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Visualizing pore architecture and molecular transport boundaries in catalyst bodies with fluorescent nanoprobes
摘要： The performances of porous materials are closely related to the accessibility and interconnectivity of their porous domains. Visualizing pore architecture and its role on functionality—for example, mass transport—has been a challenge so far, and traditional bulk and often non-visual pore measurements have to suffice in most cases. Here, we present an integrated, facile fluorescence microscopy approach to visualize the pore accessibility and interconnectivity of industrial-grade catalyst bodies, and link it unequivocally with their catalytic performance. Fluorescent nanoprobes of various sizes were imaged and correlated with the molecular transport of fluorescent molecules formed during a separate catalytic reaction. A direct visual relationship between the pore architecture—which depends on the pore sizes and interconnectivity of the material selected—and molecular transport was established. This approach can be applied to other porous materials, and the insight gained may prove useful in the design of more efficient heterogeneous catalysts.
关键词： porous materials,molecular transport,fluorescence microscopy,catalyst bodies,heterogeneous catalysts
更新于2025-09-23 15:21:01
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Perspectives on the adsorption of CO2 on amine-modified silica studied by infrared spectroscopy
摘要： Amine-modified adsorbents are being researched for their potential to capture CO2 from various gas mixtures, and we review how IR spectroscopy has been used to study the associated CO2–amine chemistry. It has been used to reveal that CO2 chemisorbs as ammonium-carbamate ion pairs especially when the amine density is high. Carbamic acid and related other moieties tend to form in parallel to the ion pairs when the amine density is low. The amines have been shown to degrade on cyclic heat treatment. To further study the formation of bicarbonates on reactive adsorption of CO2 and H2O, degradation of the organics, and the use of other supports than silica are suggested.
关键词： porous materials,FT-IR spectroscopy,amine-modified silica,carbon capture,CO2 adsorption
更新于2025-09-23 15:21:01
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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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Rise and side infiltration in opals and porous materials for their skin-free replica synthesis
摘要： A floating opal placed on a certain liquid will cause the liquid to climb through the opal gaps, fill all its pores, and stop almost of its upper surface without covering it. A drop of solution with a surface tension much lower than that of water, deposited on a hydrophilic substrate near an opal, rapidly spread over a large surface forming a film which will surround the opal and infiltrate it from the side without covering it. High quality, skin-free, inverse opals can be synthesized by rise and side infiltration of solution in opals. The overlayer absence leads to the fabrication of mechanically robust, crack-free, completely filled photonic crystals which preserve the long rage order of initial opals. Inverse opals of sodium silicate were synthesized starting from polystyrene nanospheres self-assembled through hanging drop technique followed by their rise and side infiltration, casting, and template removal. Crystalline material inverse opals such as glycine, sodium chloride, and sulfur were also synthesized.
关键词： skin-free,photonic crystals,inverse opals,rise infiltration,porous materials
更新于2025-09-23 15:19:57
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[IEEE 2019 International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD) - Ottawa, ON, Canada (2019.7.8-2019.7.12)] 2019 International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD) - Simulation of Lateral Near- and Far-Field Profiles of Gain-Guided High-Power Semiconductor Lasers
摘要： The conversion of electrical to mechanical power on a sub-centimeter scale is a key technology in many microsystems and energy harvesting devices. In this paper, we present a type of a capacitive energy conversion device that uses capillary pressure and electrowetting to reversibly convert electrical power to hydraulic power. These microhydraulic actuators use a high surface-to-volume ratio to deliver high power at a relatively low voltage with an energy conversion efficiency of over 65%. The capillary pressure generated grows linearly with shrinking capillary diameter, as does the frequency of actuation. We present the pressure, frequency, and power scaling properties of these actuators and demonstrate that power density scales up as the inverse capillary diameter squared, leading to high-efficiency actuators with a strength density exceeding biological muscle. Two potential applications for microhydraulics are also demonstrated: soft-microrobotics and energy harvesting.
关键词： electrowetting,Microhydraulics,porous materials,energy conversion,electrocapillary,microsystems,soft robotics,energy harvesting,microrobotics,actuator,microfluidics,PDMS
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Bulk Power System Dynamics with Varying Levels of Synchronous Generators and Grid-Forming Power Inverters
摘要： The conversion of electrical to mechanical power on a sub-centimeter scale is a key technology in many microsystems and energy harvesting devices. In this paper, we present a type of a capacitive energy conversion device that uses capillary pressure and electrowetting to reversibly convert electrical power to hydraulic power. These microhydraulic actuators use a high surface-to-volume ratio to deliver high power at a relatively low voltage with an energy conversion efficiency of over 65%. The capillary pressure generated grows linearly with shrinking capillary diameter, as does the frequency of actuation. We present the pressure, frequency, and power scaling properties of these actuators and demonstrate that power density scales up as the inverse capillary diameter squared, leading to high-efficiency actuators with a strength density exceeding biological muscle. Two potential applications for microhydraulics are also demonstrated: soft-microrobotics and energy harvesting.
关键词： microsystems,electrocapillary,soft robotics,PDMS,actuator,energy conversion,microfluidics,electrowetting,energy harvesting,porous materials,Microhydraulics,microrobotics
更新于2025-09-16 10:30:52
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Manganese oxide nanofoam prepared by pulsed laser deposition for high performance supercapacitor electrodes
摘要： Manganese oxide nanofoam has been prepared by pulsed laser deposition, from a metallic Mn target in a 5 Torr pressure O2 buffer atmosphere. The as-prepared samples were heat-treated at different temperatures (300?C-500?C) in air. Both as-deposited and heat-treated samples have a high porosity foam-like morphology, as shown by Field Emission Scanning Electron Microscopy. High Resolution Transmission Electron Microscopy revealed that the nanofoam is composed by linked nanoparticles with slight crystallization and growth of the nanoparticles due to heat-treatment, which was confirmed by X-ray diffraction, Raman Spectroscopy and X-ray Photoelectron Spectroscopy. These techniques also showed a variable oxide composition upon heat treatment. The supercapacitive properties of manganese oxide nanofoam treated at 300?C exhibited a specific capacitance higher than 1000 F/g, in the 0 to +1.0 V potential range. After heat treatment at 400?C and 500?C, the specific capacitance decreased compared to that of the 300?C treated sample. An increase of about 130% in the initial capacitance was obtained after 500 cycles for this sample. However, it decreases to one third of the maximum value after 5000 cycles. The results shows that the obtained manganese oxide nanofoam has very high specific capacitance but need to improve the cycle stability.
关键词： microstructures,pulsed laser deposition,porous materials,supercapacitors,nanofoam,manganese oxides
更新于2025-09-11 14:15:04
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Designing surface-enhanced Raman scattering (SERS) platforms beyond hotspot engineering: emerging opportunities in analyte manipulations and hybrid materials
摘要： Surface-enhanced Raman scattering (SERS) is a molecule-specific spectroscopic technique with diverse applications in (bio)chemistry, clinical diagnosis and toxin sensing. While hotspot engineering has expedited SERS development, it is still challenging to detect molecules with no specific affinity to plasmonic surfaces. With the aim of improving detection performances, we venture beyond hotspot engineering in this tutorial review and focus on emerging material design strategies to capture and confine analytes near SERS-active surfaces as well as various promising hybrid SERS platforms. We outline five major approaches to enhance SERS performance: (1) enlarging Raman scattering cross-sections of non-resonant molecules via chemical coupling reactions; (2) targeted chemical capturing of analytes through surface-grafted agents to localize them on plasmonic surfaces; (3) physically confining liquid analytes on non-wetting SERS-active surfaces and (4) confining gaseous analytes using porous materials over SERS hotspots; (5) synergizing conventional metal-based SERS platforms with functional materials such as graphene, semiconducting materials, and piezoelectric polymers. These approaches can be integrated with engineered hotspots as a multifaceted strategy to further boost SERS sensitivities that are unachievable using hotspot engineering alone. Finally, we highlight current challenges in this research area and suggest new research directions towards efficient SERS designs critical for real-world applications.
关键词： non-wetting surfaces,porous materials,Surface-enhanced Raman scattering,SERS,plasmonic surfaces,chemical coupling,hotspot engineering,semiconductors,piezoelectric polymers,analyte manipulation,hybrid materials,graphene
更新于2025-09-04 15:30:14
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<i>In Situ</i> IR Spectroscopy of Mesoporous Silica Films for Monitoring Adsorption Processes and Trace Analysis
摘要： Adsorption of molecules on high-surface-area materials is a fundamental process critical to many fields of basic and applied chemical research; for instance, it is among the simplest and most efficient principles for separating and remediating polluted water. However, established experimental approaches for investigating this fundamental process preclude in situ monitoring and thus obtaining real-time information about the ongoing processes. In this work, mid-infrared attenuated total reflection (ATR) spectroscopy is introduced as a powerful technique for quantitative in situ monitoring of adsorption processes and thus enrichment of traces of organic pollutants from aqueous solution in ordered mesoporous silica films. The synthesis, functionalization, and characterization of two silica films with 3D hexagonal and cubic pore structure on silicon ATR crystals are presented. Benzonitrile and valeronitrile as model compounds for aromatic and aliphatic water pollutants are enriched in hydrophobic films, while the matrix, water, is excluded from the volume probed by the evanescent field. Enrichment times of <5 s are observed during in situ measurements of benzonitrile adsorbing onto the film from aqueous solution. The sensing system is calibrated using the Freundlich adsorption equation as a calibration function. Enrichment factors of benzonitrile and valeronitrile within the film were determined to be >200 and >100, respectively, yielding detection limits in the low ppm range. Furthermore, fast and complete desorption of the analyte, ensuring reliable regeneration of the sensor, was verified. Lastly, we derive and experimentally validate equations for ATR spectroscopy with thin film adsorption layers to quantify the absolute mass of adsorbed pollutant in the film. The excellent agreement between recorded absorptions at target wavenumbers of the target analytes and corresponding simulations corroborates the validity of the chosen approach.
关键词： infrared spectroscopy,functional coatings,sensor,porous materials,thin film
更新于2025-09-04 15:30:14
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Solution combustion synthesis of ZnO powders using various surfactants as fuel
摘要： Single phase ZnO powders were synthesized by solution combustion method using various surfactants as fuel. The effects of hydrocarbon tail length on the combustion behavior, phase evolution, morphology, optical properties, and photocatalytic activity were studied by thermal analysis, X-ray diffraction, electron microscopy, and photoluminescence spectroscopy techniques. The specific surface area and pore volume increased with the addition of citric acid as auxiliary fuel due to the increase of released gaseous products. ZnO powders obtained by mixed fuels show higher crystallinity and specific surface area, leading to the higher photodegradation of methylene blue under ultraviolet irradiation. Moreover, the photocatalytic activity increased in the presence of ZnO powders prepared by the longest hydrocarbon tail.
关键词： ZnO,Surfactant,Photocatalytic activity,Porous materials
更新于2025-09-04 15:30:14