Silver Nanoplates Research Articles

Shape-Dependent Electrocatalytic Reduction of CO2 to CO on Triangular Silver Nanoplates.

Electrochemical reduction of CO2 (CO2RR) provides great potential for intermittent renewable energy storage. This study demonstrates a predominant shape-dependent electrocatalytic reduction of CO2 to CO on triangular silver nanoplates (Tri-Ag-NPs) in 0.1 M KHCO3. Compared with similarly sized Ag nanoparticles (SS-Ag-NPs) and bulk Ag, Tri-Ag-NPs exhibited an enhanced current density and significantly improved Faradaic efficiency (96.8%) and energy efficiency (61.7%), together with a considerable durability (7 days). Additionally, CO starts to be observed at an ultralow overpotential of 96 mV, further confirming the superiority of Tri-Ag-NPs as a catalyst for CO2RR toward CO formation. Density functional theory calculations reveal that the significantly enhanced electrocatalytic activity and selectivity at lowered overpotential originate from the shape-controlled structure. This not only provides the optimum edge-to-corner ratio but also dominates at the facet of Ag(100) where it requires lower energy to initiate the rate-determining step. This study demonstrates a promising approach to tune electrocatalytic activity and selectivity of metal catalysts for CO2RR by creating optimal facet and edge site through shape-control synthesis.

Strong Enhancement of Photoelectric Conversion Efficiency of Co-hybridized Polymer Solar Cell by Silver Nanoplates and Core-Shell Nanoparticles.

A new way was meticulously designed to utilize the localized surface plasmon resonance (LSPR) effect and the light scattering effect of silver nanoplate (Ag-nPl) and core-shell Ag@SiO2 nanoparticles (Ag@SiO2-NPs) to enhance the photovoltaic performances of polymer solar cells (PSCs). To prevent direct contact between silver nanoparticles (Ag-NPs) and photoactive materials which will cause electrons quenching, bare Ag-nPl were spin-coated on indium tin oxide and silica capsulated Ag-NPs were incorporated to a PBDTTT-C-T:PC71BM active layer. As a result, the devices incorporated with Ag-nPl and Ag@SiO2-NPs showed great enhancements. With the dual effects of Ag-nPl and Ag@SiO2-NPs in devices, all wavelength sensitization in the visible range was realized; therefore, the power conversion efficiency (PCE) of PSCs showed a great enhancement of 14.0% to 8.46%, with an increased short-circuit current density of 17.23 mA·cm-2. The improved photovoltaic performances of the devices were ascribed to the LSPR effect and the light scattering effect of metallic nanoparticles. Apart from optical effects, the charge collection efficiency of PSCs was improved after the incorporation of Ag-nPl.

Sensing the facet orientation in silver nano-plates using scanning Kelvin probe microscopy in air

The work function of nano-materials is important for a full characterization of their electronic properties. Because the band alignment, band bending and electronic noise are very sensitive to work function fluctuations, the dependence of the work function of nano-scale crystals on facet orientation can be a critical issue in optimizing optoelectronic devices based on these materials. We used scanning Kelvin probe microscopy to assess the local work function on samples of silver nano-plates at sub-micrometric spatial resolution. With the appropriate choice of the substrate and based on statistical analysis, it was possible to distinguish the surface potential of the different facets of silver nano-plates even if the measurements were done in ambient conditions without the use of vacuum. A phenomenological model was used to calculate the differences of facet work function of the silver nano-plates and the corresponding shift in Fermi level. This theoretical prediction and the experimentally observed difference in surface potential on the silver nano-plates were in good agreement. Our results show the possibility to sense the nano-crystal facets by appropriate choice of the substrate in ambient conditions.

Bulk Surfaces Coated with Triangular Silver Nanoplates: Antibacterial Action Based on Silver Release and Photo-Thermal Effect.

A layer of silver nanoplates, specifically synthesized with the desired localized surface plasmon resonance (LSPR) features, was grafted on amino-functionalized bulk glass surfaces to impart a double antibacterial action: (i) the well-known, long-term antibacterial effect based on the release of Ag+; (ii) an “on demand” action which can be switched on by the use of photo-thermal properties of silver nano-objects. Irradiation of these samples with a laser having a wavelength falling into the so called “therapeutic window” of the near infrared region allows the reinforcement, in the timescale of minutes, of the classical antibacterial effect of silver nanoparticles. We demonstrate how using the two actions allows for almost complete elimination of the population of two bacterial strains of representative Gram-positive and Gram-negative bacteria.

Efficiency enhancement in dye-sensitized solar cells using the shape/size-dependent plasmonic nanocomposite photoanodes incorporating silver nanoplates.

In this work, we describe the efficiency enhancement in dye-sensitized solar cells (DSSCs) by using TiO2/silver nanoplate plasmonic nanocomposite photoanodes. The nanocomposite photoanodes with tunable plasmonic properties assembled from shape/size-selected silver (Ag) nanoplates were applied to enhance the light absorption for high-performance DSSCs. It was found that the localized surface plasmon resonance can be tuned over a range from 500 to 1000 nm, which is strongly dependent on the shape and size of Ag nanoplates and the refractive index of the surrounding dielectric. The effects of the size and shape of Ag nanoplates on the surface plasmonic resonance and the efficiency of DSSCs were evaluated experimentally. Furthermore, a three-dimensional finite element method was employed to investigate the localized surface plasmon resonance (LSPR) for the shape and size effect of Ag nanoplates.

Detection of creatinine on triangular silver nanoplates surface using surface-enhanced Raman scattering sensor

In this study, we attempt to detect various concentrations of creatinine molecules on the triangular silver nanoplate films surface using a self-build surface-enhanced Raman scattering (SERS) sensor. The SERS sensor system consists of a butterfly laser diode, Inphotonic Raman fibre, Ocean Optics spectrophotometer and sensor chamber to contain the creatinine sample. Triangular-shaped silver nanoplate films were prepared on quartz surface by self-assembly technique. Detection of creatinine was done by irradiating creatinine on the triangular nanoplates surface using 785 nm of the laser light. It was found that the enhancement of the creatinine Raman peaks is linear with the creatinine concentrations. The lowest creatinine concentration that was detected by this SERS sensor is 0.005 M.

Synthesis of silver nanoplate based two-dimension plasmonic platform from 25 nm to 40 μm: growth mechanism and optical characteristic investigation in situ

We show high-purity synthesis, structural engineering and in situ optical investigation of a 2D plasmonic platform using huge silver nanoplates.

A systematic study of triangular silver nanoplates: one-pot green synthesis, chemical stability, and sensing application.

While there has been remarkable success in generating silver (Ag) nanoplates, and they have considerable potential applications, their degradation behavior in certain environments remains poorly understood. In the current work, we investigated the chemical stability of triangular Ag nanoplates. A one-step water-based synthesis method regulated by the coordination of ligands to Ag cations was successfully employed to produce triangular Ag nanoplates with a high yield. The Ag nanoplates were irreversibly degraded when they were aged with poly(styrene-4-sulfonate) (PSS) at room temperature, and the corresponding localized surface plasmon resonances (LSPR) of the Ag nanoplates changed as well. In contrast, when the Ag nanoplates were aged with potassium persulfate (KPS), the shape evolution of Ag nanoplates was found to depend on the external temperature, and the Ag nanoplate solutions showed different final colors when different external temperatures were applied. These results exhibit important implications for the behavior of triangular Ag nanoplates in a wide variety of plasmonic applications and can be applied to the colorimetric sensing of the temperature history.

Antibacterial Activities of Silver Nanoplates Controlled by Pulsed Laser

Antibacterial Activities of Silver Nanoplates Controlled by Pulsed Laser

Direct deposition of silver nanoplates on quartz surface by sequence pre-treatment hydroxylation and silanisation

Silver nanoparticles deposited on quartz substrates are widely used as SERS substrates. The nanoparticles can be deposited directly from colloidal solution by dipping technique. However, the adhesion of the particles on the quartz surface is very poor. Normally the substrate is pre-treated with hydroxylation or silanisation process. In this paper, we have demonstrated that the application of the sequence pre-treatment hydroxylation and silanisation have improved the density of silver nanoplates desposited on the quartz surface.•Sequence hydroxylation and silanisation pre-treatment assists the deposition of the nanoplate on the surface.•Various immersion times of the quartz surface into the colloidal nanoplates determined size distributions and density surface of the nanoplates on the surface.

Visual detection of glucose using triangular silver nanoplates and gold nanoparticles

A sensitive spectrophotometric detection of glucose based on triangular silver nanoplates (Ag TNPs) coupled with gold nanoparticles (Au NPs) was carried out.

Seed-Mediated Electrochemical Growth of Silver Nanoplates

A seed-mediated electrochemical method was used to grow Ag nanoplates with controllable size. The sodium citrate tribasic dihydrate was used as the capping agent to control the growth of Ag seeds, and L-ascorbic acid was employed as the reducing agent in electrolyzing growth of Ag nanoplates. Ag nanoplates with size ranging from 250 nm to 2.2 μm and thickness in several tens of nanometer have been realized. The influence of input electric current, seeds content and reaction time on the size and size uniform of Ag nanoplates were discussed and analyzed. Our method can primly control the kinetic growth process of Ag nanoplates and slow down the reaction rate, and can be easily scaled for mass production.

Detection of creatinine on triangular silver nanoplates surface using surface-enhanced Raman scattering sensor

Detection of creatinine on triangular silver nanoplates surface using surface-enhanced Raman scattering sensor

Effects of pulsed laser irradiation on gold-coated silver nanoplates and their antibacterial activity.

Gold-coated silver nanoplates, when subjected to pulsed laser irradiation, changed their shape from triangular to spherical, accompanied by a shift of their extinction spectra. The simple single crystal structure of the silver nanoplates changed to multiple small crystal domains. The ratio of silver to gold of the particles also changed from 22 : 1 to 4.5 : 1, enabling more silver to be released. As a result, the antibacterial activity of the gold-coated silver nanoplates was significantly increased after pulsed laser irradiation.

Preparation and Characterization of Ultra-Fine Silver Powder by Hydrogen Peroxide and Ascorbic Acid Reduction

In this work, using chemical reduction method, we synthesized silver particles with different sizes and morphologies by simply changing the proportion of the associative reducing agents. More specifically, when the reducing agent is ascorbic acid, the morphologies of silver particles are quasi-spherical shapes, the diameter size of silver nanoparticles was in the range from 200 nm to 300 nm. When the reducing agent is hydrogen peroxide, the morphologies of silver particles are irregular bulks, the diameter size of silver nanoparticles was in the range from 1 um to 2 um. When the volume ratio of ascorbic acid (0.09M) and hydrogen peroxide (0.98M) is 1: 1, the morphologies of silver particles are unique, they are coral clusters reunited by long silver nanoplates.

Fabrication of 3D vertically aligned silver nanoplates on nickel foam-graphene substrate by a novel electrodeposition with sonication for efficient supercapacitors

We have developed a facile, low-cost and novel method to fabricate three-dimensional (3D) vertically aligned Ag nanoplates (NPs) on nickel foam-graphene (NFG) substrate using electrodeposition with sonication (S-Electrodeposition) growth in a AgNO3 solution. The vertically deposited Ag NPs with irregular polyhedron shapes standing on the surface of NFG attributes to enhance the surface area, and sequentially be beneficial for supercapacitor. The novel architecture of composite Ag/nickel-foam graphene with sonication ((Ag@NFG)S1) exhibits a specific capacitance (SC) of 900Fg−1 at an applied current density of 0.5Ag−1, a value 3.5-fold higher than that of the composite (Ag@NFG)S0 without sonication and sixfold higher than NFG. Moreover, the composite (Ag@NFG)S1 shows good long-term cyclic stability after 5000 cycles and columbic efficiency was almost 99% with the initial value. This study provides a new strategy to enhance the capacitive properties of NFG based composites, which is a promising candidate for the application of energy storage devices.

Plasmon Resonant Silica-Coated Silver Nanoplates as Contrast Agents for Optical Coherence Tomography

Silica-coated silver nanostructures are identified as potential contrast agents for visible and near-infrared bio-imaging applications due to their high optical extinction caused by localized surface plasmon resonance (LSPR), improved chemical stability, and lower toxicity. We demonstrate the potential of plasmon resonant silica-coated silver nanoplates as a contrast agent for optical coherence tomography (OCT). It is shown that, triangular-shaped silica-coated silver nanoplates (SSNPs) with a side length of 170 ± 5 nm, base silver thickness of 10 ± 1 nm, and silica shell thickness of 40 ± 2 nm, exhibit higher optical extinction at a 1300 nm wavelength range, thus making them an excellent contrast agent for OCT imaging. Optical extinction characterization using OCT is found to be reasonably consistent with ultraviolet (UV)-Vis-near infrared (NIR) spectroscopy and finite difference time-domain (FDTD)-based analysis. Ex vivo studies on pig adipose tissue demonstrate that LSPR-induced enhanced scattering in SSNPs contributes to the OCT signal, leading to images with better contrast. Moreover, average A-scan profiles acquired at different time delays show the downward propagation of SSNPs and the extension of signal enhancement at the deeper regions. Speckle variance OCT images show that SSNPs are efficiently distributed over the targeted tissue region, demonstrating their applicability in a large lesion area.

Single layer graphene band hybridization with silver nanoplates: Interplay between doping and plasmonic enhancement

In this paper, we report single layer graphene (SLG) hybridized with silver nanoplates, in which nanoplates act as either a charge doping or a field enhancement source for the SLG Raman spectrum. Surprisingly, the stiffening of both G and 2D peaks of more than 10 cm−1 was observed with no plasmonic enhancement of peaks, indicating that p-doping from nanoplates on SLG is occurring. Such observation is explained in terms of the contact separation distance between the graphene and the silver nanoplates being enough (∼4 Å) to cause a Fermi level shift in graphene to allow p-doping. When nanoplates were modified in shape with laser irradiation by either photothermal plasmon printing or laser induced ablation, the charge doping was lifted and the strong plasmonic enhancement of Raman signals was observed, indicating that the separation distance is increased. Further, when the nanoplates are oxidized, the two effects on the Raman bands of SLG are turned off, returning the Raman signals back to the original SLG state.

DNA-Mediated Morphological Control of Silver Nanoparticles.

It is demonstrated that DNA can be used to control the synthesis of silver nanoplates with different morphologies using spherical silver seeds. UV-vis spectroscopy, transmission electron microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy are used to characterize the synthesized nanoparticles. Silver nanoprisms are encoded by poly C and poly G, while silver flower bouquets and silver nanodiscs are synthesized using poly A and poly T, respectively. The length of DNA is found to have little effect on the morphology of silver nanoparticles. Moreover, the synthesized silver nanoplates are found to have high surface enhanced Raman scattering enhancement ability, good antibacterial activity, and good biocompatibility. These discoveries will broaden the application of DNA in nanoscience and will provide a new platform to investigate the interaction between DNA sequences and silver nanoparticles.

Ferric ion-assisted in situ synthesis of silver nanoplates on polydopamine-coated silk

In the present study, a ferric ion (Fe3+)-assisted in situ synthesis approach was developed to grow silver (Ag) nanoplates on the polydopamine (PDA)-coated silk without the use of additional reductants. The essential role of Fe3+ in the formation of Ag nanoplates is revealed by comparing the morphologies of Ag nanostructures prepared on the silk-coated PDA film with/without Fe3+ doping. Scanning electron micrographs show that high-density Ag nanoplates could be synthesized in the reaction system containing 50μg/mL FeCl3 and 50mM AgNO3. The size of the Ag nanoplate could be tuned by adjusting the reaction duration. Based on the data, a mechanism involving the Fe3+-selected growth of Ag atoms along the certain crystal faces was proposed to explain the fabrication process. Transmission electron microscopy and X-ray diffractometry indicate that the Ag nanoplates possess good crystalline structures. Raman spectra demonstrate that the nanoplates could strongly enhance the Raman scattering of the PDA molecules. The Ag nanoplate-coated silk could be utilized as a flexible substrate for the development of surface-enhanced Raman scattering biosensors.