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1.
A stable and translucent Bi@Bi4Ti3O12/TiO2 film was fabricated on conventional glass substrates for the first time. The film exhibited a good photocatalytic performance and efficient self-cleaning capability against organic dyes under full spectral irradiation and visible light irradiation. Bi4Ti3O12/TiO2 film was first prepared on a glass substrate with colloidal silica as a high temperature binder, followed by implantation of nanoscale Bi in it by an in-situ partially reduction of Bi4Ti3O12 to generate Bi@Bi4Ti3O12/TiO2 films. The improved photocatalytic ability is probably attributed to the surface plasmon resonance of Bi atom as well as the enhanced electron transfer efficiency and synergistic effect of Bi4Ti3O12 and TiO2. According to trapping experiments, hydroxyl radicals (OH) were active species in the photocatalytic degradation of dyes under full spectral light irradiation and possible photocatalytic mechanism was proposed. The film prepared in this work may well have potential practical applications in many aspects, such as cleansing treatments for high building external decorative panels and also systematic characterization of the film suggests that the in-situ reduction is an effective and simple way to produce nanoscale Bi@Bi4Ti3O12.  相似文献   

2.
Crystalline Bi12TiO20 and Bi4Ti3O12 particles were selectively synthesized by rapid microwave-assisted sol-gel method. During the thermal decomposition process of the dried gel, microwave calcination played a key role in producing single phase Bi12TiO20. Our Bi12TiO20 demonstrated one of the highest visible-light photocatalytic activities for MO degradation among the reported bismuth titanate particles with various compositions. Single phase Bi4Ti3O12 can also be prepared by either a conventional calcination at high temperature or a combined heat treatment of a conventional heating followed by microwave calcination. The photocatalytic reaction rate constant of the Bi4Ti3O12 prepared by microwave calcination was three times higher than that of conventionally calcined Bi4Ti3O12, further confirming the advantage of microwave calcination in preparation of highly photocatalytically active bismuth titanate.  相似文献   

3.
The growth of interfacial compounds between TiO2 and Bi2O3 during transient liquid phase bonding at 900, 1000 and 1100 °C for various times was investigated. The microstructures and compositions of compounds in joints were analyzed by means of SEM and EPMA. It was found that the compound Bi4Ti3O12 forms initially and replaces the Bi2O3 interlayer. Bi2Ti4O11 then arises at the interface between Bi4Ti3O12 and TiO2 and the metastable Bi2Ti2O7 phase appears last at the interface between Bi4Ti3O12 and Bi2Ti4O11. The modes and activation energies of the growth of Bi4Ti3O12 and Bi2Ti4O11 were determined respectively. Holes in the middle of the joint heated at 1100 °C for 24 h were also found.  相似文献   

4.
Aurivillius oxide semiconductors are important photocatalyst because of their unique electronic structure and layered crystal. In this paper, two kinds of Aurivillius oxide semiconductors heterostructures based on Bi4Ti3O12 nanofibers frameworks and BiOCl nanosheets are successfully synthesized by combining the electrospinning technique and solvothermal method. The high-resolution transmission electron microscopy results reveal that an intimate interface between Bi4Ti3O12 nanofibers and BiOCl nanosheets forms in the heterojunctions. Photocatalytic tests show that the BiOCl/Bi4Ti3O12 heterostructures exhibit enhanced photocatalytic activity than bare Bi4Ti3O12 and BiOCl, mainly owing to the photoinduced interfacial charge transfer based on the photosynergistic effect of the BiOCl/Bi4Ti3O12 heterojunction. At the end, the photocatalytic mechanism with O2 production was studied.  相似文献   

5.
《Ceramics International》2016,42(4):4779-4787
This paper describes a highly efficient and robust solar photocatalytic treatment for the degradation of methyl orange dye over bio-synthesized Bi2O3 nanoflakes. Bio-mimetic way is adapted to synthesis Bi2O3 nanoflakes from the plant source of rambutan (Nephelium lappaceum L.) fruit peel extract. The bio-synthesized nanoflakes were characterized using X-ray diffraction studies, ultra-violet-visible diffuse reflectance spectra, field emission scanning electron microscope, high resolution transmittance electron microscope, energy dispersive X-ray spectroscopy, BET Surface area, ultra-violet-visible spectrophotometer and FT-IR spectroscopy. The photocatalytic activity of Bi2O3 nanoflakes were investigated using methyl orange dye under direct sunlight illumination in open atmosphere. The result shows that Bi2O3 nanoflakes were effectively degrading the dye to about 94.66% at 10 h of exposure time. The decreases in chemical oxygen demand values from 88.8 mg/l to 16.2 mg/l, shows the mineralization of methyl orange dye along with color removal.  相似文献   

6.
In this work, the formation of Bi4Ti3O12 by solid state reaction from Bi2O3 and TiO2 starting powders has been studied. The Bi4Ti3O12 formation occurs through an intermediate Bi12TiO20 sillenite phase formed at temperatures sligthly over 300 °C. This sillenite phase is stable up to ∼750 °C, but in the presence of TiO2 reacts to form Bi4Ti3O12 at temperatures >500 °C. Raman spectroscopy has been used to evidence the amorphization of TiO2, demonstrating that the Bi4Ti3O12 formation occurs through the reaction of sillenite Bi12TiO20 and TiO2.  相似文献   

7.
《Ceramics International》2020,46(11):18656-18660
Hexagonal plate-like nanoparticles (NPs) of the layered perovskite La4Ti3O12 were fabricated using liquid-feed flame spray pyrolysis (LF-FSP) followed by subsequent heat-treatments. Their photocatalytic activity was evaluated using decolorization of methyl orange solutions under Uv irradiation. LF-FSP combusts metalloorganic precursor aerosols to produce mixtures of cubic simple perovskite (ABO3) phase and lanthanum oxycarbonate (La2O4·846C0.846) phase with very low agglomeration and average particle sizes (APSs) of 23 nm (as-produced NPs). Rietveld refinement of synchrotron XRD powder patterns verified that the simple perovskite in the as-produced NPs is LaTiO3 (originally cubic Pm-3m-type space group) and heat-treating gives NPs of the trigonal layered perovskite La4Ti3O12 (R-3-type space group). La4Ti3O12 NPs heat-treated at 1100 °C/3-6h/air exhibits hexagonal plate-like morphology and high crystallinity offering enhanced photocatalytic degradation of methyl orange solutions compared to the as-produced NPs. The LF-FSP approach to obtaining layered perovskite La4Ti3O12 NPs provides a simple route to photocatalytic materials in reasonable quantities.  相似文献   

8.
Herein, an affordable and novel approach to design Bi2O3-sensitized hierarchically mesoporous ZnO nanoparticles (NPs) with a variety of Bi2O3 contents is achieved for Hg(II) reduction upon visible light exposure. TEM images of both ZnO and 3% Bi2O3/ZnO samples exhibit nanoscale spherical-like structures with a regular shape and a particle size of ~30 nm. The incorporation of Bi2O3 on hierarchically mesoporous ZnO networks allows visible light to be harvested in a broad range, and the mesoporous 3% Bi2O3/ZnO heterostructure demonstrates the best photocatalytic efficiency for Hg(II) reduction with a value of ~100% after 60 min. The photoreduction rate over the 3% Bi2O3/ZnO heterostructure is enhanced 10 and 20 times more than that of TiO2-P25 and ZnO NPs. The rate constant of the 3% Bi2O3/ZnO heterostructure is 16.8 and 33.6 fold larger than that of TiO2-P25 and ZnO NPs. The superior Hg(II) photoreduction performance could be ascribed to the synergistic effect, excellent visible-light harvest, large surface area, and pore volume provided by incorporating Bi2O3 and the heterojunction design between p-type Bi2O3 and n-type ZnO. This alignment of the electronic bands provides charge carrier separation, thereby decreasing the recombination rate. Finally, the mechanisms and kinetics for the photocatalytic reduction of Hg(II) are proposed.  相似文献   

9.
The mechanism by which Bi0.5Na0.5TiO3 and Bi4.5Na0.5Ti4O15 templates are synthesized via a topochemical microcrystal conversion method using Bi4Ti3O12 precursor and TiO2 particles was investigated based on their crystal structures. The Bi0.5Na0.5TiO3 template consisted of a mixture of plate-like and equiaxed particles, whereas the Bi4.5Na0.5Ti4O15 template consisted only of plate-like particles. The size of the plate-like and equiaxed particles was dependent on the size of the Bi4Ti3O12 precursor and TiO2 particles, respectively. The Lotgering factor and piezoelectric constant of textured Bi0.5(Na0.8K0.2)0.5TiO3 ceramics prepared using the Bi0.5Na0.5TiO3 template were lower than those of the textured Bi0.5(Na0.8K0.2)0.5TiO3 ceramics prepared from the Bi4.5Na0.5Ti4O15 template. This can be attributed to the small amount of plate-like particles in the Bi0.5Na0.5TiO3 template caused by the inevitable co-existence of equiaxed particles.  相似文献   

10.
《Ceramics International》2017,43(6):5292-5301
The development of heterostructured semiconductor photocatalysts makes a noteworthy advancement in environmental purification technology. In this work, a novel heterostructured Bi2O3−CeO2−ZnO, fabricated by a combination of microwave-assisted hydrothermal and thermal decomposition methods, showed an enhanced photocatalytic activity for Rhodamine B (RhB) degradation under sunlight, as compared to pristine ZnO, Bi2O3, CeO2, and commercial Degussa TiO2-P25. The obtained products were thoroughly characterized by various techniques including X- ray powder diffraction (PXRD), field emission scanning electron microscopy (FE-SEM), elemental color mapping, energy-dispersive X-ray spectroscopy (EDAX), Raman spectrometry, Fourier transform infrared (FT-IR) spectroscopy, UV–visible diffuse reflectance spectroscopy (UV–vis DRS), and photoluminescence (PL) spectroscopy. PXRD analysis reveals that the heterostructure has the monoclinic lattice phase of α-Bi2O3, the cubic phase of CeO2 and the hexagonal wurtzite phase of ZnO. FE-SEM images show that Bi2O3−CeO2−ZnO has an ordered mixture of nanorod and nanochain structures. EDAX, elemental color mapping, Raman and FT-IR analyses confirm the successful formation of the heterostructured Bi2O3−CeO2−ZnO. The UV–Vis DRS results demonstrate that Bi2O3−CeO2−ZnO exhibits wide visible-light photoabsorption in 400–780 nm range. Moreover, the reduction in PL intensity of the heterostructured Bi2O3−CeO2−ZnO, when compared to the pristine Bi2O3, CeO2, and ZnO, indicates enhanced charge separation. The study on the mechanism displayed that the improved photocatalytic activity of Bi2O3−CeO2−ZnO could be attributed to (1) the efficient separation of photoinduced electrons and holes of the photocatalysts, caused by the vectorial transfer of electrons and holes among ZnO, CeO2 and Bi2O3, and (2) the wide visible-light photoabsorption range. This study introduces a new class of promising sunlight-driven photocatalysts.  相似文献   

11.
The lead-free piezoelectric material sodium bismuth titanate (NBT, Na0.5Bi0.5TiO3) has attracted considerable attention owing to its promising dielectric, piezoelectric, and electrical properties. However, the literature on the binary subsystems is contradictory and there are only limited data for the ternary system. The present work surveys all of the reports of the binary subsystems Bi2O3 – TiO2 and Na2O – TiO2 and synthesizes these data into inclusive revised versions. The compatibilities for the ternary system Na2O – Bi2O3 – TiO2 were determined experimentally, thus enabling the construction of a complete isothermal section at 800 °C. The compatibilities associated with the problematic binary subsystem Na2O – Bi2O3, which experiences extreme volatilisation, were determined through the generation of the absent standard-state thermodynamic functions for the relevant binary and ternary phases, thus providing a full suite of thermodynamic data for this system. The thermodynamic stability diagrams for Na2O, Bi2O3, and TiO2 thus were calculated. The isothermal section also addresses the contradictions in the literature concerning the formation of solid solutions of Bi12TiO20-x / Bi12-xTi1+xO20+0.5x, pyrochlore (Bi2Ti2O7 / NawBi2-xTi2-yO7-z), BTO (Bi4Ti3O12 / NaxBi4Ti3O12+0.5x), and NBT (Na0.5Bi0.5TiO3 / Bi1±xNaxTiO3.5±x). Further, it was observed that the congruent melting point of NBT, which was determined to be 1225 °C, was preceded by the onset of gradual structural destabilization at 940 °C. Also, the NBT rhombohedral → tetragonal phase transformation was observed at an onset temperature of ∼250 °C. The present work thus provides platform data for the fabrication and reactivities of materials in the ternary system Na2O – Bi2O3· TiO2 and its binary subsystems.  相似文献   

12.
F-doped TiO2 nanotubes were prepared by impregnation method. The prepared catalysts were characterized by XRD, TEM, and XPS. The photocatalytic activity of F-doped TiO2 nanotubes was evaluated through the photodegradation of aqueous methyl orange. The experiments demonstrated that the F-doped TiO2 nanotubes calcined at 300 °C possessed the best photocatalytic activity. Compared with pure TiO2 nanotubes, the doping with F significantly enhanced the photocatalytic efficiency. The high photocatalytic activity was ascribed to several beneficial effects produced by F-doping: creation of oxygen vacancies, presence of Ti3+, and so on. An erratum to this article can be found at  相似文献   

13.
Fe3+ doped together with Au deposited TiO2 (Au/Fe3+–TiO2) was successfully prepared, which shows excellent photocatalytic activity for degradation of methyl orange (MO) under both UV and visible light (λ > 420 nm) illumination. Fe3+ has been confirmed by EPR to substitute for Ti4+ in the TiO2 lattice, and Au exists as Au0 on the surface of the photocatalyst indicated by the results of XRD. Fe3+ and Au have synergistic effects on improving the photocatalytic activity of TiO2. A proposed mechanism concerning the synergistic effects is discussed to explain the improvement of the photocatalytic activities.  相似文献   

14.
《Ceramics International》2023,49(18):30224-30229
Dense MgO–12% TiO2(w) ceramics containing 12 wt% TiO2, which were doped with Li2CO3–Bi2O3 composite sintering aids, were prepared at a low sintering temperature of 950 °C in this study. The effects of sintering additives on the sintering characteristics, phase composition, microstructure, and dielectric and mechanical properties of the ceramic samples were systematically investigated, and the influences of their phase composition and microstructure on the dielectric and mechanical properties were examined. The introduction of sintering aids produced a new Bi4Ti3O12 phase in the sample structure, while the residual Bi2O3 mixed with the newly formed Mg2TiO4 and Bi4Ti3O12 phases distributed at MgO grain boundaries formed a structure surrounding MgO grains. This structure filled the pores in the ceramic sample, which increased its density and enhanced the mechanical properties. At a Li2CO3–Bi2O3 content of 15 wt%, the density, flexural strength, and Vickers hardness of the ceramic samples reached their maximum values of 3.4 g/cm3, 218.9 MPa, and 778.7 HV, respectively. However, the further increase in the Li2CO3–Bi2O3 content deteriorated their dielectric properties although the dielectric constant and dielectric loss remained below 13.4 and 2.1 × 10−3, respectively. The findings of this work indicate that Li2CO3–Bi2O3 sintering aids can significantly lower the sintering temperature of MgO–12% TiO2(w) ceramics and control their dielectric and mechanical properties through microstructural changes.  相似文献   

15.
TiO2 nanoparticles modified with 5-(p-hydroxylphenyl)-10,15,20-triphenylporphyrin (HTPP), 5-(p-hydroxylphenyl)-10,15,20-triphenylporphyrin zinc (ZnHTPP) and trans-dichloro-5-(p-hydroxylphenyl)-10,15,20-triphenylporphyrin tin (SnHTPP) were prepared in order to improve the visible photocatalytic activity of TiO2 nanoparticles. The photocatalytic activity of the modified TiO2 nanoparticles was investigated by carrying out the photodegradation of methyl orange in aqueous solution under visible light irradiation. The TiO2 nanoparticles modified with SnHTPP show the highest visible photocatalytic activity with a degradation ratio of 86% of methyl orange after 180 min irradiation among three catalysts. This result indicates that the central metal ions in porphyrins can significantly influence the sensitization efficiency of porphyrins. In addition, the photoelectrochemical behavior of the modified TiO2 nanoparticles was examined and related to their photocatalytic activity. Finally, the photocatalytic mechanism was discussed preliminarily.  相似文献   

16.
《Ceramics International》2019,45(16):20386-20395
Bi2Ti2O7 nanopowders were synthesised via two different methods i.e. Pechini (P) and Co-Precipitation (C) method by annealing at 550 °C for 16 h. The effect of synthesis technique on photocatalytic activity of Bi2Ti2O7 nanopowders was extensively studied. Formation of pure Bi2Ti2O7 pyrochlore phase was observed in both samples. Various crystallographic parameters obtained by reitveld analysis of X-Ray Diffraction (XRD) spectra of both samples infer the formation of a highly loose crystallographic structure in P sample. The smaller crystallite size of P sample correlates with the observed blue shift in the Raman spectra, furthermore decreasing the particle size in P sample. P sample exhibits higher specific surface area, mean pore diameter and total pore volume which is inferred by Brunauer-Emmett-Teller (BET) analysis. Higher photocatalytic activity of P sample can be attributed to the formation of distorted crystallographic structure and higher specific surface area.  相似文献   

17.
Liquidus line in the high-Bi2O3-containing region of the TiO2–Bi2O3 system was determined experimentally. The equilibrating and quenching technique with subsequent electron probe microanalyser (SEM-EDS) microanalysis were employed. Based on the data, liquidus line was constructed between 60 and 92 mol% Bi2O3. The current results showed a higher solubility of Bi2O3 in the liquid phase in equilibrium with the Bi4Ti3O12 compound compared with the existing phase diagram. In addition, differential scanning calorimetry (DSC) was used to estimate the transformations covering the composition range from 60 to 95 mol% Bi2O3. Further, the phase diagram of the TiO2–Bi2O3 system was calculated using a quasichemical model for the liquid phase. The thermodynamic properties of the intermediate compounds were estimated from the data of TiO2 and Bi2O3 pure solids.  相似文献   

18.
In the current investigation a series of oxygen-rich bismuth oxychloride Bi12O17Cl2 samples through an ethylene glycol-solvothermal route were constructed at different calcination temperatures and fully characterized by X-ray diffraction patterns, scanning electron microscopy, Fourier transformed infrared spectroscopy, X-ray photoelectron spectroscopy, UV–Vis diffuse reflectance spectra, X-ray energy dispersion spectroscopy, and photoluminescence spectra. It was demonstrated that the calcination temperatures indeed had a crucial effect on the crystallinity, grain size, morphology, optical property, and charge carrier separation of Bi12O17Cl2 series. These Bi12O17Cl2 samples showed significantly improved photocatalytic degradation over dye Rhodamine B and colorless antibiotic tetracycline hydrochloride. Particularly, the best candidate, the sample 350 °C—Bi12O17Cl2 could show apparent reaction rate constants that were nearly 28.2, 1.2 times of N–TiO2 over Rhodamine B and tetracycline hydrochloride, respectively. The possible reason of enhancing photocatalytic performance by various Bi12O17Cl2 samples calcined at different temperatures was discussed and major oxidative radicals maybe generated during photocatalytic processes were detected.  相似文献   

19.
《Ceramics International》2016,42(16):18443-18452
Highly efficient visible-light-driven heterojunction photocatalysts, spindle-shaped nanoporous TiO2 coupled with graphitic g-C3N4 nanosheets have been synthesized by a facile one-step solvothermal method. The as-prepared photocatalysts were characterized by X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), N2 adsorption-desorption analysis and UV–vis diffuse reflectance spectrometry (DRS), proving a successful modification of TiO2 with g-C3N4. The results showed spindle-shaped nanoporous TiO2 microspheres with a uniform diameter of about 200 nm dispersed uniformly on the surface of graphitic g-C3N4 nanosheets. The g-C3N4/TiO2 hybrid materials exhibited higher photocatalytic activity than either pure g-C3N4 or nanoporous TiO2 towards degradation of typical rhodamine B (RhB), methyl blue (MB) and methyl orange (MO) dyes under visible light (>420 nm), which can be largely ascribed to the increased light absorption, larger BET surface area and higher efficient separation of photogenerated electron–hole pairs due to the formation of heterostructure. In addition, the possible transferred and separated behavior of electron–hole pairs and photocatalytic mechanisms on basis of the experimental results are also proposed in detail.  相似文献   

20.
TiO2/MoS2 composite was encapsulated by hydrophobic SiO2 nanoparticles using a sol–gel hydrothermal method with methyltriethoxysilane (MTES), titanium tetrachloride (TiCl4), and molybdenum disulfide (MoS2) as raw materials. Then, a novel dual functional composite film with hydrophobicity and photocatalytic activity was fabricated on a glass substrates via the combination of polydimethylsiloxane adhesives and hydrophobic SiO2@(TiO2/MoS2) composite particles. The influence of the mole ratios of MTES to TiO2/MoS2 (M:T) on the wettability and photocatalytic activity of the composite film was discussed. The surface morphology, chemical compositions, and hydrophobicity of the composite film on the glass substrate were investigated by scanning electron microscopy, transmission electron microscopy, X-ray powder diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and water contact angle (water CA) measurements. The results indicated that the composite film exhibited stable superhydrophobicity and excellent photocatalytic activity for degradation of methyl orange (MO) even after five continuous cycles of photocatalytic reaction when M/T was 7:1. The water CA and degradation efficiency for MO remained at 154° and 94%, respectively. Further, the composite film showed a good non-sticking characteristic with the water sliding angle (SA) at about 4°. The SiO2@(TiO2/MoS2) composite consisting of hydrophobic SiO2 nanoparticles and TiO2/MoS2 heterostructure could provide synergistic effects for maintaining long-term self-cleaning performance.  相似文献   

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