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Synergistic Effect of Plasma and Laser Processes in Liquid for Alloyed-Nanoparticle Synthesis
摘要： Cu-Ag-alloy nanoparticles (NPs) are synthesized from micropowders of pure Cu and Ag by two consecutive nonequilibrium processes based on plasma and lasers in liquids. The plasma process reduces the size of the particles forming the initial powders from micrometer size to nanometer size, at which the laser fluence is sufficient to melt them, making alloying possible. Measurements at macroscopic (solution absorption), microscopic (scattering of individual NPs), and nanoscopic (electron microscopy) scales confirm alloying of NPs and homogenization of size and composition. This has a noticeable effect on the final colloidal solution, which absorbs yellow-orange light (550–600 nm) after laser treatment. With a synthesis rate of 360 mg/h, this process opens up possibilities for nonequilibrium nanometallurgy of functional NPs.
关键词： plasma process,Cu-Ag-alloy nanoparticles,laser process,nonequilibrium nanometallurgy,functional NPs
更新于2025-09-19 17:13:59
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Synthesis of Si NPs from River Sand Using the Mechanochemical Process and its Applications in Metal Oxide Heterojunction Solar Cells
摘要： In this article, simple two-steps process for the synthesis of silicon nanoparticles (Si NPs) from river sand of Bangladesh and application of the synthesized Si NPs for the improvement of the performance of the metal oxide heterojunction solar cells (HJSCs) have been investigated. A modified aluminothermic reaction was performed to extract highly pure silicon from sand. Later, ultrasonication on the extracted silicon in hydrofluoric acid (HF) was done to synthesis Si NPs from extracted Si. Afterward, the prepared Si NPs were used to dope CuO absorber for the fabrication of CuO/ZnO heterojunction solar cell. Properties of extracted Si and its effect after doping in copper oxide (CuO) were studied by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray (EDX), X-ray Fluorescence (XRF), Fourier Transform Infrared Rays (FTIR), UV-Vis Spectroscopy, Raman and Photovoltaic study. Experimental results indicate that the extracted Si is polycrystalline in nature. The optical absorbance of CuO was enhanced significantly as a result of Si NPs doping and consequently, photoconversion efficiency was found to enhance more than 30% when Si NPs doped CuO was used in the Al/Si NP-CuO/ZnO/FTO heterostructure as a solar cell. This all spin-coated heterojunction solar cell showed a photoconversion efficiency of 1.16%. The photovoltaic responses reveal that the prepared Si NPs can be utilized for the improvement of the performance of HJSCs. This study on modified aluminothermically extracted Si NPs provide valuable insight and easy route for the preparation of Si NPs from sand and its applications in photovoltaic technology.
关键词： Mechanochemical process,Aluminothermic reduction,Si NPs,Sand,ZnO/CuO heterojunction,Si-Al eutectic mixer
更新于2025-09-19 17:13:59
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Plasmonic cellulose textile fiber from waste paper for BPA sensing by SERS
摘要： Flexible plasmonic Surface-enhanced Raman scattering (SERS) substrates were fabricated using cellulose textile fibers, in which the textile fibers were recycled from waste paper in an eco-friendly way. The Glycidyltrimethylammonium chloride (GTAC) with positive charges was grafted onto the surface of the cellulose textile fibers through cationization. Plasmonic silver nanoparticles (Ag NPs) with negative charges were decorated onto the cellulose textile fibers via electrostatic interactions. After cationization, the variation range of the diameter of the cellulose textile fibers was significantly increased because part of the cellulose was dissolved under alkaline condition, leading to more ‘hot spots’ for SERS during the shrinking process. The cellulose textile fiber-Ag NPs nanocomposite was employed for monitoring bisphenol A (BPA) in water and soft drink by SERS and the sensitivity of BPA detection achieved 50 ppb. The recovery values of BPA in soda water samples were from 96% to 105%. These results illustrate that the cellulose textile fiber-Ag NPs nanocomposite can be used as flexible, high sensitivity SERS substrates for detecting harmful ingredients in food or environment.
关键词： flexible sensor,BPA,Cellulose textile fiber,SERS,plasmonic NPs
更新于2025-09-19 17:13:59
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Bacterial killing efficacy of synthesized rod shaped cuprous oxide nanoparticles using laser ablation technique
摘要： Recent interests with copper nanoparticles (Cu-NPs) has arisen because of its low cost and antibacterial properties, as it may be one of the very important alternatives to silver NPs. Pulsed laser ablation of a solid target (copper) in liquid media is used to synthesize colloidal oxide copper (Cu2O and CuO NPs) NPs. These oxides of copper NPs were synthesized using Nd:YAG laser energy to maintain a 40 mJ/pulse wavelength at 1064 nm. During the synthesis of colloidal NPs only two conditions were opted, employing double distilled water (without PEG) and 10% preparation of PEG. Both NPs were prepared under the similar parameters such as optimized instrument settings, laser energy and time of laser exposure (1 h ablation). Further, these copper oxide NPs were characterized by advance technologies including UV–visible, X-ray diffraction, transmission electron microscopy and attenuated total reflection Fourier transform infrared spectroscopy techniques. The significant antibacterial properties of synthesized materials were also observed. The cuprous oxide NPs, showed remarkable antibacterial effect conducted using disc diffusion techniques. The minimum inhibitory concentration and minimum bactericidal concentration of synthesized Cu2O NPs were recorded as 120 and 140 μg/L respectively against Staphylococcus aureus used as positive control. Therefore, based on the findings of present study Cu2O NPs can be exploited as stable antimicrobial agents for multipurpose uses.
关键词： Polyethylene glycol,Laser ablation,Antibacterial,UV–visible,Copper oxide NPs
更新于2025-09-19 17:13:59
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Fabrication and characterization of PSi/nanometal hybrid structures by laser for CO gas sensor
摘要： Mesoporous silicon (mesoPSi) layers fabricated by the photoelectrochemical etching (PECE) method in hydrofluoric acid (HF) are active as carbon monoxide gas sensors. The modified porous silicon (PSi) can be used with noble metals to manufacture an effective gas sensor. Embedded gold, platinum, and palladium nanoparticles Au, Pt, and Pd-NPs could modify the surface morphology of mesoPSi and form mesoPSi/AuPtPd-NPs hybrid structures through a simple and dipping process in fixed salt concentrations. The morphology of the hybrid structures has been studied using scanning electron microscopy and X-ray diffraction. The prepared gas sensor has measured the electrical characteristics at room temperature. Shape, nanoparticle size, and specific surface area strongly influenced the current–voltage characteristics. The results show that Au, Pd, and Pt-NPs sizes prepared by the dipping process for mesopore-like structures were in the range from 0.64 to 7.53 nm. Besides, considerable improvements in the response, recovery times and sensitivity of gas sensor were noticed when decreasing the incorporated Au, Pd, and Pt-NPs to the mesoPSi matrix.
关键词： SEM,Gas sensing,Photoelectrochemical,AuPtPd-NPs hybrid structures,MesoPSi
更新于2025-09-19 17:13:59
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Femtomolar Detection of Spermidine using Au Decorated SiO <sub/>2</sub> Nanohybrid on Plasmon-Coupled Extended Cavity Nanointerface: A Smartphone based Fluorescence Dequenching approach
摘要： Coupling of photons with molecular emitters in different nanocavities have resulted in transformative plasmonic applications. The rapidly expanding field of surface plasmon-coupled emission (SPCE) has synergistically employed subwavelength optical properties of localized surface plasmon resonance (LSPR) supported by nanoparticles (NPs) and propagating surface plasmon polaritons assisted by metal thin films for diagnostic and point-of-care analysis. Gold nanoparticles (AuNPs) significantly quench the molecular emission from fluorescent molecules (at close distances < 5 nm). More often, complex strategies are employed for providing a spacer layer around the AuNPs to avoid direct contact with fluorescent molecules, thereby preventing quenching. In this study we demonstrate a rapid and facile strategy with the use of Au-decorated SiO2 NPs (AuSil), a metal (Au)-dielectric (SiO2) hybrid material for dequenching the otherwise quenched fluorescence emission from radiating dipoles and to realize 88-fold enhancement using the SPCE platform. Different loading of AuNPs were studied to tailor fluorescence emission enhancements in spacer, cavity and extended (ext.) cavity nanointerfaces. We also present femtomolar detection of spermidine using this nanohybrid in a highly desirable ext. cavity interface. This interface serves as an efficient coupling configuration with dual benefits of spacer and cavity architectures that has been widely explored hitherto. The multifold hot-spots rendered by the AuSil nanohybrids assist in augmented electromagnetic (EM)-field intensity that can be captured using a smartphone based SPCE platform presenting excellent reliability and reproducibility in spermidine detection.
关键词： fluorescence enhancements,extended cavity nanointerface,Au-decorated SiO2 NPs (AuSil),dequenching,surface plasmon-coupled emission
更新于2025-09-19 17:13:59
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Development of ZnO Nanoparticles as an Efficient Zn Fertilizer: Using Synchrotron-Based Techniques and Laser Ablation to Examine Elemental Distribution in Wheat Grain
摘要： Zinc (Zn) deficiency is an important problem worldwide, adversely impacting human health. Using a field trial in China, we compared the foliar-application of both ZnO nanoparticles (ZnO-NPs) and ZnSO4 on winter wheat (Triticum aestivum L.) for increasing the Zn concentration within the grain. We also used synchrotron-based X-ray fluorescence microscopy (μ-XRF) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) to examine the distribution of Zn within the grain. We found that ZnO-NPs increase the Zn concentration in the wheat grain, increasing from 18 mg·kg-1 in the control up to 40 mg·kg-1 when the ZnO-NPs were applied four times. These grain Zn concentrations in the ZnO-NP-treated grains are similar to those recommended for human consumption. However, the ZnO-NPs were similar in their effectiveness to ZnSO4. When examining trace element distribution in the grain, the trace elements were found to accumulate primarily in the aleurone layer and the crease region across all treatments. Importantly, Zn concentrations in the grain endosperm increased by nearly 30-fold relative to the control, with this markedly increasing Zn within the edible portion. These results demonstrate that ZnO-NPs is a suitable fertilizer for increasing Zn within wheat grain and can potentially be used to improve human nutrition.
关键词： X-ray fluorescence microscopy (μ-XRF),foliar application,wheat,Zn biofortification,laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS),ZnO-NPs
更新于2025-09-19 17:13:59
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Optical and Thermal Properties of Laser-Ablated Platinum Nanoparticles Graphene Oxide Composite
摘要： Platinum nanoparticles were synthesized in graphene oxide aqueous solution using a laser ablation technique to investigate the effect of optical linear, nonlinear and thermal properties of platinum-graphene oxide nanocomposite solution. The samples were prepared with different ablation times. The platinum nanoparticles that formed a spherical shape on the surface of graphene oxide solution were authenticated using UV-visible spectrum and transmission electron microscopy patterns. The particle size decreased with increasing ablation time, and the concentration and volume fraction of samples were increased. To obtain the optical linear, nonlinear and thermal properties of platinum-graphene oxide nanocomposite solution, UV-visible spectroscopy, Z-scan, thermal lens and photoacoustic techniques were used. Consequently, the linear and nonlinear refractive indices increased with an increase in the volume fraction of platinum nanoparticles. It was observed from the spatial self-phase modulation patterns that, the optical nonlinear property of the graphene oxide was enhanced in the presence of platinum nanoparticles, and the nonlinearity increased with an increase in the volume fraction of platinum nanoparticles inside the graphene oxide solution. The thermal diffusivity and thermal effusivity of platinum nanoparticles graphene oxide were measured using a thermal lens and photoacoustic methods, respectively. The thermal diffusivity and thermal effusivity of samples were in the range of 0.0341 × 10?5 m2/s to 0.1223 × 10?5 m2/s and 0.163 W s1/2 cm?2 K?1 to 0.3192 W s1/2 cm?2 K?1, respectively. Consequently, the platinum enhanced the optical and thermal properties of graphene oxide.
关键词： graphene oxide,z-scan,spatial self-phase modulation,Pt-NPs,platinum nanoparticles/graphene oxide composite,laser ablation,photoacoustic,thermal lens
更新于2025-09-16 10:30:52
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Plasmonic Response of Light-Activated, Nano-Gold Doped Polymers
摘要： Incorporation of metallic nanoparticles (NPs) in polymer matrix has been used to enhance and control dissolution and release of drugs, for targeted drug delivery, as antimicrobial agents, localized heat sources, and for unique optoelectronic applications. Gold NPs in particular exhibit a plasmonic response that has been utilized for photothermal energy conversion. Because plasmonic nanoparticles typically exhibit a plasmon resonance frequency similar to the visible light spectrum, they present as good candidates for direct photothermal conversion with enhanced solar thermal efficiency in these wavelengths. In our work, we have incorporated ~3-nm-diameter colloidal gold (Auc) NPs into electrospun polyethylene glycol (PEG) fibers to utilize the nanoparticle plasmonic response for localized heating and melting of the polymer to release medical treatment. Auc and Auc in PEG (PEG+Auc) both exhibited a minimum reflectivity at 522 nm or approximately green wavelengths of light under ultraviolet-visible (UV-Vis) spectroscopy. PEG+Auc ES fibers revealed a blue shift in minimum reflectivity at 504 nm. UV-Vis spectra were used to calculate the theoretical efficiency enhancement of PEG+Auc versus PEG alone, finding an approximate increase of 10 % under broad spectrum white light interrogation, and ~14 % when illuminated with green light. Auc enhanced polymers were ES directly onto resistance temperature detectors and interrogated with green laser light so that temperature change could be recorded. Results showed a maximum increase of 8.9 °C. To further understand how gold nanomaterials effect the complex optical properties of our materials, spectroscopic ellipsometry was used. Using spectroscopic ellipsometry and modeling with CompleteEASE? software, the complex optical constants of our materials were determined. The complex optical constant n (index of refraction) provided us with optical density properties related to light wavelength divided by velocity, and k (extinction coefficient) was used to show the absorptive properties of the materials.
关键词： spectroscopic ellipsometry,photothermal energy conversion,polyethylene glycol,metallic nanoparticles,plasmonic response,UV-Vis spectroscopy,gold NPs,electrospun fibers
更新于2025-09-16 10:30:52
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PL Tunable GaN Nanoparticles Synthesis through Femtosecond Pulsed Laser Ablation in Different Environments
摘要： The tunable photoluminescence (PL) property is very important for gallium nitride (GaN) nanoparticles in the application of ultraviolet and blue optoelectronic devices, while conventional methods are not so satisfactory that alternative methods for preparing GaN nanoparticles should be studied. In this paper, ultra-small and well dispersed GaN nanoparticles are fabricated through femtosecond pulse laser ablation in air, water and ethanol. For the PL spectra of GaN nanoparticles, there are no shifts in air, red shifts in water and blue shifts in ethanol compared with the intrinsic PL spectra of bulk GaN. The X-ray photoelectron spectroscopy (XPS) results demonstrate that the various PL spectra can be due to the different components inside the GaN nanoparticles, which not only have effect on the PL emissions, but also greatly influence the intensity of PL. This study validates that the ablation environment has a great adjustable effect on the properties of GaN nanoparticles.
关键词： GaN-NPs,ablation environments,fs-PLAL,tunable PL properties
更新于2025-09-16 10:30:52