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TiO <sub/>2</sub> coating prepared by mechanical alloying treatment for photocatalytic degradation
摘要： In this study, a nanostructured TiO2 coating was successfully prepared on a large-scale titanium plate by a simple one-step surface mechanical alloying (SMA) treatment. The coating was characterised to determine the morphological and composition changes with SMA. The coating was ～60 μm thick and composed of 5 nm diameter rutile TiO2 particles. The photocatalytic activity of the nanostructured TiO2 coating was studied via the ultraviolet–visible (UV–vis) decolorisation of aqueous rhodamine-B. The results showed that the photocatalytic degradation e?ect in 5 h of the f30 mm nanostructured TiO2 coating was comparable to that of 20 mg raw TiO2 under similar UV–visible light irradiation. One-step SMA was demonstrated as an appropriate method to produce a high-performance photocatalytic plate.
关键词： Photocatalysis,black TiO2,organic dye degradation,nanostructured TiO2 coating,surface mechanical alloying
更新于2025-09-09 09:28:46
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Large Scale Synthesis of ZnO Nanostructures of Different Morphologies through Solvent-free Mechanochemical Synthesis and their Application in Photocatalytic Dye Degradation
摘要： Well crystalline, near-stoichiometric zinc oxide nanostructures of different morphologies are fabricated in large scale, utilizing a simple, cost effective mechanochemical synthesis in absence of solvent. Effects of ionic and nonionic surfactants along with the concentration of hydrolyzing agent on the evolution of nanostructure morphology have been studied. It has been observed that while a cationic surfactant such as Cetyltrimethylammonium Bromide (CTAB) favors the nanostructures to growth along their polar c-axis, a nonionic surfactant such as Polyvinylpyrrolidone (PVP) reduces their preferred c-axis growth. Increase of hydrolyzing agent in the reaction mixture enhances the growth rate of the nanostructures. The nanostructures have been tested for photodegradation of anionic dye molecules such as Methylene Blue (MB). All the nanostructures manifest high photocatalytic performance. Apart from morphology, the specific surface area, crystal plane orientation and the concentration of basic sites at surface are seen to contribute significantly to the photocatalytic performance of the zinc oxide nanostructures.
关键词： Mechanochemical Synthesis,Photocatalysis,Nanostructures,ZnO,Dye Degradation
更新于2025-09-04 15:30:14
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Photocatalytic Performance on Visible Light Induced ZnS QDs-MgAl Layered Double Hydroxides Hybrids for Methylene Blue Dye Degradation
摘要： Semiconductor hybrids based photocatalytic reaction is one of the prominent methods to treat wastewater, containing the organic pollutants. In the present work, we report the development of ZnS QDs-LDH hybrid structure for the photocatalytic treatment of methylene blue (MB) dye. The as-synthesized ZnS QDs-LDH hybrid structure was characterized by XRD, FESEM, HRTEM, EDX, XPS, and FTIR to analyze the formation, morphology and chemical structure. The UV-Vis DRS was used to investigate the optical absorption characteristics of the ZnS QDs-LDH hybrid. The photocatalytic performance of the as-prepared samples was investigated against the methylene blue dye molecule under UV-Vis light irradiation. The scavenging experiments were carried out in order to probe the radical formation by using EDTA, benzoquinone, and 2-proponal. The cycling experiments were performed to check the stability of the ZnS QDs-LDH hybrid photocatalyst after repeated photodegradation experiments.
关键词： ZnS Quantum dots,Layered double hydroxides,Photocatalytic activity,Methylene blue dye degradation,Water treatment
更新于2025-09-04 15:30:14
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Effect of temperature on structural and optical properties of solvothermal assisted CdS nanowires with enhanced photocatalytic degradation under natural sunlight irradiation
摘要： Photocatalytic degradation of toxic dyes is an important topic across the globe. This paper reports the photocatalytic degradation of methylene blue (MB) dye using cadmium sulfide (CdS) nanowires as a photocatalyst under natural sunlight irradiation. The CdS nanowires were successfully synthesized by a solvothermal route using ethylenediamine as a solvent with a series of different reaction temperature from 160 to 200 °C for a fixed time of 24 h. Multiple characterization techniques were used to investigate the structural, morphology, optical and photocatalytic study of as-synthesized CdS samples. The XRD patterns reveal highly crystalline CdS nanomaterials with a hexagonal crystal structure. The FESEM and HRTEM observations clearly confirmed a large number of uniform nanowires grown in different directions and interconnected with each other. The stoichiometric ratio of Cd:S is almost 1:1, confirmed by EDS analysis. Room temperature PL spectra of CdS nanowires exhibit a narrow emission at a wavelength of 512 nm. The CdS nanowires synthesized at 200 °C shows the excellent photocatalytic performance with highest photodegradation efficiency has reached up to 98.75% within 20 min, under sunlight irradiation. The 93.06% and 89.10% photodegradation efficiency were observed in CdS nanowires synthesized at 180 °C and 160 °C, respectively. From these result, it is observed that the crystallite size and morphology of CdS nanowires are the influence factors for the photodegradation efficiency of MB dye. Furthermore, the mechanism of MB dye photodegradation using CdS nanowires was discussed. These CdS nanowires with high photocatalytic activity can be used for future in water pollutant degradation.
关键词： Hexagonal CdS,Solvothermal synthesis,MB dye degradation,Reaction temperature,Sunlight irradiation
更新于2025-09-04 15:30:14
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Enhanced visible-light photoelectrochemical hydrogen evolution through degradation of methyl orange in a cell based on coral-like Pt-deposited TiO2 thin film with sub-2 nm pores
摘要： TiO2 nanoparticles exhibit good photocatalytic activity for hydrogen evolution through water splitting; however, they demonstrate weak activity under visible light irradiation due to the wide band gap of TiO2. Deposition with noble metals such as platinum, as cocatalyst, led to the red-shift of the absorption edge of rutile TiO2; however, its activity is not significant for the photoelectrochemical (PEC) degradation of azo dyes such as methyl orange (MO). Herein, we investigated the photoelectrocatalytic degradation reaction of MO in a PEC cell based on Pt-deposited TiO2 thin film. The performance of the cell increased through the formation of mesoporous coral-like structures with sub-2 nm pores and the formation of defect states on the electrode surface. UV–vis studies confirmed, when methanol was added, the PEC cell exhibited a much higher MO degradation efficiency (99.6% after 28 min UV irradiation) than in the absence of methanol (64.7%). GC–MS studies confirmed the oxidation of methanol to formaldehyde, reacting on the electrode surface, followed by the reduction of the protons into hydrogen over the Pt sites. Also, the conversion of formaldehyde to formic acid and formic acid to CO2 are possible mechanisms to increase the hydrogen evolution rate to 418 μmol/h under visible light irradiation. Reaction of adsorbed active species within the surface of coral-like TiO2 structures with sub-2 nm pores provides high activity of the proposed PEC cell for visible-light-driven water splitting. These research studies may be continued to the design of other efficient semiconductor photocatalysts.
关键词： Photoelectrocatalytic activity,Photoelectrochemical cell,Coral-like TiO2 nanopores,Hydrogen production,Dye degradation
更新于2025-09-04 15:30:14
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Stability study of natural green dye based DSSC
摘要： Evolution of solar cell based on natural molecules flourished expeditiously, which is a good alternative for silicon-based solar cells or thin film technologies due to their low assembling cost, lightweight and flexibility. But natural dye-based dye-sensitized solar cell (DSSC) has low cell efficiency and stability, which limits the use of organic solar cells. In this research, natural green dye extracted from spinach (Spinacia oleracea) and used as a sensitizer source for natural dye-based DSSC. The measured cell efficiency of natural green dye-sensitized DSSC was 0.398%. Also, the cell stability test has been carried out by measuring the degradation rate (cell efficiency) by aging the dye molecule for DSSC has been conducted after 48, 96, 144 and 196 hours under 100mW/cm2 illumination (1.5 AM) at the ambient condition.
关键词： natural green dye,degradation,DSSC,chlorophyll,TiO2,stability
更新于2025-09-04 15:30:14
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Bimetallic metal organic frameworks: Magnetically separable heterogeneous catalyst for efficient organic transformation and photocatalytic dye degradation
摘要： A new bimetallic MOF (BMOF) has been synthesized using iron and zinc as inorganic metal nodes and 1-4, benzenedicarboxylic acid (BDC) as organic linker molecule. BMOF was confirmed with Single crystal X-ray diffraction (SCXRD), X-ray photoelectron spectroscopy (XPS), Transmission electron microscopy-high angle annular dark-field imaging (TEM-HAADF), Field emission scanning electron microscopy-energy dispersive x-ray analysis (FESEM-EDX), Vibrating sample magnetometer (VSM) and inductively coupled plasma-mass spectrometry (ICP-MS) analysis. The synthesized BMOF shows excellent optical and magnetic properties. BMOF acts as a heterogeneous catalyst and show high catalytic activity towards bis(indolyl)methane synthesis and photocatalytic degradation of methylene blue (MB) under visible light illumination.
关键词： Metal-organic frameworks,dye degradation,Bis(indolyl)methanes,photocatalysis
更新于2025-09-04 15:30:14
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Revisiting structural and photocatalytic properties of g-C3N4/TiO2: Is surface modification of TiO2 by calcination with urea an effective route to “solar” photocatalyst?
摘要： g-C3N4/TiO2 derived from the surface modification of TiO2 by calcination with urea has been widely studied as a “visible-light-active” photocatalyst for environmental purification applications. However, few attentions have been paid to the structure characterization and the photocatalytic properties of the resultant nanocomposite photocatalysts under a practical sunlight irradiation. Here we employ various characterization techniques, including TGA, XRD, TEM, XPS, UV-Vis spectrum, and N2-sorption analysis to characterize the evolutions in phase crystal structure, microstructure and optical properties of g-C3N4/TiO2 nanohybrids synthesized through calcining a mechanical mixture of urea and Evonik Aeroxide P-25 TiO2 (P25) at 350-500 oC. The thermal pyrolysis of urea leads to the surface decoration of TiO2 with graphitic carbon nitrate (g-C3N4) at temperatures above 400 oC. The photocatalytic properties of the resultant g-C3N4/TiO2 nanoparticles are evaluated through photocatalytic decoloration of methylene blue (MB) and reduction of Cr(VI) to Cr(III) under visible (420 nm), UV (365 nm), and simulated solar light irradiations. The nanohybrid photocatalysts, as most previous studies reported, show much higher photocatalytic activity under visible light irradiation than the single-component counterparts, i.e. P25 or g-C3N4. However, under solar and UV irradiation, no considerable improvements are found, which is caused by the decrease in redox potential upon interfacial charge carrier transfer between g-C3N4 and TiO2. Moreover, g-C3N4/TiO2 shows an ultralow photocatalytic activity in Cr(VI) reduction. The surface modification with organic g-C3N4 is assumed to tune the surface properties (e.g. hydrophilicity) of TiO2. Our results demonstrate that photocatalytic activity in UV range is as important as that in visible range, and developing efficient “solar” photocatalysts should balance both since they might be incompatible with each other.
关键词： graphitic carbon nitrate,dye degradation,TiO2 nanoparticles,Cr (VI) reduction,semiconductor photocatalysis,Aeroxide P25,charge carrier transfer
更新于2025-09-04 15:30:14
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Carbon nanotube based metal-organic framework nanocomposites: Synthesis and their photocatalytic activity for decolorization of colored wastewater
摘要： Herein, Materials Institute Lavoisier (MIL-125(Ti))/carbon nanotube (CNT) nanoporous composites (MIL/CNT) were synthesized by hydrothermal method. Different amounts of CNT (0.01 g and 0.03 g) were used to synthesize nanocomposites (denoted as MIL/CNT(0.01) and MIL/CNT(0.03), respectively). The synthesized nanomaterials (MIL, MIL/CNT(0.01) and MIL/CNT(0.03)) were characterized by XRD, FTIR, TGA, BET, SEM, and zeta potential and used for photocatalytic dye degradation. Reactive Black 5 (RB5) was used as a model pollutant. The zeta potential of MIL and MIL/CNT (0.01) were ?27.7 mV and 19.2 mV, respectively. The data showed that that MIL/CNT(0.01) nanocomposite had higher photocatalytic dye degradation due to the synergistic effect of CNT. Dye decolorization by the nanomaterials followed the zero-order kinetics reaction. The decolorization rate was 0.0015, 0.0019, 0.0024 mg/L min for MIL, MIL/CNT(0.01) and MIL/CNT(0.03), with the correlation coefficient of 0.9639, 0.9906, and 0.9757, respectively. The synthesized catalysts were reusable over two cycles.
关键词： Metal-organic framework-carbon nanotube nanocomposite,Photocatalytic dye degradation,Reactive Black 5,Synthesis
更新于2025-09-04 15:30:14
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Two bimetallic metal–organic frameworks capable of direct photocatalytic degradation of dyes under visible light
摘要： Two bimetallic metal–organic frameworks (MOFs), specifically {2[LiM(TDA)2(DMF)]·NH2+(CH3)2}n (M = Co (HNU-29) or Zn (HNU-30), TDA = 2,5-thiophenedicarboxylate), were synthesized by solvothermal methods. X-ray crystal structures of the two MOFs showed them to be isostructural. Thus, in both cases, the metal secondary building units were connected by TDA2? ligands to form a 3D framework whose structure can be simplified to the twofold interpenetrated dia net. HNU-29 showed excellent photocatalytic activity for the degradation of methylene blue (MB) under visible light even without the addition of H2O2 as an electron acceptor, remaining stable even after several cycles of reuse. The MB degradation followed first-order kinetics, and the photocatalytic degradation mechanism was found to be related to the effective ligand-to-metal charge transfer within the framework.
关键词： Photocatalysis,Methylene blue,Metal–organic frameworks,Visible light,Dye degradation
更新于2025-09-04 15:30:14