NbCTx-supported bimetallic NPs@ZIF-8 nanohybrid as ECL signal amplifier and peroxidase mimics for chromogranin a immunosensing in human serum and saliva.

Niobium carbide (NbCTx), a key component of the MXene family renowned for its utilization in lithium-ion batteries and supercapacitors, remains largely underutilized in biosensing applications. This study introduces a notably sensitive and label-free dual-mode electrochemiluminescence (ECL) and colorimetric immunosensor to specifically detect chromogranin A (CgA) in biological fluids. Initially, AuAg bimetallic nanoparticles (BiMNPs) were synthesized using NbCTx as a reducing and supporting material.

Density Functional Theory Investigation of Temperature-Dependent Properties of Cu-Nitrogen-Doped Graphene as a Cathode Material in Fuel Cell Applications.

In this study, density functional theory (DFT) was used to investigate the influence of temperature on the performance of a novel Cu-nitrogen-doped graphene Cu-N/Gr nanocomposite as a catalyst for the oxygen reduction reaction (ORR) in fuel cell applications. Our DFT calculations, conducted using Gaussian 09w with the 3-21G/B3LYP basis set, focus on the Cu-nitrogen-doped graphene nanocomposite cathode catalyst, exploring its behavior at three distinct temperatures: 298.15 K, 353.

Cu - Nitrogen doped graphene (Cu-N/Gr) nanocomposite as cathode catalyst in fuel cells - DFT study.

Novel Cu-nitrogen doped graphene nanocomposite catalysts are developed to investigate the Cu-nitrogen doped fuel cell cathode catalyst. Density functional theory calculations are performed using Gaussian 09w software to study the oxygen reduction reaction (ORR) on Cu-nitrogen doped graphene nanocomposite cathode catalyst in low-temperature fuel cells. Three different nanocomposite structures Cu-N/Gr, Cu-N/Gr and Cu-N/Gr were considered in the acidic medium under standard conditions (298.

Enhancement of luminous efficacy of polymer light-emitting diodes with silver-nanoparticles by oxygen-plasma treatment.

Silver-nanoparticles deposited on indium tin oxide (AgNPs/ITO) with different O -plasma treatment times are used as the anode window substrate for polymer light-emitting diodes (PLED). When AgNPs/ITO with an O -plasma treatment time of 10 min is used for PLED, a maximum current efficiency of 3.33 cd/A is realized, which is notably higher than that of a reference PLED (1.

Visible-Range Multiple-Channel Metal-Shell Rod-Shaped Narrowband Plasmonic Metamaterial Absorber for Refractive Index and Temperature Sensing.

Multiple resonance modes in an optical absorber are necessary for nanophotonic devices and encounter a challenge in the visible range. This article designs a multiple-channel plasmonic metamaterial absorber (PMA) that comprises a hexagonal arrangement of metal-shell nanorods in a unit cell over a continuous thin metal layer, operating in the visible range of the sensitive refractive index (RI) and temperature applications. Finite element method simulations are utilized to investigate the physical natures, such as the absorptance spectrum, magnetic flux and surface charge densities, electric field intensity, and electromagnetic power loss density.

Enhanced photoluminescence and shortened lifetime of DCJTB by photoinduced metal deposition on a ferroelectric lithography substrate.

The photodeposition of metallic nanostructures onto ferroelectric surfaces could enable new applications based on the assembly of molecules and patterning local surface reactivity by enhancing surface field intensity. DCJTB (4-(dicyanomethylene)-2-t-butyl-6-(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran) is an excellent fluorescent dye and dopant material with a high quantum efficiency used for OLED displays on the market. However, how to raise the photoluminescence (PL) and reduce the lifetime of DCJTB in a substrate remain extraordinary challenges for its application.

Theoretical Study of CO Adsorption Interactions with Cr-Doped Tungsten Oxide/Graphene Composites for Gas Sensor Application.

The present study explores the CO adsorption properties with graphene, tungsten oxide/graphene composite, and Cr-doped tungsten oxide/graphene composite using density functional theory (DFT) calculations. The results of the study reveal the Cr-doped tungsten oxide/graphene composites, g-CrW O ( = 2 to 4), to have a lowered highest occupied molecular orbital-lowest unoccupied molecular orbital (HOMO-LUMO) energy gap, high surface reactivity, and a strong cluster-graphene binding energy, hence exhibiting a strong adsorption interaction with CO. The CO adsorption interaction shows physisorption properties by having a greater tendency for Mulliken and natural bond orbital (NBO) charge transfer supported by a strong physisorption interaction toward the g-CrW O ( = 2 to 4) composite with HOMO-LUMO energy gaps of -0.

Improved Refractive Index-Sensing Performance of Multimode Fano-Resonance-Based Metal-Insulator-Metal Nanostructures.

This work proposed a multiple mode Fano resonance-based refractive index sensor with high sensitivity that is a rarely investigated structure. The designed device consists of a metal-insulator-metal (MIM) waveguide with two rectangular stubs side-coupled with an elliptical resonator embedded with an air path in the resonator and several metal defects set in the bus waveguide. We systematically studied three types of sensor structures employing the finite element method.

Magnetic Field-Enhancing Photocatalytic Reaction in Micro Optofluidic Chip Reactor.

A small external magnetic field (100-1000 Oe) was demonstrated to enhance the photocatalytic degradation of methyl orange (MO) using TiO NPs in micro optofluidic chip (MOFC) reactors. The rectangular shape of the fluidic channel and TiO deposited only onto the lower glass substrate leads to a selectively enhancing photocatalytic reactions by magnetic field in specific directions. Utilizing ethyl alcohol as a scavenger presented the difference between generated hot-hole (hVB) and hot-electron (eCB) pathways of photocatalytic reactions.

Depolying Tunable Metal-Shell/Dielectric Core Nanorod Arrays as the Virtually Perfect Absorber in the Near-Infrared Regime.

In this paper, the coupled Ag-shell/dielectric-core nanorod for sensor application is investigated and the different dielectric core plasmonic metamaterial is adopted in our design. The operational principle is based on the concept of combining the lattice resonance, localized surface plasmon resonance (SPR), and cavity plasmon resonance modes within the nanostructure. The underlying mechanisms are investigated numerically by using the three-dimensional finite element method and the numerical results of coupled solid Ag nanorods are included for comparison.

Tunable plasmonic effects arising from metal-dielectric nanorods.

We have investigated the plasmonic effects in a two-dimensional periodic array of metallodielectric nanorods with and without the rotational angle, in which the integration of the localized surface plasmon resonance (SPR) and hollow plasmon resonance (HPR) properties is performed. Four patterns of nanostructures are investigated. We make use of the three-dimensional finite element method to obtain the simulation results, which demonstrate that the localized SPR and HPR in metallodielectric nanorods enhance the near-field intensity and increase the depth of the transmittance dip, providing an additional degree of freedom in the control of the light wave at the nanoscale.

Simultaneous realization of high sensing sensitivity and tunability in plasmonic nanostructures arrays.

A plasmonic nanostructure (PNS) which integrates metallic and dielectric media within a single structure has been shown to exhibit specific plasmonic properties which are considered useful in refractive index (RI) sensor applications. In this paper, the simultaneous realization of sensitivity and tunability of the optical properties of PNSs consisting of alternative Ag and dielectric of nanosphere/nanorod array have been proposed and compared by using three-dimensional finite element method. The proposed system can support plasmonic hybrid modes and the localized surface plasmonic resonances and cavity plasmonic resonances within the individual PNS can be excited by the incident light.

Fabrication of three dimensional split ring resonators by stress-driven assembly method.

We demonstrate a self-assembly strategy for fabricating three dimensional (3D) metamaterials. This strategy represents the desired 3D curving prongs of the split ring resonators (SRRs) erected by metal stress force with appropriate thin film parameters. Transmittance spectra and field patterns corresponding to each resonance modes are calculated by finite element method (FEM).

Long-ranging propagation based on resonant coupling effects using a series connection of ten nanoshells in a plasmon waveguide.

A two-dimensional plasmon waveguide in the form of rows of silver-shell nanorods distributed in a hexagonal lattice is proposed and compared to the solid-silver case. The transport of energy flow due to surface plasmon coupling is investigated using the finite element method for visible range wavelengths. The proposed waveguide is divided into several sections, with each section consisting of ten nanorods.

Design of plasmonic toroidal metamaterials at optical frequencies.

Toroidal multipoles are the subject of growing interest because of their unusual electromagnetic properties different from the electric and magnetic multipoles. In this paper, we present two new related classes of plasmonic metamaterial composed of purposely arranged of four U-shaped split ring resonators (SRRs) that show profound resonant toroidal responses at optical frequencies. The toroidal and magnetic responses were investigated by the finite-element simulations.

Plasmon field enhancement in silver core-protruded silicon shell nanocylinder illuminated with light at 633 nm.

We show, to the best of our knowledge, the first simulation result of the strong plasmonic field coupling and enhancement at the Ag/Si interface of a silver core/protruded silicon shell nanocylinder by using the finite-element method. The strong plasmon field, with a slow effective phase velocity accumulated at the Ag/Si interface, which results from the large effective index of the surface plasmon due to the nearly identical real parts with opposite signs of the permittivities of silver and silicon at 633 nm, is analyzed. When the silicon shell has shallow protrusions of proper periodicity to meet the phase matching condition between the incident light and the surface plasmon wave at the Ag/Si interface, a higher scattered electric field and a higher sensitivity to the refractive index change of the surrounding medium can be achieved.

Electromagnetic energy vortex associated with sub-wavelength plasmonic Taiji marks.

The Taiji symbol is a very old schematic representation of two opposing but complementary patterns in oriental civilization. Using electron beam lithography, we fabricated an array of 70 × 70 gold Taiji marks with 30 nm thickness and a total area of 50 × 50 µm(2) on a fused silica substrate. The diameter of each Taiji mark is 500 nm, while the period of the array is 700 nm.

Enhanced surface plasmon resonance based on the silver nanoshells connected by the nanobars.

Enhanced surface plasmon resonances in a silvershell nanocylindrical pair connected by a different type of nanobar that interacts with incident plane wave of transverse magnetic polarization are simulated by use of the finite element method. Arrays of silver nanoshells connected by silver nanobars are also investigated. The proposed structure exhibits a red-shifted localized surface plasmon that can be tuned over an extended wavelength range by varying the width of the nanobar and the dielectric constant in dielectric holes (DHs).

Controlling surface plasmon of several pair arrays of silver-shell nanocylinders.

We studied, numerically, the characteristics of the surface plasmon of a system consisting of several pair arrays of silver-shell nanocylinders. Effects from different numbers of pair arrays, illumination wavelengths, and the core refractive index of silver-shell nanocylinders are studied by using the finite-element method. Results show that the peak wavelengths shift to shorter wavelengths (blueshifted) when the number of pair arrays increases from three to six.

Surface plasmon resonance in a hexagonal nanostructure formed by seven core shell nanocylinders.

A hexagonal nanostructure formed by seven core shell nanocylinders filled with different dielectric cores is investigated. The surface plasmon resonance in such a hexagonal nanostructure under conditions of different illumination wavelengths, dielectric cores, angles of incidence, and thicknesses of silver shells is studied by use of the finite element method. Simulation results show that the resonant wavelength is redshifted as the dielectric constant and the size of the core increase.

Three-dimensional analysis of surface plasmon resonance modes on a gold nanorod.

We investigate the surface optical properties of a gold (Au) nanorod by using the finite-element method in a three-dimensional model. Results from the near-field optical images show spatially oscillatory patterns (nodal fields) on the surface, and these are attributable to plasmon-mode wave functions. We interpret these phenomena in terms of the electric field nodes on the surface of the rod, and the results show good agreement with our experimental observation in the optical images.

Near-field optical properties and surface plasmon effects generated by a dielectric hole in a silver-shell nanocylinder pair.

Near-field optical properties and surface plasmon effects in a silver-shell nanocylinder pair with five different dielectric holes (DHs) that interact with a transverse magnetic mode incident plane wave are simulated by use of the finite-element method, which includes the investigation of particle-particle interaction. The proposed structure exhibits a redshifted localized surface plasmon that can be tuned over an extended wavelength range by varying the dielectric constant in DHs and the thickness of the nanocylinder silver shell. The increase in the near-field intensity is attributed to a larger effective size of DH that is filled with a higher refractive medium.

High birefringence photonic crystal fiber with a complex unit cell of asymmetric elliptical air hole cladding.

High birefringence induced by elliptical air hole photonic crystal fibers (EHPCFs) is analyzed numerically using the finite-element method. Statistical correlations between the birefringence and the various parameters are obtained. We found that the complex elliptical air hole is better than that of a circular one to obtain high birefringence in photonic crystal fibers.

Coupling technique for efficient interfacing between silica waveguides and planar photonic crystal circuits.

We describe a two-step-size tapered structure with one defect pair that can markedly enhance the coupling efficiency at the entrance and exit terminals of a planar photonic crystal (PPC) waveguide. PPC waveguides are composed of circular dielectric rods set in two-dimensional square lattices. On the basis of our simulations, we found that the optimized scheme maximizes the power transmission above 90% at a wavelength of 1.