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Femtosecond Spectroscopy of Au Hot-Electron Injection into TiO2: Evidence for Au/TiO2 Plasmon Photocatalysis by Bactericidal Au Ions and Related Phenomena
摘要： In the present work, we provide evidence for visible light irradiation of the Au/TiO2 nanoparticles’ surface plasmon resonance band (SPR) leading to electron injection from the Au nanoparticles to the conduction band of TiO2. The Au/TiO2 SPR band is shown to greatly enhance the light absorption of TiO2 in the visible region. Evidence is presented for the light absorption by the Au/TiO2 plasmon bands leading to the dissolution of Au nanoparticles. This dissolution occurs concomitantly with the injection of the hot electrons generated by the Au plasmon into the conduction band of TiO2. The electron injection from the Au nanoparticles into TiO2 was followed by femtosecond spectroscopy. The formation of Au ions was further confirmed by the spectral shift of the transient absorption spectra of Au/TiO2. The spectral changes of the SPR band of Au/TiO2 nanoparticles induced by visible light were detected by spectrophotometer, and the morphological transformation of Au/TiO2 was revealed by electron microscopy techniques as well. Subsequently, the fate of the Au ions was sorted out during the growth and biofilm formation for some selected Gram-negative bacteria. This study compares the bactericidal mechanism of Au ions and Ag ions, which were found to be substantially different depending on the selected cell used as a probe.
关键词： electron injection,antibacterial effects,genes expression,DNA repair,quorum sensing,plasmon photocatalysis,biofilms,gold nanoparticles,porins
更新于2025-11-21 11:20:42
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Synthesis of hybrid zinc-based materials from ionic liquids: a novel route to prepare active Zn catalysts for the photoactivation of water and methane
摘要： A new and simple route for the preparation of zinc-based materials is proposed in this work. The synthesis of zinc oxide from the hydrolysis of imidazolium trichlorozincate ionic liquids (ILs) produces catalytic active nanostructured materials, where the size and shape (irregular particles, nanorods) are dependent on the synthetic conditions employed. Indeed, the hydrolysis of trichlorozincate ILs prepared by an equimolar ionic liquid:ZnCl2 ratio afforded irregular particles, while increasing the IL amount (2:1 and 4:1) drives to the formation of nanorods. These hybrid zinc oxide materials were able to promote the photoactivation of water and methane at 25 °C affording up to 1417 μmolH2.g-1.h-1 and up to 67 μmolCO2.g-1.h-1, respectively. Moreover, tuning the reaction conditions a microstructured zinc-based mineral named simonkolleite was prepared with the expected hexagonal-like morphology. This compound was also applied as an alternative and efficient photocatalyst in the activation of water (972 μmolH2.g-1.h-1) and methane (12.6 μmolCO2.g-1.h-1).
关键词： Zinc oxide,photocatalysis,semiconductors,simonkolleite,ionic liquids,nanomaterials
更新于2025-11-21 11:18:25
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Selective Detection of Trinitrophenol by Amphiphilic Dimethylaminopyridine-Appended Zn(II)phthalocyanines at the Near-Infrared Region
摘要： Novel amphiphilic Zn(II)phthalocyanines (ZnPcs) peripherally substituted with four and eight dimethylaminopyridinium units (ZnPc1 and ZnPc2) were synthesized by cyclotetramerization of the corresponding phthalonitriles. The effect of aggregation and photophysical (fluorescence quantum yields and lifetimes) and photochemical (singlet oxygen generation and photodegradation under light irradiation) properties was investigated. The chemosensing ability of ZnPcs toward explosive nitroaromatic compounds was explored in aqueous medium. This study demonstrates that ZnPc1 and ZnPc2 show fluorescence quenching behavior upon interaction with different nitro analytes and show unprecedented selectivity toward 2,4,6-trinitrophenol with a limit of detection (LOD) of 0.7?1.1 ppm with a high quenching rate constant (Ksv) of 1.6?2.02 × 105. The near-infrared (NIR) fluorescence in thin films was quenched efficiently because of the photoinduced electron-transfer process through strong intermolecular π?π and electrostatic interactions. The sensing process is highly reversible and free from the interference of other commonly encountered nitro analytes. Further, experiments were performed to demonstrate the use of ZnPcs as efficient heterogeneous photocatalysts in the reduction of nitro explosives. The smart dual performance of multicharged ZnPcs in aqueous media quantifies them as attractive candidates in developing sensor materials at the NIR region and to possibly convert the toxic explosives into useful scaffolds. These results provide an interesting perspective toward elaboration of stable fluorescent systems for the selective sensing behavior of nitro explosives and their facile heterogeneous catalytic behavior in the reduction reactions.
关键词： trinitrophenol,photocatalysis,explosive detection,near-infrared,fluorescence quenching,dimethylaminopyridinium,Zn(II)phthalocyanines
更新于2025-11-21 11:08:12
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One-step synthesis of hexylresorcinol calix[4]arene-capped ZnO–Ag nanocomposites for enhanced degradation of organic pollutants
摘要： In this study, hexylresorcinol calix[4]arene (HRCA) is introduced into the reaction system, and HRCA-capped ZnO–Ag nanocomposites are prepared via a simple one-step reflux method. HRCA is used not only as a reducing agent for deoxidizing Ag+ to Ag, but also as a protectant for wrapping around the microstructure of the formed ZnO–Ag. The prepared samples are characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy (TEM), high-resolution TEM, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, and water contact angle. The Ag nanoparticles and ZnO adhere to each other and HRCA molecules encapsulate on the surface of ZnO–Ag nanocomposites. HRCA-capped ZnO–Ag nanocomposites with different Ag contents are investigated for use in photodegradation of organic pollutants (rhodamine B (RhB) and levofloxacin hydrochloride). The sample with 10.20 mol% Ag, denoted as ZA3, exhibits the highest catalytic activity for photodegradation of RhB and levofloxacin hydrochloride. Moreover, ZA3 exhibits high stability during photodegradation of organic pollutants even after multiple reuses. The possible photocatalytic mechanism is discussed. We believe that ?O2– and h+ are the chief active species responsible for the photocatalytic activity of HRCA-capped ZnO–Ag nanocomposite system. HRCA-capped ZnO–Ag nanocomposite is expected to be an effective photocatalyst with potential application to sewage treatment under sunlight.
关键词： HRCA-capped ZnO–Ag,Photocatalysis,Resorcinol calix[4]arene,Ag seed
更新于2025-11-21 11:03:13
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Fabrication of nanometer-sized high-silica SAPO-5 and its enhanced photocatalytic performance for methyl orange degradation
摘要： Higher efficient degradation of methyl orange (MO) was demonstrated with nanometer-sized high-silica SAPO-5. By a hydrothermal process, synthesized high-silica SAPO-5 and low-silica SAPO-5 showed Si-to-Al ratios of 4.20 and 0.11, respectively. High-silica SAPO-5 showed much better MO degradation efficiency with a dosage of 70 mg in MO solution with a concentration of 10 mg/L under ultraviolet illumination. High-silica SAPO-5 also exhibited good producibility for preparation and stable photocatalytic activity even after the fifth recycling test. Optical characterizations of DRS, XPS, photocurrent density and time-resolved fluorescence were carried out for SAPO-5 samples. Finally, free radical and hole scavenging experiments were investigated for high-silica SAPO-5, and a MO photodegradation mechanism based on the charge transfer excited state of [Al2+–O?]* was proposed. This work highlights great prospects of high-silica SAPO-5 for organic pollutant removal with virtues of ideal efficiency and environmental friendliness.
关键词： Photocatalysis,High-silica,Nanometer-sized,SAPO-5
更新于2025-11-21 11:01:37
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Enhanced Charge Separation in g-C3N4 – BiOI Heterostructures for Visible Light Driven Photoelectrochemical Water Splitting
摘要： Heterojunctions of the low bandgap semiconductor bismuth oxyiodide (BiOI) with bulk multilayered graphitic carbon nitride (g-C3N4) and few layered graphitic carbon nitride sheets (g-C3N4-S) are synthesized and investigated as an active photoanode material for sunlight driven water splitting. HR-TEM and elemental mapping reveals formation of a unique heterostructure between BiOI platelets and the carbon nitride (g-C3N4 and g-C3N4-S) network that consisted of dendritic BiOI nanoplates surrounded by g-C3N4 sheets. The presence of BiOI in g-C3N4-S/BiOI and g-C3N4-S/BiOI nanocomposites extends the visible light absorption profile from 500 nm up to 650 nm. Due to excellent charge separation in g-C3N4/BiOI and g-C3N4-S/BiOI, evident from quenching of the carbon nitride photoluminescence (PL) and a decrease in the PL lifetime, a significant increase in photoelectrochemical performance is observed for both types of g-C3N4-BiOI heterojunctions. In comparison to heterojunctions of bulk g-C3N4 with BiOI, the nancomposite consisting of few layered sheets of g-C3N4 and BiOI exhibits higher photocurrent density due to lower recombination in few layered sheets. A synergistic trap passivation and charge separation is found to occur in the g-C3N4-S/BiOI nanocomposite heterostructure which results in a higher photocurrent and a lower charge transfer resistance.
关键词： visible light driven photocatalysis,earth abundant semiconductor heterostructures,Graphenic semiconductors,photoelectrochemistry
更新于2025-11-21 11:01:37
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G‐C3N4‐SiC‐Pt for Enhanced Photocatalytic H2 Production from Water under Visible Light Irradiation
摘要： The g-C3N4 and SiC has drawn increasing attention for application to visible light photocatalytic hydrogen evolution from water splitting due to their unique band structure and high physicochemical stability. In this study, g-C3N4-SiC heterojunction with loaded noble metal was constructed. The g-C3N4-SiC-Pt composite photocatalysts were successfully prepared by the combination method of a bio-reduction, sol-deposition and calcination. The layers of g-C3N4 were thinned and the SiC and Pt nanoparticles simultaneously were tightly bound to g-C3N4 by calcination in the process of preparing the g-C3N4-SiC-Pt. The heterojunction formed in the interface of SiC and g-C3N4 enhances the separation efficiency of the photogenerated electron-hole pairs. These composite photocatalysts achieve a high hydrogen evolution rate of 595.3 μmol·h-1·g-1 with a 1wt% of deposited Pt, 3.7- and 2.07-fold higher than g-C3N4-bulk and g-C3N4-SiC under visible-light irradiation with a quantum efficiency of 2.76% at 420 nm, respectively.
关键词： visible light,g-C3N4-SiC-Pt photocatalysts,hydrogen evolution,photocatalysis
更新于2025-11-21 11:01:37
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Fabrication of Fe-doped SrTiO3 photocatalyst with enhanced dinitrogen photofixation performance
摘要： SrTiO3 as semiconducting photocatalyst has been extensively investigated due to its band edges meeting the thermodynamic requirements for water splitting, but a few attention has been concentrated on its application in the NH3 synthesis via N2 photofixation process. Herein, Fe-doped SrTiO3 (FexSr1-xTiO3) products (0 ≤ x ≤ 0.20) were synthesized via a hydrothermal process followed by calcination at 700oC. All FexSr1-xTiO3 products (0.03 ≤ x ≤ 0.20) deliver an enhanced N2 fixation ability, and FexSr1-xTiO3 (x = 0.10) achieves the best NH3 production activity of 30.1 μmol g-1 h-1, which is 3.2-hold higher than that of SrTiO3 alone. Once the x value is higher than 0.10, FexSr1-xTiO3 will transform into composites containing Fe-doped SrTiO3 and α-Fe2O3, which acts as charge recombination sites, thus causes a decreased N2 fixation activity. Further investigations demonstrate that the surface Fe3+-doped sites can not only chemisorb and activate N2 molecules, but also promote the interfacial electron transfer from Fe-doped SrTiO3 to N2 molecules, and thus significantly improve the N2 fixation ability. The present Fe-doped SrTiO3 products exhibit characteristic features such as stable and efficient N2 fixation ability as well as simultaneous realization of N2 reduction and H2O oxidation without co-catalyst, which are of significance in artificial photosynthesis with H2O as electron and proton sources.
关键词： Photocatalysis,Fe-doped SrTiO3,Dinitrogen photofixation,N2 molecule activation
更新于2025-11-21 11:01:37
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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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Photocatalytic properties of TiO2@Polymer and TiO2@Carbon aerogel composites prepared by atomic layer deposition
摘要： Monolithic structured TiO2/aerogel composites were prepared from resorcinol-formaldehyde polymer aerogel (RFA) and its carbon aerogel (RFCA) derivative. A resorcinol-formaldehyde hydrogel was synthesized in a sol-gel reaction and transformed into polymer aerogel by supercritical drying. The RFA was converted to carbon aerogel by pyrolysis at 900 °C in dry N2. Amorphous and crystalline TiO2 layers were grown from TiCl4 and H2O precursors by atomic layer deposition (ALD) at 80 °C and 250 °C, respectively, on both RFA and RFCA. The substrates and the composites were studied by N2 adsorption, TG/DTA-MS, Raman, SEM-EDX and TEM techniques. Their photocatalytic activity was compared in the UV catalyzed decomposition reaction of methyl orange dye.
关键词： ALD,photocatalysis,carbon aerogel,TiO2,resorcinol-formaldehyde polymer aerogel
更新于2025-11-20 15:33:11