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Graphene oxide-based zirconium oxide nanocomposite for enhanced visible light-driven photocatalytic activity
摘要： In the present investigation, an efficient visible light-active, graphene oxide-based zirconium oxide nanocomposite (GO–ZrO2) has been synthesized by co-precipitation method. The synthesized photocatalyst was characterized by XRD, FTIR, FE-SEM, EDS, TEM, TGA, PL, UV-DRS and BET surface area analysis. The characterization results illustrate the homogeneous dispersion of ZrO2 nanoparticles in the GO–ZrO2 nanocomposite with excellent harmony between GO and ZrO2 nanoparticles. The photocatalytic efficiency of the synthesized GO–ZrO2 nanocomposite was evaluated by photodegradation of hazardous, water-soluble rhodamine B and methylene blue dyes under visible light irradiation. The 90% photocatalytic degradation of rhodamine B dye (with initial conc. 30 mg/L) was observed in 105 min of visible light irradiation, while 99.23% of methylene blue (with initial conc. 100 mg/L) dyes degradation was observed in just 60 min using 25 mg/100 ml dose of GO–ZrO2 nanocomposite as a photocatalyst. The mechanistic investigation using scavengers suggest that the superoxide (O2·?) is the most reactive species involved in the photodegradation of organic dyes. The synthesized photocatalyst GO–ZrO2 nanocomposite also exhibits excellent thermal stability and reusability.
关键词： Methylene blue,Rhodamine B,Photocatalytic activity,Zirconium oxide,Graphene oxide,Visible light,Co-precipitation method
更新于2025-09-23 15:23:52
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Covalent organic framework as an efficient, metal-free, heterogeneous photocatalyst for organic transformations under visible light
摘要： Visible-light active, heterogeneous, and organic photocatalysts exhibit a more sustainable and environmentally friendly alternative to classical metal-based catalysts. Two-dimensional covalent organic frameworks (2D-COFs) with permanent porosity, columnar π-arrays and excellent stability, that can become an excellent platform for heterogeneous photocatalysis of organic transformations. Here we report a predesigned imine-based COF with electron donor and acceptor structure. And new framework possesses large surface area, high crystallinity, outstanding stability and broad absorption range in the visible-light region as well as good photoelectric response characteristics. Importantly, it was found to be a highly effective heterogeneous photocatalyst for reductive dehalogenation of phenacyl bromide derivatives and α-alkylation of aldehydes under irradiation of visible-light. In addition, the COF gave good recyclability and could be reused after a simple separation manipulation. The current present still reveals a great prospect for 2D-COFs as metal-free, heterogeneous photocatalysts for organic transformations.
关键词： visible light,photocatalysis,heterogeneous catalysis,metal-free,covalent organic frameworks
更新于2025-09-23 15:23:52
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Interfacial engineering of Fe2O3@BOC heterojunction for efficient detoxification of toxic metal and dye under visible light illumination
摘要： Recent developments of small band gap semiconductor coupled bismuth carbonate (BOC) heterojunction are advantageous for photocatalysis application because of their improved solar harvesting ability and enhanced charge-carrier collection. In this work, we have developed iron (III) oxide decorated bismuth carbonate (Fe2O3@BOC) heterojunction via a simple two-step process. The developed heterojunction exhibits excellent photocatalytic activity towards reduction of carcinogenic and mutagenic Cr(VI) to nontoxic Cr(III) and degradation of toxic dye [methylene blue (MB)] under visible light illumination. Further investigation revealed that the loading of Fe2O3 nanoparticles had an impact on efficient charge carrier collection at the interface of Fe2O3@BOC heterojunctions. The unprecedented photocatalytic activity for Fe2O3@BOC1 heterojunction at room temperature could be attributed due to the enhancement in light absorption ability and suppression of electron–hole pair recombination at the heterojunction interface. In addition, reduction in efficacy of the heterojunction with increase in loading of Fe2O3 nanoparticles on BOC surface further confirms the role of interface on the modulation of photocatalytic activity. The role of photogenerated electrons and reactive oxygen species involved during photocatalytic reduction of Cr(VI) and degradation of MB was studied in detail. Moreover, recyclability experiment demonstrates that the developed photocatalyst can be reused without decay in performance. Finally, development of inexpensive prototype reactor is demonstrated towards reduction of Cr(VI) and degradation of MB under continuous flow operation. Thus, good efficacy of the developed reactor for cleaning of toxic pollutants in water makes the heterojunction (Fe2O3@BOC1) a promising photocatalyst for water purification in near future.
关键词： photocatalytic activity,charge separation,Heterojunction,toxic pollutants,visible light
更新于2025-09-23 15:23:52
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Photocatalytic oxidation of gaseous benzene, toluene and xylene under UV and visible irradiation over Mn-doped TiO2 nanoparticles
摘要： The photocatalytic oxidation of gaseous benzene, toluene and xylene (BTX) over un-doped, 0.1 and 1 wt% Mn-TiO2 nanoparticles under ultraviolet and visible irradiation was studied in atmosphere of synthetic air or inert gas. The photocatalytic decomposition efficiency and the oxidation products were determined using a Static Photochemical Reactor coupled with FTIR spectroscopy. BTX underwent efficient decomposition over Mn-TiO2 photocatalysts under UV irradiation, more with oxygen presence and less without oxygen. More important toluene and xylene went substantial decomposition over 0.1 mol% Mn-TiO2 under visible irradiation with oxygen presence. The main final oxidation products in the UV photocatalysis of BTX were CO2, CO and H2O, with CO2 and CO yields 4 and 2 respectively. The conversion percentage of benzene, toluene, and xylene to CO2 were 63.6%, 56.4%, 51.8%, and to CO 29%, 26.5%, 23.2%, respectively. In the visible photocatalysis of toluene and xylene the yields of CO were insignificant. Formation of carbon containing deposits on TiO2 surfaces was observed after extensive UV photocatalysis of toluene and xylene, and such by-products surface coverage may reduce the photocatalytic activity of TiO2 samples. Some aspects of the photocatalytic mechanism were examined.
关键词： Mn-doped TiO2,Visible - light photocatalysis,Photodegradation of Benzene,Indoors air pollution,Xylene,Toluene
更新于2025-09-23 15:23:52
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Efficient photocatalytic debromination of 2,2?,4,4?-tetrabromodiphenyl ether by Ag-loaded CdS particles under visible light
摘要： Highly active and visible light-driven Ag-loaded CdS photocatalysts were prepared via a hydrothermal synthesis and photodeposition method. The removal and debromination of 2,2?,4,4?-tetrabromodiphenyl ether was achieved efficiently using this Ag-loaded CdS under visible light, with a removal efficiency of 100% and a debromination ratio of 44.3% being achieved within 30 min. Both the reaction solvent and the water content were found to have a strong influence on the removal efficiency and the debromination ratio. In addition, the stepwise debromination preference was ortho > para, thereby indicating that the main debromination pathway was electron reduction. The stability and efficiency of these Ag-loaded CdS photocatalysts for the removal of BDE47 were satisfactory, and so our results confirmed the development of a promising visible light-driven catalyst for the removal of polybrominated diphenyl ethers.
关键词： Debromination ratio,Visible light-driven,Ag-loaded CdS,Photocatalyst,Removal efficiency
更新于2025-09-23 15:23:52
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Low-cost effective photocatalytic activity under visible light of pitch-based porous carbon nanofiber composites aided by zinc oxide
摘要： To explore and develop an economical, novel, and effective photocatalyst for the degradation of methylene blue (MB) under visible-light irradiation, polyacrylonitrile (PAN)/pitch-based carbon nanofibers (CNFs) with ZnO (PPZn) are successfully produced by one-step electrospinning of PAN, pitch, and zinc acetate in dimethylformamide (DMF) solution. The charge separation rate, adsorption capacity, and visible-light harvesting effects are all enhanced by the synergistic effect of PAN/pitch-based CNFs and ZnO coupling. The resulting PPZn photocatalysts exhibit excellent removal capacity of 100% of MB within 30 min and a kinetic rate constant of 0.018 min?1 under visible light. PPZn also exhibits a consistent and stable photocatalytic performance by maintaining nearly 100% removal of 15 ppm MB over 8 regeneration cycles. The PP-based CNFs in PPZn act as a charge reservoir to afford fast transport for suppressing the e?–h? recombination and high electrical conductivity induced by the pitch, thereby expanding the visible-light response. The PP(3)Zn composites demonstrate a promising potential as a low-cost photocatalyst material offering excellent photocatalytic efficiency in the visible-light spectrum.
关键词： Carbon nanofiber,ZnO,Methylene blue,Pitch,Visible light,Photocatalytic activity
更新于2025-09-23 15:23:52
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A sustainable solution for removal of glutaraldehyde in saline water with visible light photocatalysis
摘要： Glutaraldehyde (GA) is the most common biocide used in unconventional oil and gas production. Photocatalytic degradation of GA in brine simulating oil and gas produced water using Ag/AgCl/BiOCl composite as a photocatalyst with visible light was investigated. Removal of GA at 0.1 mM in 200 g/L NaCl solution at pH 7 was 90% after 75 min irradiation using 5 g/L of the photocatalyst. The GA removal followed pseudo-first order reaction with a rate constant of 0.0303 min?1. At pH 5 or at 300 g/L NaCl, the photocatalytic removal of GA was almost completely inhibited. Similar inhibitions were observed when adding dissolved organic carbon (from humic acid) at 10 and 200 mg/L, or Br? at 120 mg/L to the system. The removal rate of GA markedly increased with increasing pH (5-9), photocatalyst loading (2-8 g/L) and under 350 nm UV (compared to visible light). On the contrary, the removal rate of GA markedly decreased with increasing NaCl and initial GA concentrations (0-300 g/L for NaCl and 0.1-0.4 mM for GA). A quenching experiment was also conducted; electron holes (h+) and superoxide (O2?-) were found as the main reactive species responsible for the removal of GA while ?OH had a very limited effect.
关键词： saline,Glutaraldehyde,produced water,hydraulic fracturing fluid,visible light photocatalysis
更新于2025-09-23 15:23:52
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Insight into visible light-driven photocatalytic performance of direct Z-scheme Bi2WO6/BiOI composites constructed in -situ
摘要： Bi2WO6/BiOI composites with enhanced photocatalytic performance were constructed in-situ by a hydrothermal routine. The Bi2WO6/BiOI composites were studied by Brunauer -Emmett-Teller (BET), X-ray di?raction patterns (XRD), UV–Vis di?use re?ectance spectra (DRS), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), surface photovoltage spectroscopy (SPS), electron spin-resonance (ESR) spectroscopy and X-ray photoelectron spectroscopy (XPS). The results support the coexistence of Bi2WO6 and BiOI in the composites. All the Bi2WO6/BiOI composites display higher separation rate of photoinduced carriers than BiOI. OH and·O2? were formed in the composite photocatalytic system. Finally, a direct Z-scheme was proposed for the Bi2WO6/BiOI composites.
关键词： Separation of photoinduced carriers,Bi2WO6,Heterojunctions,Visible light photocatalytic property,BiOI
更新于2025-09-23 15:23:52
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Constellation-Optimal Beamformers For Multiuser MISO Broadcast Visible Light Communications
摘要： In this paper, we design energy-efficient space constellations for multiuser multi-input single-output (MISO) visible light communication broadcast systems with channel state information (CSI) at the receiver in the three scenarios: 1) with CSI at the transmitter (CSIT), 2) with statistical CSIT and 3) without CSIT. By utilizing the cooperation of multiuser interference, optimal multidimensional additively uniquely decomposable constellation groups are designed to optimize the received worst-case performance metrics of all users subject to two commonly used power constraints, i.e., average and peak optical power constraints. The resulting optimal designs are proved to be pulse amplitude modulation with an optimal beamformer, which can be efficiently attained by numerical search for Scenarios 1 and 2 and be given in a closed-form for Scenario 3. One of the common significant advantages of these designs is fast demodulation of the sum signal from a noisy received signal, since these optimal designs result in an equivalent ideal scalar AWGN channel. Comprehensive computer simulations demonstrate that our designs significantly outperform traditional zero-forcing, minimum mean square error and time-division methods.
关键词： Additively uniquely decomposable constellation group,multi-input single-output,maximum likelihood detection,optimal multidimensional constellation,visible light communications,broadcast channels
更新于2025-09-23 15:23:52
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Construction of Pt-decorated g-C3N4/Bi2WO6 Z-scheme composite with superior solar photocatalytic activity toward rhodamine B degradation
摘要： Highly efficient visible-light-driven Pt-decorated g-C3N4/Bi2WO6 hybrid photocatalysts were successfully prepared via a photodeposition method. The microstructures and optical properties of the prepared samples were characterized by transient photocurrent experiments, X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), UV-vis diffused reflectance spectra (DRS), photoluminescence (PL), electron spin resonance (ESR) spectroscopy and X-ray photoelectron spectroscopy (XPS) techniques. FESEM and TEM images show that metallic Pt particles disperse on the surface of g-C3N4/Bi2WO6 hybrid. Pt-decorated g-C3N4/Bi2WO6 compsites exhibited excellent DRS attribute to the surface plasmonic resonance (SPR) of Pt particles and g-C3N4/Bi2WO6. The PL results verified that the suitable band potential of g-C3N4 and Bi2WO6 for construction of Z-type photocatalytic system. In the photocatalytic experiment, results showed that Pt(1%)-g-C3N4/Bi2WO6 photocatalysts displayed higher photocatalytic activity than either pure g-C3N4 or Bi2WO6 for the degradation of Rhodamine B (RhB). Additionally, the free-radical trapping experiments and ESR disclose that the hole (h+), superoxide radical (·O2-) and hydroxyl radical (·OH) acted as reactive species. Based on above, a possible plasmonic Z-scheme mechanism for organics degradation over Pt-decorated g-C3N4/Bi2WO6 was proposed.
关键词： g-C3N4/Bi2WO6,Visible light irradiation,Z-scheme heterojunction,Pt-decorated
更新于2025-09-23 15:23:52