Ultrasonic-Assisted Synthesis of Monodisperse Ag Nanoparticles and Their Applications in Surface Enhanced Raman Scattering and Fluorescence Enhancement

Monodisperse Ag nanoparticles with diameters of about 3.4 nm were synthesized by a facile ultrasonic synthetic route at room temperature with the reduction of borane-tert-butylamine in the presence of oleylamine （OAm） and oleic acid （OA）. The reaction parameters of time, the molar ratios of OAm to OA were studied, and it was found that these parameters played important roles in the morphology and size of the products. Meanwhile, surface enhanced Raman spectrum （SERS） property suggested the Ag nanoparticles exhibited high SERS effect on the model molecule Rhodamine 6G. And also, two-photon fluorescence images showed that the silver nanoparticles had high performances in fluorescence enhancement.

Enhanced Photocatalytic Efficiency of TiO2 by Combining the Modification of Ag Nanoparticles with the Application of Anodic Bias

Ag-TiO2/ITO film electrode was used as photoanode to investigate the feasibility of a hybrid technology of Ag nanoparticles combined with the application of anodic bias. The results showed that the deposited Ag and applied anodic bias have an apparent additive effect.

In situ introduction of dispersed metallic Ag nanoparticles into the channels of mesoporous carbon CMK-3

An in situ reduction method has been developed to fabricate metallic Ag nanoparticles inside the channels of mesoporous carbon CMK-3. This approach combines function of the CMK-3 surface by oxidation using HNO3 with the subsequent absorption of Ag^＋ The resultant nanocomposite materials were characterized by nitrogen adsorption, X-ray diffraction, Auger electron spectroscopy and transmission electron microscopy. Compared with the conventional impregnation method, our approach shows that Ag nanonarticles of 2-4 nm can be uniformlv incorporated into CMK-3.

Formation of Copolymer-Ag Nanoparticles Composite Micelles in Three-dimensional Co-flow Focusing Microfluidic Device

A novel method was presented to create composite micelles of amphiphilic copolymers and Ag nanoparticles(NPs) in a three-dimensional co-flow focusing microfluidic device(3D CFMD). Self-assembly of the copolymers was initiated by the fast mixing of water and a blend dispersion of hydrophobic Ag NPs and amphiphilic copolymers. At the same time, the hydrophobic Ag NPs enter the core of copolymer micelles, based on the hydrophobic interaction. The copolymer-Ag NPs composite micelles have a core-shell structure with copolymer shell and Ag NPs core. COMSOL Multiphysics is used to simulate the concentration distribution of copolymers and Ag NPs under different flow rates. Co-assembly microfluidic conditions are determined based on simulation results. Under suitable microfluidic conditions, both block copolymers and gradient copolymers can co-assemble with hydrophobic Ag NPs to form composite micelles, respectively. This microfluidic coassembly method will have a good prospect in the preparation of composite micelles of amphiphilic copolymers and metal nanoparticles.

Polarization dependence of the light coupling to surface plasmons in an Ag nanoparticle & Ag nanowire system

Polarization dependence of the coupling of excitation light to surface plasmon polaritons （SPPs） was investigated in a Ag nanoparticle-nanowire waveguide system （a Ag nanoparticle attached to a Ag nanowire）. It was found that under the illumination of excitation light on the nanoparticle-nanowire junction, the coupling efficiency of light to SPPs depends on the polarization of the excitation light. Theoretical simulations revealed that it is the local near-field coupling between the nanoparticle and the nanowire that enhances the incident light to excite the nanowire SPPs. Because the shapes of the Ag nanoparticles differ, the local field intensity, and thus the excitement of the nanowire SPPs, vary with the polarization of the excitation light.

Green synthesis of Ag nanoparticles: Effect of algae life cycle on Ag nanoparticle production and long-term stability

Spherical Ag nanoparticles（AgNPs） were biologically synthesized using four different extracts prepared from Parachlorella kessleri algae cultivated for 1, 2, 3 and 4 weeks. The influence of algae life cycle on AgNPs formation and effect of different storage conditions on AgNPs long-term stability were investigated. The age of algae influenced the rate of AgNPs synthesis and amount of AgNPs in solution. The age of algae did not influence the AgNPs long-term stability. UV–vis and TEM observation revealed that long-term stability of AgNPs can be influenced by storage temperatures, and low temperature positively influences the AgNPs stability. AgNPs stored at dark and at temperature of ~5 °C showed the best long-term stability regardless of the culture age. Such AgNPs remained spherical, fine（5-20 nm） and stable（no agglomeration） even after 6 months.

Completely Green Synthesis of Ag Nanoparticles Stabilized by Soy Protein Isolate under UV Irradiation

A completely green pathway for the preparation of Ag nanoparticles was proposed, by using soy protein isolate （SPI） as stabilizer under UV irradiation and H2O as the environmentally benign solvent throughout the preparation. Transmission electronic microscopy （TEM） and zeta potential characterization results indicated that the Ag nanoparticles were stable and well dispersed with an average diameter about 13 nm, and X-ray diffraction （XRD） analysis of SPI/Ag composite nanoparticles confirmed the formation of metallic silver. UV-Vis spectrum showed that the Ag nanoparticles dispersion solution had the maximum absorbance at about 430 nm due to surface plasmon resonance of the Ag nanoparticles. Infrared spectroscopy confirmed that the polypeptide backbone of SPI was not cleaved during the conjugation process and that some active amino groups were oxidized. The SPI/Ag composite nanoparticles have excellent antibacterial activity against two representative bacteria, staphylococcus aureus （Gram positive） and escherichia coli （Gram negative） in the presence of SPI.

Enhanced optical absorption by Ag nanoparticles in a thin film Si solar cell

Thin film solar cells have the potential to significantly reduce the cost of photovoltaics. Light trapping is crucial to such a thin film silicon solar cell because of a low absorption coefficient due to its indirect band gap. In this paper, we investigate the suitability of surface plasmon resonance Ag nanoparticles for enhancing optical absorption in the thin film solar cell. For evaluating the transmittance capability of Ag nanoparticles and the conventional antireflection film, an enhanced transmittance factor is introduced. We find that under the solar spectrum AM1.5, the transmittance of Ag nanoparticles with radius over 160 nm is equivalent to that of conventional textured antireflection film, and its effect is better than that of the planar antireflection film. The influence of the surrounding medium is also discussed.

Aligned Elongation of Ag Nanoparticles Embedded in Silica Irradiated with High Energy Ni Ions

Metallic nanoparticle （NP） shapes have a significant influence on the property of composite embedded with metallic NPs. Swift heavy ion irradiation is an effective way to modify shapes of metallic NPs embedded in an amorphous matrix. We investigate the shape deformation of Ag NPs with irradiation fluence, and 357 MeV Ni ions are used to irradiate the silica containing Ag NPs, which are prepared by ion implantation and vacuum annealing. The UV-vis results show that the surface plasmon resonance （SPR） peak from Ag NPs shifts from 400 to 377nm. The SPR peak has a significant shift at fluence lower than 1 × 10^14 ions/cm2 and shows less shift at fluence higher than 1 × 10^14 ions/cm2. The TEM results reveal that the shapes of Ag NPs also show significant deformation at fluence lower than 1 × 10^14 ions/cm2 and show less deformation at fluence higher than 1 × 10^14 ions/cm2. The blue shift of the SPR peak is considered to be the consequence of defect production and Ag NP shape deformation, Based on the thermal spike model calculation, the temperature of the silica surrounding Ag particles first increases rapidly, then the region of Ag NPs close to the interface of Ag/silica is gradually heated. Therefore, the driven force of Ag NPs deformation is considered as the volume expansion of the first heated silica layer surrounding Ag NPs.

Synthesis and Characterization of Ag Nanoparticles Addition on BPSCCO Superconducting Thin Films

The growth of epitaxial Ag nanoparticles doped (Bi, Pb)-2223 thin films on Si (111) substrates by pulsed laser deposition (PLD) and post-deposition oxygen annealing have been achieved. The phase identification and gross structural characteristics of synthesized films explored through X-ray diffractometer reveal that all the samples crystallize in orthorhombic structure. DC electrical resistivity measurements were done by the standard four-probe method and the results showed improvement in Tc by increasing Ag nanoparticles to 1.0 wt% which had a maximum enhancement in Tc for all investigated films. The surface morphology investigated through scanning electron microscope (SEM) and atomic force microscopy (AFM) results showed that an increase in Tc with the appropriate Ag nanoparticles addition in the samples is associated with the enhancement of Bi (Pb)-2223 phase formation.

Synchronous activation of Ag nanoparticles and BiOBr for boosting solar-driven CO_(2)reduction

Artificial photosynthesis of valuable chemicals from CO_(2)is a potential way to achieve sustainable carbon cycle.The CO_(2)conversion activity is still inhibited by the sluggish charge kinetics and poor CO_(2)activation.Herein,Ag nanoparticles coupled Bi OBr have been constructed by in-situ photoreduction strategy.The crafting of interface between Ag nanoparticles and Bi OBr nanosheets,achieving an ultra-fast charge transfer.The Bi OBr semiconductor excited electrons and plasmonic Ag nanoparticles generated high-energy hot electrons synchronous accelerates the C=O double bond activation.Thus,the optimized Ag/BiOBr-2 heterostructure shows excellent CO_(2)photoreduction activity with CO production of 133.75 and 6.83μmol/g under 5 h of 300 W Xe lamp and visible light(λ>400 nm)irradiation,which is 1.51 and 2.81 folds versus the pristine Bi OBr,respectively.The mechanism of CO_(2)photoreduction was in-depth understood through in-situ FT-IR spectrum and density functional theory calculations.This study provides some new perspectives into efficient photocatalytic CO_(2)reduction.

Self-derivation and reconstruction of silver nanoparticle reinforced cobalt-nickel bimetallic hydroxides through interface engineering for overall water splitting

Designing efficient and long-lasting non-metal electrocatalysts is an urgent task for addressing the issue of kinetic hysteresis in electrochemical oxidation reactions.The bimetallic hydroxides,catalyzing the oxygen evolution reaction(OER),have significant research potential because hydroxide reconstruction to generate an active phase is a remarkable advantage.Herein,the complete reconstruction of ultrathin CoNi(OH)_(2) nanosheets was achieved by embedding Ag nanoparticles into the hydroxide to induce a spontaneous redox reaction(SRR),forming heterojunction Ag@CoNi(OH)_(2) for bifunctional hydrolysis.Theoretical calculations and in situ Raman and ex situ characterizations revealed that the inductive effect of the Ag cation redistributed the charge to promote phase transformation to highly activate Ag-modified hydroxides.The Co-Ni dual sites in Co/NiOOH serve as novel active sites for optimizing the intermediates,thereby weakening the barrier formed by OOH^*.Ag@CoNi(OH)_(2) required a potential of 1.55 V to drive water splitting at a current density of 10 mA cm^(-2),with nearly 98.6% Faraday efficiency.Through ion induction and triggering of electron regulation in the OER via the synergistic action of the heterogeneous interface and surface reconstruction,this strategic design can overcome the limited capacity of bimetallic hydroxides and bridge the gap between the basic theory and industrialization of water decomposition.

Synthesis, Characterization and Remedial Action of Biogenic Silver Nanoparticles and Chitosan-Silver Nanoparticles against Bacterial Pathogens

Custard apple is a dry land fruit.Its leaves exhibit different pharmacological activities.In the present study,both silver(Ag)nanoparticles and chitosan-coated Ag(Chi-Ag)nanoparticles were fabricated using the aqueous leaf extract of the custard apple plant.During preliminary phytochemical analysis,various types of phytocompounds were found in the aqueous leaf extract of the same plant.Next,both nanoparticles were physiochemically characterized.FTIR analysis exhibited the fingerprint vibrational peaks of active bioactive compounds in plant extract,Ag nanoparticles,and Chi-Ag nanoparticles.UV/Visible spectral analysis revealed the highest absorbance peak at 419 nm,indicating the presence of Ag nanoparticles.XRD analysis presented the face-centered cubic(FCC)structure of both prepared nanomaterials.Further,the average crystalline size of both Ag nanoparticles and Chi-Ag nanoparticles was calculated to be 23 and 74 nm,respectively.FESEM analysis showed the spherical and cubical shapes of Ag nanoparticles and Chi-Ag nanoparticles,respectively.EDS analysis indicated a peak around 3.29 keV,conforming to the binding energies of Ag ions.The biogenic nanomaterial also showed strong antibacterial activity against all tested bacterial pathogens.

MXene-derived TiO_(2)nanosheets decorated with Ag nanoparticles for highly sensitive detection of ammonia at room temperature

Due to their large surface-to-volume ratio and low electronic noise,two-dimensional transition metal carbides(Ti_(3)C_(2)T_(x) MXene)and their derived transition metal oxides have demonstrated significant potential for use in high-precision gas sensing.However,the construction of high-sensitivity Ti_(3)C_(2)T_(x) MXene-based gas sensors operated at room temperature(RT)is still a major challenge.Herein,we demonstrate a sensitive nanocomposite prepared by uniformly anchoring silver nanoparticles(AgNPs)on Ti_(3)C_(2)T_(x) MXene-derived transition metal oxide(TiO_(2))nanosheets for high-sensitivity NH_(3) detection.AgNPs can not only serve as spacers to effectively prevent the restacking of MXene-derived TiO_(2)nanosheets and ensure an effective transmission highway for target gas molecules,but also enhance the sensitivity of the sensor through chemical and electronic sensitization.By integrating the unique merits of the individual components and the synergistic effects of the composites,the optimized Ag@TiO_(2)nanocomposite-based sensors revealed an extraordinary response value of 71.8 to 50 ppm NH_(3) at RT with a detection limit as low as 5 ppm.In addition,the Ag@TiO_(2)NH_(3) sensor also exhibits excellent selectivity and outstanding repeatability.This strategy provides an avenue for the development of MXene derivatives for advanced gas sensors.

Improved triethylamine sensing properties of fish-scale-like porous SnO_(2) nanosheets by decorating with Ag nanoparticles

Three dimensional(3D)porous nanostructures assembled by low-dimensional nanomaterials are widely applied in gas sensor according to porous structure which can facilitate the transport of gas molecules.In this work,fish-scale-like porous SnO 2 nanomaterials assembled from ultrathin nanosheets with thick-ness of 16.8 nm were synthesized by a facile hydrothermal route.Then Ag nanoparticles were decorated on the surface of SnO_(2) nanosheets via one-step method to improve their gas-sensing performances.The sensing properties of pristine SnO_(2) and Ag/SnO_(2) nanosheets were investigated intensively.After deco-rating with Ag nanoparticles,the characteristics of SnO_(2) based sensor for triethylamine detection were significantly improved.Especially,the Ag/SnO_(2) based sensor with Ag content of 2 at%exhibited the highest triethylamine sensing sensitivity at optimum work temperature of 170?C.The improved sensing properties of Ag/SnO_(2) sensors were attributed to the sensitizing actions of Ag nanoparticles as well as the unique hierarchical porous architecture.

Detection of H_2O_2 at a composite film modified electrode with highly dispersed Ag nanoparticles in Nafion

Ag nanoparticles were prepared by using the ion-exchange of Nafion combined with electrochemical reduction on the electrode. Ag nanoparticles are highly dispersed in Nafion film with an average size of 4.0±0.2 nm.The amount of Ag nanoparticles can be readily controlled by the amount of Nafion coated on the electrode.Thus obtained Ag nanoparticles exhibit good catalytic activity for the reduction of H2O2 with a linear response to H2O2 in the concentration range of 0.04-8.0 mmol/L with a sensitivity of 0.34μA/mmol/L and a detection limit of 1.0×10^（-8） mol/L.

Enhancement of second-order harmonic generation in polarized BaTiO_3 thin films embedded with Ag nanoparticles

RECENTLY, much attention has been paid to optical properties of ferroelectric thin films. Be-

Laser stripping of Ag shell from Au@Ag nanoparticles

Metallic nanoparticles(NPs)are a class of important materials with widespread applications due to their chemical stability and high photothermal conversion efficiency.It is essential to post-control the morphology and structure of metallic NPs for practical applications.Laser processing of metallic NPs has been widely investigated.Most of previous studies on the reshaping process have been related to the single metallic NPs,and no attempt has been made to separate the components in bimetallic NPs.Here,the stripping of Ag shell from Au@Ag NPs based on ultrafast laser excitation was investigated.The experimental work combined spectrum and microscopy analysis showed the structure transformation of Au@Ag NPs.Through the electric field simulation,the stripping of the Ag shell may arise from the electric field effect.

The rapid detection for methane of ZnO porous nanoflakes with the decoration of Ag nanoparticles

Realizing the real-time detection of CH4 is important for the safety of human life.A facile hydrothermal method was used to synthesize Ag nanoparticlesdecorated ZnO porous nanoflakes(PNFs)in this study.The characterization results confirmed that Ag nanoparticles had been decorated in ZnO nanoflakes with the thickness of~10 nm.The gas-sensing properties of Ag-decorated ZnO nanoflakes were also investigated.While the gas-sensing performances of ZnO were remarkably improved by decorating Ag nanoparticles on the surface of ZnO nanoflakes,the response of the Agdecorated ZnO sensor to 3000 ppm CH4 is almost 1.3 times as high as that of pristine ZnO sensor.The obtained Ag/ZnO sensor exhibits better long-term stability and shorter response recovery time(5/38 s)in the comparison with pristine ZnO,demonstrating the possibility for the actual detection of CH4.The enhanced CH4 sensing performance can be attributed to the synergism between the unique hierarchical porous structure and the sensitizing actions utilized by the Ag nanoparticles.