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Hierarchically assembled porous TiO2 nanoparticles with enhanced photocatalytic activity towards Rhodamine-B degradation
摘要： Despite tremendous advances in the development of photocatalysts for waste water treatment, the harmful chemicals used in the synthesis reaching the water bodies add up new environmental issues. In this work, hierarchically assembled porous TiO2 nanoparticles (TiO2 NPs) were prepared by an acid-free eco-friendly hydrothermal approach via condensation of alkoxide precursor (titanium (IV) tert-butoxide). Fine tuning of textural properties was facilitated by change in the hydrothermal treatment time. The structure, morphology and the physicochemical properties of the synthesized samples were characterized by XRD, TGA, N2 adsorption-desorption, FE-SEM, and FE-TEM analysis. N2 adsorption-desorption displays a unique double-slit model isotherms for all the samples. The BJH mesopore distribution curves exhibit intense peak at 6.9 nm and slightly broad peak at 46.1 nm in all the samples with further broad peaks in the range of 80-95 nm. The results showed that the photocatalytic activity is highly depend on the textural properties especially pore diameter. The activity and pore diameter were found to follow the trend: TiO2-12h > TiO2-48h > TiO2-24h > TiO2-6h whereas the surface area and crystallite size follows the trend: TiO2-48h > TiO2-12h > TiO2-24h > TiO2-6h. Overall, a simple strategy is presented and could be extended to produce various metal oxides for photocatalytic degradation of various other pollutants and microorganisms.
关键词： Synergistic effect,Rhodamine B degradation,Hierarchical pore structure,TiO2 nanoparticles
更新于2025-09-12 10:27:22
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Facile green and one-pot synthesis of purple perilla derived carbon quantum dot as a fluorescent sensor for silver ion
摘要： Coalbed methane (CBM) reservoir pore structure is extremely complex and heterogeneous. With the fractal theory, the geometric and structural characteristics of the pore structure could be quanti?ed. However, few studies have aimed to understand the fractal features of compositional-based macrolithotypes (bright, semi-bright, semi-dull, and dull coals). In this work, samples from the Hancheng area, in the southeastern Ordos Basin, China, were collected to investigate the fractal features of pore structures for macrolithotypes and calculate fractal dimensions (Da1 and Da2 for adsorption pores; Ds1 and Ds2 for seepage pores) based on low temperature N2 adsorption and mercury intrusion data, respectively. Meanwhile, the impact of the fractal dimensions on the gas adsorption capacity and the seepage ability were discussed. The results demonstrate that when bright coal turns into dull coal, the vitrinite content, helium permeability, and gas adsorption capacity gradually decrease, while the coal density, mineral content, and ash yield increase. Since the Da1 and Ds1 either deviate from the natural fractal dimension (2 < D < 3) or have a poor correlation with macrolithotypes, Da2 and Ds2 are regarded as the adsorption and seepage pore fractal dimensions, respectively. Of all the coal macrolithotypes, bright coal has the smallest BET speci?c surface area and micropore proportion, which results in the smallest fractal dimension Da2, while for the dull coal, this is just the contrary; due to the higher mineral content, a higher Da2 of the dull coal indicates a more complicated adsorption pore structure, and the coal with a larger Langmuir volume has a smaller Da2. For the seepage pores, when the bright coal turns into dull coal, the macropore proportion gradually decreases, but the pore proportion tends toward equilibrium, and the mercury withdrawal e?ciency increases; the dull coal has a larger Ds2, indicating a more complex seepage pore structure than that in the bright coal. Due to the decreasing macropore proportion and mineral ?lling, Ds2 demonstrates an obvious negative correlation with the helium permeability and macropore proportion.
关键词： Adsorption pore,Pore structure,Seepage pore,Fractal dimension,Coal macrolithotype
更新于2025-09-11 14:15:04
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Characterization and analysis on micro-hardness and microstructure evolution of brass subjected to laser shock peening
摘要： In view of the temperature distribution of the high-temperature geothermal tunnels, the surrounding rock temperature was divided into four grades (40 (cid:1)C, 60 (cid:1)C, 80 (cid:1)C and 100 (cid:1)C) to simulate the hot-dry environment. Using the standard curing environment as a reference condition, the mechanical properties and pore structure characteristics of concrete for shotcrete use under hot-dry environments at different temperatures were studied by mechanical and mercury intrusion porosimetry (MIP) tests. Fractal dimension of pore structure was calculated through the fractal model based on thermodynamic method. Bivariate correlation analysis was conducted on the curing temperature and the pore structure parameters. The results show that the 40 (cid:1)C hot-dry environment is conducive to enhance the mechanical properties of concrete and optimize its pore structure at the age of 1d. However, the hot-dry environments after 7 days will deteriorate the mechanical properties and pore structure of concrete, and the higher the temperature, the more obvious the deterioration. There is a significant correlation between curing temperature and porosity of capillary pores, median pore diameter, average pore diameter and fractal dimension.
关键词： Pore structure,Surrounding rock temperature,Mechanical property,Fractal dimension,Concrete for shotcrete use,High-temperature geothermal tunnel,Hot-dry environment
更新于2025-09-11 14:15:04
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Dopant-Free Squaraine-Based Polymeric Hole-Transporting Materials with Comprehensive Passivation Effects for Efficient All-Inorganic Perovskite Solar Cells
摘要： Quantum-dot (QD) white light-emitting diodes (LEDs) are promising for illumination and display applications due to their excellent color quality. Although they have a high quantum yield close to unity, the reabsorption of QD light leads to high conversion loss, significantly reducing the luminous efficacy and stability of QD white LEDs. In this report, SBA-15 mesoporous particles (MPs) with two-dimensional hexagonal pore structures (2D-HPS) are utilized to largely enhance the luminous efficacy and color-conversion efficiency of QD white LEDs in excess of 50%. The reduction in conversion loss also helps QD white LEDs to achieve a lifetime 1.9 times longer than that of LEDs using QD-only composites at harsh aging conditions. Simulation and testing results suggest that the waveguide effect of 2D-HPS helps in reducing the reabsorption loss by constraining the QD light inside the wall of 2D-HPS, decreasing the probability of being captured by QDs inside the hole of 2D-HPS. As such, materials and mechanisms like SBA-15 MPs with 2D-HPS could provide a new path to improve the photon management of QD light, comprehensively enhancing the performances of QD white LEDs.
关键词： stability,two-dimensional hexagonal pore structure,reabsorption,luminous efficacy,SBA-15 mesoporous particle,quantum-dot white light-emitting diode
更新于2025-09-11 14:15:04
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Theoretical analysis of experimental densification kinetics in final sintering stage of nano-sized zirconia
摘要： The experimental densi?cation kinetics of 7.8 mol% Y2O3-stabilized zirconia was analyzed theoretically during isothermal sintering in the ?nal stage. By taking concurrent grain growth into account, a possible value of the grain-size exponent n was examined. The Coble’s corner-pore model recognized widely was found not to be applicable for explaining the densi?cation kinetics. The corner-pore model of n = 4 shows a signi?cant divergence in the kinetics at di?erent temperatures. Microstructural observation shows that most pores are not located at grain corners and have a size comparable to the surrounding grains. The observed pore structure is similar to the di?usive model where single pore is surrounded by dense body. The di?usive model combined with theoretical sintering stress predicts n = 1 or n = 2, which shows a good consistence to the measured densi?cation kinetics. During sintering of nano-sized powder, it is found that the densi?cation kinetics can be explained distinctively by the di?usive single-pore model.
关键词： Pore structure,Sintering,Grain-growth,Kinetics,Densi?cation
更新于2025-09-04 15:30:14