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Photocatalytic oxidation of nitrogen oxides over {001}TiO2: the influence of F? ions
摘要： A series of anatase TiO2 nanosheets with different percentage of {001} facets ({001}TiO2) were synthesized through a hydrothermal route using tetrabutyltitanate as a titanium precursor and HF as a shape controlling agent. The amount of HF exhibits an obvious influence on the structures and activities of TiO2 samples. The adsorbed surface F? ions on the {001} facets of the anatase TiO2 were removed by washing them with NaOH solution. The as-prepared catalysts were characterized by X-ray diffraction, Brunner?Emmet?Teller measurements, ultraviolet-visible diffuse reflectance spectroscopy, scanning electron microscopy, transmission electron microscopy techniques, and X-ray photoelectron spectroscopy analysis. The results indicated that all the as-prepared catalysts showed an anatase crystalline and nanosheet structure, as well as a strong ultraviolet light absorbance. With the increase of HF content, the crystallite size and the percentage of {001} facets increased first and later decreased, state the opposite change observed in BET. When the content of HF was 4.4 mL, the percentage of {001} facets reached the maximum up to 61.62%. After all samples were treated with 0.1 M NaOH solution, the percentage of {001} facets increased to a maximum of 64.46%. All the samples washed by NaOH solution exhibited much higher photocatalytic activity for NOx oxidation under UV light irradiation than P25, {101}TiO2, and {001}TiO2 without NaOH washing, suggesting that the surface F? ions inhibited the photocatalytic NOx oxidation. Moreover, the results showed that the NaOH-washed {001}TiO2 has a high humidity tolerance.
关键词： Surface F? ions,{001}TiO2,Photocatalysis,NOx oxidation
更新于2025-09-19 17:15:36
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High-sensitive optical temperature sensing based on 5D1 emission of Eu3+ in YVO4
摘要： By studying the temperature-induced red-shift of the V-O charge transfer band (CTB) edge in YVO4:10% Eu3+, we demonstrate a high-sensitive strategy for optical temperature sensing using the combination of the temperature-induced enhancement of the excitation in the tail of the CTB and the thermal population of 5D1 state of Eu3+. Under a constant 358 nm excitation, the integrated emission intensity corresponding to 5D1 → 7F1 transition of Eu3+ exhibits drastic temperature dependence ranging from 300 to 480 K. A high relative sensitivity SR was obtained to be 3923/T2. Temperature cycling tests were performed to evaluate the reusability and feasibility as temperature sensors. Our results indicate the potential use of the proposed strategy for high performance optical thermometry.
关键词： Charge transfer band,Rare earth ions,Thermal population,Optical temperature sensing,Luminescence
更新于2025-09-19 17:15:36
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Electronic structure and optical properties of Ln(III) nitrate adducts with 1,10-phenanthroline
摘要： Adducts of tris-nitrates of rare-earth elements Ce(III), Nd(III), Eu(III), and Er(III) with two molecules of 1,10-phenanthroline with formula Ln(NO3)3(Phen)2 are studied by X-ray photoelectron spectroscopy (XPS) and quantum chemistry (DFT/TDDFT). The geometric structure for DFT modeling is build using X-ray diffraction data. To analyze the composition and differences of the electronic structure in the series under study, XPS spectra were obtained for which interpretation was performed using calculated data. It has been shown that the molecule of Phen, when attached to the complexes of nitrates, is polarized, leads to an increase in absorption in the visible region and reduces the energy gap between HOMO and LUMO. Experimental absorption spectra were obtained, described and interpreted using TDDFT simulation. The transitions in adducts from π to π * MO in Phen ligands determine the main absorption band. The reasons for the absence of luminescence in adducts with ions Ce(III), Nd(III), and Er(III) are revealed by the example of the correlation diagram of singlet and triplet levels. A possible origin of coloring of adducts is determined using TDDFT.
关键词： Optical properties,Nitrates,DFT,Lanthanide ions,Photoelectron spectroscopy
更新于2025-09-19 17:15:36
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Rapid Quantitative Fluorescence Detection of Copper Ions with Disposable Microcapsule Arrays Utilizing Functional Nucleic Acid Strategy
摘要： In this work, an economical and easy-to-use microcapsule array fabricated by ice printing technique has been realized for ultrasensitive fluorescence quantification of copper ions employing functional nucleic acid strategy. With ice printing, the detection reagents are sealed by polystyrene (PS) film isolation and photopolymer, which guarantees a stable and contamination-free environment for functional nucleic acid reaction. Our microcapsule arrays have shown long-term stability (20 days) under ?20 °C storage in frozen form before use. During the Cu2+ on-site detection, 1 μL sample is simply injected into the thawy microcapsule by a microliter syringe under room temperature, and after 20 minutes the fluorescence result can be obtained by an LED transilluminator. This method can realize the detection limit to 100 nM (100 fmol/μL) with high specificity.
关键词： ice printing,functional nucleic acid,fluorescence detection,copper ions,microcapsule arrays
更新于2025-09-19 17:15:36
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Characteristics of the Structural State of Bismuth Ions in Bismuth-Borate Glasses
摘要： The properties and graphical plots of the properties of bismuth-borate glasses in a wide range of compositions — 20 to 80 mol.% Bi2O3 — are presented. In multi-bismuth glasses both the boron and bismuth ions are found in two coordination states: B3+, B4+ and Bi3+, Bi6+. The [BiO3] groups play the role of a conventional glass former but manifest weakly in the IR spectra.
关键词： structure of bismuth-borate glasses,properties of bismuth-borate glasses,lead-free low-melting glasses,structural role of Bi ions
更新于2025-09-19 17:15:36
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Enhanced upconversion and downshifting emissions from Tm3+, Yb3+ co-doped CaZrO3 phosphor in the presence of alkali ions (Li+, Na+ and K+)
摘要： The Tm3+, Yb3+ co-doped CaZrO3 phosphor samples have been synthesized through solid state reaction method in the absence and presence of alkali metal ions (i.e. Li+, Na+, K+). The X-ray diffraction (XRD) study shows the formation of CaZrO3 crystal with orthorhombic phase. The Tm3+, Yb3+ co-doped CaZrO3 phosphor emits intense upconversion emission in blue (474 nm) and NIR (799 nm) regions due to 1G4 → 3H6 and 3H4 → 3H6 transitions of Tm3+ ions, respectively on excitation with 980 nm radiation. The emission intensity is significantly enhanced in the presence of alkali ions due to charge compensation and asymmetry in the crystal field. The emission intensity in the case of Na+ co-doped phosphor is maximum and at 1 W pump power, it is increased by ~ 44 and ~ 31 times in blue and NIR regions, respectively as compared to without alkali ions co-doped phosphor. The downshifting emission in blue region has been observed due to oxygen vacancy and Tm3+ ions on excitation with 277 and 360 nm radiations which is enhanced significantly in the presence of alkali ions. Thus, the intense blue emission by this material is suitable for blue and white light emitting phosphors.
关键词： Calcium Zirconate,Downshifting,Alkali ions,Upconversion,Rare earth
更新于2025-09-19 17:15:36
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Luminescence properties of Bi doped La2O3 powder phosphor
摘要： Different concentrations of bismuth doped lanthanum oxide (La2-xO3:Bix) phosphor powder (x = 0.001, 0.002, 0.003, 0.004, 0.006, 0.008 and 0.01) were synthesised by means of the sol-gel combustion method at 250 °C using citric acid as the fuel. The product was annealed at different temperatures and the luminescence properties were investigated. The maximum emission was obtained for the sample which was doped with x = 0.002 and annealed at 1200 °C in air. The X-ray diffraction analysis confirmed that all samples crystallized in the La2O3 hexagonal phase. The scanning electron microscopy data showed that the grain size increased with increasing annealing temperature and the shape of the grains changed from rectangular to more round, but faceted, after annealing at 1200 °C in air. Energy dispersive X-ray spectroscopy confirmed the chemical composition, while diffuse reflectance spectroscopy was used to study the absorption of the La2-xO3:Bix samples. All the samples were absorbing in the ultraviolet range between 220 to 320 nm. The band gap of the La2O3 pure host sample was obtained from the reflectance data as 5.1 eV. Excitation at a wavelength of 308 nm resulted in a single broad blue luminescence emission band centered at 462 nm. The excitation and emission bands were attributed to transitions between the 1S0 ground state and the 3P1 excited state of Bi3+ ions, with a Stokes shift of 1.35 eV.
关键词： La2O3,Photoluminescence,Bismuth ions
更新于2025-09-19 17:15:36
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Irradiation effects of swift heavy ions on palladium films deposited on 6H-SiC substrate
摘要： The irradiation effect of swift heavy ions on palladium (Pd) films deposited on 6H-SiC was investigated. The samples were irradiated by Xe26+ ions with the energy of 167 MeV at fluences of 1 × 1013 cm?2 and 3 × 1014 cm?2 at room temperature. Phase identification, residual stress and surface morphology were investigated with X-ray diffraction (XRD) and scanning electron microscopy (SEM). The XRD results showed that the as-deposited sample was composed of Pd and SiC with no evidence of a reaction between Pd and SiC. No reaction was observed for the lower irradiation fluence, only an increase in the Pd peak intensities was observed indicating improvement in the crystallinity of the material. A reaction between Pd and SiC forming PdSi and Pd2Si was observed after irradiation at a fluence of 3 × 1014 cm?2. The stress measurements indicated that the films were having tensile and biaxial stress not exceeding 200 MPa. A decrease in stress values was observed with an increase in irradiation fluence. The surface morphology of the as-deposited was flat and composed of small granules. There was an increase in granule sizes due to irradiation at 1 × 1013 cm?2. Irradiating at 3 × 1014 cm?2 caused grain agglomeration and clustering.
关键词： Palladium,SiC,Swift heavy ions,Stress,Irradiation
更新于2025-09-19 17:15:36
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Bismuth Ions Selective Fluorescent Chemosensor Based on Rhodamine-B
摘要： A new rhodamine-based compound (L1) has been synthesized and applied as an "off-on" chemosensor for Bi3+. The complexation behaviour of chemosensor with different metal ions including Bi3+ ions in EtOH/H2O (4:1, v/v) was studied on UV-visible absorption spectra and fluorescent spectra. Results showed that the chemosensor (L1) is highly selective for Bi3+ over other cations such as Hg2+, Fe2+, Mn2+ and Ca2+. This selectivity can be attributed to the photoinduced electron transfer mechanism (PET) of the sensor in the presence of Bi3+. The complex solution (L1-Bi3+) exhibited reversibility with EDTA.
关键词： Fluorescent chemosensor,Rhodamine-B,Bismuth ions.
更新于2025-09-19 17:15:36
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Dual Functional S-Doped g-C3N4 Pinhole Porous Nanosheets for Selective Fluorescence Sensing of Ag+ and Visible-Light Photocatalysis of Dyes
摘要： This study explores the facile, template-free synthesis of S-doped g-C3N4 pinhole nanosheets (SCNPNS) with porous structure for fluorescence sensing of Ag+ ions and visible-light photocatalysis of dyes. As-synthesized SCNPNS samples were characterized by various analytical tools such as XRD, FT-IR, TEM, BET, XPS, and UV–vis spectroscopy. At optimal conditions, the detection linear range for Ag+ was found to be from 0 to 1000 nM, showing the limit of detection (LOD) of 57 nM. The SCNPNS exhibited highly sensitive and selective detection of Ag+ due to a significant fluorescence quenching via photo-induced electron transfer through Ag+–SCNPNS complex. Moreover, the SCNPNS exhibited 90% degradation for cationic methylene blue (MB) dye within 180 min under visible light. The enhanced photocatalytic activity of the SCNPNS was attributed to its negative zeta potential for electrostatic interaction with cationic dyes, and the pinhole porous structure can provide more active sites which can induce faster transport of the charge carrier over the surface. Our SCNPNS is proposed as an environmental safety tool due to several advantages, such as low cost, facile preparation, selective recognition of Ag+ ions, and efficient photocatalytic degradation of cationic dyes under visible light.
关键词： cationic dyes,pinhole porous nanosheet,photocatalytic degradation,visible light,Ag+ ions,S-doped g-C3N4,fluorescence sensing
更新于2025-09-19 17:15:36