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SiO2-stabilized Bi nanoparticles: a high active and stable visible light photocatalyst
摘要： A SiO2-coated Bi nanoparticle structure in 40?60 nm with high activity and stability was designed by a liquid phase chemical reduction method. The effect of SiO2 layer on high active Bi nanoparticles was studied by X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, and thermo-gravimetric and differential thermal analysis characterizations. The SiO2 layer effectively enhanced the stability of Bi core without having negative effect on its activity. The as-prepared Bi@SiO2 nanoparticles showed high activity and recycling stability both in photocatalytic degradation of pollutant (rhodamine B and bisphenol A, respectively) and hydrogen exhalation reaction (HER). The photocatalytic degradation mechanism of Bi@SiO2 nanoparticles under visible light irradiation was discussed. The porous structure of SiO2 layer performed transport channel for electrons and active species, and enhanced the plasmonic photocatalytic effect of Bi.
关键词： HER.,stabilization,photocatalytic activity,Bi@SiO2 nanoparticles
更新于2025-09-19 17:15:36
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A single light spot GC detector employing localized surface plasmon resonance of porous Au@SiO <sub/>2</sub> nanoparticle multilayer
摘要： This paper describes the synthesis of a nano-porous multilayered film consisting of Au@SiO2 nanoparticles. This film was used to miniaturize the size of a localized surface plasmon resonance (LSPR)-based capillary gas chromatograph (GC) detector. A layer-by-layer (LbL) approach with proper surface reaction sequences was used to create a multilayer structure that consisted of as many as five layers of Au@SiO2 nanoparticles. The center wavelength of LSPR was shifted from 520 to 634 nm due to the approximation of additional layers of nanoparticles. The vapor response time for this Au@SiO2 multilayer LSPR sensor was identical to that of an Au nanoparticle monolayer, which confirmed that this multilayer structure has a high level of gas permeability. The multilayer was synthesized inside a glass capillary for use as a GC detector. Due to the enhancement of absorbance, the gas chromatographic signal was obtained via a single spotlight that penetrated one side of the glass capillary and was then reflected by a silver mirror coated on the opposite side. The detection limits were ≤20 ng for cyclohexanone and m-xylene.
关键词： gas chromatography,localized surface plasmon resonance,multilayer film,miniaturization,Au@SiO2 nanoparticles,VOC detection
更新于2025-09-19 17:15:36
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Few-cycle laser driven reaction nanoscopy on aerosolized silica nanoparticles
摘要： Nanoparticles offer unique properties as photocatalysts with large surface areas. Under irradiation with light, the associated near-fields can induce, enhance, and control molecular adsorbate reactions on the nanoscale. So far, however, there is no simple method available to spatially resolve the near-field induced reaction yield on the surface of nanoparticles. Here we close this gap by introducing reaction nanoscopy based on three-dimensional momentum-resolved photoionization. The technique is demonstrated for the spatially selective proton generation in few-cycle laser-induced dissociative ionization of ethanol and water on SiO2 nanoparticles, resolving a pronounced variation across the particle surface. The results are modeled and reproduced qualitatively by electrostatic and quasi-classical mean-field Mie Monte-Carlo (M3C) calculations. Reaction nanoscopy is suited for a wide range of isolated nanosystems and can provide spatially resolved ultrafast reaction dynamics on nanoparticles, clusters, and droplets.
关键词： ethanol,water,SiO2 nanoparticles,photocatalysts,nanoparticles,Mie Monte-Carlo calculations,momentum-resolved photoionization,reaction nanoscopy,near-fields
更新于2025-09-19 17:13:59
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Calcination effect to the physical and optical properties of Zn <sub/>2</sub> SiO <sub/>4</sub> composite prepared by impregnation of ZnO on SiO <sub/>2</sub> amorphous nanoparticles
摘要： In this study, Zn2SiO4 composite-based ceramic was synthesised using amorphous SiO2 nanoparticles as a silicon source. The amorphous SiO2 nanoparticles which obtained from a simple precipitation process were mixed with aqueous zinc nitrate. Amorphous SiO2 nanoparticles were encapsulated by the zinc source in aqueous solution, dried, and subjected to calcination. The underwent calcination showed the changing of phases, morphology, and size with increased temperatures. During calcination, ZnO phase appeared at the beginning of heating temperature and Zn2SiO4 phase started to emerge at 800 °C onwards, as shown by XRD patterns. The optical band gap analysis of Zn2SiO4 composite was determined to be within the range of 3.12 to 3.19 eV. The diffusion of zinc ions into SiO2 nanoparticles with high surface area also reduced the phase formation temperature for Zn2SiO4, compared to a conventional solid state method. This optical characteristic is expected to be a potential candidate for phosphor materials in opto-electronic devices application.
关键词： optical properties,Zn2SiO4 composite,amorphous SiO2 nanoparticles,phosphor materials,calcination
更新于2025-09-10 09:29:36