Structure Of Ag Research Articles

Effects of CO and NO atmospheres on the morphology of Ag, Ni, and Ir nanoparticles

Metal nanoparticles are widely used in multiphase catalytic reactions due to their excellent physicochemical properties, which are mainly determined by their size and shape. Therefore, predicting and controlling the shape and structure of metal nanoparticles under reaction conditions has been a popular topic of interest among researchers. In this study, we conducted a systematical investigation to the equilibrium structure of Ag, Ni, and Ir nanoparticles within a mixed gas environment of CO and NO, employing a multiscale structural reconstruction model. This model demonstrates the ability to accurately predict the equilibrium configuration of metal nanoparticles under reactive conditions. Our investigation reveals a notable presence of negative surface energy in the phase diagrams representing Ag, Ir, and Ni nanoparticle configurations. This distinctive feature signifies that the nanoparticles undergo a process of splitting. While undergoing temperature and total pressure variations, the transformation in the structure of Ni nanoparticles is comparatively less evident in contrast to that of Ag and Ir nanoparticles. This discrepancy primarily stems from the pronounced energy barrier posed by the substantial rejection of CO and NO molecules at the surface of Ni nanoparticles. Notably, the structural modifications within Ag nanoparticles manifest solely within the confines of low-temperature ranges. Furthermore, our observations underscore the significant impact exerted by the ratios of CO and NO partial pressures on both the structure and the count of active sites within the metal nanoparticles.

Low-temperature sintering of silver-ammonia complex organic composite ink shows high conductivity for humidity sensors

The development of flexible electronic devices is faced with the challenge of difficult fabrication of complex functional structures on flexible substrates. In this paper, a high viscosity ink of silver-ammonia complex was developed based on the reductive ink principle. Using the electrohydrodynamic direct writing, composite fiber patterned printing was achieved on a flexible substrate. By low-temperature sintering of precursor fibers for reduction, a dense silver structure was formed on the surface, resulting in the formation of Ag/PEO conductive fibers. This approach avoided the high temperature damage to the flexible substrate and the adhesion of materials, while demonstrating good conductivity. The Ag/PEO conductive fibers exhibited different sensitivities to H2O molecules in low, medium, and high humidity environments, which were used to design a flexible Ag structure humidity sensor (ASHS) as a functional material. The ASHS showed a linear response relationship and a fast response speed in an environmental humidity range of 11 % to 75 %RH, enabling real-time monitoring of human respiration. This study demonstrates a promising application prospect of the silver-ammine complex ink in the field of flexible electronic devices.

Structural transformations in Cu, Ag, and Au metal nanoclusters.

Finite-temperature structures of Cu, Ag, and Au metal nanoclusters are calculated in the entire temperature range from 0K to melting using a computational methodology that we proposed recently [M. Settem et al., Nanoscale 14, 939 (2022)]. In this method, Harmonic Superposition Approximation (HSA) and Parallel Tempering Molecular Dynamics (PTMD) are combined in a complementary manner. HSA is accurate at low temperatures and fails at higher temperatures. PTMD, on the other hand, effectively samples the high temperature region and melts. This method is used to study the size- and system-dependent competition between various structural motifs of Cu, Ag, and Au nanoclusters in the size range 1-2nm. Results show that there are mainly three types of structural changes in metal nanoclusters, depending on whether a solid-solid transformation occurs. In the first type, the global minimum is the dominant motif in the entire temperature range. In contrast, when a solid-solid transformation occurs, the global minimum transforms either completely to a different motif or partially, resulting in the co-existence of multiple motifs. Finally, nanocluster structures are analyzed to highlight the system-specific differences across the three metals.

In vitro analysis of novel trimetallic (Ag–Cu–Ni TNC) to handle benzene and benzopyrene pollutants in an aqueous environment

In this study, a trimetallic nanocomposite comprising Silver Copper–Nickel (Ag–Cu–Ni TNC) was synthesized and analysed for its efficiency in degrading benzene and benzopyrene, which has five fused benzene rings. Fabrication of trimetallic nanocomposites were characterized using UV spectroscopy, FTIR studies, SEM EDAX, and DLS results. XRD confirmed the cubic crystalline Fcc structure of Ag–Cu–Ni TNC. Photocatalytic degradation analysis revealed that Ag–Cu–Ni TNC has the efficient photocatalytic ability, and the optimum condition required for efficient degradation of benzene and benzopyrene was identified as 2 μg/mL of PAH molecule, 10 μg/mL of Ag–Cu–Ni TNC at pH 5, stirring time of 2 h placed under UV light. Based on these optimum conditions, kinetic and isotherm studies were performed, revealing that the adsorption of benzene and benzopyrene by Ag–Cu–Ni TNC fits well with the Pseudo-second order kinetic model and Freundlich isotherm model. Thus, our study's adsorption of PAH molecule from aqueous solution takes place through chemisorption and involves heterogeneous adsorption phenomena.

In situ fabrication of Ag decorated porous ZnO photocatalyst via inorganic–organic hybrid transformation for degradation of organic pollutant and bacterial inactivation

In this study, in situ silver (Ag) - porous ZnO photocatalysts were synthesized via solvothermal and post-annealing treatment. The formation of the porous ZnO structure due to the removal of organic moieties from the inorganic–organic hybrids Ag-ZnS(en)0.5 during the annealing process. The optimal Ag–ZnO photocatalyst showed excellent photocatalytic degradation activity, with 95.5% orange II dye and 97.2% bisphenol A (BPA) degradation under visible light conditions. Additionally, the photocatalytic inactivation of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) led to a 97% inactivation rate after 2 h under dark conditions. Trapping experiments suggest that the superoxide anion (▪O2−) radicals are the main active species to degrade the organic dye. The improved photocatalytic dye degradation activity and inactivation of bacteria were attributed to the synergistic effect of Ag and porous ZnO structure, increased surface area, and efficiently separated the photoexcited charge carriers. This work could provide an effective strategy for the synthesis of porous structures toward organic pollutant degradation and bacterial inactivation in wastewater.

Highly Sensitive Detection of Formaldehyde by Laser-Induced Graphene-Coated Silver Nanoparticles Electrochemical Sensing Electrodes.

Formaldehyde (HCHO) poses a grave threat to human health because of its toxicity, but its accurate, sensitive, and rapid detection in aqueous solutions remains a major challenge. This study proposes a novel electrochemical sensor composed of a graphene-based electrode that is prepared via laser induction technology. The precursor material, polyimide, is modified via the metal ion exchange method, and the detective electrode is coated with graphene and silver nanoparticles. And the special structure of graphene-coated Ag was demonstrated using scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM), and X-ray diffraction (XRD), Fourier transform infrared (FT-IR), and X-ray photoelectron spectroscopy (XPS) results show that graphene provides more sites for Ag NRs to be exposed and increases the surface area of contact between the solution and the detection object. In addition, differential pulse voltammetry (DPV) analysis exhibits high linearity over the HCHO concentration range from 0.05 to 5 μg/mL, with a detection limit of 0.011 μg/mL (S/N = 3). The Ag NPs in the electrochemical reaction will adsorb the intermediate •CO and •OH, catalyze their combination, and finally convert to CO2 and H2O, respectively. A microdetection device, specially designed for use with commercial micro-workstations, is employed to fully demonstrate the practical application of the electrode, which paves a way for developing formaldehyde electrochemical sensors.

Super-high interface adhesion through silver/polyimide heterojunction

Metallized polymer film is becoming increasingly common in cutting-edge technology fields, and interface adhesion is the key factor affecting service performance. In this article, we used all-wet process to prepare Ag/Polyimide composite film with ultra-high interface adhesion (Over 25 N/cm). The influence of etching and reduction on interface adhesion was analyzed using central composite experiments and response surface methodology. Microcracks on polyimide (PI) surface were the basis for the formation of mechanical interlocks. And combined with SEM, EDS, and XPS data, the effect of Ag structure and composition on interface adhesion during reduction was summarized. The role of Ag aggregations at interface was explained, and concluded the detachment of Ag aggregations during peeling and high temperature was the main reason of failure. RFID tag, Circuit, and Cu/Ag/PI film (Resistivity: 9.3 × 10−6 Ω·cm) were made, which confirmed the compatibility and usability of Ag/PI film.

The role of ligand isomerism in the solid-state structures of AgI formamidine complexes

The role of ligand isomerism in the solid-state structures of Ag^I formamidine complexes

Coinage metals doped 1T′ WS2 as efficient bifunctional electrocatalyst towards ORR and HER: A first principles study

The electrocatalytic activities of Cu, Ag and Au doped 1T′ WS2 as electrocatalysts for oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER) in acidic medium are explored by means of first principles calculations. The stability of these doped systems are inspected in terms of formation energy and charge transfer analysis upon doping. Highest amount of charge transfer towards the dopant is observed for systems with lowest formation energy. For all the doped systems, charge is transferred to the dopant that substitutes the anionic S atom validating the doping scheme and stability of the doped systems. ORR proceeds only via the energetically efficient four electron pathway on Cu doped 1T′ WS2 with a monotonically exothermic free energy profile. In the case of Ag and Au doped structures, ORR occurs competitively via both two and four electron pathways due to the marginal free energy difference in the 2nd protonation step between these two pathways and produces both H2O or H2O2 competitively as the end product. Study of the effect of electrode potential variation on the free energy profiles reveals the overpotential for ORR on Cu, Ag and Au doped 1T′ WS2 to be 0.85 V, 0.80 V and 0.66 V respectively via the four electron pathway. Proneness of Cu doped 1T′ WS2 towards only the four electron pathway and low overpotential for ORR makes it the promising cathode electrocatalyst for ORR among the considered systems. Further study of the HER activity of Cu, Ag and Au doped 1T′ WS2 reveals the Gibbs free energy of H+ ion adsorption on Cu doped 1T′ WS2, Ag doped 1T′ WS2 and Au doped 1T′ WS2 to be −0.14 eV, −0.17 eV and 0.18 eV respectively indicating high efficiency of those system towards HER in acidic medium.

Self-passivated CdS buffer layer for antimony sulfide solar cells

Sb2S3 has been paid extensive attentions as absorber for solar cells. Comparing with some oxides, CdS exhibits excellent compatibility to Sb2S3 therefore is most commonly used as buffer layer (BL) materials for Sb2S3 solar cells. Proper passivation can enhance the performance of CdS buffer layer thus raising the performances of Sb2S3 solar cells. Herein, we put forward a self-passivation strategy to enhance the performance of CdS by a two-step deposition process to fabricate the self-passivated CdS BL. First, we adopted spin coating combined with annealing process to prepare flaked CdS on FTO, then we performed passivation process to the CdS by depositing another layer of CdS with chemical bath deposition (CBD) method. After Sb2S3 was deposited on the self-passivated CdS by hydrothermal method, a solar cell with FTO/CdS (∼90 nm)/Sb2S3 (160 nm)/Spiro-OMeTAD(48 nm)/Ag(32 nm)structure was obtained by deposition of hole transport layer and Ag electrodes. Comparing with the single spin-coating processed CdS BL or single chemical bath deposited CdS BL, the self-passivated CdS presents better performance. The CBD process presents distinctive passivation effects to the first layer. In consequence, we obtained the highest PCE of 6.04 % in the Sb2S3 solar cells on the self-passivated CdS BL. The present work supplies a unique route to enhance the performances of CdS buffer layer.

Performance optimization of a CsGeI3-based solar device by numerical simulation

Germanium-based halide perovskites (CsGeI3) are good absorbers materials for eco-friendly perovskite solar devices. In this work, a numerical analysis via SCAPS-1D software, is done to enhance the performance of a device already experimentally realized (FTO/TiO2/CsGeI3/Spiro-OMeTAD/Ag). After selecting SnO2 and CuI as best Charge transport materials (CTMs) in front of others, we have optimized their thicknesses, we investigated the impact of: CsGeI3 thickness, its defect density (Nt), its acceptor concentration, CuI doping density, SnO2 doping density, SnO2/CsSnI3 defect density, CsSnI3/CuI defect density, also the impact of shunt resistance, series resistance, and temperature. Finally, we have achieved a new solar device based on CsGeI3, with a fully inorganic FTO/ SnO2/CsGeI3/CuI/Ag structure. The final output parameters are PCE = 15.68 %, FF = 73.45 %, JSC = 22.56 mA/cm2 and VOC = 0.946 V at room temperature. The results are beneficial for the design and manufacture of CsGeI3-based solar devices.

Ruthenium, rhodium and iridium complexes of a silyl-substituted N-heterocyclic carbene ligand and their catalytic performance in hydrosilylation of terminal alkynes

Herein, [Ru(NHC)(p-cymene)Cl2] (3) and [MCl(NHC)(cod)] (M=Rh (4) or Ir (5)) (cod=1,5‒cyclooctadiene) complexes of a silyl‒substituted N-heterocyclic carbene ligand (NHC) have been prepared by the transmetalation reaction between Ag‒NHC (2) and corresponding starting metal compound. The characterization of the complexes has been completed by NMR spectroscopy and elemental analyses. Solid state structures of Ag- (2) and Rh-NHC (4) have also been determined by single crystal X-ray analysis. [RhCl(NHC)(CO)2] type bis-carbonyl complex (6) has also been prepared and CO stretching frequencies pointed the strong σ‒donor ability of the silyl-substituted NHC. The catalytic activity of all complexes have been examined in hydrosilylation of terminal alkynes. Among the complexes, Ir-NHC has been found out as active catalyst with around 90% conversion and β‒(Z) selectivity at room temperature. Further studies revealed that this complex is able to maintain its stability in catalytic reaction conditions, chemoselective to alkynes in the presence of alkenes, and operable in scale-up reactions. In contrast, bis-carbonyl Rh-NHC performed 82% β‒(Z) selectivity with full conversion of alkyne in first 4 h of reaction, but when reaction time was extended to 24 h, almost all β‒(Z) vinylsilane isomerised to thermodynamically more stable β‒(E).

Improved Differential Evolution Algorithm for Sensitivity Enhancement of Surface Plasmon Resonance Biosensor Based on Two-Dimensional Material for Detection of Waterborne Bacteria

Due to the large number of waterborne bacteria presenting in drinking water, their rapid and accurate identification has become a global priority. The surface plasmon resonance (SPR) biosensor with prism (BK7)-silver(Ag)-MXene(Ti3T2Cx)-graphene- affinity-sensing medium is examined in this paper, in which the sensing medium includes pure water, vibrio cholera (V. cholera), and escherichia coli (E. coli). For the Ag-affinity-sensing medium, the maximum sensitivity is obtained by E. coli, followed by V. cholera, and the minimum is pure water. Based on the fixed-parameter scanning (FPS) method, the highest sensitivity is 246.2 °/RIU by the MXene and graphene with monolayer, and with E. coli sensing medium. Therefore, the algorithm of improved differential evolution (IDE) is obtained. By the IDE algorithm, after three iterations, the maximum fitness value (sensitivity) of the SPR biosensor achieves 246.6 °/RIU by using the structure of Ag (61 nm)-MXene (monolayer)-graphene (monolayer)-affinity (4 nm)-E. coli. Compared with the FPS and differential evolution (DE) algorithm, the highest sensitivity is more accurate and efficient, and with fewer iterations. The performance optimization of multilayer SPR biosensors provides an efficient platform.

High‐pressure Synthesis, Structure, IR Spectroscopy, and Theoretical Calculations of the New Silver Tetraborate Ag2B4O7 with a Unique Crystal Structure

AbstractAg2B4O7 is synthesized at high‐pressure/high‐temperature conditions of 11 GPa and 1073 K in a multianvil device. It crystallizes in the monoclinic centrosymmetric space group P21/c (no. 14) with four formula units per unit cell (Z=4). The cell parameters are a=787.53(3), b=651.63(2), c=943.88(3) pm, β=107.911(2)°, and V=460.90(3) Å3. Ag2B4O7 crystallizes in a unique crystal structure that consists of complex anionic borate layers with Ag+ ions in between. Additionally, the silver cations show argentophilic interactions. The compound was analysed via single‐crystal and powder diffraction as well as infrared spectroscopy. Furthermore, theoretical calculations at HSEsol level were conducted.

Structure and Reactivity of Ag(I) Complexes Bearing Tridentate Phosphinine Ligands

Structure and reactivity of novel Ag(I) complexes with tridentate phosphinine (phosphabenzene) ligands are discussed in this article. An equilibrium between the dimer and the monomer was observed for the λ3-phosphinine Ag(I) complex in the solution state. The λ3-phosphinine Ag(I) complex can be oxidized by PhI(OAc)2 to afford λ5-phosphinine species, maintaining the coordination to the metal center. Photochemical properties of the Ag(I) complexes were also investigated, and the emission of the λ3-phosphinine Ag(I) complex showed solvatochromic behavior.

Breakdown and Photoconductivity Enhancement by Mixed Reflective Al-Doped ZnO/Ag Electrode in Vertical SiC Photoconductive Switch

an axial-triggering vertical SiC photoconductive switch with Al-doped ZnO placed under the Ag electrode is developed to enhance breakdown strength and photoconductivity. Traditional and new devices with the AZO/SiC/Ag and AZO/SiC/AZO/Ag structures, respectively, were prepared. Test results show that the conductivity of the new device is approximately 1.2 times higher than that of the old one, attributable to the diffuse reflection effects of the AZO/Ag mirror. Under high bias voltages of up to 16.5 kV/mm and a 30-ns pulse width laser input, the new device shows significantly enhanced breakdown strength. The new device has a lifetime of >1E4 shots, whereas the old device has a maximum lifetime of approximately 1E2 shots. The new device can continuously output electrical pulses for 10 minutes at a 100 Hz repetition rate, 30-ns pulse width, and 100 A peak current without breakdown.

Silver doped ZnSnO3/SnO hybrid nanostructures as DSSC photoanodes: Charge injection dynamics, slow recombination kinetics and simulation studies

Sol-gel synthesis was used to develop a new hybrid photoanode material, a spherical zinc stannate/tin oxide nanorod named ZSTP. The subsequent step involves doping ZSTP with silver using a precursor called silver nitrate. The undoped sample was labelled as ZSTP, whereas silver-doped composites containing 1, 2, and 3 wt% silver were labelled as ZSTP-Ag1, ZSTP-Ag2 and ZSTP-Ag3 respectively. The pattern of powder X-ray diffraction (PXRD) with 2θ values of 26.52 and 33.84 confirms the orthorhombic structure of ZSTP and silver-doped samples. In the FT-IR spectra of the ZSTP and their silver-doped samples, the stretching frequency for Zn–O–Sn is observed at 1100 and 1464 cm−1. In addition, the surface-adsorbed Ag peaks at 1384 cm−1. The XPS spectra of ZSTP-Ag3 confirms the existence and structure of SnO and Ag. Examining the morphology with a scanning electron microscope (SEM) and transmission electron microscope (TEM) reveals a porous structure with adsorbed Ag on the surface. Doped silver appears as tiny spherical particles on the surfaces, whereas SnO nanorod zinc stannate appears as spherical particles in the TEM image. In-depth optical experiments were conducted to evaluate the characteristics of hybrid composites for DSSC applications. It was explored how the dye aggregates on the surface of silver-doped ZSTP. On the basis of the energy levels of their conductance bands, the electron transfer kinetics and energy transfer mechanism were predicted. Under a conventional one-sun illumination condition, the output photocurrent and photovoltage of these DSSC materials are evaluated. ZSTP-Ag3 offered the highest PCE at 1.38%. Due to the role of Ag2O in electron transfer, silver doped samples based devices offer a high FF (0.7) and steady photovoltage. Using the photovoltage decay curve, the recombination time (τrec) and rate (krec) were calculated to confirm a slower rate of recombination. Using simulated results, the overall performance of the DSSC is compared and validated.

Identification of a Novel Keto Sugar Component in Streptococcus pneumoniae Serotype 12F Capsular Polysaccharide and Impact on Vaccine Immunogenicity.

Implementation of conjugate vaccine technology revolutionized the ability to effectively elicit long-lasting immune responses to bacterial capsular polysaccharides. Although expansion of conjugate vaccine serotype coverage is designed to target residual disease burden to pneumococcal serotypes not contained in earlier vaccine versions, details of polysaccharide Ag structure, heterogeneity, and epitope structure components contributing to vaccine-mediated immunity are not always clear. Analysis of Streptococcus pneumoniae serotype 12F polysaccharide by two-dimensional nuclear magnetic resonance spectroscopy and mass spectrometry revealed a partial substitution of N-acetyl-galactosamine by the keto sugar 2-acetamido-2,6-dideoxy-xylo-hexos-4-ulose (Sug) in up to 25% of the repeat units. This substitution was not described in previous published structures for 12F. Screening a series of contemporary 12F strains isolated from humans (n = 17) identified Sug incorporation at varying levels in all strains examined. Thus, partial Sug substitution in S. pneumoniae serotype 12F may have always been present but is now detectable by state-of-the-art analytical techniques. During the steps of conjugation, the serotype 12F Sug epitope is modified by reduction, and both polysaccharide PPSV23 and conjugate PCV20 vaccines contain 12F Ags with little to no Sug epitope. Both PCV20 and PPSV23 vaccines were evaluated for protection against circulating 12F strains with varying amounts of Sug in their repeat unit based on an opsonophagocytic killing assay involving HL-60 cells and rabbit complement. Both vaccines elicited human-derived neutralizing Abs against serotype 12F, independent of Sug level between ∼2 and 25 mol%. These findings suggest that the newly identified serotype 12F Sug epitope is likely not an essential epitope for vaccine-elicited protection.

Crystal Growth and Crystal Structures of Gold(V) Compounds: Cu(AuF6)2, Ag(AuF6)2, and O2(CuF)3(AuF6)4 ⋅ HF

AbstractCrystal growth from anhydrous hydrogen fluoride solutions of M2+(M=Cu, Ag) and [AuF6]−gave M(AuF6)2salts (M=Cu, Ag). Similar attempts to prepare single crystals of the corresponding nickel, zinc and magnesium salts failed. The crystal structure of Cu(AuF6)2consists of layers of Cu2+cations connected by [AuF6]−anions, thus forming slabs. Only van der Waals interactions exist between adjacent slabs. The crystal structure of Ag(AuF6)2consists of a three‐dimensional framework in which Ag+cations are linked by [AuF6]−anions. Both structures are members of the MII(XVF6)2family, in which seven different structure types have been observed to date. In the crystal structure of O2(CuF)3(AuF6)4 ⋅ HF, the bridging AuF6units connect [−Cu−F−Cu−F−]∞chains to form stacks between which O2+cations and HF molecules are located.

Arabinogalactan Structures of Repetitive Serine-Hydroxyproline Glycomodule Expressed by Arabidopsis Cell Suspension Cultures.

Arabinogalactan-proteins (AGPs) are members of the hydroxyproline-rich glycoprotein (HRGP) superfamily. They are heavily glycosylated with arabinogalactans, which are usually composed of a β-1,3-linked galactan backbone with 6-O-linked galactosyl, oligo-1,6-galactosyl, or 1,6-galactan side chains that are further decorated with arabinosyl, glucuronosyl, rhamnosyl, and/or fucosyl residues. Here, our work with Hyp-O-polysaccharides isolated from (Ser-Hyp)32-EGFP (enhanced green fluorescent protein) fusion glycoproteins overexpressed in transgenic Arabidopsis suspension culture is consistent with the common structural features of AGPs isolated from tobacco. In addition, this work confirms the presence of β-1,6-linkage on the galactan backbone identified previously in AGP fusion glycoproteins expressed in tobacco suspension culture. Furthermore, the AGPs expressed in Arabidopsis suspension culture lack terminal-rhamnosyl residues and have a much lower level of glucuronosylation compared with those expressed in tobacco suspension culture. These differences not only suggest the presence of distinct glycosyl transferases for AGP glycosylation in the two systems, but also indicate the existence of minimum AG structures for type II AG functional features.