Nanoparticles as Catalysts: Exploring Potential Applications

W demonstrate a technique for improving the conversion efficiency in conventional silicon (Si) solar cells by using surface plasmon resonance (SPR) effects to harvest incident light energy over metal finger electrodes. Although the light absorption region beneath the metal finger electrodes cannot generate photocurrent, in this study, we employ the extraordinary transmission phenomenon, due to SPR effects, to significantly enhance the degree of light harvesting below the metal electrodes and, thereby, improve the efficiency of the entire solar cell. Therefore, the negative effect of covering the absorption area with opaque metal finger electrodes can be minimized or eliminated completely by taking advantage of the SPR effect of the metal electrodes.

Chapter 8 - Nanoengineering light-emitting materials for sensing applications

This article presents the proposed structure and simulation results from analytical modeling of a refractive index sensor and a corrosion sensor in a D-shaped single-mode optical fiber using the lossy mode resonance (LMR) and surface plasmon resonance (SPR) effects. The combined sensor consists of two cascaded D-shaped sensor regions. The first, a bilayer of titanium dioxide - aluminum, operates under LMR condition, while the second, a bilayer of gold - titanium dioxide, operates under SPR condition. The sensors are interrogated by transmitted light at 1310 and 1550 nm, in TE and TM modes. Sensor sensitivities and operating ranges are presented.

Surface plasmon resonance effect of silver decorated on BiOCl and its enhanced sunlight-active photodegradation of rhodamine B (RhB) dye and ofloxacin (OFL) antibiotic

We demonstrate a strategy for incorporating plasmon resonant metallic nanoparticles in the construction of hierarchical TiO(2) spheres. Localized electric fields can be produced by the addition of Au nanoparticles, which can excite dye molecules more effectively than incident far-field light. The synergistic effect of surface plasmon resonance with constructed TiO(2) nanostructures has been investigated, and was confirmed by optical spectroscopy, J-V characteristics, EIS analysis and OCVD measurements. When Au nanoparticles are incorporated into the constructed TiO(2) spheres, the device achieves a power conversion efficiency of 6.62%, a 4.6% increase compared to the device based on constructed TiO(2) spheres without plasmon resonant Au nanoparticles, and a 17.4% increase compared to that without any treatment.

Promotional effect of surface plasmon resonance on direct formation of hydrogen peroxide from H2 and O2 over Pd/Graphene-Au nanorod catalytic system

The BiOBr/Bi/Bi2WO6 photocatalyst with SPR effect and Z-scheme heterojunction synergistically degraded RhB under visible light

In this study, gold-loaded titanium dioxide was prepared by an impregnation method to investigate the effect of surface plasmon resonance (SPR) on photoactivity. The deposited gold nanoparticles (NPs) absorb visible light because of SPR. The effects of both the gold content and the TiO2 size of Au/TiO2 on SPR and the photocatalytic efficiency were investigated. The morphology, crystal structure, light absorption, emission from the recombination of a photoexcited electron and hole, and the degree of aggregation were investigated using transmission electron microscopy (TEM), X-ray diffraction (XRD), UV-visible-diffuse reflectance spectra (UV-VIS-DRS), photoluminescence (PL) spectroscopy, and turbidimetry, respectively. Photocatalytic activity was evaluated by the decolorization of methyl orange solution over modified titania under UV and UV/GLED (green light emitting diode) illumination. Au/TiO2 NPs exhibited an absorption peak (530-570 nm) because of SPR. The results of our photocatalytic experiments indicated that the UV-inducedly photocatalytic reaction rate was improved by simultaneously using UV and green light illumination; this corresponds to the adsorption region of SPR. Au/TiO2 could use the enhanced electric field amplitude on the surface of the Au particle in the spectral vicinity of its plasmon resonance and thus improve the photoactivity. Experimental results show that the synergistic effect between UV and green light for the improvement of photoactivity increases with increasing the SPR absorption, which in turn is affected by the Au content and TiO2 size.

Solid waste derived nanocomposite of Ag (0) loaded Fe2O3-SiO2 for solar power degradation of antibiotics

Porous graphdiyne loading CoOx quantum dots for fixation nitrogen reaction

Constructing hybrid semiconductor photocatalysts and increasing the charge-carrier density are effective strategies for enhancing the photocatalytic performance of ZnO. This study elucidates the synergistic effects of electron trapping and surface plasmon resonance (SPR) on the activity of ZnO photocatalysts. Ag/ZnO nanocomposites were synthesized on Kanthal coils using a two-step method involving the immobilization of ZnO on Kanthal coils and the coupling of Ag nanoparticles. XPS and RTPL analyses verified the synergistic effects of electron trapping and SPR on the activity of the Ag/ZnO nanocomposites. The photocatalytic performance of the composite was evaluated in the degradation of rhodamine B (RhB) dye. The Ag/ZnO nanocomposite exhibited significantly enhanced removal efficiency for RhB dye (38.2–70.5% depending on the deposition time). The Ohmic contact at the Ag/ZnO heterojunction extended the lifetime of the photoinduced charge carriers, whereas the SPR facilitated the generation of more electrons for the photocatalytic reaction. However, the excessive deposition of Ag nanoparticles compromised the photocatalytic performance of the Ag/ZnO nanocomposite. This study provides valuable insights for developing efficient ZnO-based photocatalytic materials for addressing environmental challenges.

Development of field-deployable instrumentation based on “antigen–antibody” reactions for detection of hemorrhagic disease in ruminants

The effect of surface plasmon resonance (SPR) on the photocatalytic water splitting was studied by employing the photocatalyst, Au/TiO2, to produce renewable solar hydrogen. It is well-known that metal particles on TiO2 can behave as electron traps, retarding the recombination of electron−hole pairs, thereby improving reaction activity. However, the electron trap is not the only mechanism responsible for the photoreaction enhancement. Our experiment on methylene blue photodegradation over Au particles proved that the SPR phenomenon was also involved in the photoreaction enhancement. Furthermore, the photocatalytic water splitting was performed on Au/TiO2 prepared by the photodeposition method. The production of hydrogen was significantly increased because Au particles not only acted as electron traps as well as active sites but also played an important role in the SPR enhancement. The intensified electric field at the interface between the Au particle and the subdomain on TiO2 was illustrated by finite element method (FEM) electromagnetic simulation.

Dependence of Raman intensity on the surface coverage of silver nanocubes in SERS active monolayers

This article presents the proposed structure and the simulation results from analytical and numerical modeling of two corrosion sensor elements in D-shaped optical fiber: one based on the lossy mode resonance (LMR) effect and the other based on the effect of surface plasmon resonance (SPR). In the first sensor element, a bilayer of titanium dioxide – aluminum (TiO2-Al) is deposited on the D-shaped region, operating in LMR conditions, while, in the second sensor element, an aluminum (Al) monolayer is deposited under D-shaped region, operating in SPR condition. The sensor elements can operate separately, enabling simultaneous two-parameter measurements at two different points, or they can operate in cascade configuration, increasing the operating range and sensitivity of the sensor set. The D-shaped region of the optical fiber is modeled with an analytical model based on the Fresnel formulation, and also with a numerical model, which uses the finite element method with the COMSOL Multiphysics 5.2 software. The transmission of light through the D-shaped region causes peculiar variations in each light polarization in each sensor element, depending on the metal thickness. Both regions are subject to a corrosive environment. The sensor elements are evaluated separately and in cascade configuration, using polarized and nonpolarized light. Finally, the obtained results show two resonance valleys for the same operating wavelength, resulting in a higher operating range with high sensitivity, compared to other corrosion sensor structures found in the literature.