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- 2019
- Dye-sensitized solar cell
- Hierarchical structure
- Light scattering
- TiO2 photoanode
- Nanomaterials and Technology
- National Sun Yat-sen University
- Wenzao Ursuline University of Languages
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Monolithic silicon carbide with interconnected and hierarchical pores fabricated by reaction‐induced phase separation
摘要： Hierarchically porous silicon carbide (SiC) monoliths were fabricated based on polycarbosilane (PCS), divinyl benzene (DVB), and decalin, by a sequence of procedures including catalyst-free hydrosilylation reaction-induced phase separation, ambient-pressure drying, calcination, and HF etching. The influences of ratios of each component on the phase separation were systematically studied. It was found that isotactic polypropylene added as a nonreactive additive could effectively tailor the microstructure and improve the mechanical properties of SiC monoliths. The resultant SiC monoliths mainly consisted of β-SiC nanocrystals, and possessed low bulk density (0.7 g/cm3), high porosity (78%), large specific area (100.6 m2/g), high compressive strength (13.5 ± 1.6 MPa), and hierarchical pores (macropores around 350 nm, mesopores around 4 nm and 20 nm). These properties make SiC monoliths promising materials for catalyst/catalyst support, gas separator, and the reinforcement of high-temperature composites.
关键词： nanocrystal,reaction induced phase separation,hierarchical pore,ambient pressure drying,SiC monolith
更新于2025-09-09 09:28:46
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Photoluminescence and Growth Mechanism of Oriented Hierarchical Fibrous-Like ZnO Nanowires
摘要： Oriented hierarchical fibrous-like ZnO nanowires with the diameter of about 30–50 nm and the length of about 15–30 um were successfully synthesized on the seed-coated Zn substrates by a simple two-step process. The morphology and structure of the obtained samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). It is shown that fibrous-like ZnO nanowires with the aspect ratio of about 500～1000 present the dense reticular structure, which are grown on ZnO nanowire arrays. But beyond that, as-prepared samples are found to be good single crystalline with hexagonal wurtzite structure and preferential grow along the c-axis. A possible growth mechanism of oriented hierarchical fibrous-like ZnO nanowires is presented in detail, revealing that the synthesis of fibrous-like ZnO nanowires should be attributed to differences in the growth rate of the different crystallographic planes and the two growth ways. The photoluminescence (PL) spectra of oriented hierarchical fibrous-like ZnO nanowires grown at 240 min shows the 5 nm blue-shift and enhanced intensity property in the UV emission.
关键词： Hydrothermal Method,Fibrous-Like ZnO Nanowires,Formation Mechanism,Oriented Hierarchical,PL Property
更新于2025-09-04 15:30:14
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A Hierarchical Multi-Classifier System for Automated Analysis of Delayered IC Images
摘要： A robust and accurate machine learning based hierarchical multi-classifier system is proposed to automate the retrieval of interconnection information from delayered Integrated Circuits (IC) images. The proposed system replaces labor-intensive manual annotation process and provides an effective approach for automated analysis of state-of-the-art deep sub-micron IC chips.
关键词： machine learning,delayered IC images,hierarchical multi-classifier system,automated analysis
更新于2025-09-04 15:30:14
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A Hierarchical Image Matting Model for Blood Vessel Segmentation in Fundus Images
摘要： In this paper, a hierarchical image matting model is proposed to extract blood vessels from fundus images. More specifically, a hierarchical strategy is integrated into the image matting model for blood vessel segmentation. Normally the matting models require a user specified trimap, which separates the input image into three regions: the foreground, background and unknown regions. However, creating a user specified trimap is laborious for vessel segmentation tasks. In this paper, we propose a method that first generates trimap automatically by utilizing region features of blood vessels, then applies a hierarchical image matting model to extract the vessel pixels from the unknown regions. The proposed method has low calculation time and outperforms many other state-of-art supervised and unsupervised methods. It achieves a vessel segmentation accuracy of 96.0%, 95.7% and 95.1% in an average time of 10.72s, 15.74s and 50.71s on images from three publicly available fundus image datasets DRIVE, STARE, and CHASE DB1, respectively.
关键词： hierarchical strategy,segmentation,fundus,trimap,vessel,region features,Image matting
更新于2025-09-04 15:30:14
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Facile synthesis of Ag/ZnO metal–semiconductor hierarchical photocatalyst nanostructures <i>via</i> the galvanic-potential-enhanced hydrothermal method
摘要： Hierarchical metal–semiconductor nanostructures (NSs) composed of a backbone made of Ag nanowire and ZnO nanorod (NR) branches were successfully prepared using the galvanic-potential-enhanced hydrothermal method. A galvanic cell structure was formed between an Al bottle anode that was used as a hydrothermal reactor and an Ag NW cathode dispersed in a hydrothermal solution. As a result, the contact-potential-driven hydrothermal growth of the ZnO NRs on the sidewalls of the Ag NWs could be achieved. The morphological and microstructure characterization confirmed the formation of well-arranged hierarchical NSs composed of Ag NW trunk and ZnO NR branch structures. The photocatalytic properties of the hierarchical Ag/ZnO NSs were investigated by degrading methylene blue (MB) dye as a model pollutant. It was found that the hierarchical Ag/ZnO NSs demonstrated a more than two-fold faster degradation rate than the pristine ZnO NSs. The high-performance photocatalytic activity of the Ag/ZnO hierarchical NSs was attributed to the synergetic effect of the metallic Ag NWs and the ZnO NRs that enhanced the charge separation and diffusion by suppressing charge recombination, as well as enhanced reaction sites and light absorption.
关键词： methylene blue degradation,Ag/ZnO,photocatalytic activity,hierarchical nanostructures,galvanic-potential-enhanced hydrothermal method
更新于2025-09-04 15:30:14
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Tetrathiafulvalene Scaffolds Based Sensitizer on Hierarchical Porous TiO <sub/>2</sub> : Efficient Light Harvesting Material for Hydrogen Production
摘要： In this work, a photochemical device that contains thioalkyl substituted tetrathiafulvalene dyes and hierarchical porous TiO2, has been designed and successfully employed in visible light-driven hydrogen production. The design strategy boost up the desirable photophysical properties of the catalysts and well supported from the optical, electrochemical and computational studies. The introduction of thioalkyl substituted tetrathiafulvalene dyes as light harvesting sensitizers onto the porous TiO2 triggers unprecedented high rate of hydrogen evolution. This study focuses on the role of thiafulvalene scaffold which can promote ultrafast interfacial electron injection from excited state dye into the hierarchical porous TiO2 conduction band. The purposeful construction of this integrated composite G3T3 (dye content 1.0 μmol in 10 mg Pt-TiO2 composite) significantly increases the hydrogen production rate of 24560 μmol.h-1g-1 cat with high apparent quantum yield (AQY) ~ 41%. In the study, both sensitizers absorption onset extends up to 500 nm in solution and 600 nm on hierarchical porous TiO2. Density functional theory (DFT) in the present study described that the HOMO levels are delocalized on anthracene as well as tetrathiafulvalene donor units, and LUMO covers on to the carboxylate anchoring group in both dyes. This study unveiled first time that a tetrathiafulvalene scaffolds in porous TiO2 attributes to positive synergistic effects in hydrogen production.
关键词： Tetrathiafulvalene,Hydrogen Production,Photocatalysis,Hierarchical Porous TiO2,Visible Light
更新于2025-09-04 15:30:14
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Highly Stable Luminous “Snakes” from CsPbX3 Perovskite Nanocrystals Anchored on Amine-Coated Silica Nanowires
摘要： CsPbX3 (X=Cl, Br and I) perovskite nanocrystals (NCs) are known for their exceptional optoelectronic properties, yet the material’s instability towards polar solvents, heat or UV irradiation greatly limits its further applications. Herein, an efficient in-situ growing strategy has been developed to give highly stable perovskite NC composites (abbr. CsPbX3@CA-SiO2) by anchoring CsPbX3 NCs onto silica nanowires (NWs), which effectively depresses the optical degradation of their photoluminescence (PL) and enhances stability. The preparation of surface-functionalized serpentine silica NWs is realized by a sol-gel process involving hydrolysis of a mixture of tetraethylorthosilicate (TEOS), 3-aminopropyltriethoxysilane (APTES) and trimethoxy(octadecyl)silane (TMODS) in a water/oil emulsion. The serpentine NWs are formed via an anisotropic growth with lengths up to 8 μm. The free amino groups are employed as surface ligands for growing perovskite NCs, yielding distributed monodisperse NCs (~8 nm) around the NW matrix. The emission wavelength is tunable by simple variation of the halide compositions (CsPbX3, X=Cl, Br or I) and the composites demonstrate a high photoluminescence quantum yield (PLQY 32-69%). Additionally, we have demonstrated the composites CsPbX3@CA-SiO2 can be self-woven to form a porous 3D hierarchical NWs membrane, giving rise to a superhydrophobic surface with hierarchical micro/nano structural features. The resulting composites exhibit high stability towards water, heat and UV irradiation. This work elucidates an effective strategy to incorporate perovskite nanocrystals onto functional matrices as multifunctional stable light sources.
关键词： colloidal CsPbX3 nanocrystal,superhydrophobic,photostability,assembled hierarchical membrane,serpentine silica nanowires
更新于2025-09-04 15:30:14
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Biomimetic Hierarchical TiO <sub/>2</sub> @CuO Nanowire Arrays-Coated Copper Meshes with Superwetting and Self-Cleaning Properties for Efficient Oil/Water Separation
摘要： Creating a practical and energy-efficient method with high efficiency to separate oil–water mixtures and emulsions is essential for sustainable aquatic ecosystem and waste oil recycling. Herein, we reported a completely inorganic hierarchical TiO2@CuO nanowire array-coated copper mesh membrane fabricated using chemical oxidation and hydrothermal recrystallization. The biomimetic hierarchical nano-/micro-structure can form a lotus-leaf-like interface with fine surface roughness and hydration ability, thus endows the membrane superhydrophilic and underwater superoleophobic nature. Thus, the as-synthesized TiO2@CuO nanowire array-coated copper mesh membrane demonstrated promising water flux of 87.6 kL·h-1·m-2 and ultrahigh separation efficiency with oil residue of only 12.4 mg·L-1 in the permeate. Moreover, the uniformly immobilized TiO2 nanoparticles exhibit UV-irradiated photocatalytic ability, which can be effectively regenerate the contaminated membrane after exposure to UV irradiations for 60 min. Therefore, this high efficiency, reusable, and easy-scalable membrane fabrication strategy may possess practical potential for next-generation oil/water separation application.
关键词： Biomimetic morphology,self-cleaning,nano-/micro- hierarchical structure,oil/water separation
更新于2025-09-04 15:30:14
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Carbonized Bamboos as Excellent 3D Solar Vapor‐Generation Devices
摘要： Given the global challenges of water scarcity, solar-driven vapor generation has become a renewed topic as an energy-efficient way for clean water production. Here, it is revealed that bamboo, as a natural hierarchical cellular material, can be an excellent 3D solar vapor-generation device by a simple carbonization progress. A floating carbonized bamboo sample evaporates water with an extremely high vapor-generation rate of 3.13 kg m?2 h?1 under 1 sun illumination. The high evaporation rate is achieved by the unique natural structure of bamboos. The inner wall of bamboo recovers the diffuse light energy and the thermal radiation heat loss from the 3D bamboo bottom, and the outer wall captures energy from the warmer environment. The high evaporation rate is also attributed to reduced vaporization enthalpy of water confined in the bamboo mesh. Such bamboo-based high-performance, low-cost, self-cleaning, solid durable, and scalable 3D vapor-generation device has attractive applications in desalination as well as industrial and domestic wastewater abatement.
关键词： solar vapor generation,latent heat,hierarchical nanostructures,thermal management,bamboos
更新于2025-09-04 15:30:14