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A Fluorescence Probe for Metal Ions Based on Black Phosphorus Quantum Dots
摘要： Fluorescence method for detecting metal ions has advantages of fast detection speed, simple operation, and low price over the conventional methods. Black phosphorus quantum dots (BP QDs) have high photoluminescence quantum yield and modifiable surface, which have great potential in the field of fluorescent probes. In this study, high quality BP QDs are prepared by pyrolysis method and are first time used as trace metal ion probes in both organic solutions and aqueous solutions. The detection limits of Hg2+ and Cu2+ in the aqueous solution are 5.3 × 10?9 m and 1.6 × 10?6 m, respectively. In addition, the detection limits of Cu2+ in the organic solution are 16 × 10?6 m. The fluorescence quenching mechanism based on the calculation of the electronic structure and adsorption energy of BP QDs after adsorption of metal ions is further explained. The results provide a new promising fluorescence probe for trace metal ions without the help of organic molecules.
关键词： electron transfer,fluorescence,black phosphorus,metal ions
更新于2025-09-19 17:13:59
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Plasmonic hot electron transfer in anisotropic Pt–Au nanodisks boosts electrochemical reactions in the visible-NIR region
摘要： Plasmonic hot electron transfer in anisotropic Pt–Au nanodisks boosts electrochemical reactions in the visible-NIR region. Anisotropic plasmonic metals have attracted significant attention in enhancing the catalytic performance of catalysts due to their broad light-harnessing capabilities and active hot electrons; however, limited investigations have been dedicated towards improving their electrochemical reaction performance in the visible and near infrared (NIR) regions. Herein, anisotropic Pt-edged Au nanodisks (NDs) were synthesized by controlling the preferential loading of Pt and used as catalysts for plasmon-enhanced electrochemical methanol oxidation reactions (MORs) under visible-NIR light irradiation by, and the light-enhanced electric current over the Pt-edged Au NDs was found to be 3-fold higher than that under dark conditions. Wavelength-dependent electric current over the Pt-edged Au NDs for the MOR in the visible-NIR light region demonstrates that the light-induced enhancement of the electric current is due to surface plasmon resonance (SPR) of the Au NDs. Furthermore, plasmonic hot electron transfer was studied by the single-particle photoluminescence images and spectra of Au NDs and Pt–Au NDs, and the dipole surface plasmon resonance (DSPR) mode was proved to be the main channel for hot electron transfer. During the electrochemical reaction under visible-NIR light irradiation, a plasmonic hot electron is transferred to the electrode, and a 'hot hole' is left on the surface, boosting the MOR.
关键词： Pt–Au nanodisks,Plasmonic hot electron transfer,electrochemical reactions,visible-NIR region
更新于2025-09-16 10:30:52
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Proton release process during the S2-to-S3 transition of photosynthetic water oxidation as revealed by the pH dependence of kinetics monitored by time-resolved infrared spectroscopy
摘要： Photosynthetic water oxidation takes place at the Mn4CaO5 cluster in photosystem II via light driven cycle of intermediates called S states (S0–S4). Clarifying how electron and proton transfer reactions are coupled with each other in the S2→S3 transition, which occurs just before the O-O bond formation, is crucial to understand the water oxidation mechanism. Here, we investigated the pH dependence of the kinetics of the S2→S3 transition using time-resolved infrared (TRIR) spectroscopy to identify the proton release phase in this transition. TRIR measurements of YD-less PSII core complexes from the D2-Y160F mutant of Thermosynechococcus elongatus showed that the last phase in this transition (τ = ~350 μs at pH 6) was strongly pH dependent, and its time constant at pH 5 was larger than that at pH 8 by a factor of more than three. In contrast, the earlier phase with a ~100 μs time constant was virtually independent of pH. These results strongly support the view that proton release is a rate-limiting step of the proton-coupled electron transfer in the last phase of the S2→S3 transition. This proton release enables electron transfer by removing an excessive positive charge from the catalytic center and hence lowering its redox potential.
关键词： Mn4CaO5 cluster,proton-coupled electron transfer,S2→S3 transition,photosynthetic water oxidation,time-resolved infrared spectroscopy
更新于2025-09-16 10:30:52
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Effects of interface adsorption configurations on dye-sensitized solar cell performance at the stoichiometric and defected TiO2 anatase (101): a theoretical investigation
摘要： Interfacial adsorption configuration plays a crucial role in influencing on the photovoltaic performance of dye-sensitized solar cells (DSSCs), and thus, theoretical investigations are needed to further understand the impacts of different absorption configurations on stoichiometric and defected TiO2 (101) surface on the short-circuit photocurrent density (JSC) and open-circuit voltage (VOC) of DSSCs. Herein, calculations of isolated dyes and dye/TiO2 systems were performed on the donor-π bridge-acceptor (D-π-A) type porphyrin sensitizers bearing different donor moieties and a α-cyanoacrylic acid anchoring group (T1-3), using DFT and TD-DFT methods. And, for the first time, comparative analysis on interfacial electron injection (IET) and density of states (DOS) were carried out on dye/TiO2 system with stoichiometric and defected surface to provide a further insight into the electronic factors in influencing the efficiency of DSSC, which can well explain the experimental variation trends of JSC and VOC. It turned out that attachment via the carboxyl and cynao groups in a tridentate binding mode can result in more efficient IET rates and an upshifted conduction band in comparison with the bidentate attachment. More interestingly, we found that the adsorption configuration on defected surface containing O2c vacancy induced more upshifted CBM and relative fast IET, especially for the bonding mode through two O atoms of carboxyl group.
关键词： interfacial electron transfer,density of states,dye-sensitized solar cells,adsorption configuration,TiO2
更新于2025-09-16 10:30:52
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The Influence of Photoinduced Processes on a Quantum Dot Surface on the Electron Transfer Efficiency in TiO2 Nanoparticle/Quantum Dot Structures
摘要： The influence of photoinduced processes occurring on the surfaces of CdSe/ZnS quantum dots is considered in relation to the functional characteristics of hybrid TiO2 nanostructure/quantum dot systems. Preirradiation of quantum dots is shown to achieve a threefold increase in electron transfer efficiency within these structures. Photoinduced processes are found to impact both the efficiency of nonradiative phenomena in quantum dots and the electron transfer in the indicated systems.
关键词： photoinduced processes onto quantum dots,photoinduced electron transfer,photoactivation,semiconducting quantum dots,hybrid structures,titanium dioxide nanoparticles
更新于2025-09-16 10:30:52
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Arylamino-fluorene derivatives: Optically induced electron transfer investigation, redox-controlled modulation of absorption and fluorescence
摘要： A series of biarylaminofluorene-based systems with donor-π-donor (D-π-D) structure have been designed and synthesized in order to study the dependence on the π-conjugated bridge length of the intervalence charge-transfer transitions (IV-CT) and of the electronic coupling between the redox centers. To this purpose cyclic voltammetry, UV/Vis-NIR, fluorescence spectroscopy and computational investigations have been carried out to characterize the electronic structure of the compounds in the neutral as well as in the mono- and dication states. Additionally, a study of related D-π compounds has been performed to elucidate the effect of the interaction between two redox centers. Interestingly it was observed that the mono- and dication species exhibit intense transition bands in the NIR region, in the 10000-15000 cm-1 range, whose intensity depends on the oxidation state and thus it can be reversibly tuned by an applied potential. In a similar way, all compounds show an oxidation state dependent fluorescence which leads to electrofluorochromism. Particularly significant is the mixed valence behavior that provides these systems singular optoelectronic properties, making them excellent active components for electrochromic and electrofluorochromic applications.
关键词： Fluorene,Optically induced electron transfer,Triarylamines,NIR-Electrochromism,Electrofluorochromism,Mixed-Valence
更新于2025-09-16 10:30:52
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Oxygen Tolerant PET-RAFT Facilitated 3D Printing of Polymeric Materials under Visible LEDs
摘要： Photopolymerization-based 3D printing process is typically conducted using free radical polymerization, which leads to fabrication of immutable materials. An alternative 3D printing of polymeric materials using trithiocarbonate (TTC) reversible addition-fragmentation chain transfer (RAFT) agents has always been a challenge for material and polymer scientists. Herein we report 3D printing of RAFT-based formulations that can be conducted fully open to air using standard digital light processing (DLP) 3D printer and under mild conditions of visible light at blue (λ max = 483 nm, 4.16 mW/cm2) or green (λ max = 532 nm, 0.48 mW/cm2) wavelength. Our approach is based on activation of TTC RAFT agents using eosin Y (EY) as a photoinduced electron-transfer (PET) catalyst in the presence of a reducing agent (triethylamine (TEA)), which facilitated oxygen tolerant 3D printing process via a reductive PET initiation mechanism. Re-activation of the TTCs present within the polymer networks enables post-printing monomer insertion into the outer layers of an already printed dormant object under a second RAFT process, which provides a pathway to design a more complex 3D printing. To our best knowledge, this is the first example of oxygen tolerant EY/TEA catalyzed PET-RAFT facilitated 3D printing of polymeric materials. We believe that our strategy is a significant step forward in the field of 3D printing.
关键词： Oxygen Tolerant,Trithiocarbonate,3D Printing,Visible Light-Induced PET-RAFT Polymerization,Digital Light Processing,Photoinduced Electron-Transfer
更新于2025-09-16 10:30:52
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Tuning the photoinduced charge transfer from CdTe quantum dots to ZnO nanofilms through Ga doping
摘要： Tuning the charge transfer rate between quantum dots (QDs) and metal oxide (MO) is important for improving the performances of QDs-MO devices. And tailoring the energy band of MO is one way to tune the charge transfer rate. In this work, we enhance the charge transfer rate between CdTe QDs and ZnO through tailoring the optical band gap of ZnO nano?lms by Ga-doping. The Ga doping in?uenced the photo luminescence (PL) performance of CdTe QDs/ZnO hybrid structures. The results of time-resolved ?uorescence spectra revealed that the charge transfer rate from CdTe QDs to ZnO nano?lms could be tuned by varying the Ga doping concentrations in ZnO. And, transfer rate were increased by up to ~4.1 times through Ga doping. In addition, the structure showed electron transfer e?ciency improvements to the tune of ~25.3%. We attribute the improvement to e?cient electron transfer via band-band transfer and the defects pathways induced by Ga-doping. The experimental results will be useful for improving the e?ciency of optical devices using QDs/ZnO hybrid structure.
关键词： Doping,Semiconductors,Electron transfer,Time-resolve ?uorescence spectra,QDs/ZnO hybrid structures
更新于2025-09-16 10:30:52
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Novel “turn off-on” sensors for detection of DNA-acrylamide interaction usingZnS quantum dots as a phosphorescent probe
摘要： A novel “turn off-on” sensor for detection of interaction between DNA and acrylamide (ACR) was developed. In this method, L-cysteine capped Mn-doped ZnS quantum dots (QDs) were used as room temperature phosphorescent probes. In the “turn-off” mode, ACR was absorbed onto the surface of QDs via electrostatic interaction, which caused a quenching effect of room-temperature phosphorescence signal by photoinduced electron-transfer mechanism. ACR was removed from the QDs’ surface with the addition of DNA. Thus, the phosphorescence emission of QDs was recovered and the system was turned to the “turn-on” mode. The quenching mechanism of QDs by ACR was collisional (dynamic) and the quenching constant, binding constant, and binding site number were calculated as 3.2 × 10 4 M (cid:0)1 , 2.04 × 10 4 M (cid:0)1 , and 1.2, respectively. An absorption spectrometric method was also used to evaluate ACR-DNA interaction and the binding constant (K) was found as 2.4 × 10 5 M (cid:0)1 . The developed biosensor is simple, is free of interferences coming from autofluorescence and scattering light, and does not need any derivatization step or sample pretreatment.
关键词： quantum dots,DNA interaction,phosphorescence,photoinduced electron transfer,Acrylamide
更新于2025-09-16 10:30:52
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Ultrafast electron transfer through silicon-vacuum interface induced by the action of intense femtosecond laser pulse
摘要： A theoretical study of the influence of a quasistationary electric field formed during emission separation of charges on ultrafast electron transfer near the silicon-vacuum interface irradiated by femtosecond laser pulses was carried out. The values of the strength of the arising quasistationary field during irradiation by femtosecond pulses with fluences near and above the silicon damage thresholds were estimated. The possibility of the formation of a dynamic optically layered structure in the near-surface layers of silicon irradiated by a femtosecond pulse resulting from a modification of its optical properties due to the depletion of electrons in the surface layer was studied. It is suggested that the time-depending dipole moment induced by the emission separation of charges should lead to the generation of electromagnetic radiation from the terahertz frequency range. The basic properties of this radiation were theoretically investigated.
关键词： Coulomb explosion,silicon,ultrafast heating,terahertz radiation,electron emission,electron transfer,femtosecond laser pulse
更新于2025-09-12 10:27:22