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3D heterostructured Ti-based Bi2MoO6/Pd/TiO2 Photocatalysts for High-Efficiency Solar Light Driven Photoelectrocatalytic Hydrogen Generation
摘要： Hydrogen fuel generation using solar light via photoelectrochemical (PEC) methods can help meet growing global energy demands and decrease environmental pollution. The key to efficient PEC hydrogen production is the synthesis of solar light driven photoelectrodes with efficient charge carrier separation. Here, we designed and prepared a ternary Bi2MoO6/Pd/TiO2 photoelectrode composed of Bi2MoO6 nanosheets, Pd nanoparticles (NPs) and TiO2 nanotube arrays (NTAs) on a Ti substrate using electrochemical methods. This novel photoelectrode had good visible light absorbance and significantly improved PEC hydrogen production rates (~5 and > 15 times higher under UV-vis and visible light irradiation, respectively, compared with TiO2 NTAs). The interfacial charge transfer mechanism of Bi2MoO6/Pd/TiO2 NTAs was comprehensively studied by comparing its PEC and photoelectrocatalytic performance with other TiO2 NTAs (i.e. Pd/TiO2 NTAs, Bi2MoO6/TiO2 NTAs and Pd/Bi2MoO6/TiO2 NTAs). For Bi2MoO6/Pd/TiO2 NTAs, Pd NPs homogeneously dispersed across the inside and outside of TiO2 nanotube walls helped to tightly anchor Bi2MoO6 nanosheets onto the TiO2 surface, forming a ternary 3D heterostructure. This structure facilitated interfacial electron injection from Bi2MoO6 to TiO2, accelerating the separation of the photogenerated electron-hole pairs. And significantly enhanced the photocurrent response and hydrogen production rate were achieved compared with other TiO2 NTAs. This 3D ternary semiconductor/metal/semiconductor heterojunction provides a viable approach for designing and synthesizing highly efficient novel photocatalysts that can effectively utilize solar energy.
关键词： TiO2 nanotube arrays,Pd nanoparticles,Bi2MoO6 nanosheets,Photoelectrocatalytic hydrogen production,Ternary photocatalyst
更新于2025-09-04 15:30:14
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Controllable Synthesis and Catalytic Performance of Gold Nanoparticles with Cucurbit[n]urils (n = 5–8)
摘要： A series of gold nanoparticles (AuNPs) was prepared in situ with different cucurbit[n]urils (CB[n]s) in an alkaline aqueous solution. The nanoparticle sizes can be well controlled by CB[n]s (n = 5, 6, 7, 8) with different ring sizes. The packing densities of CB[5–8] and free surface area on AuNPs were determined. A direct relationship was found between the ring size and packing density of CB[n]s with respect to the AuNP-catalyzed reduction of 4-nitrophenol in the presence of NaBH4. The larger particle size and higher surface coverage of bigger CB[n]-capped AuNPs significantly decreased the catalytic activity. Furthermore, this work could lead to new applications that utilize AuNPs under an overlayer of CB[n]s for catalysis, sensing, and drug delivery.
关键词： gold nanoparticles,catalysis,cucurbit[n]urils,controllable synthesis
更新于2025-09-04 15:30:14
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Bismuth Ferrite Second Harmonic Nanoparticles for Pulmonary Macrophage Tracking
摘要： Recently, second harmonic generation (SHG) nanomaterials have been generated that are efficiently employed in the classical (NIR) and extended (NIR-II) near infrared windows using a multiphoton microscope. The aim was to test bismuth ferrite harmonic nanoparticles (BFO-HNPs) for their ability to monitor pulmonary macrophages in mice. BFO-loaded MH-S macrophages are given intratracheally to healthy mice or BFO-HNPs are intranasally instilled in mice with allergic airway inflammation and lung sections of up to 100 μM are prepared. Using a two-photon-laser scanning microscope, it is shown that bright BFO-HNPs signals are detected from superficially localized cells as well as from deep within the lung tissue. BFO-HNPs are identified with an excellent signal-to-noise ratio and virtually no background signal. The SHG from the nanocrystals can be distinguished from the endogenous collagen–derived SHG around the blood vessels and bronchial structures. BFO-HNPs are primarily taken up by M2 alveolar macrophages in vivo. This SHG imaging approach provides novel information about the interaction of macrophages with cells and the extracellular matrix in lung disease as it is capable of visualizing and tracking NP-loaded cells at high resolution in thick tissues with minimal background fluorescence.
关键词： two-photon-laser scanning microscopy,macrophages,third harmonic generation,nanoparticles,second harmonic generation
更新于2025-09-04 15:30:14
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Fast discrimination of bacteria using a filter paper–based SERS platform and PLS-DA with uncertainty estimation
摘要： Rapid and reliable identification of bacteria is an important issue in food, medical, forensic, and environmental sciences; however, conventional procedures are time-consuming and often require extensive financial and human resources. Herein, we present a label-free method for bacterial discrimination using surface-enhanced Raman spectroscopy (SERS) and partial least squares discriminant analysis (PLS-DA). Filter paper decorated with gold nanoparticles was fabricated by the dip-coating method and it was utilized as a flexible and highly efficient SERS substrate. Suspensions of bacterial samples from three genera and six species were directly deposited on the filter paper–based SERS substrates before measurements. PLS-DA was successfully employed as a multivariate supervised model to classify and identify bacteria with efficiency, sensitivity, and specificity rates of 100% for all test samples. Variable importance in projection was associated with the presence/absence of some purine metabolites, whereas confidence intervals for each sample in the PLS-DA model were calculated using a resampling bootstrap procedure. Additionally, a potential new species of bacteria was analyzed by the proposed method and the result was in agreement with that obtained via 16S rRNA gene sequence analysis, thereby indicating that the SERS/PLS-DA approach has the potential to be a valuable tool for the discovery of novel bacteria.
关键词： Chemometrics, partial least squares discriminant analysis,Surface-enhanced Raman spectroscopy,Reliability estimation,16S rRNA gene sequence analysis,Gold nanoparticles
更新于2025-09-04 15:30:14
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Determination of Number Density of Particles Together with Measurement of Their Sizes by Dynamic Light Scattering
摘要： A method is proposed for measuring the size of particles in a dynamic light scattering analyzer along with a determination of their number density in suspension. It is shown that this method can be used to measure the parameters of various nanoparticles, including nonspherical ones. An experimental prototype of a dynamic light scattering analyzer for measuring the number density of nanoparticles along with their sizes is described.
关键词： number density,dynamic light scattering,extinction,nanoparticles
更新于2025-09-04 15:30:14
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Sodium Doping Effect on Optical Permittivity, Band Gap Structure, Nonlinearity and Piezoelectric Properties of PZT Nano-colloids and Nanostructures
摘要： In this research, effects of sodium atoms doping on optical properties of lead zirconate titanate (PZT) nanoparticles (NPs) are studied and compared with undoped particles. Analyses show formations of PZT nanostructures with dimensions below 30 nm. X-ray diffraction patterns show that the particle size increases and the intensity of the preferred direction decreases as the doping sodium atoms are used in the structure. Analyzing absorption spectra of the colloidal solutions shows doped particles are better absorbers at violet-green region of spectra. Also, it has been concluded that PZT NPs only have indirect optical band gap that is narrower for doped particles. Optical permittivity of the ?lms has been compared using a numerical method and shows the prominent effect of doping on real and imaginary parts of permittivity. Also, z-scan experiments have been done to measure thermo-optical and nonlinear absorption coef?cients of the nano-colloids using continue wave Nd-YAG laser illumination. Finally, sodium doping effects on piezoelectric properties of the samples are investigated using a Michelson interferometer.
关键词： z-scan,Piezoelectric,Michelson interferometer,dispersion curve,PZT nanoparticles
更新于2025-09-04 15:30:14
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Reversible Photodoping of TiO <sub/>2</sub> Nanoparticles for Photochromic Applications
摘要： Observations on the strong photochromic effect of crystalline TiO2 quantum dots (mean size ≈ 4 nm) are presented. The synthesized quantum dots consist of irregularly shaped anatase TiO2 nanoparticles (NPs) and are dispersed in butanol (8% by mass). Obtained NPs exhibit a dramatic photoresponse to UV light, enabling effective transmittance modulation in a broad wavelength range extending from the visible to near-infrared region, and even the thermal black body radiation regime beyond 10 μm. The exceptional photoresponse is attributed to hole-scavenging by butanol, TiO2 self-reduction, injection of electrons to the conduction band, and consequent localized surface plasmon resonances in NPs. The observed optical effect is reversible, and the initial high transmittance state can be restored simply by exposing the NPs to air. The applied NP synthesis route is economic and can be easily scaled for applications such as smart window technologies.
关键词： UV light,TiO2 nanoparticles,localized surface plasmon resonances,transmittance modulation,photochromic
更新于2025-09-04 15:30:14
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Dynamics of Molecules Physically Adsorbed onto Metal Oxide Nanoparticles: Similarities between Water and a Flexible Polymer
摘要： Water at interfaces is considered present and important within almost all physical processes. Interfacial water shows nonbulk properties, however, its structure/organization and dynamics are on a still open debate. In parallel to that, the interfacial polymer in nanocomposites exhibits modi?ed structure and dynamics, the latter characteristic being widely considered responsible for the improved nanocomposite properties. One of the most suitable tools for studying dynamics of a variety of small molecules and macromolecules is broadband dielectric spectroscopy (BDS), mainly due to its high resolving power. BDS is employed here in combination with isothermal hydration and has proved quite illuminating in recording for the ?rst time striking similarities in the dynamics behavior between water molecules and ?exible polydimethylsiloxane macromolecules, when the latter molecules are individually adsorbed physically on the attractive surfaces of metal oxide nanoparticle. The qualitative similarities between water and polymer interfacial dynamics, for example, in their exhibiting time-scale and the elevation of the respective activation energy upon increasing of interfacial molecules fraction, lay most probably at the origins of the same main surface-adsorbed molecule interaction, i.e.. the hydrogen bonding. Whereas, the quantitative di?erences in molecular dynamics, e.g., slower, more energetically demanding, and cooperative interfacial dynamics for the polymer than for water, arise from the di?erent scale of the two molecular motions (<1 nm for water and ≥1 nm for the polymer) and/or from alternations in interfacial layer density.
关键词： dielectric spectroscopy,water,nanoparticles,polydimethylsiloxane,interfaces,dynamics,hydrogen bonding
更新于2025-09-04 15:30:14
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High-Performance Transparent and Flexible Electrodes Made by Flash-Light Sintering of Gold Nanoparticles
摘要： Metallic nanowire-based transparent electrodes (TEs) are potential alternatives to indium tin oxide (ITO). To achieve a high performance [sheet resistance (Rs) <100 Ω/sq, transmittance (T%) > 90%], the nanowires must have a high length-to-diameter (L/D) ratio to minimize the number of wire-to-wire junctions. Attempts to produce TEs with gold nanowires have been made, and the results reveal difficulties in achieving the requirements. A successful strategy involves creating templated gold nanonetworks through multiple procedures. Here, we present a simple and efficient method that uses flash-light sintering of a gold nanonetwork film into gold TEs (Rs: 82.9 Ω/sq, T%: 91.79%) on a thin polycarbonate film (25 μm). The produced gold TEs have excellent mechanical, electrical, optical and chemical stabilities. Mechanisms of the formation of gold nano-networks and the effect of flash-light have been analyzed. Our findings provide a scalable process for producing transparent and flexible gold electrodes with a total processing time of less than 8 min without the use of heating, vacuum processing, organic chemicals and without any material loss. This is possible because all the gold nanoparticles have been aggregated and filtrated on the filter membranes. The area density of gold is 0.094 g/m2 leading low material costs, which is very competitive with the price of commercial TEs.
关键词： flexible electrode,high performance,transparent electrode,gold nanoparticles,flash-light sintering
更新于2025-09-04 15:30:14
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Bimetallic PtAu Alloy Nanoparticles-Integrated g-C <sub/>3</sub> N <sub/>4</sub> Hybrid as an Efficient Photocatalyst for Water-to-Hydrogen Conversion
摘要： Herein, we report the synthesis of metal (Pt and Au) and metal alloy (PtAu) nanoparticles (NPs) integrated graphitic carbon nitride (g?C3N4) hybrid using a facile solvothermal route for water splitting application. The metal and metal alloy NPs with varying percentages of Pt and Au are found to be in the size range of 3?5 nm and uniformly distributed on the g?C3N4 sheets. The metal and metal alloy NPs act as cocatalyst for g?C3N4 to enhance the photocatalytic activity for hydrogen (H2) generation through higher light absorption and efficient charge separation. The alloy composition plays an important role to maximize the photoactivity, with an optimized PtAu/g?C3N4 sample delivered 1009 μmol g?1 h?1 of H2. The visible light assisted photocatalytic H2 evolution is further investigated with the optimized PtAu alloy NPs integrated g?C3N4. This study presents a robust, stable, and easily synthesizable PtAu/g?C3N4 hybrid material as a promising photocatalyst for H2 generation through water splitting.
关键词： alloy nanoparticles,heterostructure,g?C3N4,water splitting,bimetallic,photoelectrochemical
更新于2025-09-04 15:30:14