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Synergetic adsorption and photo-Fenton degradation of methylene blue by ZnFe <sub/>2</sub> O <sub/>4</sub> /SiO <sub/>2</sub> magnetic double-mesoporous-shelled hollow spheres
摘要： Adsorption and Fenton technologies have been widely employed to deal with wastewater. ZnFe2O4/SiO2 magnetic double-mesoporous-shelled hollow spheres (MDSHSs) were feasibly synthesized by a solvothermal method. The as-synthesized MDSHSs show excellent adsorption and selectivity for methylene blue (MB), which it took about only 1 min to reach the adsorption equilibrium. About 50% MB was removed by adsorption, and other 50% MB was degraded under further photo-Fenton process. Effects of experimental conditions on the adsorption and photo-Fenton process were investigated. The mechanisms of MDSHSs formation and photo-Fenton process were proposed. Total organic carbon (TOC) reduction reached as high as 90% with 60 mg/L of MB for 90 min. The experimental results indicated that MDSHSs exhibit a remarkable adsorption and catalytic activity for photo-Fenton process in a wide pH range of 3.3–11.0. Simultaneously, the composite shows an excellent stability and reusability.
关键词： photo-Fenton,magnetic property,porous materials,ZnFe2O4/SiO2,adsorption
更新于2025-09-23 15:19:57
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Nanoscaled Fractal Superstructures via Laser Patterninga??A Versatile Route to Metallic Hierarchical Porous Materials
摘要： A laser-based procedure for the preparation of metallic hierarchical porous materials is introduced and exemplified on tin, copper, silicon, titanium, and tungsten surfaces to demonstrate its general applicability. The impact of suitably tuned nanosecond laser pulses triggers a process in which laser-induced metal ablation and instantaneous recondensation of partially oxidized metals lead to cauliflower-like superstructures comprising a hybrid micro-/nanopatterning. Repeated scanning with the intense focused beam over the surface creates microstructures of hierarchically tunable porosity in a layer-by-layer design. The 3D morphology of these superstructures is analyzed using tomographic data based on focused ion-beam scanning electron microscopy to return a fractal dimension of Df = 2.79—practically identical to a natural cauliflower (Df ≈ 2.8), even though the plant is four orders of magnitude larger than the superstructures generated through the laser process. The high Df value signifies a complex morphology that boasts a huge external surface. The introduced concept enables convenient access to a variety of metallic hierarchical porous materials, which are key to performance in environmentally and technologically relevant areas like energy generation, storage, and conversion, as well as sensing and catalysis.
关键词： fractal morphology,cauliflower-like superstructures,porous nanostructures,self-organizing microstructures,scalable patterning
更新于2025-09-23 15:19:57
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Metal Filled Nanostructured Silicon With Respect to Magnetic and Optical Properties
摘要： Within this work the utilization of nanostructured silicon as host material with various magnetic nanostructures is reviewed whereas the magnetic and optical properties of the gained composite systems are elucidated. The metal filling of the pores is mainly performed by electroless deposition or by electrodeposition which is discussed by means of some examples. Furthermore, two different types of porous silicon (PSi) morphology are used for the deposition procedure. On the one hand microporous silicon offering luminescence in the visible range is utilized as template material. It offers a branched morphology with a structure size between 2 and 5 nm. In this case not only the magnetic response is investigated but also the influence of the metal filling on the optical properties. On the other hand mesoporous and macroporous silicon in it’s low pore regime is employed which offers straight pores with diameters up to 90 nm. In this case the magnetic response strongly depends on the size, the geometry and the spatial distribution of the metal deposits within the pores. A crucial role plays also the morphology of the porous silicon, especially the distance between adjacent pores which is an important parameter regarding magnetic interactions.
关键词： magnetic nanostructures,porous silicon,magnetic properties,electrodeposition,luminescence
更新于2025-09-23 15:19:57
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Development of Pd/TiO2 Porous Layers by Pulsed Laser Deposition for Surface Acoustic Wave H2 Gas Sensor
摘要： The influence of sensitive porous films obtained by pulsed laser deposition (PLD) on the response of surface acoustic wave (SAW) sensors on hydrogen at room temperature (RT) was studied. Monolayer films of TiO2 and bilayer films of Pd/TiO2 were deposited on the quartz substrates of SAW sensors. By varying the oxygen and argon pressure in the PLD deposition chamber, different morphologies of the sensitive films were obtained, which were analyzed based on scanning electron microscopy (SEM) images. SAW sensors were realized with different porosity degrees, and these were tested at different hydrogen concentrations. It has been confirmed that the high porosity of the film and the bilayer structure leads to a higher frequency shift and allow the possibility to make tests at lower concentrations. Thus, the best sensor, Pd-1500/TiO2-600, with the deposition pressure of 600 mTorr for TiO2 and 1500 mTorr for Pd, had a frequency shift of 1.8 kHz at 2% hydrogen concentration, a sensitivity of 0.10 Hz/ppm and a limit of detection (LOD) of 1210 ppm. SAW sensors based on such porous films allow the detection of hydrogen but also of other gases at RT, and by PLD method such sensitive porous and nanostructured films can be easily developed.
关键词： bilayer films,pulsed laser deposition (PLD),palladium,hydrogen sensor,surface acoustic wave (SAW),Pd/TiO2,porous morphology,titanium dioxide
更新于2025-09-23 15:19:57
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Femtosecond laser-induced surface structuring of the porous transport layers in proton exchange membrane water electrolysis
摘要： In proton exchange membrane water electrolysis (PEMWE) cells the performance and thus the conversion efficiency are influenced by the interface between the porous transport layer (PTL) and the catalyst layer (CL). In the following paper, this interface is modified by the use of femtosecond laser-induced surface structuring, so that the specific surface area of the titanium based fibers of the PTL is increased. The resulting morphology exhibits two roughness levels of (i) a relatively coarse structure featuring tips of a few micrometers in diameter and depth, which are each covered in turn by (ii) a substructure of smaller tips of a few to several hundred nanometers in diameter and depth. PEMWE electrochemical characterization and short-term stress tests reveal that the cell performance is increased due to the laser-structuring of the PTL surface towards the CL. For instance, the cell voltage is reduced by approximately 30 mV after 100 h at 4 A cm?2. These beneficial effects are observed over the entire current density range and thus correspond to a decreased equivalent cell resistance of at least 6 mΩ cm2 for electrical interfacial contact losses and at least 2 mΩ cm2 for mass transport losses. A physical characterization by scanning electron microscopy shows that the CL surface is much rougher and more jagged when using laser-structured fibers. Thus, the gaseous oxygen and the liquid water transport both from and to the active sites of the catalyst seem to be improved.
关键词： catalyst layer,cell performance,proton exchange membrane water electrolysis,porous transport layers,femtosecond laser-induced surface structuring
更新于2025-09-23 15:19:57
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Generation of graded porous structures by control of process parameters in the selective laser melting of a fixed ratio salt-metal feedstock
摘要： The demonstration of salt dissolution incorporated within laser powder-bed fusion fabrication processes has allowed the creation of complex porous structures without the need for sophisticated design algorithms. This serves to simplify the process, for porous structure creation in powder-bed fabrication techniques, creating a new opportunity for the realisation of optimised structures. A new methodology is presented here in which modulation of the energy density while using a single feedstock material enables three-dimensional control of porosity, ranging from 20 % to 49 %. Through structured experimentation, the response of the material to varying the process parameters in selective laser melting is evaluated and nested structures of distinct densities and morphologies are created. Correlation of the process parameters with modulus and ultimate compressive stress are established. A simple-assembly algorithm was used to generate complex parts consisting of locally assigned porosities having characteristic properties.
关键词： Selective laser melting,Graded materials,Mechanical performance,Controlled-porosity,Additive manufacturing,Cellular structures,Porous
更新于2025-09-23 15:19:57
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Heat transfer model of a 50 kW solar receiver-reactor for thermochemical redox cycling using cerium dioxide
摘要： This work reports on the development of a transient heat transfer model of a solar receiver-reactor designed for thermochemical redox cycling by temperature and pressure swing of pure cerium dioxide in the form of a reticulated porous ceramic (RPC). In the first, endothermal, step the cerium dioxide RPC is directly heated with concentrated solar radiation to 1500 °C while under vacuum pressure of less than 10 mbar, thereby releasing oxygen from its crystal lattice. In the subsequent, exothermic, step the reactor is re-pressurized with carbon dioxide as it cools, and at temperatures below 1000 °C the partially reduced cerium dioxide is re-oxidized with a flow of carbon dioxide. To analyze the performance of the solar reactor and to gain insight into improved design and operational conditions, a transient heat transfer model of the solar reactor for a solar radiative input power of 50 kW during the reduction step was developed and implemented in ANSYS CFX. The numerical model couples the incoming concentrated solar radiation using Monte-Carlo ray tracing, incorporates the reduction chemistry by assuming thermodynamic equilibrium, and accounts for internal radiation heat transfer inside the porous ceria by applying effective heat transfer properties. The model was experimentally validated using data acquired in a high-flux solar simulator, where temperature evolution and oxygen production results from model and experiment agreed well. The numerical results indicate the prominent influence of solar radiative input power, where increasing it substantially reduces reduction time of the cerium dioxide structure. Consequently, the model predicts a solar-to-fuel energy conversion efficiency of > 6% at a solar radiative power input of 50 kW; efficiency > 10% can be obtained provided the RPC macro porosity is substantially increased and better volumetric absorption and uniform heating is achieved. Managing the ceria surface temperature during reduction to avoid sublimation is a critical design consideration for direct absorption solar receiver-reactors.
关键词： design optimization,reactor modelling,ceria,thermochemical cycles,solar energy,reticulated porous ceramic
更新于2025-09-23 15:19:57
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Controllable nitrogen doping and specific surface from freestanding TiO2@carbon nanofibers as anodes for lithium ion battery
摘要： Further modification of carbon and transition metal composites has become a hot spot in the preparation of anode materials for lithium ion battery, including various morphologies, nitrogen doping and porous introduction. However, the synergistic effect of specific surface area and nitrogen doping content of composite materials on the electrochemical performance as anode materials for lithium ion batteries has not been revealed. In this paper, the carbon nanofibers loaded with titanium dioxide are fabricated via electrospinning method followed by calcination process with simple addition admixture of diisopropyl azodiformate in precursor solution. The pores are introduced into the composite with controllable nitrogen doping and surface area simultaneously. The specific capacity of titanium dioxide @carbon nanofibers has been increased from 192.2 mAh g?1 to 336 mAh g?1 due to the increased nitrogen content of the composite from 7.18% to 10.21%, and elevated specific surface area from 67.23 to 111.15 m2 g?1, which can endow the composite superior conductivity and more active sites. The capacity contribution of the total specific capacity has decreased from 60.8% to 44.7% compared with original sample, proving that increasing diffusion controlled Faradaic Li-ion insertion origins from nitrogen doping.
关键词： Lithium battery,Porous carbon nanofibers,Nitrogen doping,Anode
更新于2025-09-23 15:19:57
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A novel design of poly (3,4-ethylenedioxythiophene):poly (styrenesulfonate)/molybdenum disulfide/poly (3,4-ethylenedioxythiophene) nanocomposites for fabric micro-supercapacitors with favourable performances
摘要： Fabric supercapacitors with mechanical flexible and excellent energy storage capacity attract considerable attention for the potential application in wearable smart electronics. A novel ternary composite electrode and assembled all-solid-state fabric supercapacitors are expected to achieve favorable electrochemical performances. The facile vapor phase polymerization method is employed to fabricate the ternary poly (3,4-ethylenedioxythiophene):poly (styrenesulfonate)/molybdenum disulfide/poly (3,4-ethylenedioxythiophene) composite electrodes. The molybdenum disulfide nanograins are incorporated into the conducting polymer matrix which further facilitates the formation of hierarchical porous structures. On account of profitable synergistic effect among three-component materials and porous structure with reinforced electronic/ionic transport, the as-prepared hybrid electrode exhibits a high areal capacitance of 51.01 mF/cm2 at current density of 0.1 mA/cm2, as well as long cycling durability with 93.6% capacitance retention after 5000 cycles of galvanostatic charge/discharge tests. Furthermore, symmetric fabric micro-supercapacitor assembled by the as-prepared electrodes is also evaluated in a belt-shaped device. This assembled device exhibits an energy density of 0.2 μWh/cm2 (1.81 mWh/cm3) and the power density of 0.09 mW/cm2 (0.82 W/cm3). These results of excellent flexibility and favourable capacitive performance indicate a promising application in portable and wearable electronic devices.
关键词： synergistic effect,ternary nanocomposites,porous structure,flexible micro-supercapacitors
更新于2025-09-23 15:19:57
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Fluorine-phenanthroimidazole Porous Organic Polymer: Efficient Microwave Synthesis and Photocatalytic Activity
摘要： A porous polymer containing a fluorophenylphenanthroimidazole core was easily prepared via one-pot Suzuki-Miyaura cross coupling reactions under microwave heating. These new metal-free polymers have demonstrated heterogeneous photocatalytic activity toward aza-Henry reaction with reasonable recyclability. Their preparation require a minimal workup to build porous networks with control over the apparent surface area and pore volume from suitable molecular building blocks containing the 2-(1H-phenanthro[9,10-d]imidazol-2-yl)-3,5-difluorophenol (PhIm-2F), as rigid and multitopic node which afforded a conjugated porous polymer (CPP-PhIm-2F). A series of fluorinated ligands have shown their capability to preparation of soluble and supported cationic Ru(bpy)2(F-phenanthroimidazole)-complexes by reaction with Ru(bpy)2Cl2 and demonstrated a beneficial effect of two fluorine atom on the photocatalytic effect.
关键词： Conjugated polymer,Ruthenium photocatalyst,Photocatalysis,Aza-Henry,Heterogenized catalyst,Porous organic polymer,Phenanthroimidazole
更新于2025-09-23 15:19:57