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Highly Efficient Cu Induced Photocatalysis for Visible-light Hydrogen Evolution
摘要： Coinage metal (Au, Ag, Cu) induced photocatalysis has emerged as a promising strategy in developing visible-light responsive photocatalysts. Though much progress has been made, yet researchers in this field faced great challenges from both low efficiency and rigorously relying on noble metal Au. In this work, a series of Cu/SrTiO3 with gradually increased Cu particle size from 2.8 to 7.7 nm were successfully prepared with in situ multistep photodeposition method. A highly efficient visible-light photocatalytic H2 evolution is achieved over 0.5 wt% Cu/SiTiO3 with an average Cu particle size of 3.9 nm, which reaches 5 fold as compared with its counterpart Au. As far as we know, it is the first time that Cu induced visible-light photocatalytic water splitting show prominently superior activity than that of Au under the same conditions. Further study reveals that the increase of Cu particle size effectively mitigates Fano interference between interband transition and localized surface plasmon resonance (LSPR), which extends the photo-induced carriers lifetime. The discovery here is supposed to ignite great research interests in exploring efficient and nonprecious Cu induced visible-light photocatalysis.
关键词： Particle size effect,Cu nanoparticles,Visible-light photocatalysis,Fano interference
更新于2025-09-10 09:29:36
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Effects of size on the phase stability and conductivity of double-doped δ-Bi2O3
摘要： Nano and micro (Bi2O3)1-x-y(Eu2O3)x(Er2O3)y (x = 0.1, 0.15, y = 0.05, 0.2) double-doped system materials are synthesized by exploiting solid-state synthesis techniques. When we use nano sized powders to synthesize the samples we call them nano; when we use micro sized powders, we call them micro. The thermal, structural, morphological and electrical properties of nano and micro structured electrolyte samples for solid oxide fuel cells (SOFCs) are characterized. As a result of XRD measurements, the face centered δ-Bi2O3 (cubic) phase is obtained for all nano samples. However, the mixed phase is obtained for some micro samples. The electrical measurements show that conductivity decreases when the amount of Er2O3 is increased. The principal conclusion of the study is that the size effect provides relatively good structural stability in intermediate temperature SOFCs (IT-SOFCs); also, the nano-Bi2O3 system has the lowest activation energy and demonstrates high electrical conductivity.
关键词： Solid electrolyte,IT-SOFC,Size effect,δ-Bi2O3,Nano-Bi2O3
更新于2025-09-10 09:29:36
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Study of Size Effect on Microstructure and Mechanical Properties of AlSi10Mg Samples Made by Selective Laser Melting
摘要： The macroscopic mechanical performance of additive manufactured structures is essential for the design and application of multiscale microlattice structure. Performance is affected by microstructure and geometrical imperfection, which are strongly influenced by the size of the struts in selective laser melting (SLM) lattice structures. In this paper, the effect of size on microstructure, geometrical imperfection, and mechanical properties was systemically studied by conducting experimental tests. A series of AlSi10Mg rod-shaped samples with various diameters were fabricated using SLM. The uniaxial tensile test results show that with the decrease in build diameter, strength and Young’s modulus of strut decreased by 30% more than the stable state. The main reasons for this degradation were investigated through microscopic observation and micro X-ray computed tomography (μ-CT). In contrast with large-sized strut, the inherent porosity (1.87%) and section geometrical deviation (3%) of ponysize strut is greater because of the effect of thermal transform and hydrogen evolution, and the grain size is 0.5 μm. The discrepancy in microstructure, geometrical imperfection, and mechanical properties induced by size effect should be considered for the design and evaluation of SLM-fabricated complex structures.
关键词： selective laser melting,size effect,microstructure,X-ray computed tomography,mechanical properties
更新于2025-09-09 09:28:46
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Transport Critical Current Density of Bi1.6Pb0.4Sr2Ca2Cu3O10)/Ag Superconductor Tapes with Addition of 50 and 70 nm MgO
摘要： added size 50 average particle and 70 nm were MgO nanoparticles with into Bi1.6Pb0.4Sr2Ca2Cu3O10(MgO)x/Ag superconductor tapes and sintered at 845 oC for 50 and 100 h. The effect of sintering time on the transport critical current density (Jc) was investigated. Jc of the tapes were measured in zero-field between 30 and 77 K and under magnetic fields at 77 K. The phase and microstructure of the tapes were examined by X-ray diffraction method and scanning electron microscopy, respectively. All tapes showed plate-like grains and a larger plate-like grain was observed in the tapes sintered for 100 h. Jc of the MgO added tapes was higher than those of the non-added tapes. Jc of the non-added tape sintered for 100 h was 10820 A/cm2 at 30 K and 1262 A/cm2 at 77 K. Jc of the tapes sintered for 100 h was higher than the tapes sintered for 50 h. The 50 nm MgO added tapes showed a higher Jc than the 70 nm MgO added tapes. Jc for the 100 h sintered MgO (50 nm) added tape was 22710 and 3070 A/cm2 at 30 and 77 K, respectively which are higher than that of the 100 h sintered MgO (70 nm) added tape. The improved Jc was attributed to the increase in flux pinning potential and improvement in the microstructure due to the addition of nano-sized MgO. This work showed the importance of the size of the added nanoparticles to the transport current properties of these superconductors.
关键词： flux pinning,transport critical current density,nano MgO,size effect
更新于2025-09-04 15:30:14
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Combined mechanochemical/thermal annealing approach for the synthesis of Co9Se8 with potential optical properties
摘要： Synthesis of Co9Se8 phase from metallic cobalt and selenium powders by one-pot mechanochemical synthesis in a planetary ball mill and subsequent thermal treatment in argon atmosphere is reported. Crystal structure and morphology of the products were characterized by X-ray diffraction, specific surface area measurements, and transmission electron microscopy. Our study revealed that only mixture with excess of Co resulted in the formation of higher fraction of the Co9Se8 phase. While milling of Co and Se in 13.5:8 ratio resulted in the synthesis of nanocrystalline hexagonal CoSe (freboldite) and only around 13?wt.% of the targeted Co9Se8 phase, additional isothermal treatment at 450?°C increased yield of the Co9Se8 phase to more than 70%. Optical properties of the product with the highest Co9Se8 fraction showed broad absorption in whole UV–Vis optical region and band-gap energy of 1.93?eV, blue-shifted relative to the bulk Co9Se8. Both UV–Vis and photoluminescence spectra indicated quantum size effect of the finest nanocrystals in Co9Se8 product. The new combined approach represents a simple, fast, and easy up-scalable route for the synthesis of Co9Se8.
关键词： thermal annealing,optical properties,mechanochemical synthesis,Co9Se8,quantum size effect
更新于2025-09-04 15:30:14