Bare Ag Research Articles

Design and construction of a novel hierarchical Ag/{1 1 1}Ag3PO4/PANI/Pt photoanode with boosted interfacial charge transfer rate and high photocurrent density > 16 mA/cm2 for sunlight-driven water splitting

In this work, a novel hierarchical photoanode structure of Ag/{111}Ag3PO4/PANI/Pt was synthesized, demonstrating a novel and facile approach to design a high-performing Ag3PO4-based photoanode for visible-light-driven solar green hydrogen (H2) generation. The Ag3PO4 photoanode with carefully curated active facets, Ag/{111}Ag3PO4, was interfaced with a conductive polyaniline (PANI) thin film and surface decorated with platinum nanoparticles (Pt NPs) to realise the combined advantages of integrating both PANI and Pt NPs as a hole-transporting layer and co-catalysts, respectively. This novel photoanode achieved a record photocurrent density of 16.34 mA/cm2 at 1.4 V vs Ag/AgCl under AM 1.5 G solar irradiation (100 mW/cm2), which outperformed that of the bare Ag/{111}Ag3PO4 photoanode and is also the highest photocurrent density reported to date for Ag3PO4-based photoanodes. The PEC enhancement is attributed to the new exploitation of the PANI-{111}Ag3PO4p-n heterojunction, the hole-transporting property of PANI and the electron-capturing capability of Pt NPs, in which their synergetic interactions effectively led to improved light absorption, enhanced charge separation and reduced charge recombination. It is foreseen that this current work can provide a base for further nanoarchitectural design strategies to construct efficient photoanodes used in PEC water splitting application.

Dry Printing of Ag–Ni Conductive Particles Using Toner-Type Printed Electronics

Printed electronics are a set of additive manufacturing methods for creating future flexible electronics on thin polymeric sheets. We proposed the toner-type, dry, page-printing of Ag–Ni composite conductive particles on flexible plastic sheets without pre-treatment. No chemical solvents are necessary to compose the inks of the electronic materials used for the toner-type printing, and no chemical treatment is required for the plastic film substrate surface. In addition, multilayer printing is simple when using toner printing because previously printed materials do not need to be resolved; furthermore, composing the thick films of the electronic materials is relatively simple. In this study, we fabricated an Ag–Ni composite toner to improve the fluidity of the toner particles compared to bare Ag particles. We successfully printed IC peripheral circuits at a resolution of 0.20 mm and demonstrated that the actual electrical circuit pattern can be formed using our method.

Non-Oxidized Bare Metal Nanoparticles in Air: A Rational Approach for Large-Scale Synthesis via Wet Chemical Process.

Metal nanoparticles (MeNPs) have been used in various industrial applications, owing to their unique physical and chemical properties different from the bulk counterparts. However, the natural oxidation of MeNPs is an imminent hindrance to their widespread applications despite much research efforts to prevent it. Here, a rational approach for non‐oxidized bare MeNPs in air, which requires no additional surface passivation treatment is reported. The direct synthetic route uses the [Gd2C]2+ · 2e− electride as an exceptional electron‐donating agent to reduce diverse metal precursors in alcoholic solvents. All synthesized bare Cu, Ag, and Sn nanoparticles are ultra‐stable in ambient air, exhibiting no trace of metal oxides even on their outermost atomic layer. This unique resistance to oxidation is ascribed to the accumulation of excess electrons on the surface of bare MeNPs, which originates from the spontaneous transfer of anionic electrons from the electride during the nanoparticle growth process. This approach provides not only a revolutionary scheme to obtain MeNPs with non‐passivated and non‐oxidized surfaces, but also fundamental knowledge about metal oxidation.

Boosting bacteria differentiation efficiency with multidimensional surface-enhanced Raman scattering: the example of Bacillus cereus.

Surface-enhanced Raman scattering (SERS) is a powerful tool for constructing biomolecular fingerprints, which play a vital role in differentiation of bacteria. Due to the rather subtle differences in the SERS spectra among different bacteria, artificial intelligence is usually adopted and enormous amounts of spectral data are required to improve the differentiation efficiency. However, in many cases, large volume data acquisition on bacteria is not only technical difficult but labour intensive. It is known that surface modification of SERS nanomaterials can bring additional dimensionality (difference) of the SERS fingerprints. Here in this work, we show that the concept could be used to improve the bacteria differentiation efficiency. Ag NPs were modified with 11-mercaptoundecanoic acid, 11-mercapto-1-undecanol, and 1-dodecanethiol to provide additional dimensionality. The modified NPs then were mixed with cell lysate from different strains of Bacillus cereus (B. cereus). Even by applying a simple PCA process to the resulting SERS spectra data, all the three modified Ag NPs showed superior differentiation results compared with bare Ag NPs, which could only separate Staphylococcus aureus (S. aureus) and B. cereus. It is believed that the multidimensional SERS could find great potential in bacteria differentiation.

Hybrid Surface-Enhanced Raman Scattering Substrates for the Trace Detection of Ammonium Nitrate, Thiram, and Nile Blue.

We report the fabrication and performance evaluation of hybrid surface-enhanced Raman scattering (SERS) substrates involving laser ablation and chemical routes for the trace-level detection of various analyte molecules. Initially, picosecond laser ablation experiments under ambient conditions were performed on pure silver (Ag) and gold (Au) substrates to achieve distinct nanosized features on the surface. The properties of the generated surface features on laser-processed portions of Ag/Au targets were systematically analyzed using UV–visible reflection and field emission scanning electron microscopy studies. Later, hybrid-SERS substrates were achieved by grafting the chemically synthesized Au nanostars on the plain and laser-processed plasmonic targets. Subsequently, we employed these as SERS platforms for the detection of a pesticide (thiram), a molecule used in explosive compositions [ammonium nitrate (AN)], and a dye molecule [Nile blue (NB)]. A comparative SERS study between the Au nanostar-decorated bare glass, silicon, Ag, Au, and laser-processed Ag and Au targets has been established. Our studies and the obtained data have unambiguously determined that laser-processed Ag structures have demonstrated reasonably good enhancements in the Raman signal intensities for distinct analytes among other substrates. Importantly, the fabricated hybrid SERS substrate of “Au nanostar-decorated laser-processed Ag” exhibited up to eight times enhancement in the SERS intensity compared to laser-processed Ag (without nanostars), as well as up to three times enhancement than the Au nanostar-loaded plain Ag substrates. Additionally, the achieved detection limits from the Au nanostar-decorated laser-processed Ag SERS substrate were ∼50 pM, ∼5 nM, and ∼5 μM for NB, thiram, and AN, respectively. The estimated enhancement factors accomplished from the Au nanostar-decorated laser-processed Ag substrate were ∼106, ∼106, and ∼104 for NB, thiram, and AN, respectively.

Ag nanoparticle interaction with complex lipidbilayer: an atomistic and coarse-grained study

Understanding nanoparticle (NP) translocation through complex cellular membranes is required for pre-evaluating their toxicity. Silver (Ag) is a common material, extensively applied in NP form for its apparent anti-bacterial properties. While so widely available, data about their interaction with lipid membranes, particularly the role of size and surface functionalization in membrane binding, is relatively scarce. As a first step, we performed all-atom biased and unbiased molecular dynamic simulations for bare Ag NPs for three sizes (1/3/5 nm diameter) with a complex membrane of DPPC:DOPC:POPC:Chol in 5:2:2:1 representing model lung membrane.

Metal-Dielectric-Graphene Hybrid Heterostructures with Enhanced Surface Plasmon Resonance Sensitivity Based on Amplitude and Phase Measurements

Metal-dielectric-graphene hybrid heterostructures based on oxides Al2O3, HfO2, and ZrO2 as well as on complementary metal–oxide–semiconductor compatible dielectric Si3N4 covering plasmonic metals Cu and Ag have been fabricated and studied. We show that the characteristics of these heterostructures are important for surface plasmon resonance biosensing (such as minimum reflectivity, sharp phase changes, resonance full width at half minimum and resonance sensitivity to refractive index unit (RIU) changes) can be significantly improved by adding dielectric/graphene layers. We demonstrate maximum plasmon resonance spectral sensitivity of more than 30,000 nm/RIU for Cu/Al2O3 (ZrO2, Si3N4), Ag/Si3N4 bilayers and Cu/dielectric/graphene three-layers for near-infrared wavelengths. The sensitivities of the fabricated heterostructures were ~ 5–8 times higher than those of bare Cu or Ag thin films. We also found that the width of the plasmon resonance reflectivity curves can be reduced by adding dielectric/graphene layers. An unexpected blueshift of the plasmon resonance spectral position was observed after covering noble metals with high-index dielectric/graphene heterostructures. We suggest that the observed blueshift and a large enhancement of surface plasmon resonance sensitivity in metal-dielectric-graphene hybrid heterostructures are produced by stationary surface dipoles which generate a strong electric field concentrated at the very thin top dielectric/graphene layer.

Enhanced surface wettability of Ag:TiO2 heterostructured assembly using double step glancing angle deposition technique

Ag nanoparticles and TiO2 nanowires were fabricated to make Ag:TiO2 heterostructured assemblies using the double-step glancing angle deposition (GLAD) technique. TiO2 nanowires and Ag:TiO2 heterostructured assemblies are prepared to compare the morphological, structural, and water contact angle (CA) measurements. Field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) have been used to analyse the growth and effective size of Ag nanoparticles and TiO2 nanowires. The x-ray diffraction (HRXRD) was carried out to analyse the crystalline size and micro lattice strain. Atomic force microscopy (AFM) analysis has been performed to modify the surface roughness and corresponding surface roughness factor. The surface wettability of the prepared samples was evaluated by measuring the water CA. For bare TiO2 nanowires and Ag:TiO2 heterostructures based samples, the static water CA is 131.6° and 81.6°, respectively. Over a 60 min duration, water CA decreased from 131.6° to 117.2° for bare TiO2 nanowires and from 81.6° to 29.6° for Ag:TiO2 heterostructures. The sliding angles of 24.14° and 33.36°, the maximum friction force of 4.01 μN and 5.39 μN, along with the work of adhesion of 24.08 mN/m and 84.18 mN/m, has been calculated for bare TiO2 nanowires and Ag:TiO2 heterostructures, respectively. The Ag:TiO2 heterostructured assembly has a higher wettability conversion rate of 2.84 × 10−6 degree−1 min−1 compared to the bare TiO2 nanowires (6.05 × 10−5 degree−1 min−1). As a result, all the improved parameters of the Ag:TiO2 heterostructured assembly have a high potential for the use of antifogging and smart surfaces application.

Design of direct Z-scheme superb magnetic nanocomposite photocatalyst Fe3O4/Ag3PO4@Sep for hazardous dye degradation

• Z-scheme Fe 3 O 4 /Ag 3 PO 4 @Sep magnetic nanocomposite photocatalyst is synthesized. • Synergy between Fe 3 O 4 , Ag 3 PO 4 , and Sepiolite is crucial for enhanced photocatalysis. • Holes and hydroxyls radicals are the main reactive species for MG dye degradation. Z-scheme Fe 3 O 4 /Ag 3 PO 4 @Sep magnetic nanocomposite photocatalyst was prepared via an eco-friendly co-precipitation approach. Various analytical methods were used to assess the structure, the morphology, and the optical absorption properties of the photocatalyst. The sepiolite as support of Ag 3 PO 4 and Fe 3 O 4 nanoparticles, prevented the aggregation and the photo-corrosion of the bare Ag 3 PO 4 , and enhanced the photocatalytic stability and activity of the photocatalyst by a synergetic effect. Further, the band gap energy of the nanocomposite photocatalyst, as determined from the density functional theory calculations, was reduced, from 2.59 eV for Ag 3 PO 4 (1 1 0), and from 2.98 eV for Fe 3 O 4 (2 2 0), to about 2.37 eV for Fe 3 O 4 /Ag 3 PO 4 @Sep. The obtained dye degradation rate value of 0.480 min −1 , was 69 times superior to pure Fe 3 O 4 , 5 times higher than the bare Ag 3 PO 4 , and 3 times higher than Ag 3 PO 4 @Sep. More importantly, Fe 3 O 4 /Ag 3 PO 4 @Sep shows continuous photocatalytic activity, even after three cycles of reuse.

Influence of glucose, sucrose, and dextran coatings on the stability and toxicity of silver nanoparticles

Aqueous colloids, consisting of 15–30 nm-sized silver nanoparticles (Ag NPs), were prepared using the reducing and stabilizing abilities of glucose, sucrose, and dextran. The long-term stability of coated Ag NPs increases from glucose over sucrose to dextran, i.e., with the increase of the molecular weight of carbohydrate molecules. The density functional theory (DFT) calculations of the partial atomic (Mulliken) charges and adsorption energies are applied to explain the enhanced stability of coated Ag NPs. All coated Ag NPs have a significantly broader concentration range of nontoxic behavior toward pre-osteoblast cells than bare Ag NPs prepared using sodium borohydride. The carbohydrate-coated Ag NPs display the same level of toxic ability against Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria as bare Ag NPs. The differences in toxicity mechanism of the coated and bare Ag NPs are a consequence of the absence and presence of co-occurring Ag+ ions in examined dispersion, respectively.

Plasmonic Core-Shell-Satellites with Abundant Electromagnetic Hotspots for Highly Sensitive and Reproducible SERS Detection.

In this work, we develop a Ag@Al2O3@Ag plasmonic core–shell–satellite (PCSS) to achieve highly sensitive and reproducible surface-enhanced Raman spectroscopy (SERS) detection of probe molecules. To fabricate PCSS nanostructures, we employ a simple hierarchical dewetting process of Ag films coupled with an atomic layer deposition (ALD) method for the Al2O3 shell. Compared to bare Ag nanoparticles, several advantages of fabricating PCSS nanostructures are discovered, including high surface roughness, high density of nanogaps between Ag core and Ag satellites, and nanogaps between adjacent Ag satellites. Finite-difference time-domain (FDTD) simulations of the PCSS nanostructure confirm an enhancement in the electromagnetic field intensity (hotspots) in the nanogap between the Ag core and the satellite generated by the Al2O3 shell, due to the strong core–satellite plasmonic coupling. The as-prepared PCSS-based SERS substrate demonstrates an enhancement factor (EF) of 1.7 × 107 and relative standard deviation (RSD) of ~7%, endowing our SERS platform with highly sensitive and reproducible detection of R6G molecules. We think that this method provides a simple approach for the fabrication of PCSS by a solid-state technique and a basis for developing a highly SERS-active substrate for practical applications.

Facile synthesis of MgS/Ag2MoO4 nanohybrid heterojunction: Outstanding visible light harvesting for boosted photocatalytic degradation of MB and its anti-microbial applications

In this paper, a novel MgS/Ag 2 MoO 4 nanocomposite (NCs) was synthesized for the evaluation of photocatalytic performance and anti-microbial activity. The particle was characterized using FT-IR, PL, HR-TEM, EDAX, XRD, XPS, SAED, UV–vis DRS, ESR, and EIS. The performance of the photocatalyst was improved by shift in band gap to 2.76 eV compared to its individual counter parts. The photocatalytic performance of MgS/Ag 2 MoO 4 NCs was much better than MgS and Ag 2 MoO 4 as individual particles. The reaction rate constant for degrading MB by MgS/Ag 2 MoO 4 was 0.011 min −1 . The degradation efficiency of MgS/Ag 2 MoO 4 (90%) was about 1.5 and 2.2 times greater than bare Ag 2 MoO 4 (62%) and MgS (41%). The photocatalytic degradation efficiency remains same with 90% efficiency after performing the reusability test for six consecutive cycles under visible light irradiation and the particles maintained photo stability even after 6 cycles. The strong interactions between the interfacial surfaces are responsible for the increase in charge separation owing to the superior activity of MgS/Ag 2 MoO 4 NCs. The mechanism was established for this enhanced activity and the key reactive species, such as hydroxyl and superoxide radicals plays a major role in the photocatalytic process. The antimicrobial activity was evaluated against E. coli and B. subtilis and the activity of Ag 2 MoO 4 was good compared to NCs and MgS. The synthesized NCs are found to be good alternative as a visible light driven photocatalyst. • MgS/Ag 2 MoO 4 NCs was synthesized by fast and facile sono-chemical method. • NCs formation improved the photocatalytic activity compared to its individual counter parts. • Achieved an effective interface transfer and separation of photoinduced electrons and holes. • The generation of both super oxide and hydroxyl radicals involved in the photocatalytic degradation. • Excellent antibacterial activity shown against E. coli and B. subtilis .

Stable and sensitive SERS-based immunoassay enabled by core-shell immunoprobe and paper-based immunosubstrate

Aiming to augment the reliability and efficiency of surface enhanced Raman scattering (SERS)-active immunoprobe, sophisticated strategies that are able to avoid the dissociation of Raman molecules and noble metal nanoparticles (NPs) in practice have drawn a considerable attention. This study confirmed that Ag@polystyrene-block-poly(acrylic acid)@Ag core-shell nanostructures possessed superior stability compared with bare Ag NPs in phosphate buffer saline solution and human serum. Combined with a unique paper-based immunosubstrate with a satisfying enhancement factor of 9.71 × 105, a robust sandwich immunostructure was constructed and conducted to monitor carbohydrate antigen 19-9 (CA19-9), presenting a low limit of detection of about 10−4 U/mL. With these exceptional features, such a proposed protocol was finally utilized to detect CA19-9 in several clinical human sera, which shown much higher sensitivity than the traditional chemiluminescence analysis.

Enhancement in visible light photocatalytic performance using silver-decorated nickel titanate nanofiber composite

The nickel titanate nanofibers (NiTiO3 NFs) and silver nanoparticles (Ag NPs) were synthesized by electrospinning and citrate reduction technique. The Ag NPs was decorated with different weight percentage onto the NFs surface by ultrasonication. Scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) not only portrayed the surface morphology of the samples but also revealed that Ag was well decorated onto the NFs surface. Photoelectrochemical (PEC) studies showcased that the surface plasmon resonance (SPR) effect of Ag NPs enhanced the NFs absorption capability by restraining the photogenerated electron-hole pairs recombination effectively. Using methylene blue (MB) solution the photocatalytic activity of the prepared catalysts was determined. The obtained results manifest that bare NiTiO3 NFs and Ag NPs degraded 42% and 55% of MB under visible light, while 3% Ag-decorated NF composite degraded 93% under visible light in 3 hr. The degradation process of pure and Ag-decorated NF composite was constant with the first-order kinetic equation. The photocatalytic performance of Ag-decorated NF composite samples was better than bare NiTiO3 NFs and Ag NPs. It was observed that the rate constant determined the dye degradation efficiency.

Improved thermal/chemical stability of flexible Ag NWs/Chitosan composite electrode integrated by chemical welding and sequential protection for better PV performance

An integration strategy of chemical welding and subsequent protection was demonstrated to address silver nanowires (Ag NWs)-based issues. Preferentially, a halogenated salt of NaCl solution was used to stimulate the junction welding thus to reduce the junction resistance, by virtue of the autocatalytic redox of Ag atoms with halogen ions and dissolved oxygen molecules. Subsequently, chitosan, possessing the biocompatible, degradable, environmentally friendly non-toxic features, was embedded to protect Ag NWs. With these two steps, the composite electrode consisting Ag NWs and chitosan reaches a lowest sheet resistance of ∼8 Ω, with a transmittance over 80% at 550 nm, along with high thermal and chemical stabilities, accompanying with excellent flexibility. Besides, it also prompts a synergistic improvement when pioneered in Cu(In, Ga)Se2 (CIGS) device as a transparent conductive electrode. It yields a power conversion efficiency of 6.6%, with 32% improvement relative to that bare Ag NWs, and 85% of the conventional one. Our findings present a new strategy for addressing instable/inefficient Ag NWs-based devices, driving their rapid development and its practical applications.

Inkjet-printed Ag@SDC core-shell nanoparticles as a high-performance cathode for low-temperature solid oxide fuel cells

This work demonstrates the superior thermostability of silver-based nanoparticle cathodes under continuous solid oxide fuel cell operation by coating the samarium-doped ceria (SDC) thin shell over silver nanoparticles. The Ag-core/SDC-shell (Ag@SDC) nanoparticles prepared by solvothermal synthesis (Ag core diameter = 48 nm; average SDC shell thickness = 2–5 nm) is inkjet-printed on electrolyte substrates as a thin film cathode. The Ag@SDC film survives the 48-h thermal annealing and its most porosities remain visibly un-agglomerated. The results of fuel cell current stability test show that the cell using the Ag@SDC nanoparticle cathode have only 3% of current degradation after 25 h, which is remarkably lower than that of the cell using the bare Ag nanoparticle cathode (96.1%). In addition, the electrochemical performance of the bare silver cathode in oxygen reduction reaction has significantly improved because of the enhanced surface oxygen adsorption/dissociation process provided by the SDC thin shell.

Anomalous effects of dielectric coated plasmonic metal nanoparticles on solar absorption enhancement in perovskite thin films

Localized surface plasmon resonances in metallic nanostructures have been extensively harnessed for light absorption enhancement in various solar cells, including perovskite solar cells (PSCs). For stabilization and functionalization, plasmonic metal nanostructures are often coated with dielectric shells. In this work, we numerically investigate the effects of dielectric coated plasmonic metal nanoparticles (NPs) on solar absorption enhancement in perovskite thin films. To our surprise, a further absorption enhancement compared with the films embedding bare Ag NPs can be achieved when using thin dielectric coating of high refractive index, while an absorption reduction in comparison with bare perovskite thin films may take place when the embedded Ag NPs are coated with thick dielectric shells of low refractive index. The physics behind is addressed within classic electrodynamics. These anomalous effects extend our knowledge of PSCs, providing guidelines for optimized design of plasmonic solar cells.

AgCu Bimetallic Electrocatalysts for the Reduction of Biomass-Derived Compounds.

The electrochemical transformation of biomass-derived compounds (e.g., aldehyde electroreduction to alcohols) is gaining increasing interest due to the sustainability of this process that can be exploited to produce value-added products from biowastes and renewable electricity. In this framework, the electrochemical conversion of 5-hydroxymethylfurfural (HMF) to 2,5-bis(hydroxymethyl)furan (BHMF) is studied. Nanostructured Ag deposited on Cu is an active and selective electrocatalyst for the formation of BHMF in basic media. However, this catalyst deserves further research to elucidate the role of the morphology and size of the coated particles in its performance as well as the actual catalyst surface composition and its stability. Herein, Ag is coated on Cu open-cell foams by electrodeposition and galvanic displacement to generate different catalyst morphologies, deepening on the particle growth mechanism, and the samples are compared with bare Ag and Cu foams. The chemical–physical and electrochemical properties of the as-prepared and spent catalysts are correlated to the electroactivity in the HMF conversion and its selectivity toward the formation of BHMF during electroreduction. AgCu bimetallic nanoparticles or dendrites are formed on electrodeposited and displaced catalysts, respectively, whose surface is Cu-enriched along with electrochemical tests. Both types of bimetallic AgCu particles evidence a superior electroactive surface area as well as an enhanced charge and mass transfer in comparison with the bare Ag and Cu foams. These features together with a synergistic role between Ag and Cu superficial active sites could be related to the twofold enhanced selectivity of the Ag/Cu catalysts for the selective conversion of HMF to BHMF, that is, >80% selectivity and ∼ 100% conversion, and BHMF productivity values (0.206 and 0.280 mmol cm–2 h–1) ca. 1.5–3 times higher than those previously reported.

Single-Step Green Synthesis of Highly Concentrated and Stable Colloidal Dispersion of Core-Shell Silver Nanoparticles and Their Antimicrobial and Ultra-High Catalytic Properties.

The versatile one-pot green synthesis of a highly concentrated and stable colloidal dispersion of silver nanoparticles (Ag NPs) was carried out using the self-assembled tannic acid without using any other hazardous chemicals. Tannic acid (Plant-based polyphenol) was used as a reducing and stabilizing agent for silver nitrate in a mild alkaline condition. The synthesized Ag NPs were characterized for their concentration, capping, size distribution, and shape. The experimental results confirmed the successful synthesis of nearly spherical and highly concentrated (2281 ppm) Ag NPs, capped with poly-tannic acid (Ag NPs-PTA). The average particle size of Ag NPs-PTA was found to be 9.90 ± 1.60 nm. The colloidal dispersion of synthesized nanoparticles was observed to be stable for more than 15 months in the ambient environment (25 °C, 65% relative humidity). The synthesized AgNPs-PTA showed an effective antimicrobial activity against Staphylococcus Aureus (ZOI 3.0 mM) and Escherichia coli (ZOI 3.5 mM). Ag NPs-PTA also exhibited enhanced catalytic properties. It reduces 4-nitrophenol into 4-aminophenol in the presence of NaBH4 with a normalized rate constant (Knor = K/m) of 615.04 mL·s−1·mg−1. For comparison, bare Ag NPs show catalytic activity with a normalized rate constant of 139.78 mL·s−1·mg−1. Furthermore, AgNPs-PTA were stable for more than 15 months under ambient conditions. The ultra-high catalytic and good antimicrobial properties can be attributed to the fine size and good aqueous stability of Ag NPs-PTA. The unique core-shell structure and ease of synthesis render the synthesized nanoparticles superior to others, with potential for large-scale applications, especially in the field of catalysis and medical.

Cetyltrimethylammonium Bromide (CTAB)-Loaded SiO2-Ag Mesoporous Nanocomposite as an Efficient Antibacterial Agent.

To date, Ag-based nanomaterials have demonstrated a high potential to overcome antibiotic resistance issues. However, bare Ag nanomaterials are prone to agglomeration in the biological environment, which results in a loss of antibacterial activity over time. Furthermore, it is still challenging to collect small-sized Ag nanomaterials right after the synthesis process. In this study, spherical-shaped Ag nanoparticles (NPs) (~6–10 nm) were attached on the surface of cetyltrimethylammonium bromide (CTAB)-loaded mesoporous silica nanoparticles (MSNs) (~100–110 nm). Antibacterial activity tests suggested that the obtained nanocomposite can be used as a highly efficient antibacterial agent against both Gram-negative and Gram-positive bacterial strains. The minimum inhibitory concentration (MIC) recalculated to pure Ag weight in nanocomposite was found to be ~1.84 µg/mL (for Escherichia coli) and ~0.92 µg/mL (for Staphylococcus aureus)—significantly smaller compared to values reported to date. The improved antibacterial activity of the prepared nanocomposite can be attributed to the even distribution of non-aggregated Ag NPs per volume unit and the presence of CTAB in the nanocomposite pores.