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Chemically exfoliated 1T-phase transition metal dichalcogenide nanosheets for transparent antibacterial applications
摘要： Two-dimensional transition metal dichalcogenides (TMDs) are promising materials for a range of applications owing to their intriguing properties including the excellent electrical performance and biocompatibility. Strikingly, 1T-phase TMDs have attracted significant interest based on their metallic properties with octahedral metal coordination where the phase transition can occur from the semiconducting 2H-phase to metallic 1T-phase by chemical intercalation-induced exfoliation process. In this regard, 1T-phase TMDs have great potential in antibacterial agents in terms of effective charge transfer between the bacterial membrane and TMD nanosheets while their biological interactions have been underexplored. To bridge this gap, we herein investigate the antibacterial activities of various 1T-phase TMDs including molybdenum disulfide (MoS2), tungsten disulfide (WS2), and molybdenum diselenide (MoSe2) toward Gram-negative bacteria Escherichia coli that exhibit the reduction of bacterial viability caused by the production of reactive oxygen species, oxidation of glutathione and other chemical functionalities. The effective antibacterial capacity of metallic 1T-phase TMDs is observed and their bactericidal mechanisms are investigated in terms of their electrical conductivity and chemical oxidation property that induce the charge transfer from bacterial membrane to TMDs leading to the continuous disruption of bacteria and loss of cellular components. Furthermore, we demonstrated the transparent antibacterial films consisting of 1T-phase TMDs in which TMD nanosheets are immobilized on the surfaces and their basal planes play an important role in antibacterial actions for practical biomedical applications. Thus, our findings provide new insights into the great potential of 1T-phase TMDs as promising building blocks for antibacterial surfaces and contribute to the widespread use of 1T-phase TMDs for practical biomedical applications.
关键词： 1T-phase,charge transfer,antibacterial activity,oxidative stress,transition metal dichalcogenide
更新于2025-11-21 11:08:12
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Z-scheme Bi2WO6/CuBi2O4 heterojunction mediated by interfacial electric field for efficient visible-light photocatalytic degradation of tetracycline
摘要： In order for the removal of Tetracycline (TC) in wastewaters, an efficient binary Bi2WO6/CuBi2O4 Z-scheme heterojunction photocatalyst was synthesized by loading Bi2WO6 (BWO) nanoparticles on CuBi2O4 (CBO) nanorods via a solvothermal route. The obtained Bi2WO6/CuBi2O4 composite displays photocatalytic activity for TC degradation more than five times higher than that for pure CBO nanorods. The recycling experiment shows that over 91% of TC can be photo-degraded by the optimal Bi2WO6/CuBi2O4 photocatalyst within 60 min even after four cycles. Results of SEM, transient photocurrent response, EIS measurement prove that solvothermal process for BWO loading can introduce rough surface with high-density negative charge on CBO, contributing to effective photo-induced carrier transfer. XPS, Mott?Schottky plots and PL spectra reveal that the loading of BWO as well as interfacial charge redistribution can induce the formation of interfacial electric field for Z-scheme heterojunction, contributing to the high oxidation and reduction capabilities ability of Bi2WO6/CuBi2O4 composite. The study on photocatalytic mechanism discloses that hole (h+) and superoxide radical (?O2?) are dominating reactive oxidation species (ROS) in the photodegradation process. This study has provided a novel route to fabricate Z-scheme photocatalysts for effective photocatalytic degradation processes.
关键词： charge transfer,Z-scheme heterojunction,environmental materials,interfacial electric field,photocatalysis,tetracycline degradation
更新于2025-11-21 10:59:37
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Tuning the Functional Groups on Carbon Nanodots and Antioxidant Studies
摘要： Carbon nanodots (CNDs) have shown good antioxidant capabilities by scavenging oxidant free radicals such as diphenyl-1-picrylhydrazyl radical (DPPH?) and reactive oxygen species. While some studies suggest that the antioxidation activities associate to the proton donor role of surface active groups like carboxyl groups (–COOH), it is unclear how exactly the extent of oxidant scavenging potential and its related mechanisms are influenced by functional groups on CNDs’ surfaces. In this work, carboxyl and the amino functional groups on CNDs’ surfaces are modified to investigate the individual influence of intermolecular interactions with DPPH? free radical by UV-Vis spectroscopy and electrochemistry. The results suggest that both the carboxyl and the amino groups contribute to the antioxidation activity of CNDs through either a direct or indirect hydrogen atom transfer reaction with DPPH?.
关键词： carbon nanodots,radical scavenging,electro-chemistry,functional groups,antioxidation,charge transfer
更新于2025-11-19 16:56:35
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Reconstructing Dual‐Induced {0 0 1} Facets Bismuth Oxychloride Nanosheets Heterostructures: An Effective Strategy to Promote Photocatalytic Oxygen Evolution
摘要： Sunlight-driven photocatalytic water splitting to generate oxygen (O2) is a promising approach for utilizing solar energy. Herein, direct Z-scheme heterostructure photocatalysts composed of ultrathin Bi3O4Cl and BiOCl nanosheets are rationally fabricated via alkaline chemical etching and solvent exfoliation for O2 evolution under visible light. With AgNO3 and FeCl3 as the electron scavenger, the optimized ultrathin Bi3O4Cl/BiOCl exhibits prominent photocatalytic activity for O2 production under visible-light illumination and the production rate (58.6 μmol g?1 h?1) is much higher than the nanocrystal heterostructure (28.5 μmol g?1 h?1). This ultrathin heterostructure system can efficiently transfer the electrons, which leads to a considerable improvement in the photocatalytic performance. Due to the suitable band edge potentials and the intense electronic interaction between two-dimensional (2D) Bi3O4Cl and 2D BiOCl, as confirmed by theoretical computations, photoluminescence, and photoelectricity tests, the ultrathin heterojunction with an internal electric field has a highly remarkable charge transfer. The intimate interface contact and {0 0 1} facets effect promote the high photocatalytic performance of the ultrathin Bi3O4Cl/BiOCl heterostructure.
关键词： remarkable charge transfer,ultrathin Bi3O4Cl/BiOCl heterostructure,facets effect,photocatalysis
更新于2025-11-19 16:51:07
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Water-sensitive ratiometric fluorescent probes and application to test strip for rapid and reversible detection of water
摘要： Naphthalimide-decorated fluorinated acetamides 1 and 2 were developed as solvent-sensitive dual emissive fluorescence probes. Particularly, 1 exhibited dual emission with a large Stokes shift for water, DMF, and DMSO solvents over other various organic solvents. The dual emission might be due to the increase of intramolecular charge transfer (ICT) of the naphthalimide moiety through the association of the difluorinated acetamide group with the solvent molecules. The 1 can give rise to a ratiometric change in the dual emission and a visual fluorescent color change depending on the water contents in organic solvents, including ethanol, methanol, acetonitrile and DMF solvents. Moreover, the 1-impregnated paper strips showed a rapid and easy-to-visualize fluorescent color change enabling water detection in organic solvents. These simple-to-use paper strips were also found to be reusable over 20 times.
关键词： Naphthalimide,Ratiometric fluorescence probe,Reusable test strip,Intramolecular charge transfer (ICT),Water detection
更新于2025-11-19 16:46:39
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Tunable Photophysical Properties of Thiophene Based Chromophores: Conjoined Experimental and Theoretical Investigation
摘要： In this paper we report synthesis and photophysical properties of six novel thiophene derivatives (ThD) with D-π-A structure. The subject of this work are three nitrophenyls (1) BT-Th-NO2 and three benzonitriles (2) BT-Th-CN, substituted at different positions of aromatic ring ((a) ortho-, (b) meta- or (c) para-). Dyes were obtained using simple three-step synthesis and their chemical structures were confirmed by 1H and 13C NMR, IR as well as high resolution mass spectrometry. The influence of positional isomerism on optical properties has been explored experimentally and theoretically. The photophysical properties were investigated using steady-state as well as time-resolved spectroscopy and the obtained results were supported by quantum-chemical calculations. TD-DFT calculations indicated that charge-transfer strength can be correlated with the observed optical properties. In addition, the influence of the acceptor position on photoluminescence spectra, fluorescence quantum yields and emission lifetimes was specified. We show that ThD optical properties can be tuned in wide spectral range by the change made in only single step of synthesis reaction.
关键词： push-pull chromophores,Thiophene derivatives,TD-DFT,quantum yield,charge transfer
更新于2025-11-19 16:46:39
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High lying energy of charge-transfer states and small energetic offsets enabled by fluorinated quinoxaline-based alternating polymer and alkyl-thienyl side-chain modified non-fullerene acceptor
摘要： Significant driving forces are the prerequisite to achieve fast and efficient charge separation in fullerene derivatives-based polymer solar cells to achieve high power conversion efficiency (PCE). However, the large driving forces both in photo-induced hole transfer (PHT) and in photo-induced electron transfer (PET) processes lead to significant energy losses, resulting in low open-circuit voltage in the devices. Recent studies indicate the driving forces in non-fullerene acceptors-based devices can be reduced to very low values but still with high PCE and low energy losses. Herein, we report a new donor:acceptor system with high lying energy of charge-transfer excitons (ECT) of 1.50 eV and very small driving forces (PHT of 0.28 eV and PET of 0.11 eV), in which a fluorinated quinoxaline-based alternating polymer (FTQ) and an alkyl-thienyl side-chain modified small molecule (ITIC-Th) are taken as the donor material and non-fullerene acceptor material, respectively. A high power conversion efficiency (PCE) of 8.19% with maximal external quantum efficiency of 71% are achieved successfully in FTQ:ITIC-Th-based device after appropriate thermal annealing treatment, indicating FTQ can be further applied as donor materials with other highly efficient NF-acceptors to achieve enhanced performances and low energy losses.
关键词： Power conversion efficiency,Driving forces,Energy of charge-transfer states,Polymer solar cells
更新于2025-11-14 17:28:48
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Aggregation-induced phosphorescence quenching method for the detection of picric acid based on melamine-passivated Mn-doped ZnS quantum dots
摘要： Melamine (MA)-passivated Mn-doped ZnS quantum dots (QDs) were synthesized by a hydrothermal method. The MA-passivated QDs can form a charge-transfer complex with picric acid (PA) at 80 °C, thereby quenching the phosphorescence of the QDs. A sensitive method for detecting PA was established based on this principle of phosphorescence quenching. When the PA concentration ranged from 2.0–180 ng mL–1, the concentration was linearly related to the quenching intensity of the QDs, with a detection limit of 1.4 ng mL–1. When applied to detect PA in environmental water samples, the proposed method showed superior analytical performance compared with other PA analysis methods. Furthermore, we verified the static quenching mechanism by density functional theory. MA on the surface of QDs and PA formed a stable structure with a binding energy of 12.43 eV.
关键词： Melamine,Picric Acid,Mn-doped quantum dots,Charge-transfer Complex,Phosphorescence
更新于2025-11-14 17:04:02
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Mechanofluorochromism based on BOPIM complexes: The effect of substituents and regulation of the direction of the emission color changes
摘要： Novel boron 2-(2′-pyridyl)imidazole (BOPIM) complexes T1, T2 and T3 with different substituents (including bromo, tert-butyl and methoxyl) on the benzene ring of BOPIM dyes have been designed and synthesized, and their optical properties in both solution and the solid state were investigated and compared. The three compounds exhibited typical intramolecular charge transfer (ICT) characteristics. Solvent-dependent UV-vis absorption, fluorescence emission spectra and quantum chemical calculation indicated a molecular push-pull electronic structure. Their ICT degrees increased with the sequence of T1 < T2 < T3. The analysis of the X-ray crystal structure revealed the twisted molecular conformation of BOPIM dyes. Furthermore, they showed remarkable reversible mechanofluorochromic (MFC) features under mechanical force. It was found that the MFC activities could be tuned easily by changing the substituents on the BOPIM dyes. T1 exhibited emission color change from bright green to yellowish green with a spectral red-shift of only 22 nm under mechanical stimuli, whereas T2 and T3 gave the large spectral red-shifts of 36 and 30 nm. Electronic and steric effects of the substitutes were proved playing significant roles in regulating the ICT effect and intermolecular interactions. More importantly, the remarkable effect of substituents on the MFC behaviors of BOPIM dyes will provide an effective way to obtain novel high-contrast MFC dyes.
关键词： Mechanofluorochromism,Substituent effect,Intramolecular charge transfer,Solid-state fluorescence,BOPIM complexes
更新于2025-11-14 15:26:12
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Correction: Boosted visible light photodegradation activity of boron doped rGO/g-C <sub/>3</sub> N <sub/>4</sub> nanocomposites: the role of C–O–C bonds
摘要： A series of two-component co-crystals driven by I···N interactions based on the bipyridine (BIPY) chromophore with one among three different co-former building blocks, iodopentafluorobenzene (IPFB), 1,4-diiodotetrafluorobenzene (DITFB) and 1,3,5-trifluoro-2,4,6-triiodobenzene (IFB), were prepared and analysed via infrared spectroscopy and single-crystal X-ray diffraction. By comparing the I···N distances in the co-crystal structures, we found that the higher the –F ratio in the building blocks the closer the contact of the I···N bond, enhancing the intermolecular interactions in these co-crystals as well. That is, the positive electrostatic potential on the iodine atom(s) in the co-formers was enhanced by the presence of strong electron-withdrawing groups. The distinct spectroscopic behaviours (fluorescence and Raman spectra) among the two-component BIPY co-crystal systems in response to hydrostatic pressure were also investigated. Interestingly, the fluorescence of BIPY–DITFB presented intriguing abnormal evolution from dark to bright, suggesting a new charge transfer state due to the decreased intermolecular distance and the enhanced I···N interactions. Theoretical simulations by Materials Studio also showed the shortened I···N distance and the increased angle of C–I···N, evidencing the enhanced I···N interactions. In contrast, BIPY–IFB showed only slightly enhanced fluorescence intensity at 550 nm consistent with BIPY–DITFB. Once the pressure was relieved, both the Raman and fluorescence spectra for BIPY co-crystal systems entirely self-recovered. Remarkable emission enhancement in a solid-state co-crystal has been rarely reported in previous publications and in fact, this study paves a unique way for designing and developing novel stimuli-responsive photo-functional materials.
关键词： co-crystals,piezochromic materials,halogen bond,intermolecular charge transfer,pressure-induced emission enhancement
更新于2025-11-14 15:14:40