye.  相似文献   

11.
In the present work, silver and sulphur codoped TiO2 (Ag–S/TiO2) photocatalysts were effectively prepared by sol–gel technique. The prepared samples were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), energy dispersive x-ray analysis (EDX), Fourier transform infrared (FTIR) spectroscopy, diffuse reflectance UV–Vis spectroscopy (UV-DRS) and photoluminescence (PL). The XRD patterns consisted of anatase crystalline phases and the particle size and shape of the prepared samples were observed by SEM and HR-TEM. The presence of doping ions was confirmed by EDX analysis, the decreased band-gap energy of Ag–S codoped TiO2 nanoparticles was investigated by UV-DRS. The decreased in the intensity of Ag–S codoped TiO2 was absorbed due to the lower separation of electron–hole pairs were confirmed by PL spectrum. The Ag–S codoped TiO2 showed higher photocatalytic activity than pure and single-doped TiO2 in the photodegradation of methylene blue (MB) aqueous solution under visible light irradiation. The given work was a good model to associate the considering of the synergistic effect of metal and non-metal codoped TiO2 in the photocatalysis and photo electrochemistry.  相似文献   

12.
An efficient visible light photocatalyst has been prepared from TiO2 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 TiO2 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 TiO2 nanoparticles in the range of visible light and hardly affect their size and crystallinity. The visible light photocatalytic activity of the as-prepared TiO2 nanocomposites is higher than that of commercial TiO2 (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   

13.
Novel combustion synthetic route for the synthesis of nanosized SnO2 is reported. X-ray, tap and powder densities of SnO2 are calculated. Adsorption of Pb2+ ions on combustion derived nanosized SnO2 is studied. The as synthesized SnO2 and lead ions adsorbed SnO2 are characterized by X-ray diffraction (XRD), scanning electron micrograph (SEM), and infrared spectroscopic (IR) techniques. The eluent is characterized by atomic absorption spectroscopy (AAS) and solution conductivity (SC) to know the reduction in the concentration and increase in conductance of lead solution after adsorption on the SnO2 surface. The potential use of solid adsorbents for the adsorption of heavy metal pollutants is envisaged in the present work.  相似文献   

14.
Sodium co-doped Zn0.95Co0.05O nanoparticles (0.01 ≤ X ≤ 0.05) were synthesized using simple wet chemical (co-precipitation) method. The structural, surface morphology and the optical properties of the prepared samples were investigated by X-ray diffraction (XRD), scanning electron microscope, UV-diffuse reflectance spectroscopy (UV-DRS) and Photoluminescence (PL) spectra measurements. The magnetic measurements of the prepared samples with vibrating sample magnetometer exhibited room temperature ferromagnetism. The results obtained from the above studies shows no trend following on Na co-doping concentrations, within our arbitrary selection limit of Na ion. However, the XRD pattern confirms the single phase of Na co-doped samples without any secondary phases. The behaviors associated with intrinsic defects are explored by UV-DRS and PL emission spectra. Further, the origin of observed ferromagnetism and its lack of dependence on Na ion doping was analysed and reported.  相似文献   

15.
Fe-doped SnS2 (SnS2:Fe) nanopowders were synthesized by cost effective chemical method and characterized by thermo gravimetric-differential thermal analysis, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and vibrating sample magnetometer techniques. The photocatalytic activity was evaluated for the degradation of congo red dye under visible light irradiation. XRD studies indicate that both the undoped and doped SnS2 nanopowders exhibit hexagonal crystal structure with a strong (1 0 1) preferential growth. Nanosized grains are evinced from the TEM images. XPS spectra confirmed the presence of Fe in the doped samples. Photodegradation efficiency increased with increase in Fe doping concentration and the SnS2:Fe nanopowder with 10 wt% Fe doping concentration exhibits a maximum efficiency of 93.94% after 180 min light irradiation. Ferromagnetic ordering of pure SnS2 improved with Fe doping. The outcome of the results indicated that Fe-doped SnS2 nanopowders are well suited as diluted magnetic semiconductor and also can be used as an efficient photocatalyst.  相似文献   

16.
Cu/Cu2O/SnO2 composites were successfully prepared with a facile microwave synthesis method. The structure of Cu/Cu2O/SnO2 composite was studied by morphology characterizations, such as X-ray diffraction, transmission electron microscopy and high-resolution transmission electron microscopy, which showed that the size of the Cu/Cu2O/SnO2 particles is 20–50 nm. The synthesis mechanism revealed that SnCl4 obstructed between Cu(OH) and ethylene glycol, preventing Cu(OH) being reduced into Cu at high temperature. The photocatalytic property of Cu/Cu2O/SnO2 composite was investigated by degrading the mixed dyestuff under the irradiation of visible light at room temperature. Benefiting from the effect of electron transfer, the photocatalytic performance of the microwave-prepared Cu/Cu2O/SnO2 composite was much better than that of pure Cu2O. The possible photocatalytic mechanism of the Cu/Cu2O/SnO2 composite catalysts was proposed and elaborated in this study. This synthesis of Cu/Cu2O/SnO2 composite may provide a method for other Cu2O/semiconductor composites microwave preparation.  相似文献   

17.
The lanthanum-doped TiO2 (La3+-TiO2) photocatalysts were prepared by coprecipitation and sol–gel methods. Rhodamine B was used as a model chemical in this work to evaluate the photocatalytic activity of the catalyst samples. The optimum catalyst samples were characterized by XRD, N2 adsorption–desorption measurement, SEM and electron probe microanalyses to find their differences in physical and chemical properties. The experimental results showed that the La3+-TiO2 catalysts prepared by coprecipitation exhibited obviously higher photocatalytic activities as compared with that prepared by the conventional sol–gel process. The optimum photocatalysts prepared by the coprecipitation and sol–gel process have similar adsorption equilibrium constants in Rhodamine B solution and particle size distribution in water medium although there are larger differences in their surface area, morphology and pore size distribution. The pores in the sol-gel prepared catalysts are in the range of mesopores (2–50 nm), whereas the pores in the coprecipitation prepared catalysts consist of bigger mesopores and macropores (>50 nm). The morphology of the primary particles and agglomerates of the La3+-TiO2 catalyst powders was affected by doping processes. The inhibition effect of lanthanum doping on the phase transformation is greater in the coprecipitation process than in the sol–gel process, which could be related with the different amount of Ti–O–La bonds in the precursors. This finding could be used for preparing the anatase La3+-TiO2 catalysts with more regular crystal structure through a higher heat treatment temperature. The optimum amount of lanthanum doping is ca. 1.0 wt.% and the surface atomic ratio of [O]/[Ti] is ca. 2.49 for 1.0 wt.% La3+-TiO2 catalysts prepared by the two processes. The obviously higher photocatalytic activity of the La3+-TiO2 samples prepared by the coprecipitation could be mainly attributed to their more regular anatase structure and more proper surface chemical state of Ti3+ species. The optimum preparation conditions are 1.0 wt.% doping amount of lanthanum ions, calcination temperature 800 °C and calcination time 2 h using the coprecipitation process. As compared with the sol-gel process, the coprecipitation process used relatively cheap inorganic raw materials and a simple process without organic solvents. Therefore, the coprecipitation method provides a potential alternative in realizing large scale production.  相似文献   

18.
Cerium-doped silver bismuth titanate—Ag0.5Bi0.5TiO3 (ABT) ceramics have been synthesized by the high-temperature solid-state reaction method. The structure and elemental examination of the prepared ceramic was analysed by X-ray diffraction (XRD), Fourier transform infrared, scanning electron microscopy and energy-dispersive spectroscopy. XRD analysis showed the presence of pyrochlore structure and secondary phase when more than 5 mol% cerium was added. The impact of temperature on cerium-doped silver bismuth titanate samples was analysed by differential thermal analysis and differential scanning calorimetry. Cerium doping caused the flaky morphology comparing with undoped sample. The homogeneity of all the samples was discussed in detail by diffuse reflectance spectrum. This is the first time the reflection process is analysed for the cerium-doped ABT system to the best of our knowledge.  相似文献   

19.
A series of Tb3+ doped CeF3 and NaCeF4 nanoparticles with different morphology and dimension were synthesized via hydrothermal method. Different organic additives, including sodium dodecyl sulfonate (SDS), polyvinylpyrrolidone (PVP), cetyltrimethyl ammonium bromide (CTAB), oleic acid (OA), polyethylene glycol (PEG), trisodium citrate (Cit) were introduced to control the crystallite size and morphology. Powder X-ray diffraction (PXRD), fourier transform infra-red spectra (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS) and down-conversion (DC) photoluminescence spectra were used to characterize the samples. The emission peaks of all the prepared samples centered at 490, 545, 585 and 621 nm which can be ascribed to the 5D47FJ (J?=?6, 5, 4, 3) transitions respectively of Tb3+ ion. However, emission intensities are strongly controlled by morphology and particle sizes which are influenced by different organic additives used in synthesis. Moreover, the crystal growth process was monitored through a series of time-dependent experiments and a possible formation mechanism has been proposed.  相似文献   

20.
Al18B4O33:Eu3+, Tb3+ whiskers have been successfully prepared by a simple gel nano-coating method using aluminum isopropoxide as the starting materials. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), photoluminescence (PL), and thermogravimetric analysis (TGA) were used characterize the samples. The results show coexistence of the crystal phase Al18B4O33, amorphous phase, and Eu3+, Tb3+ ions of the samples with initial addition Al/B ratios from 3 to 1 are incorporated into the amorphous phase. The Al18B4O33:Eu3+, Tb3+ whiskers are very straight with an average diameter of 600 nm and lengths ranging from 5 to 10 μm. Under ultraviolet excitation at 365 nm, samples show mainly exhibit the characteristic emission of Eu3+ corresponding to \( ^{ 5} {\text{D}}_{ 0} \to {\text{F}}_{ 1 , 2} \) transitions due to an efficient energy transfer occurs from Tb3+ to Eu3+.  相似文献   

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