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Photocatalytic and Photo-Fenton Catalytic Degradation Activities of Z-Scheme Ag2S/BiFeO3 Heterojunction Composites under Visible-Light Irradiation
摘要： Z-scheme Ag2S/BiFeO3 heterojunction composites were successfully prepared through a precipitation method. The morphology and microstructure characterization demonstrate that Ag2S nanoparticles (30–50 nm) are well-decorated on the surfaces of polyhedral BiFeO3 particles (500–800 nm) to form Ag2S/BiFeO3 heterojunctions. The photocatalytic and photo-Fenton catalytic activities of the as-derived Ag2S/BiFeO3 heterojunction composites were evaluated by the degradation of methyl orange (MO) under visible-light irradiation. The photocatalytic result indicates that the Ag2S/BiFeO3 composites exhibit much improved photocatalytic activities when compared with bare Ag2S and BiFeO3. The optimum composite sample was observed to be 15% Ag2S/BiFeO3 with an Ag2S mass fraction of 15%. Furthermore, the addition of H2O2 can further enhance the dye degradation efficiency, which is due to the synergistic effects of photo- and Fenton catalysis. The results of photoelectrochemical and photoluminescence measurements suggest a greater separation of the photoexcited electron/hole pairs in the Ag2S/BiFeO3 composites. According to the active species trapping experiments, the photocatalytic and photo-Fenton catalytic mechanisms of the Ag2S/BiFeO3 composites were proposed and discussed.
关键词： polyhedral BiFeO3 particles,photo-Fenton catalysis,Ag2S nanoparticles,photocatalysis,Z-scheme Ag2S/BiFeO3 heterojunction
更新于2025-11-19 16:46:39
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Multi-layer CeO2-wrapped Ag2S microspheres with enhanced peroxidase-like activity for sensitive detection of dopamine
摘要： A novel core-shell structure Ag2S@CeO2 microspheres were synthesized by growing multi-layer CeO2 onto Ag2S particles. Compared with pure Ag2S, the resultant composite catalyst exhibited highly improved peroxidase-like activity. Influences of pH, temperature, H2O2 concentration and the amount of catalyst on the catalytic activity of Ag2S@CeO2 were investigated. Besides, Ag2S@CeO2 displayed a strong affinity towards H2O2 and 3,3',5,5'-tetramethylbenzidine (TMB). Based on the excellent peroxidase-like activity of Ag2S@CeO2 microspheres, a highly sensitive and selectivity colorimetric method for dopamine detection was developed. The possible catalytic mechanism was also studied using fluorescent probe analysis. It is believed that the efficient biosensor based on the as-prepared Ag2S@CeO2 microspheres can apply for biological analysis and environmental monitoring.
关键词： Core-shell,Ag2S,CeO2,Peroxidase,Dopamine
更新于2025-11-14 17:15:25
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Construction of flower-like MoS2/Ag2S/Ag Z-scheme photocatalysts with enhanced visible-light photocatalytic activity for water purification
摘要： Flower-like MoS2/Ag2S/Ag nanocomposites have been elaborately designed and synthesized successfully for the first time. The prepared MoS2/Ag2S/Ag nanocomposites as a novel photocatalysts present effective photocatalytic performance for the photodegradation of congo red (CR), tetracycline hydrochloride (TC-HCl) and disinfection for Pseudomonas aeruginosa (P. aeruginosa). For the photodegradation of TC-HCl, the effect of the pH of the initial solution and photocatalysts dosage was investigated. Furthermore, intermediates of TC-HCl degradation were verified by GC–MS analysis and the possible pathway of the photodegradation was also proposed. The electron paramagnetic resonance (EPR) technique and trapping experiments verified the electron transport path is Z-scheme system (PS-C-PS). Among them, Ag as an electron mediator enhanced the electron transmission rate and accelerated the separation efficiency of photogenerated carriers.
关键词： MoS2/Ag2S/Ag,Photocatalytic,Tetracycline hydrochloride,Water disinfection,Z-scheme
更新于2025-09-23 15:23:52
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Room temperature synthesis of Au NR@Ag2S and Au NR@Ag2S/CdS core-shells using a facile photochemical approach
摘要： In this work, Au nanorods with tunable longitudinal plasmon resonance were synthesized using hydroquinone as complimentary surfactant. Ag2S quantum dots (QDs) were grown directly on Au nanorods using the replacement of cetyltrimethylammonium bromide (CTAB) with 3-Mercaptopropionic acid (MPA) via a novel photochemical approach. X-ray diffraction revealed the presence of Au cubic structure as well as Ag2S monoclinic phase. Fourier-transform infrared spectroscopy, electrochemical impedance spectroscopy and cyclic voltamettery confirmed the successful substitution of CTAB with MPA as an appropriate capping agent for the growth of Ag2S and CdS quantum dots. UV-Vis spectroscopy demonstrated a red shift of plasmon resonance peak from 750 nm up to 835 nm indicating the increase of dielectric constant of surrounded Au nanorods due to the formation of Ag2S QDs as shell. Photoluminescence spectroscopy revealed near Infrared (NIR) emission of Au@Ag2S core-shells as an indication of controllable size of Ag2S during the growth time. Transmission electron microscopy (TEM) images clearly showed the formation of Ag2S QDs as shell around Au nanorods. To indicate the flexibility of current growth method, CdS QDs were also grown on Au@Ag2S core-shells only by addition of Cd precursor to as prepared Au@Ag2S colloidal solution and continuation of UV illumination. The clear and intense visible light emission of the sample together with the NIR emission of Ag2S and gradual red shift of plasmon resonance of Au nanorods with elapsing photochemical treatment time were the indication of successful growth of Ag2S/CdS on Au nanorods. TEM images clearly showed Au@Ag2S/CdS almond shape core-shells. This method has the simplest chemistry and the procedure is very simple, rapid (less than 2 h), energy efficient and scalable for large production of such core-shells.
关键词： Au nanorods,Metal-semiconductor core-shells,Ag2S QDs,Photoluminescence,Electroimpedance spectroscopy
更新于2025-09-23 15:22:29
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A facile room-temperature synthesis of three-dimensional coral-like Ag2S nanostructure with enhanced photocatalytic activity
摘要： Morphology is a crucial factor in determining the chemical, optical, and electrical properties of nanoscale materials. In this work, we utilized a facile room-temperature deposition method to synthesize three-dimensional (3D) coral-like Ag2S nanostructures. The formation mechanism of 3D coral-like Ag2S nanostructures was proposed by tracking the reaction process. In comparison with 0D Ag2S nanoparticles and 1D Ag2S nanowires of similar size, 3D coral-like Ag2S nanostructures exhibit higher pore volume, photocatalytic activity and cyclic stability for degradation of methyl orange (MO). Surface photovoltage measurement, electrochemical impedance spectroscopy, and Mott–Schottky analysis showed that compared to other Ag2S nanostructures, 3D coral-like Ag2S nanostructures have the strongest surface photovoltaic response, longest carrier lifetime, and highest carrier density.
关键词： Carrier lifetime,Surface photovoltage,Ag2S,3D coral-like nanostructure,Photocatalytic activity
更新于2025-09-23 15:21:21
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Type-II heterojunction constructed by Ag2S-coupled ZnO microspheres with visible light-responsive antibacterial activity
摘要： ZnO nanorods-assembled microspheres were photosensitized with a layer of low bandgap Ag2S nanoparticles on the branched nanorods to get a type-II core/shell heterojunction (ZnO@Ag2S). The heterojunction with unique band configuration exhibited better visible light-responsive antibacterial activity than pure ZnO, which is attributed to the inhibition of photocarrier recombination and efficient charge separation and transfer. Scavenger test confirmed that the photoinactivation of bacteria was directed by the (cid:1) radicals and photogenerated holes. The growth of Gram-negative bacteria was more effectively restrained by ZnO@Ag2S than that of Gram-positive bacteria and fungi because of structural difference of cell walls.
关键词： ZnO@Ag2S,Composite materials,Mechanism,Semiconductors,Photocatalytic activity
更新于2025-09-23 15:21:01
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Photocatalytic study of ZnS-Ag2S nanocomposites-effect of thioglycerol
摘要： Nanocomposites (NCs) of different band gap semiconductors provide better photocatalytic activity as compared to that of monolithic semiconductor nanoparticles (NPs). With the aim to investigate the effect of organic capping agent (thioglycerol; TG in the present study) on photocatalytic activity, ZnS-Ag2S NCs have been synthesized in the presence of TG using simple chemical precipitation route. For comparative studies, NCs have been synthesized under same synthesis conditions without TG. Structural studies were done using X-Ray diffraction (XRD) technique. Morphological features of as prepared samples were recorded by high resolution transmission electron microscopy (HRTEM). UV–Vis and photoluminescence studies were carried out to study the optical properties of synthesized samples. Photocatalytic studies of as-synthesized NCs have been carried out by selecting crystal violet (CV) as a model organic pollutant. It is observed that NCs (synthesized in absence of TG) exhibit better photocatalytic activity as compared to the TG capped NCs. The results of the present study may helpful in practical application of these composites in the area of photocatalysis and other related optical applications.
关键词： Thioglycerol,Ag2S,Photocatalysis,ZnS
更新于2025-09-23 15:21:01
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Controlled Synthesis of Ag <sub/>2</sub> Te@Ag <sub/>2</sub> S Corea??Shell Quantum Dots with Enhanced and Tunable Fluorescence in the Second Neara??Infrared Window
摘要： Fluorescence in the second near-infrared window (NIR-II, 900–1700 nm) has drawn great interest for bioimaging, owing to its high tissue penetration depth and high spatiotemporal resolution. NIR-II fluorophores with high photoluminescence quantum yield (PLQY) and stability along with high biocompatibility are urgently pursued. In this work, a Ag-rich Ag2Te quantum dots (QDs) surface with sulfur source is successfully engineered to prepare a larger bandgap of Ag2S shell to passivate the Ag2Te core via a facile colloidal route, which greatly enhances the PLQY of Ag2Te QDs and significantly improves the stability of Ag2Te QDs. This strategy works well with different sized core Ag2Te QDs so that the NIR-II PL can be tuned in a wide range. In vivo imaging using the as-prepared Ag2Te@Ag2S QDs presents much higher spatial resolution images of organs and vascular structures as compared with the same dose of Ag2Te nanoprobes administrated, suggesting the success of the core–shell synthetic strategy and the potential biomedical applications of core–shell NIR-II nanoprobes.
关键词： NIR-II nanoprobes,Ag2Te@Ag2S,bioimaging,core–shell quantum dots
更新于2025-09-23 15:19:57
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Facile Synthesis of Noncytotoxic PEGylated Dendrimer Encapsulated Silver Sulfide Quantum Dots for NIR-II Biological Imaging
摘要： Near-Infrared-II (NIR-II, 1000-1700 nm) bioimaging features high penetration depth and high spatio-temporal resolution compared to traditional fluorescence imaging, but the key is to develop stable and biocompatible NIR-II fluorophores suitable for in vivo applications. Silver sulfide quantum dots (Ag2S QDs) have been demonstrated excellent for in vivo NIR-II imaging with unique optical properties and decent biocompatibility, but they often require complex post modifications for in vivo applications. Herein we demonstrate a facile one-pot strategy to synthesize the PEGylated dendrimer-encapsulated Ag2S QDs useful for in vivo NIR-II imaging. Silver ions were first loaded into the core of acylthiourea-functionalized dendrimer (PEG-PATU) through the coordination between silver ions and acylthiourea groups, followed by the addition of sodium sulfide to form Ag2S QDs in situ. The resulting PEG-PATU Ag2S QDs hold excellent NIR-II fluorescence signal, and thus could be executed for high efficiency labelling and tracking of A549 cancer cells mobility in vivo and real time visualization of vast circulatory network of a mouse.
关键词： in vivo imaging,PEGylated dendrimer,one-pot synthesis,Ag2S QDs,NIR-II bioimaging
更新于2025-09-23 15:19:57
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Microwave activated synthesis of Ag2S and Ag2S@ZnS nanocrystals and their application in well-performing quantum dot sensitized solar cells
摘要： Incident photon-to-current conversion e?ciency (IPCE) of CdS based quantum dot sensitized solar cells (QDSCs) is a major drawback in their low e?ciency. Here we report a new trend in fabrication of QDSC with enhanced IPCE with application of as prepared Ag2S and Ag2S@ZnS QDs as a co sensitizer. Ag2S and Ag2S@ZnS QDs were synthesized ?rst using a microwave method and were examined by means of XRD, TEM and UV–Vis spectroscopy. Then the prepared QDs were applied for the fabrication of QDSCs using a novel drop casting method. The results revealed a signi?cant enhancement of IPCE as well as short current density (12.5 mA·cm?2) and cell e?ciency (3%). The enhancement is directly related to well absorption of Ag2S with low band gap in the visible range and e?ective injection of photo-excited electrons to CdS compact layer according to suggested band diagram. Ag2S@ZnS co-sensitizer showed an enhancement in photocurrent density due to successful passivation of Ag2S QDs and suppressing recombination on their surface.
关键词： Ag2S@ZnS quantum dots,QD sensitized solar cells,IPCE,Drop casting
更新于2025-09-23 15:19:57