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Enhanced Photoreduction of Chromium(VI) Intercalated Ion Exchange in BiOBr <sub/>0.75</sub> I <sub/>0.25</sub> Layers Structure by Bulk Charge Transfer
摘要： Owing to its low separating and utilizing efficiency of photo-generated charges in the bulk, the application of photocatalytic technique has been restricted for decades. In this paper, based on interlayer ion-exchange between BiOBr0.75I0.25 layers, we demonstrated a specific interfacial process of photocatalytic Cr(VI) reduction by a direct bulk-charge transfer. The results showed that Cr(VI) was effectively converted to nontoxic Cr(III), even under neutral conditions (pH = 7.0). According to ultraviolet-visible spectroscopy (UV-Vis), X-ray powder diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analysis, the CrO4 2? anion was readily intercalated into the anion lattice layer of BiOBr0.75I0.25 by ion-exchange with OH? in the interlayer, forming a =Bi-O-CrO3 ? complex. Electron paramagnetic resonance (EPR) and photoelectron-chemistry measurements further revealed that excitation of =Bi-O- CrO3 ? by irradiation was crucial for photocatalytic detoxification of Cr(VI) under pH 7.0. The excitation of =Bi-O-CrO3 ? in BiOBr0.75I0.25 strengthened the bulk-charge transfer as follows: (i) electron transfer from O-II to CrVI produced CrV and O-I, respectively, via ligand-to-metal charge transfer excitation; and (ii) electron injection from BiOBr0.75I0.25 to [=Bi-O?I-CrVO3 ?]* (or exportation hole to valence band) resulted in the reduction of Cr(V) to Cr(III). After that, the newly formed Cr(III) in the interlayer of BiOBr0.75I0.25 was de-intercalated into solution due to the space charge repulsion between Cr3+ and Bi2O2 2+ slab, resulting in stable Cr(VI) reduction performance in a wide pH range from 2.0 to 7.0.
关键词： Bulk-charge transfer,Intercalated ion-exchange,De-intercalation,Photocatalytic reduction
更新于2025-09-23 15:23:52
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Fabrication of pyrimidine/g-C3N4 nanocomposites for efficient photocatalytic activity under visible-light illumination
摘要： In this work, a series of pyrimidine/g-C3N4 photocatalysts has been synthesized via a facile solvothermal method for the first time. The structure, elemental composition and morphology of the photocatalysts were characterized by FT-IR, SEM, XPS, N2 adsorption-desorption isotherms and BET characterization methods. The photocatalytic activity of the pyrimidine/g-C3N4 materials was investigated by the degradation of rhodamine solution under visible-light illumination. The pyrimidine/g-C3N4 photocatalyst with 1 wt% of pyrimidine shows the highest photocatalytic activity for the degradation of RhB, which can be mainly ascribed to the effective interfacial charge transfer within the pyrimidine/g-C3N4 photocatalyst and the cooperation effect of the excellent contact interface between g-C3N4 and pyrimidine. The main active species during the photodegradation process are determined by the radical trapping experiments, proving that the superoxide radical (?O2-) and the hydroxyl radical (?OH) play the main role in the photocatalytic reactions.
关键词： Photocatalysis,Pyrimidine,Charge transfer,g-C3N4
更新于2025-09-23 15:23:52
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Multi-configurational Ehrenfest simulations of ultrafast nonadiabatic dynamics in a charge-transfer complex
摘要： Multi-configurational Ehrenfest (MCE) approaches, which are intended to remedy the lack of correlations in the standard mean-field Ehrenfest method, have been proposed as coherent-state based ans?tze for quantum propagation [D. V. Shalashilin, J. Chem. Phys. 130, 244101 (2009)] and also as the classical limit of the variational Gaussian-based multiconfiguration time dependent Hartree (G-MCTDH) method [S. R?mer and I. Burghardt, Mol. Phys. 111, 3618 (2013)]. In the present paper, we establish the formal connection between these schemes and assess the performance of MCE for a coherent-state representation of the classical-limit subsystem. As a representative model system, we address the ultrafast, coherent charge transfer dynamics in an oligothiophene-fullerene donor-acceptor complex described by a two-state linear vibronic coupling model. MCE calculations are compared with reference calculations performed with the MCTDH method, for 10–40 vibrational modes. Beyond a dimensionality of 10 modes, it is shown that the correct representation of electronic coherence depends crucially on the sampling of initially unoccupied Gaussians.
关键词： nonadiabatic dynamics,Multi-configurational Ehrenfest,Gaussian wavepackets,MCTDH,ultrafast dynamics,charge-transfer complex
更新于2025-09-23 15:23:52
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Enhanced photoluminescence and ultrahigh temperature sensitivity from NaF flux assisted CaTiO3: Pr3+ red emitting phosphor
摘要： The Pr3+ doped CaTiO3 red emitting phosphor with enhanced PL and ultrahigh temperature sensing was prepared via NaF flux assisted solid-state reaction. All samples had the orthorhombic perovskite phase and no impurity was found. The typical sample mainly had sphere-like morphology with particle size of ~670 nm. The optical bandgap values were ~3.62-3.63eV. The Pr3+ quenching content was 0.6 mol% and the ET mechanism for quenching was the d-d interaction with the critical distance of 26.09 ?. A certain amount of NaF flux could enhance red emission attributed to 1D2→3H4 transition owing to improving the crystallinity of phosphors and reducing point defects near Pr3+ through the substitution of O2- by F- and Ca2+ by Na+. The energy storage trap (oxygen vacancy) near IVCT state played the key role for trapping electrons, accounting for the LAG emission and the average depth of trap was 0.39 eV. The CIE chromaticity coordinates were very close to that of the ideal red light and the CP was as high as 99.98%. The maximal Sa and Sr was as high as ~0.015 K-1 and~ 5.2% K-1, respectively. The thermal induced relaxation between the 3Pj levels and 1D2 level through the IVCT state was supposed to account for the excellent optical temperature sensing. Our work may provide a useful inspiration for developing ultrahigh sensitive optical temperature sensors.
关键词： Praseodymium,Calcium titanate,Optical thermometry,Intervalence charge transfer state
更新于2025-09-23 15:23:52
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Synthesis and photoluminescence properties of different structural cuprous complexes regulated by benzoxazole ligands and halogen/pseudohalide ions
摘要： Reaction of 2-(2’-pyridyl)benzoxazole (2-PBO), 2-(4’-pyridyl)benzoxazole (4-PBO) and 2,2-(1,4-butanediyl)bis-1,3-benzoxazole (BBO) ligands with CuX (X = I, Br, SCN) afforded a binuclear copper(I) complex [Cu(2-PBO)(μ2-I)]2 (1) and three copper(I) coordination polymers [Cu4(4-PBO)4(μ3-I)4]n (2), {[Cu(4-PBO)(μ3-SCN)]2}n (3) and {[Cu(BBO)(μ2-Br)]2}n (4). The structural analysis revealed that the all copper(I) ions are four-coordinated and the geometric structure around the central copper(I) atom possessing slightly distorted tetrahedral geometry in complexes 1-4. Halogen or pseudohalide ions can not only act as counter anions, but also as ligands participation in coordination when the cuprous ion coordination sites are not saturated. Due to the different coordination modes of the benzoxazole ligands, in order to satisfy the tetra-coordination of cuprous ions, halogen or pseudohalide ions adopt μ2 and/or μ3-bridging modes to synergistically complete coordination. Photoluminescence investigation show that complexes 1, 3 and 4 have two emission peaks, the high energy band peak is attributed to MLCT[d10(Cu)→π*] and XMCT, the low energy band peak is caused by the 3CC emission. This may be due to the presence of μ2-X (X=I, Br, S) in these complexes. However complex 2 only had one emission peak, which may be attributed to MLCT[d10(Cu)→π*] and XMCT.
关键词： Cuprous complex,Charge-transfer,Photoluminescence,Crystal structure,Benzoxazole
更新于2025-09-23 15:23:52
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Synthesis, characterization and photophysical properties of a new class of pyrene substituted 1,3,4-oxadiazole derivatives
摘要： We have designed and synthesized a series of a new class of pyrene substituted 1,3,4- oxadiazole derivatives (abbreviated as 3(a-e)) through palladium catalyzed Suzuki-Miyaura cross coupling reaction. The chemical structures of the probes were characterized by using analytical techniques namely 1H NMR, 13C NMR, FT-IR and GC-MS. The novel bipolar molecules consist of pyrene as an electron donor unit (D) and electron-deficient 1,3,4-oxadiazole as an acceptor unit (A) linked via extending π conjugation through a phenyl spacer with para linkages (D-π-A). Intramolecular charge transfer is improved by structure-property relationship. The detailed photophysical/solvatochromic properties of newly synthesized derivatives have been studied employing steady state spectroscopic techniques. The photophysical studies revealed that compounds emit strong indigo-blue fluorescence and efficient blue emission extending into blue-green in solid phase with high quantum yields. Thermal and morphological stabilities of the derivatives were studied employing DSC and TGA measurements. In addition, density functional theory (DFT) computations have been carried out to demonstrate various intramolecular interactions that cause the stabilization of the compound leading to its optoelectronic applications. The highest occupied molecular orbital energy (HOMOs), lowest unoccupied molecular orbital energy (LUMOs), the energy bandgap, chemical hardness (η), softness (δ), electronegativity (χ) and chemical potential (μ) were computed with the help of frontier molecular orbitals. The results were compared and discussed with the experimental results. The results demonstrate that the novel pyrene containing oxadiazole derivatives could be used as small organic molecules for multifunctional organic light-emitting devices (OLED)/optoelectronic devices.
关键词： Intramolecular charge transfer (ICT),1,3,4-Oxadiazole,Quantum yield,Pyrene,Density functional theory
更新于2025-09-23 15:23:52
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Bright red-emitting highly reliable styryl probe with large stokes shift for visualizing mitochondria in live cells under wash-free conditions
摘要： Bright red-emitting pyridinium cyanine based styryl probe 2 is synthesized in good yields. Probe 2 demonstrated a large Stokes’ shift (Δλ ≈ 128 nm, 4227 cm-1 in DCM) and excellent fluorescent quantum yield (?fl ≈ 0.2 - 0.7) due to strong Intra-molecular charge transfer (ICT). Probe 2 found to exhibit exceptional selectivity for cellular mitochondria in both normal (COS-7) and cancer (A549) cell lines. Probe 2 is readily applicable as a “wash-free” dye to visualize mitochondria as it does not require post-staining washing prior to imaging. Styryl probe 2 also showed an excellent biocompatibility as the calculated LC50 (lethal concentration, 50%) value was > 20 μM. Probe 2 emission did not show any interferences from anionic species or other biological molecules. Probe 2 is readily excitable (λex ~460 and λem ~618 nm) with the available laser (454 nm) in commercial microscopes and thus it can be a useful probe for mitochondrial tracking in live cells.
关键词： Wash-free application,Biocompatibility,Intra-molecular charge transfer (ICT),Styryl dye,Large Stokes shift,Mitochondria selectivity
更新于2025-09-23 15:23:52
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Ultrafast spectroscopy of the primary charge transfer and ISC processes in 9-anthraldehyde
摘要： The ultrafast charge transfer (CT) and the following intersystem crossing (ISC) processes of 9-anthraldehyde were investigated in ethanol and hexane using femtosecond transient absorption spectroscopy combined with quantum chemical calculations. The CT was observed within 0.11 ps in ethanol and 0.23 ps in hexane. Due to the stronger polarity in ethanol, the CT is faster than in hexane. The following ISC is determined to be 22.3 ps and 21.4 ps in two solvents, respectively. However, the timescales of ISC are similar in both solvents since the excited energies of the S1 and triplet states are close.
关键词： Time-resolved transient absorption spectroscopy,intramolecular charge transfer,radiationless intersystem crossing
更新于2025-09-23 15:23:52
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Scintillation properties of Ce-doped Yb3Al5O12 single crystals
摘要： Yb3Al5O12 (YbAG) single crystals were prepared by the Floating Zone (FZ) method with and without doping with different concentrations of Ce, and then we evaluated their basic scintillation properties. All the samples showed scintillation with emission peaks in the range from 300 nm to 600 nm. The origin of this emission peak was attributed to the charge transfer luminescence of Yb3+. In addition, the Ce-doped samples showed three strong emission bands, in which the emission origin is also predominantly due to the charge transfer emission but the spectrum was deformed due to a self-absorption by the 4f-5d transitions of Ce3+. Scintillation decay profiles of all the samples were approximated by a sum of two exponential decay functions, and the obtained decay times were 1 and 9-10 ns. Among the present samples, the 0.5% Ce-doped sample showed the lowest scintillation afterglow level. All the samples demonstrated a full energy peak in the pulse height spectrum measured under 241Am 5.5 MeV α-ray irradiation. Among the present samples, the undoped sample showed the highest light yield with a value of 20 ph/5.5MeV-α.
关键词： Ce3+,Charge transfer luminescence,Garnet,Scintillation
更新于2025-09-23 15:23:52
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Tuning charge transfer at the electron donor/acceptor assembly through vibration-induced aggregation of P3HT chains in solution
摘要： In this report, we developed a test platform to probe charge transfer at a model electron donor/acceptor system in which charge transfer rate is investigated through electrical contact resistance in a metal oxide/organic semiconductor/metal oxide structure using transmission line method (TLM). Aluminum (Al)-doped zinc oxide (AZO) films were adopted as source and drain electrodes. Molecular ordering of the organic semiconductor was systematically varied through vibration-induced aggregation (VIA) treatment of poly(3-hexylthiophene) (P3HT) polymer chains in solution to probe the effect of molecular ordering of P3HT (donor) in contact with AZO (acceptor) on interfacial charge transfer at the electron donor (P3HT)/acceptor (AZO) interface crucial in determining device performance of optoelectronic devices. Enhanced charge transfer at the donor/acceptor interface containing P3HT film treated with VIA process was demonstrated by reduction of the contact resistance via TLM. More efficient charge transfer at the AZO/sonicated-P3HT/AZO compared with AZO/pristine-P3HT/AZO results from enhanced charge carrier mobility of P3HT near the interface, blocking back-transfer of injected holes from P3HT to the AZO electrode, as demonstrated by theoretical prediction. Effect of VIA treatment on charge transfer at the electron donor/acceptor interface is confirmed through comparing the AZO/P3HT contact resistance depending on the degree of VIA for P3HT polymer chains by varying sonication time. Our work presented here demonstrates that improvement in structural arrangement of polymer chains leads to efficient charge transfer at interface.
关键词： Sonication,Charge transfer,p3ht
更新于2025-09-23 15:23:52