Surface Plasmon Resonance Of Ag Research Articles

Insight into the highly efficient degradation of PAHs in water over graphene oxide/Ag3PO4 composites under visible light irradiation

Polycyclic aromatic hydrocarbons (PAHs) are associated with adverse health effects in humans, and the photocatalysis degradation is regarded as promising technology to remove contaminants from environment. Although many TiO2-based photocatalysts were reported to be active for this process, the efficiency is still quite low. In this work, graphene oxide (GO) enwrapped silver phosphate composites were found to exhibit superior activities in the photocatalytic degradation process of a variety of PAHs (naphthalene, phenanthrene and pyrene) under visible light irradiation. The optimum amount of GO was 3.0wt%. Within several minutes or even seconds’ visible light irradiation, naphthalene, phenanthrene and pyrene can be completely oxidized. Meanwhile, good photocatalytic activity was retained after six cycles run. The trapping experiments gave evidence that degradation was mediated by photogenerated holes, superoxide radicals and hydroxyl radical, different from others OH was found to play a role in the process of pyrene photoreaction. Gas chromatography-mass spectrometer (GC-MS) technique was employed to analyze photodegradation intermediates. Based on the identified intermediates, the plausible photooxidation pathways of PAHs over the surface of GO/Ag3PO4 were proposed. Ultimately, a possible synergetic mechanism associated with Ag surface plasmon resonance effect of GO/Ag3PO4 composite for PAHs photodegradation was suggested. The superior photocatalytic system for the removal of PAHs was presented and simultaneously it shed light on photodegradation of PAHs from a practical point of view.

In Situ Growth of Low-Dimensional Silver Nanoclusters with Their Tunable Plasmonic and Thermodynamic Behavior.

Optical properties of noble metal nanostructures associated with localized surface plasmon resonance (SPR) are technically important for optical switches and plasmonic devices. In this work, silver nanoclusters are embedded inside the soda-lime glass matrix, followed by a thermal annealing process in an open air atmosphere for 1 h. The effects of thermal annealing on the plasmonic behavior of Ag nanoclusters embedded in the glass matrix are studied with UV–vis spectroscopy and photoluminescence. In the SPR spectra, a 14 nm blue shift is observed in the visible range under the influence of thermal annealing at a higher temperature. The thermal effects on Ag particle size and SPR have been illustrated for plasmonic properties. The structural and elemental investigation of as-grown Ag nanoclusters is confirmed by X-ray diffraction, high-resolution transmission electron microscope, and X-ray photoelectron spectroscopy. The structural, plasmonic, and thermodynamic properties associated with the growth mechanism of Ag nanoclusters have been explained under the thermal process. Enthalpy (ΔH), entropy (ΔS), and Gibbs energy (ΔG) for Ag nanoclusters growth and nucleation are significantly calculated and interpreted at different temperatures. An empirical relation among the ΔH, ΔS, and ΔG is developed vis-a-vis activation energy (97.70 J/mol), which is calculated by the Arrhenius linear equation.

Effect of Ag nanostructures and annealing process on the localized surface plasmon resonance properties of Ag-based AZO films

Ag nanoparticles were obtained in Ag/AZO and AZO/Ag/AZO films by magnetron sputtering method at room temperature with different deposition time. The morphology of Ag nanoparticles is strongly affected by the particle size, shape and distribution as well as annealing temperatures, which determine the optical response of films. The high quality of AZO film with better crystallinity can enhance the optical transmittance and a good coverage by AZO as top layer on Ag nanoparticles can also enhance the surface plasmon resonance (SPR) absorption of Ag in long wavelengths. The mechanisms involved in shifts and broadening of SPR peaks have been explained detailedly. The effect of annealing process on SPR of Ag and photoelectric properties of AZO/Ag/AZO films can be also discussed. It is shown that the SPR peak of 664 nm only appears in AZO/Ag (5 s)/AZO film and no SPR peaks are found in annealed AZO/Ag/AZO films. The AZO/Ag (20 s)/AZO film annealed at 300 °C shows a great figure of merit (\(F_{\text{TC}}\)) of 4.8 × 10−2 Ω−1 because of high visible optical average transmittance of 85% and low sheet resistance (\(R_{\text{S}}\)) of 4.1 Ω/sq. The overall results reveal that annealing process can improve the electrical property of film and may not be able to promote the SPR of Ag nanoparticles, especially when AZO top layer is added. The introduction of Ag nanoparticles in AZO/Ag/AZO films should be very effective for improving the SPR or photoelectric properties of films depending on deposition conditions and annealing process.

Investigation on Optical Properties of Ag–Au Alloy Nanoparticles

The outstanding chemical stability of Au and intense localized surface plasmon resonance of Ag make it possible to obtain a nanostructure with a good balance of good chemical stability and optical response. In this paper, we investigated the relationship between optical properties and the composition and size of Ag–Au alloy nanoparticle with numerical calculation by applying experimental data. Simplified empirical formulas are proposed through numerical simulation. The properties of extinction efficiency and the relative contribution of scattering and absorption efficiency to the extinction efficiency have been researched in detail. The calculated result and experimental data has been compared, and good agreement is obtained. Our work contributes greatly to catalysis application of Au–Ag alloy NPs in specific regions.

Facet-Dependent Optical and Photothermal Properties of Au@Ag–Cu2O Core–Shell Nanocrystals

This study examines the facet-dependent optical properties of size-tunable Ag–Cu2O core–shell nanocrystals with 38, 42, and 50 nm cubic Ag cores. The Ag cores were prepared from octahedral Au seeds. The Cu2O shells are single-crystalline. In the case of Au@Ag–Cu2O nanocrystals with 42 nm Ag cores, the Ag surface plasmon resonance (SPR) absorption band at 485 nm has been widely red-shifted to 730, 755, and 775 nm for rhombic dodecahedra, truncated octahedra, and cuboctahedra, respectively, after forming the Cu2O shells. The Ag SPR band positions are mostly fixed despite large changes in the shell thickness, showing the presence of facet-dependent optical properties. Because of the strong Ag SPR band absorption, all samples exhibit a better photothermal activity than that of Au–Cu2O nanocrystals. Facet-dependent heat transmission may be present for particles with a Ag SPR band much deviated from the laser wavelength, but this phenomenon is lost for particles with an SPR band approaching the excitation wavel...

Eco-friendly synthesis of silver nanoparticles and its larvicidal property against fourth instar larvae of Aedes aegypti.

In this study, larvicidal activity of silver nanoparticles (AgNPs) synthesised using apple extract against fourth instar larvae of Aedes aegypti was determined. As a result, the AgNPs showed moderate larvicidal effects against Ae. aegypti larvae (LC50 = 15.76 ppm and LC90 = 27.7 ppm). In addition, comparison of larvicidal activity performance of AgNPs at high concentration prepared using two different methods showed that Ae. aegypti larvae was fully eliminated within the duration of 2.5 h. From X-ray diffraction, the AgNP crystallites were found to exhibit face centred cubic structure. The average size of these AgNPs as estimated by particle size distribution was in the range of 50-120 nm. The absorption maxima of the synthesised Ag showed characteristic Ag surface plasmon resonance peak. This green synthesis provides an economic, eco-friendly and clean synthesis route to Ag.

Enhanced activity of Ag[sbnd]MgO[sbnd]TiO2 catalyst for photocatalytic conversion of CO2 and H2O into CH4

Using solar energy to recycle carbon dioxide (CO2) offers a brand new opportunity for simultaneous mitigation of the global climate change effect and production of energy-bearing compounds. Silver (Ag) and magnesium oxide (MgO) co-modified titania (TiO2) (AgMgTi) synthesized through a combined impregnation and photo-deposition process. The catalysts were characterized through surface area analysis, X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), ultraviolet-visible (UV–vis) diffuse reflectance spectroscopy, and photoluminescence spectrum (PL). The TEM and XPS analysis demonstrated the presence of Ag nanoparticles (NPs) on the AgMgTi catalyst. The synergistic activities of Ag NPs and MgO significantly contributed to CO2 photoreduction to methane (CH4). CH4 yield over the AgMgTi catalyst was 20 times higher than over P25 TiO2, and was higher than over single modified catalysts (MgOTiO2 or AgTiO2) under either ultraviolet (UV) or UV–vis irradiation. MgO on the surface of TiO2 enhanced the chemisorption of CO2 and/or initiated the CO2 reduction process, and hence facilitated the conversion of CO2 to CH4. Under UV light excitation, the deposited Ag NPs facilitated the separation of electron–hole due to the formation of Schottky barriers on the metal-semiconductor interface. Visible light in the solar spectrum improved the energy of trapped electrons on Ag NPs through enhanced localized electric field attributed to the Ag surface plasmon resonance (SPR) effect. Abundant electrons with higher energy facilitated CH4 formation. Therefore, more CH4 was obtained under UV–vis irradiation comparing to that under UV irradiation. This study demonstrated that the AgMgTi catalyst can effectively utilize full spectrum solar energy for simultaneous reduction of CO2 and production of energy-bearing compounds.

Confinement of Ag3PO4 nanoparticles supported by surface plasmon resonance of Ag in glass: Efficient nanoscale photocatalyst for solar H2 production from waste H2S

Ag3PO4 is a good photocatalyst but ubiquitously known for its photocorrosion problem during photocatalytic reaction. Therefore, stabilization of Ag3PO4 with retaining its fundamental properties has immense importance. With this motivation, we designed Ag3PO4 glass nanocomposite to resolve the problem of photocorrosion. Moreover, the effect of size quantization on photocatalytic activity has also been demonstrated by growing the cubic Ag3PO4 nanoparticles with size in the range of 3–9nm in glass matrix via melt and quenching method. The band gap of Ag3PO4 has been tuned (2.56–2.25eV) in glass matrix with respect to size. Considering the size tunable band gap of Ag3PO4 glass nanocomposite within visible region, it is demonstrated as a photocatalyst for hydrogen (H2) production from copious hazardous waste H2S. The utmost H2 production i.e. 3920.4μmolh−1g−1 is obtained using 1 gm of Ag3PO4 glass nanocomposite powder. The apparent quantum yield for H2 production is calculated to be 5.51% for Ag3PO4 glass nanocomposite. Interestingly, presence of plasmonic Ag was also observed in Ag3PO4 glass nanocomposite which contributes for H2 production through enhanced light absorption, efficient charge separation and improved stability. Recycling study of sample reveals stable H2 production efficiency and good stability of the photocatalyst. Surprisingly, catalyst can be reused many times and recovery of catalyst is possible just rinsing with distilled water. All these results demonstrate directly the feasibility of designing a new generation photocatalysts.

In-situ preparation and dielectric properties of silver-polyarylene ether nitrile nanocomposite films

Novel silver-polyarylene ether nitrile (Ag/PEN) nanocomposite films were fabricated by using in-situ compositing and solution-casting methods. The morphology of Ag nanoparticles and the interfaces between Ag and PEN matrix were investigation by UV–vis spectra and scanning electron microscope (SEM). The SEM results showed that Ag nanoparticles were dispersed uniformly in the PEN matrix. When the content of Ag is below 1 wt%, spherical Ag nanoparticles with diameter in 80–110 nm were observed. While the content of Ag is over 1 wt%, Ag nano-rods over 300 nm in length were formed. UV–vis spectra showed the absorption of surface plasmon resonance of Ag centered at 450–480 nm, and the peak split into two peaks with more than 1 wt% Ag. Mechanical measurements indicated that the tensile strength and tensile modulus of Ag/PEN nanocomposites were significantly improved compared with pure PEN. The glass transition temperature (T g) raised up slightly after the incorporation of Ag nanoparticles into the PEN matrix. Dielectric measurement showed that the dielectric constant increased from 4.10 to 5.80 when the content of Ag nanoparticles varied from 0 % to 2.0 wt% at 1 kHz. The dielectric loss (tan δ) was still at the lower level after the content of Ag nanoparticles increased, just 0.017 (1 kHz) even when the content of Ag nanoparticles reached 2.0 wt%. The Ag nanoparticle fillers reduced the volume resistivity of the composites significantly, which makes them promising candidates in the application of organic dielectric materials and antistatic materials.

Facile in situ synthesis of plasmonic nanoparticles-decorated g-C3N4/TiO2 heterojunction nanofibers and comparison study of their photosynergistic effects for efficient photocatalytic H2 evolution.

Ternary heterostructured nanofibers (NFs) consisting of plasmonic noble metal nanoparticles (Au, Ag, or Pt NPs), graphitic carbon nitride nanosheets (g-C3N4 NSs), and TiO2 NPs were synthesized in situ via a facile electrospinning technique combined with a subsequent thermal oxidation/reduction process. The thermal-reduced plasmonic NPs with sizes from 5 to 10 nm are dispersed uniformly into the heterojunctions of the NFs that are formed by thermal oxidation etching of exfoliated g-C3N4 NSs in the electrospun TiO2 nanofibrous matrix, as evidenced by microscopic and electronic structure analyses. In comparison to single-component photocatalysts, such as g-C3N4 NSs or TiO2 NFs, these ternary heterostructures exhibit significantly high photocatalytic activity for H2 evolution under simulated sunlight irradiation. The enhanced photoactivities are attributed to the strong photosynergistic effect between the surface plasmon resonance (SPR) and the heterojunction interface sensitization, which results in the improvement of charge-carrier generation and separation in the ternary heterostructured NFs. Further investigations indicate that coupling heterojunction sensitization on the g-C3N4/TiO2 interface with Ag SPR effects by plasmonic resonant energy transfer is the optimal strategy for synergistically improving the charge-carrier kinetics to achieve highly efficient photocatalytic H2 evolution. It is believed that our present study offers a promising method for the rational integration of multi-component photocatalytic systems that can realize high photocatalytic performances for use in solar-to-fuel conversion.

Improving g-C3N4 photocatalysis for NOx removal by Ag nanoparticles decoration

In order to overcome the intrinsic drawback of pristine g-C3N4, we prepared g-C3N4 nanosheets with enhanced photocatalytic performance by Ag nanoparticles decoration using urea as the precursor. It was revealed that the monodispersed Ag nanoparticles were deposited on the surface of g-C3N4 nanosheets. The Ag/g-C3N4 nanocomposites were applied in removal of NOx in air under visible light irradiation. The results showed that the decoration of Ag nanoparticles not only enhanced the photocatalytic activity of g-C3N4 nanosheets, but also benefited the oxidation of NO to final products. The increased visible light absorption arising from the surface plasmon resonance of Ag and improved separation and transfer of photoinduced carriers over Ag/g-C3N4 composites were demonstrated by the UV–vis diffuse reflectance spectra and photoluminescence spectra, respectively. It was therefore proposed that the enhanced photocatalytic activity of Ag/g-C3N4 composites could be attributed to the extended light response range and enhanced charge separation due to the introduction of Ag nanoparticles.

Efficient enhancement of hydrogen production by Ag/Cu2O/ZnO tandem triple-junction photoelectrochemical cell

Highly efficient semiconductor photoelectrodes for solar hydrogen production through photocatalytic water splitting are a promising and challenge solution to solve the energy problems. In this work, Ag/Cu2O/ZnO tandem triple-junction photoelectrode was designed and prepared. An increase of 11 times of photocurrent is achieved in the Ag/Cu2O/ZnO photoelectrode comparing to that of the Cu2O film. The high performance of the Ag/Cu2O/ZnO film is due to the optimized design of the tandem triple-junction structure, where the localized surface Plasmon resonance of Ag and the hetero-junctions efficiently absorb solar energy, produce, and separate electron-hole pairs in the photocathode.

Influence of size, shape and core-shell interface on surface plasmon resonance in Ag and Ag@MgO nanoparticle films deposited on Si/SiO x.

Ag and Ag@MgO core–shell nanoparticles (NPs) with a diameter of d = 3–10 nm were obtained by physical synthesis methods and deposited on Si with its native ultrathin oxide layer SiOx (Si/SiOx). Scanning electron microscopy and transmission electron microscopy (TEM) images of bare Ag NPs revealed the presence of small NP aggregates caused by diffusion on the surface and agglomeration. Atomic resolution TEM gave evidence of the presence of crystalline multidomains in the NPs, which were due to aggregation and multitwinning occurring during NP growth in the nanocluster source. Co-deposition of Ag NPs and Mg atoms in an oxygen atmosphere gave rise to formation of a MgO shell matrix surrounding the Ag NPs. The behaviour of the surface plasmon resonance (SPR) excitation in surface differential reflectivity (SDR) spectra with p-polarised light was investigated for bare Ag and Ag@MgO NPs. It was shown that the presence of MgO around the Ag NPs caused a red shift of the plasmon excitation, and served to preserve its existence after prolonged (five months) exposure to air, realizing the possibility of technological applications in plasmonic devices. The Ag NP and Ag@MgO NP film features in the SDR spectra could be reproduced by classical electrodynamics simulations by treating the NP-containing layer as an effective Maxwell Garnett medium. The simulations gave results in agreement with the experiments when accounting for the experimentally observed aggregation.

Improvement on the Performance of Holographic Polymer-Dispersed Liquid Crystal Gratings with Surface Plasmon Resonance of Ag and Au Nanoparticles

An investigation and comparison of the characteristics of holographic polymer-dispersed liquid crystal (H-PDLC) gratings doped with Ag and Au nanoparticles (NPs) is presented. The experimental results show that the diffraction efficiency and electro-optical properties of holographic gratings are improved through the addition of Ag and Au NPs. It is notable that Ag NP-doped gratings have far superior performance than those containing Au NPs. Furthermore, we find that the diffraction efficiency improvement can be explained as being due to the surface plasmon resonance of the metal NPs embedded in the PDLC. We theoretically simulate the surface plasmon resonance (SPR) wavelengths of the Ag and Au NPs within the PDLC and find that the laser wavelength used to fabricate the holographic gratings is much closer to the SPR wavelength of Ag NPs than that of Au NPs. Atomic force microscopy images show that the phase separation of the Ag-doped grating is improved, and the grating structure is much smoother than those of the undoped samples and the Au NP-doped samples, because of the SPR properties of the Ag NPs in the PDLC microstructure during the holographic recording process.

Adjustable surface plasmon resonance with Au, Ag, and Ag@Au core-shell nanoparticles

We report an experimental study on the synthesis of metal nanoparticles (NPs) with adjustable optical density based on surface plasmon resonance (SPR). Metal NPs prepared by laser ablation in liquid method and the effect of laser parameters on the size, distribution, wavelength of SPR of Ag, Au, and mixture of Ag-Au, and Ag core/Au shell NPs are investigated. Our results show that the adjustable SPR band can be achieved in each class of NPs which is suitable for adjustable optical window applications.

Sulfonated graphene oxide–ZnO–Ag photocatalyst for fast photodegradation and disinfection under visible light

Synthesis of efficient visible-light-driven photocatalyst is urgent but challenging for environmental remediation. In this work, for the first time, the hierarchical plasmonic sulfonated graphene oxide–ZnO–Ag (SGO–ZnO–Ag) composites were prepared through nanocrystal-seed-directed hydrothermal method combining with polyol-reduction process. The results indicated that SGO–ZnO–Ag exhibited much faster rate in photodegradation of Rhodamine B (RhB) and disinfection of Escherichia coli (E. coli), than ZnO, SGO–ZnO and ZnO–Ag. SGO–ZnO–Ag totally degraded RhB dye and kill 99% of E. coli within 20min under visible light irradiation. The outstanding performences of SGO–ZnO–Ag were attributed to the synergtic merits of SGO sheets, ZnO nanorod arrays and Ag nanoparticles. Firstly, the light absorption ability of SGO–ZnO–Ag composite in the visible region was enhanced due to the surface plasmon resonance of Ag. In addition, the hierarchical structure of SGO–ZnO–Ag composite improved the incident light scattering and reflection. Furthermore, SGO sheets faciliated charge transfer and reduce electron–hole recombination rate. Finally, the tentative mechanism was proposed and verified by the photoluminescence (PL) measurement as well as the theoretical finite-difference time-domain (FDTD) simulation. In view of above, this work paves the way for preparation of multi-component plasmonic composites and highlights the potential applications of SGO–ZnO–Ag in photocatalytic wastewater treatment field.

Preparation and enhanced properties of dye-sensitized solar cells by surface plasmon resonance of Ag nanoparticles in nanocomposite photoanode

A series of TiO2 photoanodes with differing amounts of Ag nanoparticles (NPs) on TiO2 in core-shell form (Ag@TiO2) are prepared and used to make a series of dye-sensitized solar cells (DSSCs). The influence of different amounts of Ag–NPs on the structure and performance of the DSSCs is investigated. Studies indicate that the short-circuit current density (Jsc), open-circuit voltage (Voc), charge lifetime and dark current of DSSCs containing Ag–NPs are significantly improved. The best performance is achieved in the DSSCs with 0.15 wt% Ag–NPs additions, with the maximum Jsc of 10.19 mA cm−2, highest Voc of 698 mV and best photoelectric conversion efficiency of 5.33%, significantly superior to that of the DSSCs with pure TiO2 photoanodes. The increase of Jsc is attributed to the enhanced dye light absorption in strength and spectral range due to the surface plasmon resonance of Ag–NPs in photoanode, while the increase of Voc may be related to the more negative level of the quasi-Fermi energy of Ag–TiO2 composite system resulting from the added Ag.

A Review of Surface Plasmon Resonance‐Enhanced Photocatalysis

AbstractIn the past decade, the surface plasmon resonance of Ag and Au nanoparticles has been investigated to improve the efficiency of photocatalytic processes. The photocatalytic production of fuels is particularly interesting for its ability to store the sun's energy in chemical bonds that can be released later without producing harmful byproducts. This Feature Article reviews recent work demonstrating plasmon‐enhanced photocatalytic water splitting, reduction of CO2 with H2O to form hydrocarbon fuels, and degradation of organic molecules. Focus is placed on several possible mechanisms that have been previously discussed in the literature. A particular emphasis is given to several aspects of these mechanisms that are not fully understood and will require further investigation.

Highly enhanced UV emission due to surface plasmon resonance in Ag–ZnO nanorods

A detailed study on the emission properties of ZnO nanorods/Ag nanoparticles for various concentrations of Ag has been presented. The photoluminescence (PL) spectra show that the near band edge (NBE) luminescence of ZnO is enhanced 10 times after Ag loading leading to an ultraviolet/visible emission ratio to 12.2 compared to a value of 1.2 for pristine ZnO nanorods. The enhancement in PL intensity is due to surface plasmon resonance coupling of the NBE emission between Ag and ZnO. We further confirm that morphology and/or surface modification do not contribute to this large increase in the band edge emission.

Carbon quantum dots/Ag3PO4 complex photocatalysts with enhanced photocatalytic activity and stability under visible light

In this study, we report the facile fabrication of Ag3PO4, CQDs/Ag3PO4, Ag/Ag3PO4 and CQDs/Ag/Ag3PO4 photocatalysts (CQDs, carbon quantum dots). For CQDs/Ag3PO4 and CQDs/Ag/Ag3PO4, because of the insoluble, photoinduced electron transfer, upconversion luminescence and electron reservoir properties of CQDs, the complex photocatalysts exhibit enhanced photocatalytic activity and structural stability over the photodecomposition of organic compounds (methyl orange) under the irradiation of visible light. Furthermore, the synergistic effect of CQDs and the intense surface plasmon resonance of Ag lead to the highest photocatalytic activity of CQDs/Ag/Ag3PO4 among Ag3PO4 and the corresponding complex photocatalysts. Our results provide an invaluable methodology for designing high-performance photocatalysts based on CQDs and related functional materials, which is promising for catalytic and new energy applications.