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Mesoporous TiO2-BiOBr Microspheres with Tailorable Adsorption Capacities for Photodegradation of Organic Water Pollutants: Probing Adsorption-Photocatalysis Synergy by Combining Experiments and Kinetic Modeling
摘要： Understanding adsorption-photocatalysis synergy helps advance solar-driven photodegradation of organic wastewater pollutants. To evaluate the synergy, mesoporous TiO2(amorphous)-BiOBr microspheres were facilely synthesized as model photocatalysts and characterized by XRD, SEM, TEM/HRTEM, XPS, nitrogen adsorption-desorption, UV-vis DRS, photoluminescence, and FTIR. The characterizations and photodegradation tests suggested that the composites had both adsorption sites and photocatalysis sites on BiOBr phase, while homogeneously distributed TiO2 in BiOBr microplates tailored the size of BiOBr crystallites. Accordingly, surface areas of the composites spanned from 22 to 155 m2/g and adsorption capacities for methyl orange (MO) ranged from 16 to 54 mg/g, controlled by the TiO2 content. In addition to experiments, kinetic modeling that combined adsorption with photocatalysis was developed and aided elucidating the synergy and quantitatively evaluating the composites with extracted rate constants from experimental data. The rate constant of the composite (Ti/Bi = 0.6) was calculated to be 3 times that of the pure BiOBr. Though adsorption promoted MO photodegradation, the capacity of the composite for MO adsorption and photodegradation decreased dramatically during the cycling tests. Nevertheless, this problem did not happen during photodegradation of rhodamine B and phenol on the composite and photodegradation of MO on pure BiOBr. This was explained by possible accumulation of degradation intermediates on the composite surface. This study provides a useful approach to investigate the adsorption-photocatalysis synergy from the perspectives of experiments and kinetic modeling and implies the necessity of scrutinizing the adverse effects of high levels of adsorption on recyclability of the photocatalysts.
关键词： Organic pollutants photodegradation,Kinetic modeling,TiO2-BiOBr microspheres,Tailorable adsorption capacities,Adsorption-photocatalysis synergy
更新于2025-11-14 17:03:37
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A molecular-based design of RGO/TiO2-PAM composite flocculant with photocatalytic self-degrading characteristics and the application of the oil sand tailings flocculant
摘要： Polymer flocculation technology has a very broad application in the flocculation industry of oil sand tailings at present. Nevertheless, the most commonly used commercial polyacrylamide flocculant has problems of low flocculation efficiency and secondary pollution. In this paper, we proposed an organic-inorganic composite flocculant with self-degrading properties for the flocculation treatment of oil sand tailings, which was prepared by photocatalytic surface initiation technique. Further, the functional groups of the materials before and after polymerization composites were characterized by infrared spectrum to explore the polymerization mechanism, the structure was observed by transmission electron microscope, and the molecular weight of polyacrylamide was measured by gel permeation chromatography. Then, the flocculation performance was characterized by the flocculation experiment (tested with simulated oil sand tailings). Subsequently, the flocculation mechanism was explored by testing the zeta potential of the organic-inorganic composites and analyzing images of sediment observed by transmission electron microscope and atomic force microscope. Finally, the test of self-degradation performance was carried out under illumination. Based on the above experiments, the following conclusions were obtained. First, the structural characterization results indicate the polymerization mechanism is that under the condition of light, the surface of the inorganic photocatalyst generates free radicals to initiate the radical polymerization of the monomers, so that the monomers successfully grow on the surface of the inorganic particles into comb structure. And then, the flocculation experiment shows that reduced graphene oxide/titanium dioxide-polyacrylamide(2:40) has the best flocculation effect, of which the supernatant transmittance is 21.4 higher and the sedimentation ratio is 8.9% higher than those of the commercial polyacrylamide. The reason for its excellent flocculation performance is that the zeta potential of the organic-inorganic composite increases, reducing repulsion of particles and flocculant molecules, simultaneously, the formed comb structure is beneficial to the expansion of the polymer chain and increases the contact area, thereby improving the flocculation effect. Ultimately, the degradation results indicates that the new organic-inorganic composite had good degradation effect, with the degradation rate up to 75.9% within 4 hours. Therefore, this work has made great contributions to solving the oil sand tailings pollution field.
关键词： Flocculant,Oil sand tailings,Photocatalytic Self-degrading,Organic-inorganic composite,Comb structure
更新于2025-11-14 17:03:37
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Metal–organic framework-derived ZnO hollow nanocages functionalized with nanoscale Ag catalysts for enhanced ethanol sensing properties
摘要： Increase of porosity and functionalization with nanoscale catalysts are two significant aspects for achieving high-performance metal oxide-based resistive gas sensors. In this work, a simple metal–organic framework (MOF) route has been developed to fabricate Ag nanocatalysts functionalized ZnO hollow nanocages (NCs). Nanoscale Ag catalysts with a small size of approximately 10 nm are uniformly encapsulated within the cavities of MOFs (ZIF-8). The high porosity, hollow structure, and functionalization with uniformly-distributed nanoscale Ag catalysts have been simultaneously achieved for MOF-derived ZnO. This type of porous Ag–ZnO hollow NCs show much enhanced ethanol sensing performances and reduced operating temperature in comparison with pure ZnO nanoparticles (NPs) and ZnO NCs. In particular, the 1 ml Ag–ZnO NCs exhibit the highest response of 84.6 to 100 ppm ethanol at 250 °C, which is 6.4 and 3.3 times higher than those of pure ZnO NPs and ZnO NCs at the optimum operating temperature of 275 °C, respectively. The Ag–ZnO NCs also display fast response/recovery times, good ethanol selectivity, and response reproducibility. The enhanced ethanol sensing properties are attributed to the synergistic effects of several points including the electron sensitization effects and catalytic effects of nanoscale Ag catalysts, porous and hollow structures, high surface area, and high surface O? species absorbing capability of Ag–ZnO NCs.
关键词： ZnO,Gas sensors,Metal–organic frameworks,Ag,Hollow
更新于2025-11-14 17:03:37
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Novel hole blocking materials based on 2,6-disubstituted dibenzo[ <i>b</i> , <i>d</i> ]furan and dibenzo[ <i>b</i> , <i>d</i> ]thiophene segments for high-performance blue phosphorescent organic light-emitting diodes
摘要： Novel hole blocking materials (HBMs) based on 2,6-disubstituted dibenzo[b,d]furan and dibenzo[b,d]thiophene segments, 3,30,300,30 0 0-(dibenzo[b,d]furan-2,6-diylbis(benzene-5,3,1-triyl))tetrapyridine (26DBFPTPy) and 3,30,300,30 0 0-(dibenzo[b,d]thiophene-2,6-diylbis(benzene-5,3,1-triyl))tetrapyridine (26DBTPTPy), are successfully designed and synthesized for high-performance blue phosphorescent organic light-emitting diodes (PhOLEDs) for the first time. Computational simulation is used to investigate the optimal structure, orbital distribution, and physicochemical properties of both molecules. Thermal, optical, and electrochemical analysis shows that 26DBFPTPy and 26DBTPTPy possess high thermal stability, deep HOMO energy levels ((cid:2)7.08 and (cid:2)6.91 eV), and a high triplet energy (ET) (2.75 and 2.70 eV). Blue PhOLEDs with 26DBFPTPy or 26DBTPTPy as a hole blocking layer (HBL) exhibit a low turn-on voltage (3.0 V) and operating voltage (4.5 V) at 1000 cd m(cid:2)2. In addition, the blue PhOLEDs with 26DBFPTPy or 26DBTPTPy show superior external quantum e?ciencies (24.1 and 23.6%) and power e?ciencies (43.9 and 42.7 lm W(cid:2)1). They also show a very small e?ciency roll-o? of about 8.5% from 100 to 1000 cd m(cid:2)2. Furthermore, they exhibit improved lifetimes compared to the similarly designed HBL with a pyridine electron transport unit and a phenyl core structure.
关键词： dibenzo[b,d]furan,hole blocking materials,dibenzo[b,d]thiophene,blue phosphorescent organic light-emitting diodes,high-performance
更新于2025-11-14 15:32:45
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Plasmonic MoO2 nanospheres assembled on graphene oxide for highly sensitive SERS detection of organic pollutants
摘要： The molybdenum oxide and graphene oxide (MoO2/GO) nanocomposite has been fabricated via simple hydrothermal assisted synthesis using Mo and MoO3 as precursors. The MoO2 nanospheres with porous hollow structure are assembled onto GO nanosheets. Profiting from the plasmonic effects of MoO2 and synergistic effect of MoO2 and GO, this hybrid nanomaterial exhibits significantly enhanced surface enhanced Raman scattering (SERS) activity for organic pollutants. The detection limit for rhodamine 6G (R6G) is 1.0 × 10?9 M, and the maximum enhancement factor (EF) reaches up to 1.05 × 107, which is the best among the semiconductor-based SERS materials. For practical application, the MoO2/GO SERS substrates are also applied to detect Methylene blue (MB) in river water, and the detection limit (1.0 × 10?8 M) can be acquired. Pyrene is also chosen as probe molecule, and quantitative determination is achieved with detection limit of 1.0 × 10?7 M. These demonstrate the well feasibility for multi-molecule detection. Furthermore, the nanocomposite displays high stability, reproducible stability, and acid and alkali resistance.
关键词： Organic pollutants,Plasmonic effect,SERS,Graphene oxide,Detection,MoO2
更新于2025-11-14 15:27:09
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Rationally Designed Fe2O3/GO/WO3 Z-Scheme Photocatalyst for Enhanced Solar light Photocatalytic Water Remediation
摘要： A novel ternary Fe2O3/GO/WO3 all-solid-state Z-Scheme photocatalyst was rationally designed. Structural, morphological, optical and electronic properties of the synthesized nanocomposite were investigated by XRD, SEM, TEM, UV-vis Diffuse Reflectance and Raman spectroscopy. The results revealed the successful synthesis of the nanocomposite materials. Uniquely, double absorption edges at 2.0 and 2.3 eV for Fe2O3/WO3 and triple absorption edges at 1.5, 1.8 and 2.1 eV for Fe2O3/GO/WO3 were investigated for the first time. Lower absorption band edges dominated for both Fe2O3/WO3 and Fe2O3/GO/WO3, while higher absorption edges dominated for pure nanomaterials. The enhanced interaction among GO, Fe2O3 and WO3 matrix explained the reduction in the CB energy leading to efficient electron separation and transformation and consequently improving the photocatalytic activity. The visible light photocatalytic performance of Fe2O3/GO/WO3 nanocomposites were evaluated for degradation of methylene blue (MB) and crystal violet (CV) dyes as model water pollutants. The photocatalytic activity for degradation of both dyes was found to be greatly enhanced in the presence of ternary Fe2O3/GO/WO3 nanocomposite as compared to nanocomposite systems of Fe2O3/WO3, WO3/GO and Fe2O3/GO or pure Fe2O3 and WO3 nanomaterials. The enhancement in the photocatalytic performance of ternary Fe2O3/GO/WO3 nanocomposite was proven to be due to the all-solid-state Z-Scheme in which the photogenerated electrons in the CB of photosystem I (WO3) transferred through GO mediator and recombined with the photogenerated holes in the VB of Fe2O3 (photosystem II). So that, the electron-hole pair recombination can be suppressed in both systems. Moreover, the photocatalytic activity of the best Fe2O3/GO/WO3 nanocomposite (FGW 30) has been tested for the degradation of phenol. The results show that 95.4 % of phenol was degraded in 120 minutes. Thus, this study provides an efficient green Z-Scheme photocatalyst for water remediation utilizing solar light.
关键词： solar light photocatalysis,organic dyes degradation,all-solid-state Z-Scheme,Ternary Fe2O3/GO/WO3,phenol mineralization
更新于2025-11-14 15:26:12
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Linking optical and chemical signatures of dissolved organic matter in the southern Argentine shelf: Distribution and bioavailability
摘要： Fluorescence spectroscopy is commonly used to investigate the distribution and dynamics of dissolved organic matter (DOM) in marine systems. However, the direct comparison with chemical signatures is essential to substantiate the molecular composition of specific fluorescent components. Here we report the relation between optical and chemical signatures of DOM in waters of the Beagle Channel (BCW) (south-east of Tierra del Fuego, in the southern Argentine shelf) at the Pacific-Atlantic connection and neighboring coastal (CW) and oceanic (OW) waters (54.75-55.75°S, 64-68°W). The relationships among concentrations of total dissolved carbohydrates (TDCHO) and amino acids (TDAA), and fluorescent DOM (FDOM), including terrestrial “humic-like” (FDOMC) and “protein-like” compounds (FDOMT), and bioavailability of DOM components were assessed from field measurements acquired in the austral summer 2012. The maximal concentrations of TDCHO, dissolved organic carbon (DOC) and FDOMc intensities were found in BCW, while the minima in OW, displaying a negative correlation with salinity. This spatial distribution of biogeochemical signals suggests that humic compounds contributed by continental runoff contain refractory carbohydrates, and FDOMC resulted as a reliable tracer of carbon pathways in the Pacific-Atlantic connection. Conversely, TDAA and FDOMT showed the opposite distributional trend, with minimal concentrations in BCW and the maxima in CW and OW. The significant positive correlation of TDAA with salinity suggests open water sources of these components, however, phytoplankton biomass (Chla) in CW and OW was significantly lower than in BCW, ruling out the assumption of autochthonous source in open waters. TDAA were negatively correlated with the abundance of heterotrophic bacteria (HB), which displayed a consistent decrease from BCW towards OW, suggesting high bacterial uptake of TDAA in the BCW. This bacterial uptake is supported by the observed variation in carbon contribution of TDAA to DOC (amino acids carbon yield, in %), which is an indicator of DOM lability. The negative correlation found between amino acids carbon yield and HB abundance reflects intense bacterial activity in BCW, where phytoplankton biomass was maximum. Hence, higher DOM “freshness” occurs in the BCW, suggesting a tight coupling between microbial production and consumption.
关键词： Pacific-Atlantic connection.,amino acids,fluorescent dissolved organic matter,carbohydrates
更新于2025-11-14 15:26:12
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Enhancing Light Outcoupling in OLEDs by Integration of Scattering Electrodes
摘要： Limited outcoupling efficiencies are still a big problem in organic light-emitting devices (OLEDs). In this contribution, a simple and general approach for enhancing the outcoupling efficiency of OLEDs is presented: by using a three-step process including electro-spray deposition of a sacrificial material (step i), thin metal-layer deposition (step ii), and elution of the sacrificial material (step iii), scattering metal structures can be fabricated that can be used in cavity OLEDs. The integration into green-emitting vacuum-processed OLEDs yields in an increased luminous efficiency and EQE by 30% and 27%, respectively.
关键词： OLED,Electrospray Deposition,Organic Electronics,Light Outcoupling
更新于2025-11-14 15:25:21
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Enhanced visible-light-driven photocatalytic activity of BiFeO3 via electric-field control of spontaneous polarization
摘要： Well-polarized BiFeO3 nanoparticles have been successfully prepared by a facile electrical poling method with the assist of a soluble organic-inorganic composite film. From XRD, TEM and SEM studies, no significant change in the crystal structure or morphology was detected after the electrical poling process. The visible-light driven photocatalytic process of poled BiFeO3 nanoparticles was accelerated by 2 times compared to unpoled BiFeO3. By combining time-resolved photoluminescence (PL), photoinduced silver deposition testing and photoelectrochemical measurements, it can be revealed that the enhanced photocatalytic performance of poled samples can be properly attributed to the promoted separation and prolonged lifetime of the photogenerated carriers caused by the ferroelectric polarization. These findings may offer a new route to promote the photocatalytic or photoelectric performances of BiFeO3 for advanced applications by adjusting the ferroelectric polarization.
关键词： BiFeO3 nanoparticles,Organic-inorganic composite film,Ferroelectric polarization,Electrical poling technology,Photocatalytic activity
更新于2025-11-14 15:24:45
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{Zn <sub/>6</sub> } Cluster Based Metal–Organic Framework with Enhanced Room-Temperature Phosphorescence and Optoelectronic Performances
摘要： Molecule-based solid-state materials with long lifetimes could enable longer migration distances for excitons, which are beneficial for vast applications in optoelectronic field. Herein, we report a hexanuclear zinc cluster based MOF exhibits highly enhanced phosphorescence about 2 orders of magnitude in comparison with the pristine phosphor ligand. The combination of both experimental and computational results suggest that the {Zn6} cluster is very important for adjusting molecular conformations, packing arrangement, and photophysical properties of the organic phosphor ligands within the MOF matrix. Optoelectronic measurements reveal that the MOF-modified electrode is catalytically active to hydrogen evolution under light irradiation in neutral solution. Thus, our study provide an effective way to achieve low-cost metal-based phosphorescence MOF, expanding its further optoelectronic applications.
关键词： optoelectronic performances,metal?organic framework,hexanuclear zinc cluster,room-temperature phosphorescence
更新于2025-11-14 15:23:50