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<i>Rhodopseudomonas palustris</i> -based conversion of organic acids to hydrogen using plasmonic nanoparticles and near-infrared light
摘要： The simultaneous elimination of organic waste and the production of clean fuels will have an immense impact on both the society and the industrial manufacturing sector. The enhanced understanding of the interface between nanoparticles and photo-responsive bacteria will further advance the knowledge of their interactions with biological systems. Although literature shows the production of gases by photobacteria, herein, we demonstrated the integration of photonics, biology, and nanostructured plasmonic materials for hydrogen production with a lower greenhouse CO2 gas content at quanti?ed light energy intensity and wavelength. Phototrophic purple non-sulfur bacteria were able to generate hydrogen as a byproduct of nitrogen ?xation using the energy absorbed from visible and near-IR (NIR) light. This type of biological hydrogen production has su?ered from low e?ciency of converting light energy into hydrogen in part due to light sources that do not exploit the organisms' capacity for NIR absorption. We used NIR light sources and optically resonant gold–silica core–shell nanoparticles to increase the light utilization of the bacteria to convert waste organic acids such as acetic and maleic acids to hydrogen. The batch growth studies for the small cultures (40 mL) of Rhodopseudomonas palustris demonstrated >2.5-fold increase in hydrogen production when grown under an NIR source (167 (cid:1) 18 mmol H2) compared to that for a broad-band light source (60 (cid:1) 6 mmol H2) at equal light intensity (130 W m(cid:3)2). The addition of the mPEG-coated optically resonant gold–silica core–shell nanoparticles in the solution further improved the hydrogen production from 167 (cid:1) 18 to 398 (cid:1) 108 mmol H2 at 130 W m(cid:3)2. The average hydrogen production rate with the nanoparticles was 127 (cid:1) 35 mmol L(cid:3)1 h(cid:3)1 at 130 W m(cid:3)2.
关键词： organic acids,near-infrared light,plasmonic nanoparticles,hydrogen production,Rhodopseudomonas palustris
更新于2025-09-16 10:30:52
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Thermocouple-tip-exposing temperature assessment technique for evaluating photothermal conversion efficiency of plasmonic nanoparticles at low laser power density
摘要： A new thermocouple (TC) tip-exposing temperature assessment technique that combines experimental temperature measurements with a numerical model of the photothermal conversion efficiency η is presented. The proposed technique is designed to evaluate η for a gold-coated superparamagnetic iron oxide nanoparticle (SPIO-Au NP) solution (26 nm, 12–70 ppm) at low continuous wave laser power (103 mW, 532 nm) irradiation in a convenient manner under ambient conditions. The TC tip temperature is measured during the first 30 s of the laser exposure, and the results are combined with a finite element model to simulate the temperature rise of the NP solution for a given concentration. The value of η is adjusted in the model until the model agrees with the measured transient TC temperature rise. Values of η = 1.00 were observed for all concentrations. Theoretical predictions of η derived by Mie theory confirmed the near unity conversion efficiency of the as-synthesized SPIO-Au NPs. Advantages of the current technique include co-locating the TC tip in the geometric center of the laser-heated region, rather than outside of this region. In addition, the technique can be done under ambient room conditions using unmodified commercially available hardware.
关键词： finite element model,plasmonic nanoparticles,low laser power density,thermocouple,photothermal conversion efficiency
更新于2025-09-16 10:30:52
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Wulff-Based Approach to Modeling the Plasmonic Response of Single Crystal, Twinned, and Core–Shell Nanoparticles
摘要： The growing interest in plasmonic nanoparticles and their increasingly diverse applications is fuelled by the ability to tune properties via shape control, promoting intense experimental and theoretical research. Such shapes are dominated by geometries that can be described by the kinetic Wulff construction such as octahedra, thin triangular platelets, bipyramids, and decahedra, to name a few. Shape is critical in dictating the optical properties of these nanoparticles, in particular their localized surface plasmon resonance behavior, which can be modeled numerically. One challenge of the various available computational techniques is the representation of the nanoparticle shape. Specifically, in the discrete dipole approximation, a particle is represented by discretizing space via an array of uniformly distributed points-dipoles; this can be difficult to construct for complex shapes including those with multiple crystallographic facets, twins, and core?shell particles. Here, we describe a standalone user-friendly graphical user interface (GUI) that uses both kinetic and thermodynamic Wulff constructions to generate a dipole array for complex shapes, as well as the necessary input files for DDSCAT-based numerical approaches. Examples of the use of this GUI are described through three case studies spanning different shapes, compositions, and shell thicknesses. Key advances offered by this approach, in addition to simplicity, are the ability to create crystallographically correct structures and the addition of a conformal shell on complex shapes.
关键词： localized surface plasmon resonance,Wulff construction,plasmonic nanoparticles,shape control,graphical user interface,DDSCAT,discrete dipole approximation
更新于2025-09-16 10:30:52
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Graphene-covered sandwich nanostructure for enhanced light absorption
摘要： At present, the combination of graphene and metal nanostructures is explored for strong light–matter interaction. In this study, the optical properties of a composite nanostructure are studied experimentally by simply coating a monolayer graphene on a sandwich nanostructure (Ag nanoparticles–SiO2 film–Ag nanoparticles) fabricated via oblique angle deposition. Results indicate that graphene coverage leads to enhanced light absorption in the visible range. The simulation results show that the interaction between graphene and nanoparticles plasmons increase the light absorption originating from the strong localized electric field of graphene. In addition, the light–graphene interaction can be tuned via plasmon resonance by changing the size of nanoparticles and the thickness of the SiO2 film. The simplicity of the fabrication process and the tunability of plasmon resonance makes the application of graphene-covered nanostructures in diverse areas promising.
关键词： Plasmonic,Nanoparticles,Light-matter interaction,Graphene
更新于2025-09-16 10:30:52
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Super absorption of solar energy using a plasmonic nanoparticle based CdTe solar cell
摘要： Improving the photon absorption in thin-film solar cells with plasmonic nanoparticles is essential for the realization of extremely efficient cells with substantial cost reduction. Here, a comprehensive study of solar energy enhancement in a cadmium telluride (CdTe) thin-film solar cell based on the simple design of a square array of plasmonic titanium nanoparticles, has been reported. The excitation of localized plasmons in the metallic nanostructures together with the antireflection coating (ARC) significantly enhances the absorption of photons in the active CdTe layer. The proposed structure attained super absorption with a mean absorbance of more than 97.27% covering a wide range from visible to near-infrared (i.e., from 300 nm to 1200 nm), presenting a 90% absorption bandwidth over 900 nm, and the peak absorption is up to 99.9%. For qualitative analysis, the photocurrent density is also estimated for AM 1.5 solar illumination (global tilt), whose value reaches 40.36 mA cm?2, indicating the highest value reported to date. The impact of nanoparticle dimensions, various metal materials, shapes, and random arrangement of nanoparticles on optical absorption are discussed in detail. Moreover, the angle insensitivity is essentially validated by examining the absorption performance with oblique incidences and it is found that the solar cell keeps high absorption efficiency even when the incidence angle is greater than 0°. Therefore, these findings suggest that the proposed broadband structure has good prospect in attaining high power conversion efficiency while reducing the device cost.
关键词： photocurrent density,titanium nanoparticles,plasmonic nanoparticles,broadband absorption,CdTe solar cell
更新于2025-09-12 10:27:22
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Near-Field-Induced Femtosecond Breakdown of Plasmonic Nanoparticles
摘要： We studied the evolution of femtosecond breakdown in lithographically produced plasmonic nanoparticles with increasing laser intensity. Localized plasmons were generated with 40-fs laser pulses with up to 1.4 × 1012 W/cm2 peak intensity. The damage morphology shows substantial variation with intensity, starting with the detachment of hot spots and stochastic nanoparticle removal. For higher intensities, we observe precise nanolithographic mapping of near-field distributions via ablation. The common feature of these phenomena is the central role played by the single plasmonic hot spot of the triangular nanoparticles used. We also derive a damage threshold value from stochastic damage trends on the arrays fostering the optimization of novel nanoarchitectures for nonlinear plasmonics.
关键词： Laser-induced damage threshold,Plasmonic nanoparticles,Plasmonics,Field enhancement mapping
更新于2025-09-12 10:27:22
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Laser Induced Plasmonic Heating with Au Decorated TiO2 Nanoparticles
摘要： In this study, we explore the feasibility of laser as source of photons for plasmonic heating of metal nanoparticles. Au decorated TiO2 nanoparticles with different Au wt.% loading were prepared using deposition-precipitation method and their physical and optical properties were characterized by X-Ray diffraction (XRD), Diffuse reflectance spectra (DRS) and Raman spectroscopy. The enhancement of the optical properties of Au plasmonic nanoparticles arises from localized surface plasmon resonance (LSPR) effect achieved under 532 nm laser irradiation. Additionally, the photothermal performance of Au/TiO2 nanofluid was tested compared with other nanofluids under visible laser irradiation. The results revealed that the temperature of Au/TiO2 nanofluid was significantly higher compared to that of bare TiO2 and pure milli-Q water, attributing to the plasmonic excitation of Au nanoparticles under laser irradiation.
关键词： Plasmonic nanoparticles,photothermal,laser irradiation
更新于2025-09-12 10:27:22
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Signature of plasmonic nanoparticles in multi-wavelength low power random lasing
摘要： A multi-wavelength plasmonic random lasing is attained by core-shell nanoparticles and the mixture of metallic nanoparticles in the host dye medium. The plasmonic nanoparticles, fabricated using laser ablation in liquid, were mixed in the corresponding dye medium and pumped with green nano-second pulsed laser. Due to this optical pumping process of plasmonic nanoparticles, amplification of the fluorescence and the lasing activity took place due to the localized surface plasmon resonance and scattering of each nanoparticle, core-shell and mixture nanoparticles. Our results show efficient coherent random lasing due to the interface between two different metallic nanoparticles in the middle part of the visible spectral region considering its applicability in the design and fabrication of compact and miniaturized random laser sources.
关键词： Plasmonic nanoparticles,Dye,Random laser,Core shell,Coherent laser
更新于2025-09-12 10:27:22
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Modulating Catalytic Performance of Metal-Organic Frameworks Composites by Localized Surface Plasmonic Resonance
摘要： Controlled integration of plasmonic nanoparticles with metal-organic frameworks (MOFs) creates a class of multifunctional nanomaterials that powerful for various applications, especially in the field of photocatalysis and photoelectrocatalysis -which recently have been witnessed a vast interest in the exploration of localized surface plasmon resonance of plasmonic NPs to improve the efficiency of catalysis processes. This perspective highlights and summarizes recent significant progress in the field of catalysis, focusing on integration strategies and considerations and several possible plasmonic enhancement mechanisms involved. Brief overviews of optical and electronics properties of plasmonic NPs is also introduced, and finally the development prospect of the field is briefly discussed.
关键词： Plasmonic nanoparticles,Metal-organic frameworks,LSPR,Catalysis,Composites
更新于2025-09-12 10:27:22
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Quantifying the photothermal conversion efficiency of plasmonic nanoparticles by means of terahertz radiation
摘要： The accurate determination of the photothermal response of nanomaterials represents an essential aspect in many fields, such as nanomedicine. Specifically, photothermal cancer therapies rely on the precise knowledge of the light-to-heat transfer properties of plasmonic nanoparticles to achieve the desired temperature-induced effects in biological tissues. In this work, we present a novel method for the quantification of the photothermal effect exhibited by nanoparticles in aqueous dispersions. By combining the spatial and temporal thermal dynamics acquired at terahertz frequencies, the photothermal conversion efficiency associated with the geometry of the plasmonic nanoparticles can be retrieved in a noncontact and noninvasive manner. The proposed technique can be extended to the characterization of all those nanomaterials which feature a temperature-dependent variation of the refractive index in the terahertz regime.
关键词： terahertz radiation,plasmonic nanoparticles,photothermal conversion efficiency,nanomedicine,photothermal therapy
更新于2025-09-12 10:27:22