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Purification of Methylene Blue via Photocatalytic Nanofibrous Membranes Containing TiO <sub/>2</sub> Nanoparticles
摘要： In this paper, titanium dioxide nanoparticles were synthesized and deposited on polyacrylonitrile nanofiber membranes via a sol-gel process. Filter structure consisted of a non-woven polyurethane-carbon substrate, polyacrylonitrile nanofiber and titanium dioxide nanoparticles. The concentration of methylene blue dye solution was measured via UV radiation. The filtration efficiency was calculated via Langmuir-Hinshelwood pseudo-first order equations. The results showed that the filtration efficiency of samples using titanium dioxide under UV rays was higher than those without titanium dioxide and UV rays in both immersing and cross-flow processes. Degradation efficiency of the cross-flow system was three times higher than that of immersing method. In the cross-flow process, the effect of three variables- pressure on the membrane, initial concentration of dye solution and pH of the dye solution was studied under UV rays. The highest efficiency obtained was 90.3% by using 1.5 bar pressure, 40 μM initial concentration and pH of 4.1.
关键词： catalysts,fibers,methylene blue,degradation,textiles,membranes
更新于2025-09-19 17:15:36
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Synergy of the catalytic activation on Ni and the CeO <sub/>2</sub> –TiO <sub/>2</sub> /Ce <sub/>2</sub> Ti <sub/>2</sub> O <sub/>7</sub> stoichiometric redox cycle for dramatically enhanced solar fuel production
摘要： Solar thermochemical approaches to CO2 and H2O splitting have emerged as an attractive pathway to solar fuel production. However, efficiently producing solar fuel with high redox kinetics and yields at lower temperature remains a major challenge. In this study, Ni promoted ceria–titanium oxide (CeO2–TiO2) redox catalysts were developed for highly effective thermochemical CO2 and H2O splitting as well as partial oxidation of CH4 at 900 1C. Unprecedented CO and H2 production rates and productivities of about 10–140 and 5–50 times higher than the current state-of-the-art solar thermochemical carbon dioxide splitting and water splitting processes were achieved with simultaneous close to complete CH4 conversions and high selectivities towards syngas. The underlying mechanism for the exceptional reaction performance was investigated by combined experimental characterization and density functional theory (DFT) calculations. It is revealed that the metallic Ni and the Ni/oxide interface manifest catalytic activity for both CH4 activation and CO2 or H2O dissociation, whereas CeO2–TiO2 enhances the lattice oxygen transport via the CeO2–TiO2/Ce2Ti2O7 stoichiometric redox cycle for CH4 partial oxidation and the subsequent CO2 or H2O splitting promoted by catalytically active Ni. Such findings substantiate the significance of the synergy between the reactant activation by catalytic sites and the stoichiometric redox chemistry governing oxygen ion transport, paving the way for designing prospective materials for sustainable solar fuel production.
关键词： thermochemical CO2 splitting,solar fuel production,density functional theory,Ni promoted ceria–titanium oxide,thermochemical H2O splitting,methane partial oxidation,redox catalysts
更新于2025-09-19 17:15:36
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Polythioethers with Controlled ?±,??a??End Groups Prepared by Visible Light Induced Thiola??Ene Click Polymerization of Dithiol and Divinyl Ether with 4a??( <i>N</i> , <i>N</i> a??diphenylamino)benzaldehyde as Organocatalyst
摘要： This study reports a step-growth click-polymerization of 1,4-benzenedimethane (BDMT) and diethylene glycol divinyl ether (DEGVE) with 4-(N,N-diphenylamino)-benzaldehyde (DPAB) as a photoredox catalyst under irradiation of visible light. DPAB exhibits a strong UV–vis absorption at 350 nm and a strong fluorescence emission at 480 nm in anisole. There is a strong fluorescence quenching between BDMT and DPAB. The molecular weight of the polythiolether can be controlled by reaction time and monomer feed ratios. More importantly, α,ω-dithiol and α,ω-divinyl telechelic polythiolether oligomers are successfully synthesized by simply changing the molar ratios of BDMT to DEGVE. 1H NMR and MALDI-TOF MS spectra demonstrate that the oligomers have high end group fidelity. In addition, strong fluorescence is observed when the α,ω-dithiol terminated polythiolether adds with N-(1-pyrenyl) maleimide, indicating that the as-prepared polythiolether bears reactive thiol end groups. Furthermore, high molecular weight polythiolether are prepared by chain extension with reactive polythiolether oligomers as macro-monomers. For example, α,ω-divinyl oligomer (Mn = 2000 g mol?1) could further react with α,ω-dithiol oligomer (Mn = 2400 g mol?1) to form high molecular weight polythiolether (Mn = 6000 g mol?1).
关键词： metal-free catalysts,thiol–ene click polymerization,photoredox catalysts,telechelic polymers,photopolymerization
更新于2025-09-19 17:13:59
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Low-temperature chemical vapor deposition growth of graphene films enabled by ultrathin alloy catalysts
摘要： This report introduces a method for fabricating graphene at low temperatures via chemical vapor deposition enabled by ultrathin (～1 nm) nickel-gold (Ni-Au) catalysts. The unique combination of high carbon (C) solubility Ni, low C solubility Au, and an ultrathin layer of a catalyst demonstrates the effectiveness to produce graphene at 450 °C with the layer number independent of growth duration. In contrast to grain-boundary defined catalyst morphology found in thicker (>20 nm) metal catalysts, the ultrathin catalyst morphology leads to the formation of nanoscale metal “islands” during the growth process, which results in curved graphene covering the catalyst. To test the effect of preactivation of the ultrathin catalyst for the formation of graphene, a preanneal process of the catalyst followed by the introduction of a carbon precursor was also investigated. The preanneal process resulted in the formation of carbon nanotubes (CNTs) in lieu of graphene, displaying the impact of the catalytic surface treatment in relation to the produced materials. The results and discussion presented here detail a low-temperature nanoscale manufacturing process that allows for the production of either graphene or CNTs on an ultrathin catalyst.
关键词： graphene,low-temperature growth,nickel-gold catalysts,chemical vapor deposition,ultrathin alloy catalysts
更新于2025-09-19 17:13:59
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Plasmonic MoO2 as co-catalyst of MoS2 for enhanced photocatalytic hydrogen evolution
摘要： Generally, photocatalytic water splitting on MoS2 nanomaterials is restricted owing to the high carrier recombination and limited utilization of the visible light. This study describes the enhancement of the MoS2-catalysed hydrogen evolution by incorporating metallic MoO2 as a co-catalyst introduced by coupling with MoS2 nanosheets through a facile calcination strategy, forming a Schottky junction between MoO2 and MoS2. The localized surface plasmon resonance effect induced by the oxygen vacancies and favourable Fermi lever position of MoO2 lead to a broad spectral response and a significant improvement in the exciton generation and dissociation. The electron gets transferred from the conduction band (CB) of MoS2 to MoO2, wherein MoO2 acts as an ‘electron pool’ that gathers the photoexcited electrons, which are rapidly shuttled to the surface of MoO2, where the redox reaction occurs due to its great metallic conductivity. Resultantly, a 242% increment in the production of hydrogen gas by MoS2/MoO2 is achieved in comparison with that of the MoS2 nanosheets.
关键词： Photocatalytical hydrogen production,co-catalysts,MoS2/MoO2,LSPR effect,Schottky junction
更新于2025-09-19 17:13:59
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Boosting the photocatalytic ability of g-C3N4 for hydrogen production by Ti3C2 MXene quantum dots
摘要： The big challenging issues in photocatalytic H2 evolution are efficient separation of the photoinduced carriers, the stability of the catalyst, enhancing quantum efficiency and requiring photoinduced electrons enrich on photocatalysts’ surface. Herein, Ti3C2 MXene quantum dots (QDs) possess the activity of Pt as co-catalyst in promotion the photocatalytic H2 evolution to form heterostructure with g-C3N4 nanosheets (NSs) (denoted as g-C3N4@Ti3C2 QDs). The photocatalytic H2 evolution rate of g-C3N4@Ti3C2 QDs composite with an optimized Ti3C2 QDs loading amounts (100 mL) is nearly 26, 3 and 10 times higher than pristine g-C3N4 NSs, Pt/g-C3N4, Ti3C2 MXene sheet/g-C3N4, respectively. The Ti3C2 QDs increase the specific surface area of g-C3N4 and boost the density of active site. Besides, metallic Ti3C2 QDs possess excellent electronic conductivity, causing the improvement of carrier transfer efficiency.
关键词： Ti3C2 MXene quantum dots,Photocatalytic H2 production,g-C3N4 nanosheets,co-catalysts
更新于2025-09-19 17:13:59
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Ultrafast Laser Manufacture of Stable, Efficient Ultrafine Noble Metal Catalysts Mediated with MOF Derived High Density Defective Metal Oxides
摘要： Supported metal nanoparticles (MNPs) undergo severe aggregation, especially when the interaction between MNPs and their supports are limited and weak where their performance deteriorates dramatically. This becomes more severe when catalysts are operated under high temperature. Here, it is reported that MNPs including Pt, Au, Rh, and Ru, with sub-2 nm size can be stabilized on densely packed defective CeO2 nanoparticles with sub-5 nm size via strong coupling by direct laser conversion of corresponding metal ions encapsulated cerous metal–organic frameworks (Ce-MOFs). Ce-MOF serves as an ideal dispersion precursor to uniformly encapsulate noble metal ions in their orderly arranged pores. Ultrafast laser vaporization and cooling forms uniform, ultra-small, well-mixed, and exceptionally dense nanoparticles of metal and metal oxide concurrently. The laser-induced ultrafast reaction (within tens of nanoseconds) facilitates the precipitation of CeO2 nanoparticles with abundant surficial defects. Due to the well-mixed ultrasmall Pt and CeO2 components with strong coupling, this catalyst exhibits exceptionally high stability and activity both at low and high temperatures (170–1100 °C) for CO oxidation in long-term operation, significantly exceeding catalysts prepared by traditional methods. The scalable feature of laser and huge MOF family make it a versatile method for the production of MNP-based nanocomposites in wide applications.
关键词： noble metal catalysts,lasers,metal oxides,defects,metal–organic frameworks
更新于2025-09-19 17:13:59
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Janusa??Structured Coa??Ti <sub/>3</sub> C <sub/>2</sub> MXene Quantum Dots as a Schottky Catalyst for Higha??Performance Photoelectrochemical Water Oxidation
摘要： MXene materials have attracted increasing attention in electrochemical energy-storage applications while MXene also becomes photo-active at the quantum dot scale, making it an alternative for solar-energy-conversion devices. A Janus-structured cobalt-nanoparticle-coupled Ti3C2 MXene quantum dot (Co-MQD) Schottky catalyst with tunable cobalt-loading content serving as a photoelectrochemical water oxidation photoanode is demonstrated. The introduction of cobalt triggers concomitant surface-plasmon effects and acts as a water oxidation center, enabling visible-light harvesting capability and improving surface reaction kinetics. Most importantly, due to the rectifying effects of Co-MQD Schottky junctions, photogenerated carrier separation/injection efficiency can be fundamentally facilitated. Specifically, Co-MQD-48 exhibits both superior photoelectrocatalysis (2.99 mA cm?2 at 1.23 V vs RHE) and charge migration performance (87.56%), which corresponds to 194% and 236% improvement compared with MQD. Furthermore, excellent photostability can be achieved with less than 6.6% loss for 10 h cycling reaction. This fills in gaps in MXene material research in photoelectrocatalysis and allows for the extension of MXene into optical-related fields.
关键词： quantum dots,MXene,Schottky catalysts,Janus particles,water oxidation
更新于2025-09-16 10:30:52
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MoC/MnO composite materials as high efficient and stable counter electrode catalysts for dye-sensitized solar cells
摘要： MoC/MnO composite materials have been easily synthesized via a two-step hydrothermal and one-step carbonization method and used as counter electrode catalysts in DSSCs for the first time. The as-prepared samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). And their electrocatalytic properties were also thoroughly studied by electrochemical impedance spectroscopy (EIS), Tafel polarization and so on. It is found that the electrocatalytic properties of the MoC/MnO CEs can be greatly enhanced. After optimizing the molar ratio of MoO3 precursor and KMnO4, the as-obtained MoC/MnO-0.25 CE has superior electrocatalytic ability, low charge transfer resistance and high incident photon-to-current conversion efficiency (IPCE). And the power conversion efficiency of the DSSC based on the MoC/MnO-0.25 CE is up to 8.00%, better than that of the DSSC used standard Pt CE (7.36%) in the same test environment, meanwhile the MoC/MnO-0.25 CE also has good electrochemical stability in the iodine-based electrolyte, which shows a promising candidate to replace Pt for DSSCs.
关键词： MoC/MnO composite materials,carbonization method,hydrothermal method,counter electrode catalysts,dye-sensitized solar cells
更新于2025-09-12 10:27:22
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Single-Atomically Anchored Cobalt on Carbon Quantum Dots as Efficient Photocatalysts for Visible Light-promoted Oxidation Reactions
摘要： Generation of efficient light-induced charge separation inside the photocatalyst is an essential factor for a high catalytic efficiency. The usual immobilization of metal or metal oxide particles on semiconductor photocatalysts offers an uncontrolled assembly of active sites during the reaction. The introduction of single metal atoms on photocatalysts can lead to extremely high atomic utilization and precise active sites. However, this approach is limited due to the lack of suitable photosensitizers for single atom immobilization. Here, we have designed photocatalytic carbon quantum dots with anchoring sites for single cobalt atoms in a defined Co-N4 structure via facile pyrolysis of vitamin B12. Carbon dots functioned as both light-harvesting antenna and support for cobalt atom with high atom loadings up to 3.27 wt.%. This new photocatalytic material demonstrated enhanced visible light absorption, efficient charge separation, and reduced electrochemical impedance, while the single Co atoms acted as the active site with strong oxidative ability. As a result, the photocatalysts showed excellent visible light-promoted photocatalytic efficiency with oxygen evolution rates up to 168 μmol h-1 g-1 via water oxidation, imine formation with high conversion (~90%) and selectivity (>99%), and complete photodegradation of organic dyes.
关键词： single-atom catalysts,oxidation reactions,carbon quantum dots,photocatalysis,visible light
更新于2025-09-12 10:27:22