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Fabrication and H <sub/>2</sub> -Sensing Properties of SnO <sub/>2</sub> Nanosheet Gas Sensors
摘要： Vertically formed and well-defined SnO2 nanosheets are easy to fabricate, involving only a single process that is performed under moderate conditions. In this study, two different sizes of a SnO2 nanosheet were concurrently formed on a Pt interdigitated electrode chip, with interconnections between the two. As the SnO2 nanosheets were grown over time, the interconnections became stronger. The ability of the fabricated SnO2 nanosheets to sense H2 gas was evaluated in terms of the variation in their resistance. The resistance of a SnO2 nanosheet decreased with the introduction of H2 gas and returned to its initial level after the H2 gas was replaced with air. Also, the response?recovery behaviors were improved as a result of the growth of the SnO2 nanosheets owing to the presence of many reaction sites and strong interconnections, which may provide multipassages for the electron transfer channel, leading to the acceleration of the reaction between the H2 gas and SnO2 nanosheets.
关键词： H2 sensing,single process fabrication,SnO2 nanosheets,gas sensors,electron transfer channel
更新于2025-09-23 15:21:01
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Bulk electronic transport impacts on electron transfer at conducting polymer electrode–electrolyte interfaces
摘要： Electrochemistry is an old but still flourishing field of research due to the importance of the efficiency and kinetics of electrochemical reactions in industrial processes and (bio-)electrochemical devices. The heterogeneous electron transfer from an electrode to a reactant in the solution has been well studied for metal, semiconductor, metal oxide, and carbon electrodes. For those electrode materials, there is little correlation between the electronic transport within the electrode material and the electron transfer occurring at the interface between the electrode and the solution. Here, we investigate the heterogeneous electron transfer between a conducting polymer electrode and a redox couple in an electrolyte. As a benchmark system, we use poly(3,4-ethylenedioxythiophene) (PEDOT) and the Ferro/ferricyanide redox couple in an aqueous electrolyte. We discovered a strong correlation between the electronic transport within the PEDOT electrode and the rate of electron transfer to the organometallic molecules in solution. We attribute this to a percolation-based charge transport within the polymer electrode directly involved in the electron transfer. We show the impact of this finding by optimizing an electrochemical thermogalvanic cell that transforms a heat flux into electrical power. The power generated by the cell increased by four orders of magnitude on changing the morphology and conductivity of the polymer electrode. As all conducting polymers are recognized to have percolation transport, we believe that this is a general phenomenon for this family of conductors.
关键词： thermogalvanic cell,electron transfer,conducting polymer
更新于2025-09-23 15:21:01
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Stepwise Two-Photon-Induced Electron Transfer from Higher Excited States of Noncovalently Bound Porphyrin-CdS/ZnS Core/Shell Nanocrystals
摘要： There has been an increasing amount of interest in stepwise two-photon absorption (2PA)-induced photochemical reactions because of their extremely lower power thresholds compared to that of the simultaneous process and drastic reaction enhancements in some cases. However, stepwise 2PA-induced photochemical reactions were reported only in single chromophores and covalently bound bi-chromophores and there are few reports on these reactions in noncovalently bound systems because of weak electronic interactions among chromophores. This study demonstrated the stepwise 2PA-induced electron transfer from higher excited states in noncovalently bound protoporphyrin IX·CdS/ZnS core/shell nanocrystals (NCs). The electron transfer from higher excited states of porphyrin to CdS NCs successfully overcomes the activation barrier associated with the wide bandgap ZnS shell, indicating that a high reduction potential can be obtained with the stepwise 2PA process. The concept presented in this study can be applied to various noncovalently bound multi-chromophore systems to explore nonlinear photoresponses.
关键词： Nonlinear,Anti-Kasha type,colloidal nanocrystals,hybrid nanomaterial,hot electron transfer
更新于2025-09-23 15:21:01
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Photoinduced Proton-Coupled Electron Transfer in Supramolecular Sn <sup>IV</sup> Di( <scp>l</scp> -tyrosinato) Porphyrin Conjugates
摘要： Proton-coupled electron transfer (PCET) plays a key role in many biological processes, and a thorough comprehension of its subtle mechanistic complexity requires the synthesis and characterization of suitable artificial systems capable of mimicking this fundamental, elementary step. Herein, we report on a detailed photophysical investigation of conjugate 1, based on a tin(IV) tetraphenylporphyrin (SnTPP) chromophore bound to two L-tyrosinato amino acids, in CH2Cl2 in combination with organic bases of different strength and the preparation of a novel conjugate 3, based on a tin(IV) octaethylporphyrin (SnOEP) in place of the tetraphenyl analogue, and its photophysical characterization in CH2Cl2 in the presence of pyrrolidine. In the case of compound 1 with all bases examined, quenching of both the singlet and triplet excited states is observed and attributed to the occurrence of concerted proton?electron transfer (CPET). Rates and quenching yields decrease with the strength of the base used, consistent with the decrease of the driving force for the CPET process. Conjugate 3 with pyrrolidine is quenched only at the triplet level by CPET, albeit with slower rates than its parent compound 1, ascribable to the smaller driving force as a result of SnOEP being more difficult to reduce than SnTPP. For both systems, the quenching mechanism is confirmed by suitable blank experiments, specific kinetic treatments, and the observation of kinetic isotope effects (KIEs). Differently from what has been previously proposed, a detailed reinvestigation of the triplet quenching of 1 with pyrrolidine shows that no long-lived radical pair state is formed, as diradical recombination is always faster than formation. This is true for both 1 and 3 and for all bases examined. The kinetics of the CPET pathways can be well described according to Marcus theory and point toward the involvement of substantial reorganization energy as typically observed for PCET processes of concerted nature.
关键词： tin(IV) porphyrin,photophysical characterization,L-tyrosinato amino acids,CPET,PCET,Proton-coupled electron transfer,kinetic isotope effects,concerted proton?electron transfer,Marcus theory
更新于2025-09-23 15:19:57
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Tailored Engineering of Bimetallic Plasmonic Au@Ag Core@Shell Nanoparticles
摘要： A distinctive synthetic method for the efficient synthesis of multifunctional bimetallic plasmonic Au@Ag core@shell nanoparticles (NPs) with tunable size, morphology, and localized surface plasmon resonance (LSPR) using Triton X-100/hexanol-1/deionized water/cyclohexane-based water-in-oil (W/O) microemulsion (ME) is described. The W/O ME acted as a “true nanoreactor” for the synthesis of Au@Ag core@shell NPs by providing a confined and controlled environment and suppressing the nucleation, growth, agglomeration, and aggregation of the NPs. High-resolution transmission electron microscopic analysis of the synthesized Au@Ag core@shell NPs revealed an “unusual core@shell” contrast, and the selected area electron diffraction and Moiré patterns showed that Au layers are paralleled to Ag layers, thus indicating the formation of Au@Ag core@shell NPs. Interestingly, the UV?visible spectrum of the Au@Ag core@shell NPs exhibited enthralling plasmonic properties by introducing a high-frequency quadrupolar LSPR mode originated from the isolated Au@Ag NPs along with a low-frequency dipolar LSPR mode originated from the coupled Au@Ag NPs. The effective plasmonic enhancement of the Au@Ag core@shell NPs is attributed to the extreme enhancement of the localized electromagnetic field by coupling of the localized surface plasmons of the Au core and Ag shell. The mechanisms for the nucleation and growth of Au@Ag core@shell NPs in W/O ME have been proposed. A unique electron transfer phenomenon between the Au core and Ag shell is elucidated for better understanding and manipulation of the electronic properties, which evinced the development of Au@Ag core@shell NPs through suppression of the galvanic replacement reaction.
关键词： localized surface plasmon resonance,Au@Ag core@shell,bimetallic plasmonic nanoparticles,electron transfer phenomenon,water-in-oil microemulsion
更新于2025-09-23 15:19:57
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Light-Triggered Dual-Modality Drug Release of Self-Assembled Prodrug-Nanoparticles for Synergistic Photodynamic and Hypoxia-Activated Therapy
摘要： Photodynamic therapy (PDT) leads to tumor hypoxia which could be utilized for the activation of hypoxia-activated prodrugs (HAPs). However, conventional photosensitizer-loaded nanoformulations suffer from aggregation-caused quenching (ACQ) effect, which limits the efficiency of PDT and synergistic therapy. Herein, prodrug-nanoparticles (NPs) are prepared by the self-assembly of heterodimeric prodrugs composed of pyropheophorbide a (PPa), hypoxia-activated prodrug PR104A, and a thioether or thioketal linkage. In addition, a novel dual-modality drug release pattern is proposed on the basis of the structural states of prodrug-NPs. Under light irradiation, PR104A is released via photoinduced electron transfer (PET) due to the aggregating state of prodrugs. With the disassembly of prodrug-NPs, ACQ effect relieves, PPa produces singlet oxygen which further promotes the reactive oxygen species (ROS)-sensitive release of PR104A. Such prodrug-NPs turn the disadvantage of the ACQ effect to facilitate drug release, demonstrating high-efficiency synergy in combination with PDT and hypoxia-activated therapy.
关键词： aggregation-caused quenching,Photodynamic therapy,drug release,photoinduced electron transfer,hypoxia-activated prodrugs,reactive oxygen species
更新于2025-09-23 15:19:57
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Yellow emissive nitrogen-doped graphene quantum dots as a label-free fluorescent probe for Fe3+ sensing and bioimaging
摘要： Rapid and sensitive fluorescence nanomaterials sensor with satisfactory selectivity has gained numerous importance for detecting multiple metal ions. Graphene quantum dot (GQD) has attracted a great deal of attentions. Herein, yellow emissive GQDs with a high quantum yield of 0.34 were achieved by nitrogen-doping. The as-prepared N-GQDs exhibited excitation-independent behavior and high optical stability. Furthermore, based on the complexation between Fe3+ and N-GQDs, the fluorescence intensity of the N-GQDs could be greatly quenched by the addition of a small amount of Fe3+ ions. The linearity range is 0-80 μM with a detection limit of 63 nM. For this reason, the proposed method was demonstrated to be selective and suitable for Fe3+ analysis in natural water samples. And, N-GQDs with the biosafety has the potentials for intracellular Fe3+ detection.
关键词： Fe3+ sensing,Photoluminescence,Electron transfer,Graphene quantum dots
更新于2025-09-23 15:19:57
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Wavefunction engineering for efficient photoinduced-electron-transfer in CuInS2 quantum dots sensitized solar cells
摘要： The high-efficiency of quantum dots (QDs) sensitized solar cells benefits from the highly efficient photoinduced-electron-transfer (PET) to external electrodes. Here, we investigated how the efficiency of the PET. Though the electron trapping can be suppressed after the ZnS surface surface defects and conduction-band (CB) offsets between core and shell materials affect the PET from CuInS2 QDs by means of time-resolved femtosecond transient-absorption and nanosecond photoluminescence spectroscopy. The transfer of 1S excited electrons from CuInS2 QDs to TiO2 films is demonstrated and we find that the surface electron-trapping can significantly reduce the efficiency of CuInS2 QDs sensitized solar cells. CB offset, which allows us to achieve a quasi-type II carrier confinement in CuInS2/CdS core/shell QDs because of their low electron-density at QD surface. The surface delocalization of electron wavefunction from CuInS2 core to CdS shell. Finally, we demonstrate that these new mechanistic understandings of the PET processes are of great crucial for improving the efficiency of CuInS2 QDs sensitized solar cells.
关键词： quantum dots sensitized solar cells,photoinduced electron-transfer,quantum dots,CuInS2,wavefunction engineering
更新于2025-09-23 15:19:57
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Tailoring Carrier Dynamics in Perovskite Solar Cells via Precise Di-mension and Architecture Control and Interfacial Positioning of Plasmonic Nanoparticles
摘要： Placing plasmonic nanoparticles (NPs) in close proximity to semiconductor nanostructures renders effective tuning of the optoelectronic properties of semiconductors through the localized surface plasmon resonance (LSPR)-induced enhancement of light absorption and/or promotion of carrier transport. Herein, we report on, for the first time, the scrutiny of carrier dynamics of perovskite solar cells (PSCs) via sandwiching monodisperse plasmonic/dielectric core/shell NPs with systematically varied dielectric shell thickness yet fixed plasmonic core diameter within electron transport layer (ETL). Specifically, a set of Au NPs with precisely controlled dimensions (i.e., fixed Au core diameter and tunable SiO2 shell thickness) and architectures (plain Au NPs and plasmonic/dielectric Au/SiO2 core/shell NPs) are first crafted by capitalizing on the star-like block copolymer nanoreactor strategy. Subsequently, these monodisperse NPs are sandwiched between the two consecutive TiO2 ETLs. Intriguingly, there exists a critical dielectric SiO2 shell thickness, below which hot electrons from Au core are readily injected to TiO2 (i.e., hot electron transfer (HET)); this promotes local electron mobility in TiO2 ETL, leading to improved charge transport and increased short-circuit current density (Jsc). It is also notable that the HET effect moves up the Fermi level of TiO2, resulting in an enhanced built-in potential and open-circuit voltage (Voc). Taken together, the PSCs constructed by employing a sandwich-like TiO2/Au NPs/TiO2 ETL exhibit both greatly enhanced Jsc and Voc, delivering champion PCEs of 18.81% and 19.42% in planar and mesostructured PSCs, respectively. As such, the judicious positioning of rationally designed monodisperse plasmonic NPs in ETL affords effective tailoring of carrier dynamics, thereby providing a unique platform for developing high-performance PSCs.
关键词： hot electron transfer,perovskite solar cells,plasmonic nanoparticles,carrier dynamics,localized surface plasmon resonance
更新于2025-09-23 15:19:57
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Symmetry controlled photo-selection and charge separation in butadiyne-bridged donora??bridgea??acceptor compounds
摘要： Electron transfer (ET) in donor-bridge-acceptor (DBA) compounds depends strongly on the structural and electronic properties of the bridge. Among the bridges that support donor - acceptor conjugation, alkyne bridges have attractive and unique properties: they are compact, possess linear structure permitting access to high symmetry DBA structures, and allow torsional motion of D and A, especially for longer bridges. We report conformation dependent electron transfer dynamics in a set of novel DBA compounds featuring butadiyne (C4) bridge, N-isopropyl-1,8-napthalimide (NAP) acceptors, and donors that span a range of reduction potentials (trimethyl silane (Si-C4-NAP), phenyl (Ph-C4-NAP), and dimethyl aniline (D-C4-NAP)). Transient mid-IR absorption spectra of the C≡C bridge stretching modes, transient spectra in the visible range and TD-DFT calculations were used to decipher the ET mechanisms. We found that the electronic excited state energies and, especially, the transition dipoles (S0→Sn) depend strongly on the dihedral angle (θ) between D and A and the frontier orbital symmetry, offering an opportunity to photo-select particular excited states with specific ranges of dihedral angles by exciting at chosen wavelengths. For example, excitation of D-C4-NAP at 400 nm predominantly prepares an S1 excited state in the planar conformations (θ ~ 0) but selects an S2 state with θ ~ 90o, indicating the dominant role of the molecular symmetry in the photophysics. Moreover, the symmetry of the frontier orbitals of such DBA compounds not only defines the photo-selection outcome, but also determines the rate of the S2→S1 charge separation reaction. Unprecedented variation of the S2-S1 electronic coupling with θ by over four orders of magnitude results in slow ET at θ ca. 0o and 90o but extremely fast ET at θ of 20-60o. The unique features of high-symmetry alkyne bridged DBA structures enable frequency dependent ET rate selection and make this family of compounds promising targets for the vibrational excitation control of ET kinetics.
关键词： transient absorption spectroscopy,electron transfer,donor-bridge-acceptor,TD-DFT calculations,butadiyne bridge
更新于2025-09-23 15:19:57