Ag Precursor Research Articles

Heterogeneous to homogeneous Cu–Ag nanoparticles by laser reduction in liquid

Controlling the compositional structure of Cu–Ag bimetallic nanoparticles (NPs) is challenging due to the immiscibility of copper and silver. We report synthesis of Cu–Ag NPs with tunable compositions and structures using femtosecond laser reduction in liquid (LRL) of solutions containing copper and silver complexes dispersed in a mixture of methanol and isopropyl alcohol. Either janus or homogeneous alloy structure of Cu–Ag NPs are produced, depending on the concentration of precursors in solution. The synthesized NPs also exhibit elemental compositions in line with Cu and Ag precursor ratios. The nonequilibrium reaction conditions of LRL produce a high density of randomly distributed Ag and Cu atoms that undergo rapid cooling as they coalesce into NPs, making LRL one of the few methods for the synthesis of homogeneous CuAg alloy NPs.

Self-Heating and Hydrophobic Nanofiber Membrane Based on Ti3C2Tx MXene/Ag Nanoparticles/Thermoplastic Polyurethane for Electromagnetic Interference Shielding and Sensing Performance

High-performance electrical nanofiber membranes with outstanding electromagnetic interference (EMI) shielding, wearable sensing, self-heating, and hydrophobic performances are highly desirable for modern integrated smart wearable electronic devices. Here, lightweight, flexible, and multifunctional Ti3C2Tx/AgNPs/thermoplastic polyurethane (TPU) nanofiber membranes are prepared through microwave-assisted reduced Ag precursors followed by drip coating of Ti3C2Tx. The introduction of polydimethylsiloxane (PDMS) can endow the nanofiber membrane with hydrophobicity. The PDMS-Ti3C2Tx/AgNPs/TPU nanofiber membrane exhibits excellent EMI shielding effectiveness (SE) of 72.7 dB and outstanding long-term stability when undergoing external forces. The strain sensor based on the PDMS-Ti3C2Tx/AgNPs/TPU nanofiber membrane shows a broad sensing range of 0%–120% with a gauge factor of 146. The pressure sensor based on the PDMS-Ti3C2Tx/AgNPs/TPU nanofiber membrane possesses a wide sensing range of 400–5000 Pa with a gauge factor of 0.35 kPa–1. In addition, the PDMS-Ti3C2Tx/AgNPs/TPU nanofiber membrane presents photothermal conversion (up to 46.6 °C at light intensity of 100 mW/cm2) and hydrophobicity with a water contact angle of 116°. The effective electromagnetic shielding, sensing capability, photothermal conversion, and hydrophobicity of PDMS-Ti3C2Tx/AgNPs/TPU nanofiber membranes enable its fascinating multifunctional applications in wearable devices and ensure its use in harsh environments.

Photocatalytic Degradation of Polyethylene Microplastics and Disinfection of E. coli in Water over Fe- and Ag-Modified TiO2 Nanotubes

In this study, Fe- and Ag-modified TiO2 nanotubes were synthesized via an anodization method as photocatalysts for degradation of polyethylene microplastics and disinfection of Escherichia coli (E. coli). The anodization voltage, as well as the Fe3+ or Ag+ concentrations on TiO2 nanotubes were evaluated and correlated to their corresponding photocatalytic properties. TiO2 nanotubes were firstly synthesized by anodization of Ti plates in a glycerol-based electrolyte, followed by incorporation of either Fe or Ag via a Successive Ionic Layer Adsorption and Reaction (SILAR) method with Fe(NO3)3 and AgNO3 as Fe and Ag precursors, respectively. UV-Vis DRS shows that the addition of Fe or Ag on TiO2 nanotubes causes a redshift in the absorption spectra. The X-ray diffractograms indicate that, in the case of Fe-modified samples, Fe3+ was successfully incorporated into TiO2 lattice, while Ag scatters around the surface of the tubes as Ag and Ag2O nanoparticles. A microplastic degradation test was carried out for 90 mins inside a photoreactor with UVC illumination. TiO2 nanotubes that are anodized with a voltage of 30 V exhibit the best degradation results with 17.33% microplastic weight loss in 90 mins. Among the modified TiO2 nanotubes, 0.03 M Ag-TiO2 was the only one that surpassed the unmodified TiO2 in terms of microplastic degradation in the water, offering up to 18% microplastic weight loss in 90 min. In terms of E. coli disinfection, 0.03M Ag-TiO2 exhibit better performance than its unmodified counterpart, revealing 99.999% bactericidal activities in 10 mins. Copyright © 2022 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Facile synthesis of ZnO–Ag nanocomposite supported by graphene oxide with stabilised band-gap and wider visible-light region for photocatalyst application

The synthesis of zinc oxide (ZnO), with the support of silver (Ag) and Graphene Oxide (GO), was carried out in several stages as a potential photocatalytic material. First, the GO was synthesized from commercial graphite using the Hummers’ method, and ZnO and Ag precursors were prepared. The second stage was the electrospinning process, followed by calcination. The solution in the electrospinning process, to produce the nanofibers, was a mixture of polymer (polyvinyl alcohol), zinc acetate, AgNO3, and GO. The fibres produced were thermally treated at 500 C for 2 h. XRD and FTIR analyses confirmed that GO was successfully synthesized from commercial graphite. ZnO and Ag had wurtzite and cubic hexagonal structures based on XRD and TEM characterization. The nanocomposites developed had increased photocatalyst characteristics: low band gap energy, such as 2.98 (ZnO), 2.76 (ZnO–Ag), 2.93 (ZnO-GO), and 2.75 (ZnO–Ag-GO). Furthermore, the nanocomposites had absorption characteristics in the visible light region. Using UV–Visible spectrophotometer, Diffuse Reflectance Spectroscopy, and Photoluminescence, it was explained that the Surface Plasmon Resonance effect possessed by Ag and GO nanoparticles had semiconductor properties that acted as electron trapping, thereby reducing or preventing the occurrence of electron–hole recombination. In conclusion, the ZnO nanocomposites with the addition of Ag and GO could improve the photocatalytic characteristics of ZnO with the potential for direct application in photodegradation of organic and textile waste in water.

Drop casting based superhydrophobic and electrically conductive coating for high performance strain sensing

Conductive polymer composites (CPCs) strain sensors exhibit promising applications in flexible electronics, people’s health monitoring, etc. It remains a big challenge to develop a simple and cost-effective method to prepare CPCs with high conductivity, corrosion resistance, strong interfacial adhesion and high sensitivity. Here, we propose a facile “drop-casting and fluorination” strategy to fabricate superhydrophobic and highly electrically conductive coating by Ag precursor adsorption onto a commercially available elastic tape, subsequent chemical reduction and final fluorination. The Ag nanoparticles could not only construct the electrically conductive network but also greatly enhance the surface roughness. The contact angle and electrical conductivity of the coating can reach as high as 156° and 126 ​S/cm, respectively. When used for strain sensing, the superhydrophobic and conductive coating shows a high gauger factor (up to 7631 with the strain from 44% to 50%) and outstanding recyclability. The strain sensor could monitor different body joint motions with the stable and reliable sensing signals even after long time treatment in a corrosive solution.

Microstructure, Corrosion Resistance and Wettability of Hydroxyapatite and Silver-Doped Hydroxyapatite

In recent years, synthesis and characterization of Ag-based materials has become an active area of research due to its application in medical area for having antimicrobial properties useful for prosthetic replacement. Pure HydroxyAPatite (HAP) and 1.5wt% Ag-doped HydroxyAPatite (AgHAP) were prepared by sol-gel process and characterized. Ca(NO3)2.4H2O was used as source of Ca precursor, P2O5 was used as a source of P precursor, and AgNO3 has been used as a source of Ag precursor. Pellets of HAP and AgHAP were made after precipitates were consolidated, dried in oven, grounded and sintered in a muffle furnace. Functional groups were determined using FTIR, and compound formations were investigated using XRD. Microstructural analysis was done using SEM and AFM. Wettability was studied using OCA in distilled water, and corrosion resistance and impedance analyses were carried out using ECA in Ringer solution. It was observed from AFM and XRD that grain size decreased from 7.05 ?m to 1.25 ?m. Improvement in corrosion resistance was observed in AgHAP. Wettability studies showed that AgHAP is more hydrophilic in comparison with pure HAP. A correlation between microstructures and properties of hydroxyapetites are discussed in this paper.

Inorganic/organic hybrid nanoparticles synthesized in a two-step radiation-driven process

In this work, we have synthesized inorganic-organic hybrid nanoparticles via radiation synthesis of inorganic nanoparticles (Ag and CeO2) in aqueous dispersions containing radiation-synthesized poly(N-vinyl pyrrolidone) (PVP) nanogels (NG). The experiments show that there are strong interactions between the inorganic precursors (Ag+ and Ce3+) and the nanogel prior to irradiation. The two hybrid systems (Ag/NG and CeO2/NG) were characterized using X-ray diffraction (XRD) and transmission electron microscopy (TEM). XRD confirms the formation of crystalline Ag and CeO2. TEM reveals that the inorganic nanoparticles are evenly distributed in/on the nanogel. Both XRD and TEM show that size of the inorganic particles is controlled by the nanogel.

Silver-Carbonaceous Microsphere Precursor-Derived Nano-Coral Ag Catalyst for Electrochemical Carbon Dioxide Reduction

The selective and effective conversion of CO2 into available chemicals by electrochemical methods was applied as a promising way to mitigate the environment and energy crisis. Metal silver is regarded as an efficient electrocatalyst that can selectively convert CO2 into CO at room temperature. In this paper, a series of coral-like porous Ag (CD-Ag) catalysts were fabricated by calcining silver-carbonaceous microsphere (Ag/CM) precursors with different Ag content and the formation mechanism of CD-Ag catalysts was proposed involving the Ag precursor reduction and CM oxidation. In the selective electrocatalytic reduction of CO2 to CO, the catalyst 15 CD-Ag showed a stable current density at −6.3 mA/cm2 with a Faraday efficiency (FE) of ca. 90% for CO production over 5 h in −0.95 V vs. RHE. The excellent performance of the 15 CD-Ag catalysts is ascribed to the special surface chemical state and the particular nano-coral porous structure with uniformly distributed Ag particles and pore structure, which can enhance the electrochemical active surface areas (ECSA) and provide more active sites and porosity compared with other CD-Ag catalysts and even Ag foil.

Ag metal interconnect wires formed by pseudoplastic nanoparticles fluid imprinting lithography with microwave assistant sintering

Nanoimprint technology has the advantages of low cost, high precision, high fidelity and high yield. The metal nanoparticle fluid is non-Newtonian fluid, which is used as the imprint transfer medium to realize high fidelity of pattern because of its shear thinning effect. In order to functionalize the metal nanoparticles microstructure, the subsequent sintering step is required to form a metal interconnect wire. Metal interconnect wire with fewer grain boundaries and fewer holes have excellent mechanical and electronic properties. In this paper, the pseudoplastic metal nanoparticle fluid was formed by Ag nanoparticle and precursor solution, and then the thermal diffusion process was completed by microwave sintering after interconnects were embossed. The influence of microwave and thermal atmosphere on the microstructure and performance of Ag Interconnect wires was analyzed and discussed, and the Ag Interconnect wires performance was determined under the influence of time and temperature parameters. In our experiments, the interconnects after microwave sintering can achieve 39% of the conductivity of bulk silver. The microwave sintering module might be integrated as the heat treatment module of the metal micro/nano pattern directly imprint lithography.

Effects of the method of active site characterization for determining structure-sensitivity in Ag-catalyzed ethylene epoxidation

Catalysts have been prepared on a low surface area α-Al2O3 support used commercially for previous generation olefin epoxidation catalysts. Prescreening of the low surface area alumina (0.73 m2/g) indicated the absence of acid catalyzed isomerization of EO at an evaluation temperature of 210 °C. A 0.1 wt% Ag base material synthesized by incipient wetness impregnation of AgNO3 was used as a base material for electroless deposition (ED) of additional Ag to increase particle sizes by controlled reduction of Ag+ directly onto the preexisting Ag surface to form weight loadings between 0.3 and 5.0 wt% metal. A 12 wt% Ag/α-Al2O3 using Ag2C2O₄ as the Ag precursor was also prepared to compare performance of the ED samples with a catalyst more typical of industrial formulations. Characterization by SEM, STEM, and hydrogen titration of oxygen precovered Ag characterized before and after catalytic evaluation indicated that microscopy is required to accurately represent distributions of Ag particle sizes, but H2 titration of O-precovered Ag gives the best representation of active sites since it directly counts the number of Ag surface sites. Larger particles >100 nm are resistant to both Ag sintering and carbon foulant; TOF values were relatively insensitive to particle size with only a 2.2 × difference between the best and worst performing samples. Selectivity, which is not a function of TOF, shows the most significant structure sensitivity effect where particle sizes follow the trend 67 nm ≈ 92 nm (58% EO) < 157 nm (67% EO) < 211–542 nm (73% EO). The lower EO selectivities were also correlated with increased fouling for the smaller Ag sizes, suggesting that more strongly bound EO precursor(s) leads to combustion and CO2/H2O formation.

Effect On The Variation Of Irradiation Time and Power Of UVC Lamp On Photocatalyst Degradation Of Iron (III) Sulfate Dye Waste

This study aimed to determine the effect of variation in irradiation time and UVC lamp power on the degradation of iron (III) sulfate dye waste with the help of photocatalyst TiO2-Ag-Zeolite nanocomposite. TiO2 used was technical TiO2, Ag precursor was AgNO3 and, zeolite powder. The method used was sol-gel for the synthesis of TiO2-Ag-Zeolite. A photoreactor with irradiation with some UVC lamps (6,8,10 W) o in the catalyst test. The experimental result of the reduction process of iron (III) sulfate with the addition of TiO2-Ag-Zeolite catalyst and variations in reaction time (10,20,30,40,50 and 60 min) obtained the highest peak concentration of about 51% at 60 min with 6 and 8 W for pH > 4.0.

Synthesis of Silver Nanocomposites for Stereolithography: In Situ Formation of Nanoparticles.

Additive Manufacturing (AM) offers remarkable advantages in relation to traditional methods used to obtain solid structures, such as the capability to obtain customized complex geometries adapted to individual requirements. The design of novel nanocomposites suitable for AM is an excellent strategy to widen the application field of these techniques. In this work, we report on the fabrication of metal/polymer nanocomposites with enhanced optical/electrical behaviour for stereolithography (SLA). In particular, we analyse the in situ generation of Ag nanoparticles (NPs) from Ag precursors (AgNO3 and AgClO4) within acrylic resins via SLA. Transmission electron microscopy (TEM) analysis confirmed the formation of Ag NPs smaller than 5 nm in all nanocomposites, providing optical activity to the materials. A high density of Ag NPs with a good distribution through the material for the larger concentration of AgClO4 precursor tested was observed, in contrast to the isolated agglomerations found when the precursor amount was reduced to 0.1%. A significant reduction in the electrical resistivity up to four orders of magnitude was found for this material compared to the unfilled resin. However, consumption of part of the photoinitiator in the formation process of the Ag NPs contributed to a reduction in the polymerization degree of the resin and, consequently, degraded the mechanical properties of the nanocomposites. Experiments with longer curing times showed that, for the higher AgClO4 concentrations tested, post-curing times of 300 min allowed an 80% degree of polymerization to be achieved. These conditions turned these materials into promising candidates to obtain solid structures with multifunctional properties.

Role of Anionic Backbone in NHC-Stabilized Coinage Metal Complexes: New Precursors for Atomic Layer Deposition.

Cu and Ag precursors that are volatile, reactive, and thermally stable are currently of high interest for their application in atomic‐layer deposition (ALD) of thin metal films. In pursuit of new precursors for coinage metals, namely Cu and Ag, a series of new N‐heterocyclic carbene (NHC)‐based CuI and AgI complexes were synthesized. Modifications in the substitution pattern of diketonate‐based anionic backbones led to five monomeric Cu complexes and four closely related Ag complexes with the general formula [M( tBuNHC)(R)] (M=Cu, Ag; tBuNHC=1,3‐di‐tert‐butyl‐imidazolin‐2‐ylidene; R=diketonate). Thermal analysis indicated that most of the Cu complexes are thermally stable and volatile compared to the more fragile Ag analogs. One of the promising Cu precursors was evaluated for the ALD of nanoparticulate Cu metal deposits by using hydroquinone as the reducing agent at appreciably low deposition temperatures (145–160 °C). This study highlights the considerable impact of the employed ligand sphere on the structural and thermal properties of metal complexes that are relevant for vapor‐phase processing of thin films.

Fabrication of Bimetallic Cu-Ag Nanoparticle-Decorated Poly(cyclotriphosphazene-co-4,4'-sulfonyldiphenol) and Its Enhanced Catalytic Activity for the Reduction of 4-Nitrophenol.

We reported a study on the preparation of bimetallic Ag–Cu nanoparticles (NPs) impregnated on PZS poly(cyclotriphosphazene-co-4,4′-sulfonyldiphenol) nanotubes via a facile and efficient reduction method. Herein, PZS nanotubes consisting of enriched hydroxyl groups are fabricated through an in situ template method, and then, fluctuating the amount ratios of Cu and Ag precursors, bimetallic NPs can be fabricated on readily prepared PZS nanotubes using NaBH4 as a reductant, which results in a series of bimetallic catalysts having tunable catalytic activity. The characterization investigations of scanning electron microscopy, X-ray diffraction, transmission electron microscopy, and Fourier transform infrared spectroscopy results show that Ag–Cu bimetallic NPs are well-dispersed, ultrasmall in size, and well-anchored on the surface of PZS nanotubes. In addition, to examine the catalytic activity and reusability of these nanocomposites, reduction of 4-nitrophenol to 4-aminophenol is utilized as a prototype reaction. The optimized Ag–Cu NPs with a copper ratio of 0.3% are well-stabilized by the organic–inorganic poly(cyclotriphosphazene-co-4,4′-sulfonyldiphenol) nanotubes. The obtained results show that bimetallic NPs have remarkably higher catalytic ability than that of their monometallic counterparts with maximum catalytic activity. These results are even better than those of noble metal-based bimetallic catalysts and pave the avenue to utilize the polyphosphazene polymer as a substrate material for highly effective bimetallic catalysts.

Tuning the Shape of Gold‐Silver Nanocrystals by Separately Controlling the Metal‐Atom Concentration in a One‐Pot Synthesis

AbstractWe report a niche synthetic strategy to manipulate the shape of gold‐silver (AuAg) nanocrystals based on kinetics control. The success of current work relies on the use of two syringe pumps to add Au and Ag precursor solutions independently at distinct injection rates, which allows the separate control over the feeding rate of Au and Ag atoms, respectively. Such strategy is validated effective in both one‐pot reduction and seeded growth involving spherical and rod‐likes Au seeds. By conducting orthogonal experiments setting two injection rates at three levels, a set of morphologies are obtained. Interestingly, AuAg alloy nanocrystals in the form of multipod, hollow protruded particles, and branched hollow nanoplate, that are rare to obtain via conventional routes, are successfully screened out, exhibiting the unique advantage of this strategy. The current work provides a feasible approach to applying kinetics control over AuAg bimetallic nanocrystals, which could be extended to other noble metals or material combinations.

Synergistic catalytic hydrolysis of ammonia borane to release hydrogen over AgCo@CN

Synergistic catalytic AB hydrolysis to generate hydrogen was achieved over AgCo@CN synthesized by auto-reduction between Co@CN and a Ag precursor.

Ultrasmall Ag clusters in situ encapsulated into Silicalite-1 zeolite with controlled release behavior and enhanced antibacterial activity

Effectively controlling the release behavior of silver bactericide to promote its antibacterial ability is highly important in the fields of chemical, biomedical and biotechnology industry. In this study, ultrasmall Ag clusters were successfully encapsulated into silicalite-1 zeolite through in situ hydrothermal approach, and the key to this success was choosing 3-mercaptopropyltriethoxysilane as ligand to facilitate Ag precursor involved into zeolite initial sol-gel system. The structure of prepared silicalite-1 zeolite encapsulation of Ag clusters (denoted as Ag@Silicalite-1) has been well defined with various characterizations and probe reactions. Benefiting from confinement effect and shape-selectivity of silicalite-1 zeolite, Ag@Silicalite-1 sample showed much better Ag + controlled release performance than that of sample with Ag nanoparticles impregnated onto silicalite-1 zeolite (denoted as Ag/Silicalite-1). The release behavior of Ag + in Ag@Silicalite-1 can be well described with ritger-peppas model. Taking killing Escherichia coli as an example, in comparison with Ag/Silicalite-1, Ag@Silicalite-1 sample displayed more efficient and sustainable antibacterial activity for its controlled release character. • Ultrasmall Ag clusters were successfully in situ encapsulated into silicalite-1 zeolite. • Encapsulated Ag clusters displayed interesting controlled release behavior and well anti-poisoning property. • Silicalite-1 encapsulated Ag clusters showed sustainable and efficient antibacterial activity.

Synthesis and Characterization of Ag-Decorated TiO2 Nanoparticles for Photocatalytic Application

TiO2 nanoparticles (TiO2) and Ag-doped TiO2 nanocomposites (Ag-TiO2) were synthesized by the Sol-Gel process using titanium tetra isopropoxide as TiO2 and AgNO3 as Ag precursors, respectively. The synthesized nanocomposites were characterized by XRD, SEM, TEM, FT-IR, and UV­-Visible analysis. The XRD results show that Ag doping increases the grain size from 22 nm to 36 nm. From the UV-Visible spectra, the redshift in absorbance was observed, which indicates the increase in grain size and it reduces the bandgap. The TEM analysis shows that all the particles are exhibited in the nanometer range. The synthesized nanoparticles show good photocatalytic activity, and they decompose the methyl orange dye within 5 hours.

Real-Time Monitoring of the In Situ Microfluidic Synthesis of Ag Nanoparticles on Solid Substrate for Reliable SERS Detection.

A sharpened control over the parameters affecting the synthesis of plasmonic nanostructures is often crucial for their application in biosensing, which, if based on surface-enhanced Raman spectroscopy (SERS), requires well-defined optical properties of the substrate. In this work, a method for the microfluidic synthesis of Ag nanoparticles (NPs) on porous silicon (pSi) was developed, focusing on achieving a fine control over the morphological characteristics and spatial distribution of the produced nanostructures to be used as SERS substrates. To this end, a pSi membrane was integrated in a microfluidic chamber in which the silver precursor solution was injected, allowing for the real-time monitoring of the reaction by UV–Vis spectroscopy. The synthesis parameters, such as the concentration of the silver precursor, the temperature, and the flow rate, were varied in order to study their effects on the final silver NPs’ morphology. Variations in the flow rate affected the size distribution of the NPs, whereas both the temperature and the concentration of the silver precursor strongly influenced the rate of the reaction and the particle size. Consistently with the described trends, SERS tests using 4-MBA as a probe showed how the flow rate variation affected the SERS enhancement uniformity, and how the production of larger NPs, as a result of an increase in temperature or of the concentration of the Ag precursor, led to an increased SERS efficiency.

Transparent back‐junction control in Cu(In,Ga)Se2 absorber for high‐efficiency, color‐neutral, and semitransparent solar module

AbstractTransparent oxide back contact of Cu(In,Ga)Se2 (CIGS) solar cells is crucial for semitransparent or bifacial CIGS photovoltaics. Parasitic GaOx resistive layer formed at the back junction, however, has been the bottleneck for transparent photovoltaic applications. Here, we show that a complementary control of the back junction enabled a high efficiency, semitransparent CIGS module. By employing a thin Ag precursor layer prior to CIGS evaporation, the back‐junction barrier could be eliminated. Atomic probe tomography measurement suggests that an appreciable amount of Ag doping in the GaOx may form hole‐tunneling channels at the back junction. We also found that potassium fluoride (KF) post‐deposition treatment (PDT) increased the back‐junction resistance and the bulk CIGS resistance compared to the case with Na PDT. The KF‐induced increased resistances turned out to be beneficial for suppressing the parasitic shunt current along the P1‐scribing region in our CIGS solar module. Interestingly, J–V rollover caused by the KF‐induced back‐junction barrier completely vanished after see‐through laser scribing of the module. We attribute the barrier‐lowering to a laser‐induced local heating at the back junction. The complementary engineering strategy introduced here would allow functional oxide back contact in CIGS photovoltaic modules for both high efficiency and semi‐transparency.