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Phosphorimetric determination of 4-nitrophenol using mesoporous molecular imprinting polymers containing manganese(II)-doped ZnS quantum dots
摘要： Mesoporous molecularly imprinted polymers (MIPs) containing mangnanese-doped ZnS quantum dots (Mn-ZnS QDs) were prepared for specific recognition and detection of 4-nitrophenol (4-NP). The Mn-ZnS QDs display orange room-temperature phosphorescence with excitation/emission peaks at 295/590 nm and a decay time of 2.0 ms. In the presence of 4-NP, the orange phosphorescence is strongly reduced. Phosphorescence drops linearly in the 0.1–100 μM 4-NP concentration range, and the detection limit is 60 nM. The detection limit is far lower than the maximally allowed 4-NP concentrations in surface water and drinking water as specified by the U.S. Environmental Protection Agency. The intraday (n = 5) and interday (n = 6) spiked recovery rates were 96.0–104.5% and 97.9–107.9%, respectively, with relative standard deviations of 0.7–4.8% and 1.8–7.5% respectively. These MIPs integrated the characteristic features of phosphorimetry and molecular imprinting. Potential interference by competitive substances, background fluorescence or scattered light are widely reduced.
关键词： Room-temperature phosphorescence,Mesoporous molecularly imprinted polymers,Photoinduced electron-transfer,4-Nitrophenol,Decay time
更新于2025-11-14 17:04:02
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Synthesis of Silver Nanoparticles Loaded onto Polymer-Inorganic Composite Materials and Their Regulated Catalytic Activity
摘要： We present a novel approach for the preparation of polymer-TiO2 composite microgels. These microgels were prepared by the in situ hydrolysis and condensation of titanium tetrabutoxide (TBOT) in a mixed ethanol/acetonitrile solvent system, using poly(styrene-co-N-isopropylacrylamide)/poly(N-isopropylacrylamide-co-methacrylic acid) (P(St-NIPAM/P(NIPAM-co-MAA)) as the core component. Silver nanoparticles (AgNPs) were controllably loaded onto the polymer-TiO2 composite microgels through the reduction of an ammoniacal silver solution in ethanol catalyzed by NaOH. The results showed that the P(St-NIPAM)/P(NIPAM-co-MAA)-TiO2 (polymer-TiO2) organic-inorganic composite microgels were less thermally sensitive than the polymer gels themselves, owing to rigid O–Ti–O chains introduced into the three-dimensional framework of the polymer microgels. The sizes of the AgNPs and their loading amount were controlled by adjusting the initial concentration of [Ag(NH3)2]+. The surface plasmon resonance (SPR) band of the P(St-NIPAM)/P(NIPAM-co-MAA)-TiO2/Ag (polymer-TiO2/Ag) composite microgels can be tuned by changing the temperature of the environment. The catalytic activities of the polymer-TiO2/Ag composite microgels were investigated in the NaBH4 reduction of 4-nitrophenol. It was demonstrated that the organic-inorganic network chains of the polymer microgels not only favor the mass transfer of the reactant but can also modulate the catalytic activities of the AgNPs by tuning the temperature.
关键词： silver nanoparticles,supported catalysts,polymer microgels,titania,reduction of 4-nitrophenol (4-NP)
更新于2025-11-14 17:03:37
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Photocatalysis as an advanced reduction process (ARP): the reduction of 4-nitrophenol using titania nanotubes-ferrite nanocomposites
摘要： TiO2 photocatalysis is an advanced process, employed worldwide for the oxidation of organic compounds, that leads to significant technological applications in the fields of health and environment. The use of the photocatalytic approach in reduction reactions seems very promising and can open new horizons for green chemistry synthesis. For this purpose, titanium dioxide nanotubes (TNTs) were developed in autoclave conditions using TiO2 P25 as a precursor material. Based on these nanotubular substrates, TiO2/CoFe2O4 (TCF) nanocomposites were further obtained by wet impregnation method. The materials were thoroughly characterized and their structural, textural, vibrational, optoelectronic and magnetic properties were determined. The composite materials combine absorbance in the visible optical range and high BET surface area values (~100 m2/g), showing extremely high yield in the photocatalytic reduction of 4-nitrophenol (4-NP), exceeding 94% within short illumination time (only 35 min). The developed nanocomposites were successfully reused in consecutive photocatalytic experiments and were easily removed from the reaction medium using magnets. Both remarkable recycling ability and high-performance stability in the photocatalytic reduction of nitrophenol were observed, thus justifying the significant economic potential and industrial perspectives for this advanced reduction process.
关键词： Cobalt ferrite,4-nitrophenol reduction.,Nanocomposite photocatalyst,TiO2 nanotubes
更新于2025-09-23 15:23:52
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Photophysical Properties of Phthalimide and Pyromellitic Diimide Tethered Imidazolium Nitrophenolate Salts
摘要： Structural aspects of the salt of 2-(3-(1H-imidazol-1-yl)propyl) isoindoline-1,3-dione (L1) with 2,4,6-trinitrophenol as well as the salts of N,N’-bis(3-imidazol-1-yl-propyl)-pyromelliticdiimide (L2) with 2,4-dinitrophenol (H24dnp) and 2,4,6-trinitrophenol (H246tnp) are reported along with the solid and solution studies on the photophysical properties of these salts. The fluorescence emission of the L1 and L2 are quenched by H24dnp and H246tnp both in solid and in solution. In solution the L1 has comparable binding constant with H24dnp and H246tnp but the relative ability to quench the fluorescence emission of L1 by H24dnp is less than the quenching abilities of the H246tnp. These two nitrophenols independently do not distinguish the L1 from L2 but the extent of quenching caused independently by the H24dnp or H246tnp on L1 or L2 make them easily distinguishable. Addition of water quenches the fluorescence emission of L1 and L2; but the addition of water to solution of the nitrophenolate salts result in the recovery of fluorescence emissions from the quenched states. The salts in solid state have short emission life-times. The PET effect prominently caused by mineral acids on L1 or L2 is not observed in the nitrophenolate salts. In solid state the O-π interactions contributed to stacking of the aromatic in the 2,4,6-trinitrophenolate salt of L2, hence it is non-fluorescent.
关键词： Binding of imidazole,Charge-assisted hydrogen bonds,Fluorescence,Cyclic imide,Nitrophenol derivatives
更新于2025-09-23 15:23:52
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Ternary Ag nanoparticles/natural-magnetic SiO2-nanowires/reduced graphene oxide nanocomposites with highly visible photocatalytic activity for 4-nitrophenol reduction
摘要： Agglomerate and reuse limit the promising application of silver nanoparticles (AgNPs) as catalyst. To eliminate those disadvantages, herein, Fe-containing silica nanowires (SiO2NWs) and reduced graphene oxide (RGO) are used as suitable substrates to prepare AgNPs/SiO2NWs/RGO nanocomposite via self-assembly approach. The nanocomposite mostly assembled with each other via intermolecular hydrogen bond and electrostatic adsorption to form a three-dimensional network structure. The AgNPs/SiO2NWs/RGO nanocomposite exhibit excellent photocatalytic activity for 4-nitrophenol reduction by NaBH4, originating from that the nearly mono-dispersed AgNPs are adhered on the surface of the SiO2NWs and RGO, allowing the effective contact of reactants with catalyst and facilitating the electron transfer between them in the reaction. The obtained nanocomposites exhibit the superior stability and can be easily recovered with their fully catalytic activities due to the hydrophobic and magnetic properties of the nanocomposites. It shows the great prospect for the 4-NP reduction in practice and is promising for wide applications in visible light catalytic reaction.
关键词： SiO2 nanowires,Photo-catalytic activity,Reduced graphene oxide,Silver nanoparticles,4-Nitrophenol reduction
更新于2025-09-23 15:22:29
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Efficient Photocatalytic Activity of MSnO3 (M: Ca, Ba, Sr) Stannates for Photoreduction of 4-Nitrophenol and Hydrogen production under UV light irradiation
摘要： This work reports the photocatalytic activity of MSnO3 (M = Ca, Ba, Sr) stannates for the degradation of the dangerous compound 4-Nitrophenol (4-NP), as well as for hydrogen generation starting from clear water. These stannates were prepared by a co-precipitation method. The photocatalytic degradation experiments under UV irradiation point out that the BaSnO3 stannate produced a total degradation of 4-NP after 3 h and this was due to its higher OH radical’s generation rate. This was confirmed by the high fluorescence signal (at 430 nm) produced after the excitation of the Teraphtalic acid/·OH complex, which was formed in presence of the BaSnO3 compound. The CaSnO3 and SrSnO3 stannates produced degradation percentages of 4-NP in the range of 80-95%. However, these stannates produced an innocuous compound: 4-aminophenol, which is widely used in the pharmaceutical industry. The results also indicated that the SrSnO3 stannate had the highest hydrogen production rate of 160 μmol·g-1·h-1. Scanning electron microscopy (SEM) analysis demonstrated that the stannates are formed of polyhedral nanoparticles with sizes in the range of 50-400 nm. The structural analysis by X-ray diffraction confirmed that the BaSnO3 stannate presents a cubic phase while the SrSnO3 and CaSnO3 stannates have an orthorrombic phase. Due to their good performance for photoreduction and hydrogen production, we consider that the stannates reported here could be candidates for the degradation of contaminants in water effluents or for the generation of a clean source of energy.
关键词： 4-Nitrophenol,Hydrogen production,Photocatalysis,Stannates
更新于2025-09-23 15:21:21
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Semiconducting Metal Oxide Photonic Crystal Plasmonic Photocatalysts
摘要： Plasmonic photocatalysis has facilitated rapid progress in enhancing photocatalytic efficiency under visible light irradiation. Poor visible-light-responsive photocatalytic materials and low photocatalytic efficiency remain major challenges. Plasmonic metal–semiconductor heterostructures where both the metal and semiconductor are photosensitive are promising for light harvesting catalysis, as both components can absorb solar light. Efficiency of photon capture can be further improved by structuring the catalyst as a photonic crystal. Here, the synthesis of photonic crystal plasmonic photocatalyst materials using Au nanoparticle-functionalized inverse opal (IO) photonic crystals is reported. A catalyst prepared using a visible-light-responsive semiconductor (V2O5) displayed over an order of magnitude increase in reaction rate under green light excitation (λ = 532 nm) compared to no illumination. The superior performance of Au-V2O5 IO is attributed to spectral overlap of the electronic bandgap, localized surface plasmon resonance, and incident light source. For the Au-TiO2 catalyst, despite coupling of the LSPR and excitation source at λ = 532 nm, this is not as effective in enhancing photocatalytic activity compared to carrying out the reaction under broadband visible light, which is attributed to improved photon adsorption in the visible by the presence of a photonic bandgap, and exploiting slow light in the photonic crystal to enhance photon absorption to create this synergistic type of photocatalyst.
关键词： photonic crystal,nitrophenol reduction,catalyst,plasmonic nanoparticles,photocatalysis
更新于2025-09-23 15:21:01
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Self-assembled BiOCl/Ti3C2T composites with efficient photo-induced charge separation activity for photocatalytic degradation of p-nitrophenol
摘要： Cocatalysts play an important role in increasing the photogenerated electron-hole separation rate of catalytic materials. Here, we selected a novel 2D material Ti3C2Tx (Tx = –OH, –O) as a cocatalyst and synthesized BiOCl/Ti3C2Tx (named as BT-n n = 0, 0.5, 1.0, 2.0, 4.0) composite materials by electrostatic self-assembly. We carefully characterized the structure, morphology and photoelectric performance of the composites, finding that we successfully synthesized 2D/2D BiOCl/Ti3C2Tx materials. The photocatalytic performance of the composites was evaluated by degradation of p-nitrophenol as a pollutant under simulated illumination. Among the composites obtained, BT-2.0 showed the best photocatalytic performance; specifically, its removal rate reached 97.86% and its degradation rate was about 3.3 times that of BT-0. Free radicals in the photocatalytic process were tested by electron paramagnetic resonance, which showed that superoxide radicals and holes are the most active free radicals in the system due to the higher photogenerated electron separation efficiency of BT-2.0. Therefore, constructing a heterojunction with Ti3C2Tx as a cocatalyst can improve the photocatalytic activity of BiOCl, which may provide new insights into the selection of novel co-catalytic materials in the field of photocatalysis.
关键词： p-nitrophenol,photocatalytic degradation,MXene,superoxide radicals,BiOCl
更新于2025-09-23 15:21:01
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Semiconductor α-Fe <sub/>2</sub> O <sub/>3</sub> Hematite Fabricated Electrode for Sensitive Detection of Phenolic Pollutants
摘要： Hematite (α-Fe2O3) semiconductor is an abundant and non-toxic catalyst for different (photo)electrochemical reactions. In this work, a selective p-nitrophenol sensor was developed by fabricating a thin-layer of a glassy carbon electrode (GCE) with 5% nafion coating binders onto α-Fe2O3 thin film synthesized by a simple and inexpensive process. High sensitivity including long-term stability, and enhanced linear dynamic range, electrochemical performance towards p-nitrophenol were achieved by a reliable current-voltage method. A linear calibration curve was observed over a wide range of p-nitrophenol concentrations. Very low detection limit (0.6 ? 0.02 nM), good limit of quantification (2.0 nM) and high sensor sensitivity (K = 74.1 μA?cm(cid:0) 2) are calculated based on noise to signal ratio of ～ 3 N/S. Very importantly, the detection range covers over 7 orders of magnitude concentrations, from nM to mM. Figures of merits are comparable with best reported results whilst using a very simple device configuration. We show that hematite is an excellent material for the development of chemical sensors to detect hazardous compounds for environmental safety in a broad scale of concentrations.
关键词： Environmental safety,Sensitivity,p-Nitrophenol sensor,Hematite α-Fe2O3,Glassy carbon electrode
更新于2025-09-23 15:21:01
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Hydrogen Peroxide-Assisted Photocatalysis under Solar Light Irradiation:Interpretation of Interaction Effects between an Active Photocatalyst and H <sub/>2</sub> O <sub/>2</sub>
摘要： In this work, the combination of H2O2 and an active visible-light-driven photocatalyst (Ag-S/PEG/TiO2) was utilized under natural solar radiation for the degradation of 2-nitrophenol (2-NP), and interaction effects between the photocatalyst and hydrogen peroxide were analyzed. For this purpose, experiments were designed using the response surface methodology based on the central composite design. The resulting data was utilized to obtain a model for the prediction of response (the degradation efficiency) as a function of two independent factors (H2O2 concentration and the photocatalyst loading). The statistical analysis indicated that optimum values of each of the two independent factors decreased by increasing the other one and vice versa. Moreover, it was found that adding the optimal amount of H2O2 to the solution, which contained just the photocatalyst, can enhance the degradation significantly (up to 45 %). However, using higher concentrations of H2O2 may decrease the efficiency. The global optimum condition was found to be 545 ppm and 316 mM for Ag-S/PEG/TiO2 loading and H2O2 concentration, respectively. In this condition, the degradation efficiency of 2-NP reached 92.4 % after only 45 min of solar light irradiation.
关键词： photocatalysis,2-nitrophenol,Ag-S/PEG/TiO2,solar degradation,H2O2-assisted
更新于2025-09-19 17:15:36