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1.
A class of direct plate-on-plate Z-scheme heterojunction SnS 2/Bi 2MoO 6 photocatalysts was synthesized via a two-step hydrothermal method. The materials were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectra, Fourier transform infrared photoluminescence emission spectra, and UV–vis diffuse reflectance spectroscopy. The photocatalytic activity was estimated via the degradation of crystal violet (CV) and ciprofloxacin (CIP). The experimental results indicated that the 5 wt% SnS 2/Bi 2MoO 6 composites exhibited significantly enhanced performance in contrast to pure Bi 2MoO 6 or SnS 2 nanoflakes, and were also superior to the popular TiO 2 (P25). The degradation reaction accorded well with the first-order reaction kinetics equation; the rate constant of CV using a SnS 2 content of 5 wt% photocatalyst was ~?3.6 times that of the Bi 2MoO 6 and 2.4 times that of SnS 2. Furthermore, a SnS 2 content of 5 wt% exhibited a 1.7 times higher photocatalytic activity of CIP than that of pure Bi 2MoO 6, and 1.3 times that of pure SnS 2. Radical trapping experiments and an electron spin resonance technique indicated that h + and ·OH were the dominant active species involved in the degradation process. A plasmonic Z-scheme photocatalytic mechanism was proposed to explain the superior photocatalytic activities and efficient separation of photogenerated electrons and holes. 相似文献
2.
In this work, Bi 2WO 6/TiO 2 nanorod heterojunction was prepared by sonochemical assisted impregnation method. After loading 2 wt% Bi 2WO 6 on TiO 2 nanorods, the photocatalytic hydrogen production rate of 2026 µmol/h/g was achieved. Compared to commercial P25 and TiO 2 nanorods, ∼13 and ∼3 folds enhanced activity was observed. The excellent photocatalytic performance of Bi 2WO 6/TiO 2 nanorod photocatalyst was mainly attributed to i) reduction of bandgap due to heterojunction formation, ii) quick transport of photogenerated charge carriers, and iii) efficient charge carrier separation supported by UV-DRS, photocurrent measurement, Impedance study, and photoluminescence spectra analysis. The Z-scheme band alignment for Bi 2WO 6/TiO 2 nanorod heterojunction was proposed based on the Mott-Schottky measurement. This result demonstrated the effective utilization of Z-scheme heterojunction of Bi 2WO 6/TiO 2 for photocatalytic reduction application. 相似文献
3.
Herein, we prepared the g-C3N4/Gd-doped Bi2WO6 Z-scheme heterojunction (BCN) composites by a simple hydrothermal method. The composites were investigated by SEM (EDX), TEM, XRD, XPS, UV–Vis DRS and PL analysis. The photocatalytic performance of composites was envaulted by degrading methylene blue (MB) under the irradiation of a 300 W mercury lamp. The results demonstrated that coupling g-C3N4 and doping Gd 3+ effectively enhanced the photocatalytic efficiency of pure Bi2WO6. The 92% of MB was degraded within 120 min by optimal 0.15–100 BCN sample, being 1.61 times as that of Bi2WO6. The greatly enhanced performance of 0.15–100 BCN was due to the synergistic effect of Gd 3+ doping and g-C3N4 coupling, which maintained high redox capacity. According to the experiment of capture active species, Z-scheme charge transfer mechanism was also deduced. This study may provide an efficient and green method for the treatment of dyestuff industrial wastewater. 相似文献
4.
Construction of heterojunction with reusability is one of the effective ways to avoid secondary pollution and strengthen photocatalysis. Herein, a magnetically recyclable Z-scheme Bi 4O 5I 2/NiFe 2O 4 heterojunction photocatalyst was successfully fabricated by a two-step hydrothermal method. Through adjusting the theoretical molar proportion of NiFe 2O 4 to Bi 4O 5I 2, it was verified that the optimal composite could decompose 98.5% Rhodamine B (RhB, 10 mg/L) within 60 min under simulative sunlight and 98.1% RhB within 80 min under visible light. According to the characterizations, the superior performance was mainly associated with the small band gap energy (2.44 eV) and efficient separation of photo-generated electrons and holes caused by the formation of heterojunction. Meanwhile, the enlarged specific area (27.6 m 2/g) provided many adsorptive sites and active sites to improve the reaction further. Moreover, the trapping experiment indicated that the photodegradation involved O 2–, OH and h +. After confirming the reliable activity, reusability and stability of the photocatalyst, an inferred mechanism was shown. In summary, the design of this magnetically recyclable Z-scheme Bi 4O 5I 2/NiFe 2O 4 heterojunction photocatalyst can become a new choice to purify wastewater. 相似文献
5.
In this work, we have elucidated the pH-induced structural evolution of bismuth molybdate photocatalyst based on a hydrothermal synthesis route. With increasing the pH value of precursor solution, pure Bi 2MoO 6 was synthesized at pH 2–5, Bi 2MoO 6-Bi 4MoO 9 mixture was obtained at pH 7–9, pure Bi 4MoO 9 was obtained at pH 11, and pure α-Bi 2O 3 was derived at pH 13. The as-derived samples mainly present particle-like shapes but with different particle sizes (except the observation of Bi 2MoO 6 nanowires in sample S-pH9). The photocatalytic performances between the samples were compared via the degradation of methylene blue (MB) under irradiation of simulated sunlight. The Bi 2MoO 6 sample synthesized at pH 2 exhibited the highest photodegradation performance ( η(30 min) = 89.8 %, kapp = 0.05007 min ?1) among the samples. The underlying photocatalytic mechanism and degradation pathways of MB were systematically analyzed. Moreover, the photodegradation performance of the Bi 2MoO 6 photocatalyst was further evaluated at different acidic-alkaline environments as well as in degrading various color and colorless organic pollutants, which provides an important insight into its practical application. 相似文献
6.
Herein we have designed an excellent type of Z-scheme Ag 2MoO 4/Bi 4Ti 3O 12 (AMO/BTO) heterojunction photocatalysts by immobilizing AMO particles onto rod-like BTO hierarchical architectures. The formation of Z-scheme AMO/BTO heterostructures was verified by various characterization techniques including XRD, UV–vis DR spectroscopy, SEM, TEM, XPS and FTIR spectroscopy. PL spectroscopy, photocurrent response and EIS analyses suggest that the creation of AMO/BTO heterojunctions is conducive to the efficient separation of photoexcited electron-hole pairs. The photocatalytic performances of the AMO/BTO composites were investigated by simulated-sunlight driving photodegradation of methylene blue (MB), tetrabromobisphenol A (TBBPA), tetracycline hydrochloride (TC), phenol and methyl orange (MO)/rhodamine B (RhB)/MB mixture solutions. It is demonstrated that the AMO/BTO heterojunction photocatalysts are endowed with excellent photodegradation performances much higher than that of bare AMO and BTO. For example, the photodegradation rate of MB by using 30 wt%AMO/BTO — confirmed to be the optimal composite sample — is about 17.0 and 14.7 times as high as that by using bare BTO and AMO, respectively. A Z-scheme electron transfer mechanism was proposed to elucidate the enhanced photodegradation performances of the AMO/BTO heterojunction photocatalysts. 相似文献
7.
Hierarchical β-Bi 2O 3/Bi 2MoO 6 heterostructured flower-like microspheres assembled from nanoplates with different β-Bi 2O 3 loadings (0–26.5 mol%) were synthesized through a one-step template-free solvothermal route. Under visible-light illumination ( λ > 420 nm), over 99% of rhodamine B was degraded within 90 min on the 21.9 mol% of β-Bi 2O 3 loading Bi 2O 3/Bi 2MoO 6 microspheres. The remarkable enhancement of photocatalytic activity of the hierarchical Bi 2O 3/Bi 2MoO 6 micro/nanostructures can be attributed to the effective separation of the photoinduced charge carriers at the interfaces and in the semiconductors. The electrons (e −) are the main active species in aqueous solution under visible-light irradiation. The Bi 2O 3/Bi 2MoO 6 also displays visible-light photocatalytic activity for the destruction of E. coli. In addition, the β-Bi 2O 3 in the hierarchical Bi 2O 3/Bi 2MoO 6 microspheres is very stable and the composite can be easily recycled by a simple filtration step, thus the second pollution can be effectively avoided. A possible photocatalytic mechanism was proposed based on the experimental results. 相似文献
8.
In the present work, a visible-light-driven Mo/Bi 2MoO 6/Bi 3ClO 4 heterojunction photocatalyst was fabricated via the Pechini sol–gel process. The type and amount of gelling agent, chelating agent and mole ratio of chelating agent to total metals were balanced to generate ultrafine nanoparticles. The Mo/Bi 2MoO 6/Bi 3ClO 4 nanocomposite as a novel photocatalyst not only exhibited an excellent visible-light photocatalytic desulfurization performance of thiophene (~97%), but also had better photodesulfurization efficiency than Mo/Bi 2MoO 6 and Bi 3ClO 4 nanostructures. The ultra-deep photocatalytic desulfurization performance of the Mo/Bi 2MoO 6/Bi 3ClO 4 nanocomposite can be attributed to the strong visible-light absorption, unique nanostructures, high separation and low recombination of electron–hole pairs due to the as-formed heterojunctions. Furthermore, a photocatalytic desulfurization mechanism was elucidated via radical trapping experiments, which revealed that the ?O 2? and ?OH radicals play a key role in the photocatalytic desulfurization process. 相似文献
9.
Multiple heterojunction system of Bi 2MoO 6/WO 3/Ag 3PO 4 was designed via constructing binary heterojunction Bi 2MoO 6/WO 3, followed by the deposition of nano-Ag 3PO 4 on the surface of Bi 2MoO 6/WO 3. Various techniques were employed to characterize the properties of the as-prepared catalytic system. In this study, the decomposition efficiency of C.I. reactive blue 19 (RB-19) was used as a measure of photocatalytic activity and the Bi 2MoO 6/WO 3/Ag 3PO 4 composite exceeded its stand-alone components (pristine Ag 3PO 4, WO 3/Ag 3PO 4 and Bi 2MoO 6/Ag 3PO 4) by 3.16 times, 2.63 times and 1.75 times, respectively. The photocatalytic tests implied that the construction of multiple heterojunction could achieve efficient separation of photo-generated electrons and holes. A possible photocatalytic mechanism for Bi 2MoO 6/WO 3/Ag 3PO 4 system was also proposed according to the results of trapping experiments. 相似文献
10.
The integration of Bi 2MoO 6 with MIL-101(Fe) as a novel structure enhanced photocatalytic activity for RhB degradation. Bi 2MoO 6/MIL-101(Fe) composites were synthesized via the solvothermal procedure and characterized by XRD, EDX, FE-SEM, TEM, FT-IR, BET, TGA, UV–vis DRS, and PL. The optimal molar ratio Bi 2MoO 6:MIL-101(Fe) equal to 1:1 showed better photocatalytic activity than Bi 2MoO 6 and MIL-101(Fe) and other heterostructure composites. The effect of pH (5–9), reaction time (60–120 min), catalyst concentration (0.1–0.5 g/L), and dye concentration (10–20 ppm) were investigated on the removal performance of RhB by using central composite face-centered (CCF). In the optimal process factors where the [Catalyst]:0.4 g/L, [RhB]:20 ppm, pH: 6.5, irradiation time: 120 min, the RhB and TOC removal efficiency were 85% and 84.2%, respectively. The holes and superoxide radicals played a major role in the degradation of RhB. The addition of salt (NaCl, Na 2SO 4, and NaHCO 3) at different concentrations (100, 200, 400, and 800 ppm) revealed that the salts have an inhibitory role in the photocatalytic performance. At low concentrations of 100 ppm, the salts had a negative effect on removal efficiency (k Pure water = 0.0155 min ?1, k NaCl = 0.0075 min ?1, k Na2SO4 = 0.0132 min ?1, k NaHCO3 = 0.006 min ?1). Increasing the salt concentration to 800 ppm caused improved efficiency for NaCl (k NaCl = 0.0141 min ?1), while for Na 2SO 4 this trend was decreasing (k Na2SO4 = 0.011 min ?1), and for NaHCO 3 sharply diminished (k NaHCO3 = 0.0026 min ?1). 相似文献
11.
In this study, layered double hydroxide [M II-Al LDH (M II = Mg/Zn)] were used as selective CO 2 adsorbents from methane stream. It prepared by microwave (MW) assisted homogenous precipitations via urea hydrolysis. The LDH structures and the type of intercalated anions were confirmed by the X-ray diffraction (XRD), Fourier transform infrared (FTIR), thermal analysis (DSC and TGA), and elemental analysis, and scanning and transmission electron microscopes (SEM and TEM) imaging. The results indicated that; the LDH morphology and the intercalated anions (carbonate and urea species) were dependent on MW power, time, and M II type. The predominant urea species were carbamate and isocyanate for Mg-Al LDH and Zn-Al LDH, respectively. The efficiencies of the LDH were tested towards CO 2 capture from methane stream using dynamic flow system under atmospheric pressure. Effect of temperature and adsorption/desorption cycles were studied. The best CO 2 adsorption capacities obtained at (30 °C) were 3.25, and 2.47 mmol g −1 for Mg-Al-LDH and Zn-Al LDH, respectively. Whereas, those for the calcined LDH (at 550 °C) were 2.96 and 2.29 mmol g −1 for Mg-Al-LDO and Zn-Al LDO, respectively. The results revealed the role of the intercalated urea derived anions type in enhancing the LDH adsorption properties to selectively capture CO 2 from methane stream. 相似文献
12.
As attractive materials for photoeletrochemical hydrogen evolution reaction (PEC HER), conjugated polymers (e.g., conjugated acetylenic polymers [CAPs]) still show poor PEC HER performance due to the associated serious recombination of photogenerated electrons and holes. Herein, taking advantage of the in situ conversion of nanocopper into Cu 2O on copper cellulose paper during catalyzing of the Glaser coupling reaction, a general strategy for the construction of a CAPs/Cu 2O Z-scheme heterojunction for PEC water reduction is demonstrated. The as-fabricated poly(2,5-diethynylthieno[3,2-b]thiophene) (pDET)/Cu 2O Z-scheme heterojunction exhibits a carrier separation efficiency of 16.1% at 0.3 V versus reversible hydrogen electrode (RHE), which is 6.7 and 1.4-times higher respectively than those for pDET and Cu 2O under AM 1.5G irradiation (100 mW cm −2) in the 0.1 m Na 2SO 4 aqueous solution. Consequently, the photocurrent of the pDET/Cu 2O Z-scheme heterojunction reaches ≈ 520 µ A cm −2 at 0.3 V versus RHE, which is much higher than pDET ( ≈ 80 µ A cm −2), Cu 2O ( ≈ 100 µ A cm −2), and the state-of-the-art cocatalyst-free organic or organic-semiconductor-based heterojunctions/homojunctions photocathodes (1–370 µ A cm −2). This work advances the design of polymer-based Z-scheme heterojunctions and high-performance organic photoelectrodes. 相似文献
13.
Photocatalysis is an attractive and green strategy for organic pollutant removal. The development of alternative and effective photocatalysts has attracted great attention. Herein, we rationally engineer an alternative rich-oxygen vacancies (OVs) Bi 2WO 6/In 2O 3 composite photocatalyst via integrating the calcination and hydrothermal method for removing organic dyes (rhodamine B). Thanks to the synergistic effect of OVs and heterojunction structure, the 80 wt% Bi 2WO 6/In 2O 3 (BiIn80) displays enhanced photocatalytic degradation effect. The degradation rate of BiIn80 is up to 97.3% under light irradiation within 120 min and the reaction rate constant k value (0.03221 min −1) is about 15-fold and 4.17-fold as high as those of In 2O 3 (0.00203 min −1) and Bi 2WO 6 (0.00772 min −1), respectively. The heterostructure of Bi 2WO 6/In 2O 3 can extend the lifespan of the photogenerated charge carriers. Moreover, the density functional theory (DFT) calculations reveal that the OVs in Bi 2WO 6/In 2O 3 can boost visible light absorbability by decreasing band gap value and serve as the extra electron transfer channels to enhance the separation efficiency of photogenerated electron-hole pairs. This study not only provides an alternative route for fabricating highly efficient heterojunction photocatalysts, but also obtains better understanding of the synergistic effect of OVs and heterojunction on enhancing the photocatalytic performance. 相似文献
14.
HT-Bi 2MoO 6 microspheres were prepared by hydrothermal method and applied in piezoelectric catalytic degradation of dye. The crystallinity, morphology, optical property, and the surface chemical state of Bi 2MoO 6 catalyst were characterized by XRD, SEM, UV–vis and XPS techniques, respectively. The effects of catalyst preparation method, catalyst amount, dyes type and reaction conditions were investigated on the piezoelectric catalytic performance. The highest degradation ratio of 98.9% was achieved with 10 mg of HT-Bi 2MoO 6 catalyst after 45 min of piezoelectric catalytic vibration. In addition, a possible piezoelectric catalytic mechanism over HT-Bi 2MoO 6 catalyst has been proposed by active species trapping experiment. ·O 2− and h + are suggested to be the main active species in the piezoelectric catalytic process. These research results show that the HT-Bi 2MoO 6 catalyst with flower-like microspheres morphology consisting of nanosheets can effectively transform mechanical energy into electrical energy by vibration to generate reactive species for the degradation of dyes. 相似文献
15.
At present, the construction of high-efficiency photocatalytic degradation system of antibiotic pollutants has become a research hotspot. In this paper, Bi 28O 32(SO 4) 10/NiAl LDH photocatalyst with three-dimensional spherical morphology was successfully prepared by hydrothermal method followed by calcination, thus applying to the degradation of tetracycline. The characterization and photochemical analysis of the resulted material were used to determine the type of formed heterojunction. Bi 28O 32(SO 4) 10 and NiAl LDH build a close contact interface. The matching band gap structure makes S-scheme heterojunction formed between the two single component. Benefited from this structure, the Bi 28O 32(SO 4) 10/NiAl LDH composite with the mass ratio of 1:1 exhibited 95% efficiency in degradation of tetracycline after irradiation for 120 min, and it is stable, reusable and universal. The apparent rate constant of TC degradation by heterojunction catalyst is greatly increased, which is 5.35 and 4.91 times that of Bi 28O 32(SO 4) 10 and NiAl LDH. Overall, this paper provides a way of thinking for the design of new bismuth based photocatalytic materials, and thus providing a reference for the rational design of S-scheme heterojunction. 相似文献
16.
Single crystals of Bi 2O 3·3MoO 3 and 3Bi 2O 3·2MoO 3 in the Bi 2O 3/1bMoO 3 binary system were grown by pulling from the melt. Single crystal Bi 2O 3·MoO 3 (Bi 2MoO 6), which is well known as Koechlinite, could not be grown successfully. A new compound 3Bi 2O 3·2MoO 3 was found to melt congruently and to be easily grown from the melt. It belongs to the monoclinic crystal system with space group C 42h. Refractive indices of Bi 2O 3·3MoO 3 and 3Bi 2O 3·2MoO 3 were investigated. 相似文献
17.
NaY(MoO 4) 2:Eu 3+ and NaY 0.9Bi 0.1(MoO 4) 2:Eu 3+ submicrometer phosphors have been synthesized by a composite technology involving hydrothermal process assisted solid state reaction at room temperature. It is revealed that crystalline water is necessary for the solid phase reaction at room temperature. The XRD patterns indicate that both NaY(MoO 4) 2:Eu 3+ and NaY 0.9Bi 0.1(MoO 4) 2:Eu 3+ submicrometer phosphors crystallize well with the scheelite structure. Both SEM and TEM images illustrate that the average grain size of NaY(MoO 4) 2:Eu 3+ and NaY 0.9Bi 0.1(MoO 4) 2:Eu 3+ is about 200 nm without conglomeration. The luminescent lifetimes and quantum efficiencies for NaY(MoO 4) 2:Eu 3+ and NaY 0.9Bi 0.1(MoO 4) 2:Eu 3+ are determined, indicating that the introduction of Bi 3+ is favorable for the luminescence of Eu 3+. 相似文献
18.
The charge transfer within heterojunction is crucial for the efficiency and stability of photocatalyst for overall water splitting (OWS). Herein, InVO 4 nanosheets have been employed as a support for the lateral epitaxial growth of ZnIn 2S 4 nanosheets to produce hierarchical InVO 4@ZnIn 2S 4 (InVZ) heterojunctions. The distinct branching heterostructure facilitates active site exposure and mass transfer, further boosting the participation of ZnIn 2S 4 and InVO 4 for proton reduction and water oxidation, respectively. The unique Z-scheme modulated charge transfer, visualized by simulation and in situ analysis, has been proved to promote the spatial separation of photoexcited charges and strengthen the anti-photocorrosion capability of InVZ. The optimized InVZ heterojunction presents improved OWS (153.3 µmol h −1 g −1 for H 2 and 76.9 µmol h −1 g −1 for O 2) and competitive H 2 production (21090 µmol h −1 g −1). Even after 20 times (100 h) of cycle experiment, it still holds more than 88% OWS activity and a complete structure. 相似文献
19.
Photocatalytic CO 2 reduction is severely limited by the rapid recombination of photo-generated charges and insufficient reactive sites. Creating electric field and defects are effective strategies to inhibit charge recombination and enrich catalytic sites, respectively. Herein, a coupled strategy of ferroelectric poling and cationic vacancy is developed to achieve high-performance CO 2 photoreduction on ferroelectric Bi 2MoO 6, and their interesting synergy-compensation relationship is first disclosed. Corona poling increases the remnant polarization of Bi 2MoO 6 to enhance the intrinsic electric field for promoting charge separation, while it decreases the CO 2 adsorption. The introduced Mo vacancy (V Mo) facilitates the adsorption and activation of CO 2, and surface charge separation by creating local electric field. Unfortunately, V Mo largely reduces the remnant polarization intensity. Coupling poling and V Mo not only integrate their advantages, resulting in an approximately sevenfold increased surface charge transfer efficiency, but also compensate for their shortcomings, for example, V Mo largely alleviates the negative effects of ferroelectric poling on CO 2 adsorption. In the absence of co-catalyst or sacrificial agent, the poled Bi 2MoO 6 with V Mo exhibits a superior CO 2-to-CO evolution rate of 19.75 µmol g −1 h −1, ≈8.4 times higher than the Bi 2MoO 6 nanosheets. This work provides new ideas for exploring the role of polarization and defects in photocatalysis. 相似文献
20.
For the remediation of antibiotic-contaminated water bodies, this study synthesized g-C 3N 4/CuBi 2O 4/Bi 2MoO 6 3D flower-like spherical photocatalysts by a solvothermal method. The tetracycline antibiotics were used as the target pollutants and degraded under visible light to evaluate the photocatalytic performance of the prepared photocatalysts. Notably, the g-C 3N 4/CuBi 2O 4/Bi 2MoO 6 photocatalyst achieved 84.6 % and 91.6 % for the degradation of tetracycline hydrochloride and chlortetracycline (100 mL, 20 mg/L), respectively, within 2 h under visible light irradiation. Furthermore, we found that the composites showed very low degradation rates for dye-based contaminants, but still exhibited excellent photocatalytic activity for antibiotics in a mixed contaminant system of dyes and antibiotics. And the intermediate was detected by gas chromatography-mass spectrometry (GC–MS), suggesting a possible photo-degradation pathway for tetracycline. Finally, biochemical experiments were carried out to further illustrate the effective degradation of antibiotics in water after photocatalytic degradation by observing and comparing the growth of mung bean seeds. 相似文献
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