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Nano-to-Microporous Networks via Inkjet Printing of ZnO Nanoparticles/Graphene Hybrid for Ultraviolet Photodetectors
摘要： Inkjet-printed photodetectors have gained enormous attention over the last decade. However, device performance is limited without post-processing, such as annealing and UV exposure. In addition, it is difficult to manipulate the surface morphology of the printed film using an inkjet printer due to the limited options of low viscosity ink solutions. Here, we employ a concept involving the control of the inkjet-printed film morphology via modulation of co-solvent vapor pressure and surface tension for the creation of a high-performance ZnO-based photodetector on a flexible substrate. The solvent boiling point across different co-solvent systems is found to affect the film morphology, which results in not only distinct photo-response time but also photo-detectivity. ZnO-based photodetectors were printed using different solvents which display a fast photo-response in low-boiling point solvents due to the low carbon residue and larger photo-detectivity in high-boiling point solvent systems due to the porous structure. The porous structure is obtained using both gas-liquid surface tension differences and solid-liquid surface differences, and the size of porosity is modulated from nano-size to micro-size depending on the ratio between two solvents or two nanomaterials. Moreover, the conductive nature of graphene enhances the transport behavior of the photocarrier, which enables a high-performance photodetector with high photo-responsivity (7.5*102 AW-1) and fast photo-response (0.18 s) to be achieved without the use of high-boiling point solvents.
关键词： Inkjet print,photodetector,ZnO nanoparticle (NP),flexible devices,microporous
更新于2025-09-23 15:19:57
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Enhanced photoelectrochemical performance of plasmonic Ag nanoparticles grafted ternary Ag/PaNi/NaNbO3 nanocomposite photoanode for photoelectrochemical water splitting
摘要： In this work, we have successfully synthesized silver nanoparticles (Ag-NPs) decorated binary PaNi/NBO nanocomposite by facile chemisorption route and demonstrated enhanced photoelectrochemical (PEC) water splitting activity. The ternary Ag/PaNi/NBO nanocomposite photoanode exhibits ~5 fold higher current density than pristine NaNbO3 nanofibers (NBO-NFs). The ternary Ag/PaNi/NBO photoanode exhibits a current density of 5.93 mA/cm2 at 0.9 V with respect to Ag/AgCl, whereas the pristine NBO-NFs photoanode exhibits only 0.85 mA/cm2 at 0.9 V. The improved performance is correlated to the high surface area, formation of the type-II heterojunction among PaNi and NBO-NFs and the introduction of the plasmonic behaviour of Ag-NPs as it expands the absorption of the visible part of the solar spectrum, which together decreases the recombination of charges with strong redox capability. Furthermore, the ternary Ag/PaNi/NBO photoanode showed lower charge transfer resistance (Rct) in the EIS measurements and improved incident photon to current efficiency (IPCE) of ~31.3% which is ~23% higher to the IPCE of bare NBO-NFs photoanode. Thus, these results suggest that the ternary Ag/PaNi/NBO nanocomposite is a promising material for PEC activity and wide practical applications.
关键词： Water Splitting,Silver nanoparticle,PaNi,NaNbO3,Ag/PaNi/NBO
更新于2025-09-23 15:19:57
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Acoustic Vibrations of Al Nanocrystals: Size, Shape, and Crystallinity Revealed by Single-Particle Transient Extinction Spectroscopy
摘要： Acoustic vibrations in plasmonic nanoparticles, monitored by an all-optical means, have attracted significant increasing interest because they provide unique insight into the mechanical properties of these metallic nanostructures. Al nanostructures are a recently emerging alternative to noble metal nanoparticles, because their broad wavelength tunability and high natural abundance make them ideal for many potential applications. Here we investigate the acoustic vibrations of individual Al nanocrystals using a combination of electron microscopy and single-particle transient extinction spectroscopy, made possible with a low-pulse energy, high sensitivity, and probe-wavelength-tunable, single-particle transient extinction microscope. For chemically synthesized, faceted Al nanocrystals, the observed vibration frequency scales with the inverse particle diameter. In contrast, triangularly-shaped Al nanocrystals support two distinct frequencies, corresponding to their in- and out-of-plane breathing modes. Unlike ensemble measurements, which measure average properties, measuring the damping time of the acoustic vibrations for individual particles enables us to investigate variations of the quality factor on the particle-to-particle level. Surprisingly, we find a large variation in quality factors even for nanocrystals of similar size and shape. This observed heterogeneity appears to result from substantially varying degrees of nanoparticle crystallinity even for chemically synthesized nanocrystals.
关键词： quality factor,Al nanocrystals,single-particle transient extinction spectroscopy,acoustic vibrations,nanoparticle crystallinity
更新于2025-09-23 15:19:57
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Plasmon-induced Ag decorated CeO <sub/>2</sub> nanorod array for photodetector application
摘要： In this work, glancing angle deposition (GLAD) has been used to grow Ag decorated CeO2 nanorod (NR) array on n-type Si substrate. The length of the NRs obtained was ～235 nm and the size of the Ag NPs varied from 13 to 41 nm. The polycrystalline and crystalline nature of CeO2 and Ag respectively was revealed via selected area electron diffraction (SAED) analysis as well as x-ray diffraction (XRD) pattern. Optical absorption measurement depicts a distinct broad peak around 413 nm that is ascribed to the localized surface plasmon resonance (LSPR) effect of Ag NPs. The Ag decorated CeO2 NR device exhibited a turn on voltage at ～3.2 V under dark, which then reduced to ～1.3 V under 35 min illumination along with the increase in device current from 2.8 to 24.5 μA cm?2 (4 V) on continuous exposure to light. Under white light illumination, a responsivity of 4.51 A W?1 was obtained at 370 nm along with the detectivity and noise equivalent power (NEP) values of 4.15×1012 jones and 0.01 pW respectively. Additionally, a fast response characteristic with rise and fall times of 74 ms and 42 ms respectively was demonstrated. Thus, these findings manifest the underlying LSPR mechanism at work in Ag/CeO2 heterojunction and reveal its high potential in UV photodetector application.
关键词： GLAD,surface plasmon,nanorod,silver,nanoparticle,cerium oxide
更新于2025-09-23 15:19:57
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Effect of irradiation time in the synthesis of Au-Ag nanoalloys by femtosecond laser
摘要： The synthesis of metallic nanoparticles can be performed by femtosecond laser-induced photoreduction of the metallic ion solution. Due to hydrogen radical and the solvated electron generated through the interaction of ultrafast laser and water medium, the dissolved metallic ion in the medium can be converted to their respective metallic atom and then precipitated into nanoparticles. When there is more than one metallic ion available in the solution, alloy nanoparticles can be generated. One parameter that affects this laser-based synthesis was the duration of laser irradiation time that has an advantage for size modification of nanoparticles. In this work, we have synthesized Au-Ag nanoalloys from the mixture of Au and Ag ion in water medium added with 0.01wt% polyvinylpyrrolidone (PVP) as a capping agent and irradiated for 5 and 10 minutes. The result showed that there was linear shifting in surface plasmon resonance (SPR) of the nanoalloys in respect with their volume fraction of the ions. The results also revealed that the nanoparticle size was indeed reduced as the laser irradiation was prolonged, i.e., Au50Ag50 has a particle size of 7.98 nm and 5.18 nm for 5 and 10 minutes irradiation time, respectively.
关键词： irradiation time,Au-Ag nanoalloys,surface plasmon resonance,femtosecond laser,nanoparticle size
更新于2025-09-23 15:19:57
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Plasmonic nanoparticles assemblies templated by helical bacteria and resulting optical activity
摘要： Plasmonic nanoparticles (NPs) adsorbing onto helical bacteria can lead to formation of NP helicoids with micron scale pitch. Associated chiroptical effects can be utilized as bioanalytical tool for bacterial detection and better understanding of the spectral behavior of helical self-assembled structures with different scales. Here, we report that enantiomerically pure helices with micron scale of chirality can be assembled on Campylobacter jejuni, a helical bacterium known for severe stomach infections. These organisms have right-handed helical shapes with a pitch of 1–2 microns and can serve as versatile templates for a variety of NPs. The bacteria itself shows no observable rotatory activity in the visible, red, and near-IR ranges of electromagnetic spectrum. The bacterial dispersion acquires chiroptical activity at 500–750 nm upon plasmonic functionalization with Au NPs. Finite-difference time-domain simulations confirmed the attribution of the chiroptical activity to the helical assembly of gold nanoparticles. The position of the circular dichroism peaks observed for these chiral structures overlaps with those obtained before for Au NPs and their constructs with molecular and nanoscale chirality. This work provides an experimental and computational pathway to utilize chiroplasmonic particles assembled on bacteria for bioanalytical purposes.
关键词： bacteria,simulation,C. jejuni,circular dichroism,plasmonic,mesoscale,gold nanoparticle,biotechnology
更新于2025-09-23 15:19:57
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Third and fifth harmonics generation in air and nanoparticle-containing plasmas using 150-kHz fiber laser
摘要： High-pulse repetition rate lasers allow significant enhancement in the average power of the low-order harmonics generation in isotropic media. We report on the third (343-nm) and fifth (206-nm) harmonics generating in air and different nanoparticle-containing laser-produced plasmas by applying Yb-doped fiber laser delivering 37-fs, 100-kHz, 1030-nm, 0.5-mJ pulses. Different characteristics of these processes (power and density dependences, influence of impeding processes, role of synthesized nanoparticles, variations of the spectral modulation of driving pulses, etc.) are analyzed. We compare the formation of the plasmas on the surfaces of aluminum, carbon, manganese, and titanium bulk species, as well as quantum dots of metal sulfides as the media for low-order harmonics generation, using 250-fs (1030-nm) and 5-ns (1064-nm) heating pulses at different delays between the heating and driving pulses. Average power of about 20 mW was estimated for the third harmonic emission from metal plasmas, with 3 × 1016 UV photons (343 nm) emitted per second.
关键词： Third harmonic generation,Fifth harmonic generation,Nanoparticle-containing plasmas,High-pulse repetition rate,Fiber laser
更新于2025-09-23 15:19:57
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Direct printing of performance tunable strain sensor via nanoparticle laser patterning process
摘要： Flexible electronics are attractive because of flexibility and portability. The circuits are printed on flexible substrates, which are delicate and heat-sensitive. Traditional photolithography, which uses high temperatures and corrosive chemicals, easily causes damages in flexible substrates. Here, we develop a low-cost nanoparticle based laser patterning process for fabrication of flexible electronics. Nanoparticles are sintered using a low-power laser as they are selectively deposited. Copper and silver particles were successfully deposited on paper and polyethylene terephthalate substrates. The effects of process parameters on deposition performance were studied to understand the process-structure–property relationship. The thermal effects of the laser on film morphology were observed. The sensitivities of the electrical properties with respect to the porosities at different laser power densities were analysed. With different laser energy levels, the process allows for selective deposition, properties control of printed patterns, and flexible substrate cutting. The fabrications of strain sensor and kirigami electronics were demonstrated.
关键词： strain sensor,electrical properties,hybrid manufacturing,Nanoparticle deposition,flexible electronics,process-structure–property relationship
更新于2025-09-23 15:19:57
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Stable nano-silver colloid production via Laser Ablation Synthesis in Solution (LASiS) under laminar recirculatory flow
摘要： As nanomaterials find applications in an increasingly diverse range of fields such as wastewater treatment, biotechnology and flexible electronics, the demand for nanomaterials with specific properties has increased. This increase is coupled with an increasing emphasis on nanomaterials with highly specific properties for specialised applications. Industrially, nanomaterials are produced via wet-chemical techniques which employ the use of solvents and reagents which are environmentally harmful. As we move forward with the use of nanomaterials, the ability to produce nanomaterials in a sustainable manner has become a topic of great significance. Towards this end, Laser Ablation Synthesis in Solution (LASiS) is a physical production technique capable of producing tailored nanomaterial colloids in a sustainable manner. These colloids are produced by ablating a solid target immersed in a solvent using a laser. Typically, LASiS is conducted in a batch process and in small volumes limiting commercial viability. To overcome this, there has been a move towards the use of continuous production via LASiS using flow systems. This allows an increase in nanomaterial yield, resulting in colloid concentrations approaching those of commercial colloids. This work investigates a new production technique incorporating a laminar recirculatory flow system to produce stable high concentration nano-silver colloids.
关键词： silver,Nanoparticle,laser ablation synthesis in solution,size-quenching
更新于2025-09-23 15:19:57
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Synthesis, characterization, and fluorescence study of tryptone-self-assembled and Zn(II)-coordinated nanoparticles
摘要： Peptides/amino acids are biodegradable and biocompatible and have been used as suitable biomaterials for many bioengineering and medical applications in the last few decades. However, sometimes they show very limited intrinsic optical properties when used as optical imaging probes for biological diagnostics and target-based drug monitoring applications. Here we synthesized novel tryptone-self-assembled and Zn(II)-coordinated nanoparticles (TZFNPs), which shifted the intrinsic fluorescence emission peak from ultraviolet (270 nm) of tryptone to the visible wavelength (470 nm). Furthermore, when coordinated with 4-chloro-7-nitrobenzofurazan (NBD-Cl), a fluorogenic reagent, the fluorescence signals of our TZFNPs were further enhanced directly and in the cellular environment as well. We also studied the fluorescent signals of these TZFNPs after transferring them into the intracellular space of U2OS and HeLa cell lines. These fluorescent nanoparticles are intrinsically fluorescent and suitable for bioimaging. We hope they will pave the new way for further applications in medical sciences from diagnostics to clinical trials.
关键词： Tryptophan,Nanoparticle,Tryptone,Fluorescence,Self-assembly,Optical imaging
更新于2025-09-23 15:19:57