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This study explores the optimization of hydrometallurgical processes for recycling lithium-ion batteries (LIBs) containing a mixture of lithium iron phosphate (LFP) and nickel–manganese–cobalt (NMC) cathodes. Two approaches were investigated: acid-excess leaching and acid-deficient leaching with residue recirculation. A design of experiments (DoE) framework was applied to assess the impact of key parameters, including sulfuric acid and hydrogen peroxide concentrations, as well as solid-to-liquid (S/L) ratios, on the dissolution yields of target metals (Ni, Mn, Co, and Li). Acid-excess leaching achieved nearly complete dissolution of target metals but required additional purification steps to remove impurities. Acid-deficient leaching with a 60% recirculation of leaching residue improved dissolution yields by up to 12.5%, reduced reagent consumption, and minimized operational complexity. The study also evaluated separation strategies for manganese and cobalt through solvent extraction. Results indicate that while acid-excess leaching offers higher yields, acid-deficient leaching with residue recirculation is more cost-effective and environmentally friendly. These findings provide valuable insights for developing sustainable LIB recycling technologies. [ABSTRACT FROM AUTHOR]

To date, the advanced synthetic approaches for palladium nanoparticle-based catalysts involve multistep, toxic, and high-cost fabrication routes with low catalytic and sensing performance. In this work, we introduce a new one-shot approach to produce highly sensitive Pd nanocomposites using a large-area polymer self-assembly strategy. This synthesis method allowed us to control the Pd nanoparticle shape and to tailor their plasmonic band positions in a wide light spectral range from ~350 to ~800 nm. We thus determined the critical synthesis conditions that give rise to a ringlike morphology in a reproducible manner. No need for a reducing agent and preliminary functionalization of the surface supporting the nanoparticles upon synthesis. To the best of our knowledge, few works have demonstrated the good performance of PdNPs in sensing. Here, we have demonstrated a robust SERS response for 4-mercaptopyridine with an enhancement factor of 4.2 × 105. We were able to exceed this high value, which matches the current maximum found in the literature, by decreasing the gap distances between Pd nanorings due to the high density of hotspots and the exacerbation of the coupling effect between PdNPs. These tailored products provide new insights for the use of Pd nanomaterials in photocatalysis applications, according to the well-established catalytic performance of Pd materials obtained in this work. [ABSTRACT FROM AUTHOR]

Diffractive approaches are needed when refractive microlenses reach their focusing limit at the micron-scale in visible light. Previously, we have reported on micron-sized optical lenses based on the diffraction of metallic nanowires. Here, we extend our study to lenses based on pairs of subwavelength dielectric scatterers. Using simulations by two-dimensional finite element method, we demonstrate that focusing holds for pair spacings as small as the wavelength-size. For pairs with distances between inner walls larger than about 1.2λ, the scattered waves generate a quadratic phase modulation on the total propagating field leading to a diffraction-limited focusing i.e. an effective optical lens effect with high numerical aperture. In addition, they have low sidelobe intensities, long depths of focus, and they have a low sensitivity with polarization. For pairs with inner wall distances smaller than about 1.2λ, the focusing phase modulation is accumulated during the propagation through the dielectric pair structure. In this work, we report only on the experimental demonstration for the case of larger wall separation to emphasize on the scattered wave effect on micro-focusing. A pair of parallel polymer lines (cylindrical lens), and a grid of polymer lines (square microlens array) with 2 μm-spacing were fabricated by two-photon induced polymerization. Their focal lengths are comparable to their separating distances, their spot-sizes are 0.37 μm and 0.28 μm at wavelength 530 nm, and their focusing efficiencies are 70% and 60%, respectively.

A new method for the fabrication of polymer waveguides between two optical fibers using a spatially controlled photopolymerization is reported. By taking advantage of the self-guiding effect of light through a photopolymerizable medium, polymer waveguides perfectly aligned with the fiber cores and strongly anchored to their surfaces are fabricated. The process is characterized by following in situ the coupling efficiency of a nonactinic laser source. Examples of waveguides exhibiting good coupling efficiency and high flexibility are given. By selecting the suitable monomers and adjusting the photonic parameters, the optical and mechanical waveguide properties (diameter, length, refractive index, rigidity, and flexibility) can be controlled in view of optical sensor applications. OCIS codes: 130.5460, 130.2790, 160.0160, 160.5470, 230.7370.

In this study, we fabricated a hybrid plasmonic/semiconductor material by combining the chemical bath deposition of zinc oxide nanowires (ZnONWs) with the physical vapor deposition of aluminum nanostructures (AlNSs) under controlled temperature and atmosphere. The morphological and the optical properties of the ZnONWs/AlNSs hybrid material fabricated at different temperatures (250, 350, and 450 °C) and thicknesses (5, 7, and 9 nm) of Al layers were investigated. By adjusting the deposition and annealing parameters, it was possible to tune the size distribution of the AlNSs. The resonant coupling between the plasmonic AlNSs and ZnONWs leads to an enhanced photoluminescence response. The photocatalytic activity was studied through photodegradation under UV-light irradiation of methylene blue (MB) adsorbed at the surface of ZnO. The MB photodegradation experiment reveals that the ZnONWs covered with 7 nm aluminum film and annealed at 450 °C exhibit the highest degradation efficiency. The comparison between ZnONws and ZnONws/AlNSs shows a photoluminescence enhancement factor of 1.7 and an increase in the kinetics constant of photodegradation with a factor of 4. [ABSTRACT FROM AUTHOR]

Herein, we introduce a mechanistic study to design a hybrid junction in metallic‐semiconductor (M/SC) nanostructures. UV‐light‐induced hot electron generation in ZnO nanostructures is used to precisely tune the photoluminescence (PL) and photocatalytic (PC) properties in hybrid Au/ZnO nanomaterials. Both enhancement and quenching of the PL and PC functionalities are observed, depending on the properties of the Au nanoparticles (AuNPs) and the Au/ZnO molecular distance. Under UV irradiation free‐ligand AuNPs quench the luminescence of ZnONPs through direct charge transfer (CT) from ZnO to the AuNPs. In contrast, capped AuNPs enhance the ZnO emission through indirect CT from AuNPs to ZnONPs facilitated by the distance created by the CTAB ligand between both constituents of the hybrid systems. It is necessary to optimise the Au/ZnO molecular distance to achieve an enhancement of both the plasmonic photocatalysis reaction and photoelectric properties of M/SC nanostructures. This phenomena is mediated by the energy transfer (ET) from ZnONPs to AuNPs. The resulting PL enhancement is described by the plasmon‐induced resonance energy transfer effect (PIRET effect). [ABSTRACT FROM AUTHOR]

Quantum dots optically excited in close proximity to a silver nanowire can launch surface plasmons. The challenge related to this promising hybrid system is to control the position of nanoemitters on the nanowire. We report on the use of a two-photon photopolymerization process to strategically position quantum dots on nanowires at controlled sites. A parametric study of the distance between the quantum dots and the nanowire extremity shows that precise control of the position of the launching sites enables command of light intensity at the wire end through surface plasmon propagation. [ABSTRACT FROM AUTHOR]

Here, we report for the first time a facile and fast one-step strategy to fabricate monodisperse gold nanocubes (GNCs) by spin-coating a gold precursor-loaded PMMA dispersion on N-doped silicon. A vapor induced phase separation allows PMMA self-assembly into a nanoporous film including the GNCs in its holes. Control of size and shape until obtaining monodisperse GNCs was achieved by tailoring the concentration of the gold precursor. Upon increasing this concentration, the optical properties of the GNCs such as the surface plasmon resonance has been red-shifted from 540 to 650 nm, in relation to the strong interaction between closely separated GNCs, increase in their number and PMMA thickness on the substrate surface. Therefore, the high density of hotspots in the gaps between closely spaced GNCs led to the sensitive detection of pyridine with an unprecedented SERS threshold of detection of 10−12 M. SERS experiments revealed the high chemical enhancement and allowed few molecule detection without any surface modification of the GNCs. [ABSTRACT FROM AUTHOR]

In this study, adsorption capacities of uremic toxins over Faujasite (HFAU) and Beta (HBEA) have been evaluated by varying the composition of solvent by using water, physiological, and sodium chloride solutions. HFAU was found to be more efficient in adsorption of these molecules. The adsorption results over HFAU were compared in various conditions to understand the adsorption mechanism. Thus, the adsorption mechanism was confirmed also by Fourier transform infrared and X-ray diffraction analysis, and it is found to be through the interaction of creatinine by hydrogen bonding on two types of sites on zeolites. Pseudo-second-order equation described well the adsorption kinetics data. Equilibrium isotherms were determined by Fowler-Guggenheim model. Finally, hydrophobic HFAU zeolite seems to be an efficient adsorbent; it is able to be easily regenerated under air, through retention of these initial adsorption properties. [ABSTRACT FROM AUTHOR]

This work describes a novel, one-shot strategy to fabricate ultrasensitive SERS sensors based on silver/poly(methyl methacrylate) (PMMA) nanocomposites. Upon spin coating of a dispersion of PMMA and silver precursor on N-doped silicon substrate, closely separated silver nanoparticles were self-assembled into uniform nanospheres. As a result, a thin hydrophobic PMMA layer embedded with Ag nanoparticles (AgNPs) was obtained on the whole silicon substrate. Consequently, a large-scale, reproducible SERS platform was produced through a rapid, simple, low-cost, and high-throughput technology. In addition, reproducible SERS features and high SERS enhancement factors were determined (SEF ~1015). This finding matches the highest SEF reported in literature to date (1014) for silver aggregates. The potential and novelty of this synthesis is that no reducing agent or copolymer was used, nor was any preliminary functionalization of the surface carried out. In addition, the AgNPs were fabricated directly on the substrate's surface; consequently, there was no need for polymer etching. Then, the synthetic method was successfully applied to prepare opaque SERS platforms. Opaque surfaces are needed in photonic devices because of the absence of secondary back reflection, which makes optical analysis and applications easier. [ABSTRACT FROM AUTHOR]

One of the key issues for SERS-based trace applications is engineering structurally uniform substrates with ultrasensitivity, stability, and good reproducibility. A label-free, cost-effective, and reproducible fabrication strategy of ultrasensitive SERS sensors was reported in this work. Herein, we present recent progress in self-assembly-based synthesis to elaborate precisely shaped and abundant gold nanoparticles in a large area. We demonstrated that shape control is driven by the selective adsorption of a cation (Na+, K+, and H+) on a single facet of gold nanocrystal seeds during the growth process. We studied SERS features as a function of morphology. Importantly, we found a correlation between the shape and experimental SERS enhancement factors. We observed a detection threshold of 10−20 M of bipyridine ethylene (BPE), which matches the lowest value determined in literature for BPE until now. Such novel sensing finding could be very promising for diseases and pathogen detection and opens up an avenue toward predicting which other morphologies could offer improved sensitivity. [ABSTRACT FROM AUTHOR]

Pointed carbon nanotips have been deposited on polymer microlensed optical fibers and used as highly resolving scattering nanoprobes. Optical characterizations supported by simulations demonstrate an efficient spatial filtering where the light scattered by the carbon tip is selectively coupled into the fiber core. As an application, a channel surface waveguide was characterized in collection mode. A special attention was given to the polarization response, and the s-polarized field is found to be slightly favored due to the detection direction. The proposed hybrid probe's robustness, the symmetric detection and design flexibility it offers, makes it an attractive tool for nano-optics. [ABSTRACT FROM AUTHOR]

We report here a real-time study of interactions induced phase separation between β-lactoglobulin (BLG) and Acacia gum (AG) by analyzing the localized surface plasmon resonance of silver nanoparticles. We showed that the binding of BLG to AG is accompanied by refractive index changes, in relation with optical properties and structural changes of the complexes formed. [ABSTRACT FROM AUTHOR]

In this paper, a novel method is proposed for selective deposition of ZnO nanoparticles (NPs) and growth of ZnO Nanorods (NRs) on multi‐dimensional patterned polymer surfaces. The method involves microfabrication of functionalized 1D, 2D, and 3D polymer structures by two‐photon polymerization (TPP) followed by selective assembly of ZnO NPs acting as seeds before growing ZnO NRs by chemical bath deposition (CBD) technique at low temperature. The immobilization of the ZnO NPs seed layer is done by electrostatic interaction between the positively charged polymer surface functionalized by amine groups and the negatively charged ZnO NPs functionalized by citrate molecules. The influence of citrate molecules on the stability of the ZnO NPs dispersions and their immobilization on the polymer surface is demonstrated. Spatially controlled and selective growth of ZnO NRs is shown at low temperatures on multi‐dimensional structures up to 9 mm2 and having different shapes, including 1D polymer lines, 2D microplates, and 3D arrays of cones. The diameter of NRs and their orientation can be controlled through the size of ZnO NPs and the shape of the polymer structure respectively. [ABSTRACT FROM AUTHOR]

Quantum dots (QDs) films or layers are extensively used for various photonic and electronic applications since recent decades. Three‐dimensional (3D) nanostructures are the elegant fashion in micro‐optics, microfluidics, biomedicine, and imaging. In particular, 3D photoluminescent nanostructures play an important role in detection and sensing as well as emitting systems. In this work, 3D photoluminescent structures containing QDs with feature sizes down to 80 nm are fabricated via two‐photon polymerization‐based direct laser writing. The photoluminescent images and emission spectra show strong local emission of blue, green, and red light from the polymer micro and nanostructures. The influence of the QDs, laser power, and writing scan speed on the resolution of the as‐prepared structures is also investigated. It turns out that the presence of QDs increases the lateral resolution where the feature size of polymer lines can reach 75 nm in 3D. This promising result paves the way for the integration of single nano‐emitters with a fine control of their spatial positioning in some nanophotonic devices. High‐resolution 3D photoluminescent polymer structures containing QDs are fabricated via two‐photon polymerization‐based direct laser writing. The photoluminescence images and spectra show strong local emission of blue, green, and red light from the polymer micro and nanostructures. The presence of QDs increases the lateral resolution where the feature size of polymer lines can reach 75 nm in 3D. [ABSTRACT FROM AUTHOR]

Here, we demonstrate for the first time a strategy to self-assemble ZnO nanoparticles (NP) on a large area by a facile one-step process. First, rough and random ZnO nanocrystals (NC), were produced by free-stabilizing aqueous synthesis. Therefore, a post thermal treatment at various temperatures ranging from 80 to 800 °C was necessary to obtain size-tunable and photoluminescent crystalline NP. The fabricated NP had both efficient UV photoluminescence and photocatalytic activity by photo-degradation of Methylene Blue (MB) dye. The annealed NP showed an absorption blue shift in the UV region with decreasing size. This shift was attributed to high quantum confinement effect since ZnO NP diameter reached values lower than the Bohr radius of ZnO (~2.7 nm). The photocatalytic activity displayed dependency on the particle's size, number, and crystallinity. Subsequently, the NP were self-assembled inside poly(methyl methacrylate) (PMMA) nanoholes. Subsequently, large area substrate of homogenous properties ZnO NP was obtained. Moreover, the synthesis facility, photoemission and photocatalytic properties of ZnO NP could be a new insight into the realization of high performance and low cost UV laser devices. [ABSTRACT FROM AUTHOR]

We report on a novel, to the best of our knowledge, active probe for scanning near-field optical microscopy (SNOM). A fluorescent nanosphere, acting as the secondary source, is grafted in an electrostatic manner at the apex of a polymer tip integrated into the extremity of an optical fiber. Thanks to the high photostability and sensitivity of the secondary source, the near-field interaction with a gold nanocube is investigated. It is shown that the spatial resolution is well defined by the size of the fluorescent nanosphere. The polarization-dependent near-field images, which are consistent with the simulation, are ascribed to the local excitation rate enhancement. Meanwhile, measurement of the distance-dependent fluorescence lifetime of the nanosphere provides strong evidence that the local density of states is modified so that extra information on nano-emitters can be extracted during near-field scanning. This advanced active probe can thus potentially broaden the range of applications to include nanoscale thermal imaging, biochemical sensors, and the manipulation of nanoparticles.

We show femtosecond direct laser-induced assembly of gold nanostructures with plasmon resonance band variable as a function of laser irradiation in a wide range of visible wavelengths. A system of 2-photon lithography is used to achieve site-selectively controlled dewetting of a thin gold film into nanostructures in which size and shape are highly dependent on the laser power. Simultaneous measurements of localized surface plasmon resonance (LSPR) and surface enhanced Raman scattering (SERS) in the presence of various concentrations of trans-1,2-bis(4-pyridyl) ethylene (BPE) as target molecule are performed in order to highlight the relationship between structural dimensions, plasmonic effect, and detection activity. The resulting gold NPs exhibit high sensitivity as both LSPR and SERS sensors and allow the detection of picomolar concentrations of BPE with a SERS enhancement factor (SEF) of 1.33 × 10 9 and a linear detection range between 10 -3 and 10 -12 M.

We demonstrate two-color nanoemitters that enable the selection of the dominant emitting wavelength by varying the polarization of excitation light. The nanoemitters were fabricated via surface plasmon-triggered two-photon polymerization. By using two polymerizable solutions with different quantum dots, emitters of different colors can be positioned selectively in different orientations in the close vicinity of the metal nanoparticles. The dominant emission wavelength of the metal/polymer anisotropic hybrid nanoemitter thus can be selected by altering the incident polarization.

In numerous applications of optical scanning microscopy, a reference tapered fiber lens with high symmetry at sub-wavelength scale remains a challenge. Here, we demonstrate the ability to manufacture it with a wide range of geometry control, either for the length from several hundred nanometers to several hundred microns, or for the curvature radius from several tens of nanometers to several microns on the endface of a single mode fiber. On this basis, a scanning optical microscope has been developed, which allows for fast characterization of various sub-wavelength tapered fiber lenses. Focal position and depth of microlenses with different geometries have been determined to be ranged from several hundreds of nanometers to several microns. FDTD calculations are consistent with experimental results.

We present a novel route to directly integrate an array of microlenses at the extremity of an optical fiber bundle. The method is based on photopolymerization at the end of the fiber. The method is based on the control of exposure dose and volume of the deposited droplet of photopolymerizable formulation. Optical properties of the integrated microlenses are discussed on the basis of FDTD calculations.

We report on the quantitative characterization of the plasmonic optical near-field of a single silver nanoparticle. Our approach relies on nanoscale molecular molding of the confined electromagnetic field by photoactivated molecules. We were able to directly image the dipolar profile of the near-field distribution with a resolution better than 10 nm and to quantify the near-field depth and its enhancement factor. A single nanoparticle spectral signature was also assessed. This quantitative characterization constitutes a prerequisite for developing nanophotonic applications.

Wavelength multiplexed holographic bit oriented memories are serious competitors for high capacity data storage systems. For data recording, two interfering beams are required whereas one of them should be blocked for readout in previously proposed systems. This makes the system complex. To circumvent this difficulty and make the device simpler, we validated an architecture for such memories in which the same two beams are used for recording and reading out. This balanced homodyne scheme is validated by recording holograms in a Lippmann architecture.