Incorporation Of Ag Nanoparticles Research Articles

Electron bridging based on ternary AgNPs/MoS2/NaTaO3 heterojunction films enhanced photocatalytic activity

The exceptional cyclic utilization performance of fixed-state thin film photocatalysts has garnered significant interest, yet their industrial application remains constrained by their low photocatalytic efficiency. In this investigation, MoS2/NaTaO3 thin films were synthesized in situ on tantalum substrates utilizing a facile hydrothermal approach. The resulting heterojunction architecture serves to facilitate efficient separation of electron-hole pairs while also notably expanding the photoresponse range. Furthermore, the incorporation of Ag nanoparticles (AgNPs) via photochemical reduction engendered the establishment of Schottky contacts (MoS2-Ag), which considerably expedited the photoinduced charge separation process. Within the context of the ternary system, the construction of electron bridges accelerates the rate of electron transfer. Hence, the designed ternary AgNPs/MoS2/NaTaO3 heterojunction films showed enhanced photocatalytic activity and degraded more than 94.6% of methylene blue (MB) after 50 min of irradiable light. Also, the composite exhibits notable antibacterial efficacy (99.99%) against S. aureus and E. coli owing to the synergistic influence of photo-induced ROS and AgNPs. Moreover, cyclic photocatalytic degradation/sterilization experiments demonstrated the proficient stability of the film.

Enhanced Interfacial Adhesion of TiO2 Nanotubes Decorated With Ag Silver Nanoparticles Prepared by Photo-Reduction Process

Abstract In the present study, the adhesion of TiO2 nanotubes (TiO2-NTs) to thicker substrates was improved by decorating them with metallic Ag nanoparticles (NPs) using the photo-reduction process. The obtained coatings were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) combined with energy-dispersive X-ray spectroscopy, and transmission electron microscope (TEM). The XRD confirmed that all TiO2-NTs crystallized in anatase after annealing at 400 °C regardless of the anodization potential. The SEM indicated that the TiO2-NTs were uniformly distributed on the substrate with an ordered and vertically aligned morphology. It also revealed that the diameter of the TiO2-NTs reached ∼100 nm. The decoration of TiO2-NTs surface with silver nanoparticles was assessed by the TEM. Moreover, a new scratch test mode called “wear mode” was performed to evaluate the wear resistance of the coatings. Results obtained by the scratch tests proved that the decorated coating with Ag nanoparticles improved the interfacial adhesion. The friction coefficient decreased from 0.65 to 0.45 when pure TiO2 was decorated with 10 min-Ag-NPs. The wear behavior was studied using a multi-pass scratch test. It was found that the wear volume reduced with the incorporation of Ag nanoparticles. The study of the damage mechanisms showed visco-elastic plastic deformation in the pure TiO2 coating.

Enhanced electrochromic properties of Ag-incorporated WO3 nanocomposite thin films

WO3 nanocomposite thin films, in which metal nanoparticles are incorporated into a WO3 matrix, offer an enhanced electrochromic response speed with color neutrality. This article reports the structural, optical, and electrochemical properties of Ag nanoparticle-incorporated electrochromic WO3 thin films with different concentrations. Room-temperature-sputtered thin films using composite targets with a low Ag concentration exhibited a random distribution of small nanoparticles. In contrast, in the film with a higher Ag concentration, the particles were merged, resulting in a single or polycrystalline phase. Surface plasmon resonance peaks were observed in the absorption spectra of the Ag–WO3 composite films, indicating the formation of metallic nanoparticles, which was also confirmed via high-resolution transmission electron microscopy. The optical bandgaps decreased gradually from 3.15 eV for WO3-δ to 3.02 and 2.99 eV for W0.97Ag0.03O3-δ and W0.91Ag0.09O3-δ thin films, respectively. The W0.91Ag0.09O3-δ thin film showed a faster switching time of 2.6 s for coloring and 4.8 s for bleaching with a higher coloration efficiency of 66.52 cm2/C than those of the WO3-δ thin film, which were 3.8 s, 6.8 s, and 58.68 cm2/C, respectively. However, transmittance modulation in the W0.91Ag0.09O3-δ thin film was inferior to that in the other films. Furthermore, the W0.91Ag0.09O3-δ thin films were black in the colored state, whereas the bare WO3-δ and W0.97Ag0.03O3-δ thin films were Prussian blue, suggesting the realization of color neutrality through the incorporation of Ag nanoparticles.

Ag nanoparticles incorporated interlayer enables ultrahigh critical current density for Li6PS5Cl-based all-solid-state lithium batteries

Agroydite Li6PS5Cl is one of the most promising solid electrolytes because of its high ionic conductivity and good processability. However, there are still many challenges with Li6PS5Cl and lithium anodes that prevent their industrialization, such as the growth of lithium dendrite and interfacial reactions. Interface modification of anodes has proven to be an effective method for solving these problems. Herein, we introduce Ag nanoparticles into the interface between Li6PS5Cl and metallic lithium and systematically investigate their interfacial properties. By incorporating silver nanoparticles, lithium dendrites can be depleted by forming Li–Ag alloys. Therefore, a denser and more stable interface between Li6PS5Cl and lithium metals is obtained. Benefiting from the above advantages, the Li/Li symmetrical battery with incorporated Ag nanoparticles exhibited an ultrahigh critical current density of up to 10 mA cm−2 and great cycling stability (more than 600 h). An all-solid-state battery with Ni-rich cathode and lithium metal anode demonstrates a high-capacity retention rate of 84% after 200 cycles at a current density of 0.5C. This study provides new insights into the construction of stable anode interfaces for the practical application of all-solid-state lithium batteries.

Synthesis of multifunctional Fe3O4@SiO2-Ag nanocomposite for antibacterial and anticancer drug delivery

Incorporating Ag nanoparticles at core–shell Fe3O4@SiO2 provides promising opportunities for biomedical applications. Here, Fe3O4@SiO2-Ag nanoparticles have been successfully synthesized using seed-mediated growth methods. Based on the results, the as-prepared composite nanoparticles have good crystallinity and a core–shell structure. It was also revealed that the nanocomposites exhibited a superparamagnetic property with a magnetic saturation value ​​of 36.42 emu/g and surface plasmon resonance (SPR) absorption at 370 nm. Furthermore, the result also demonstrated that the as-prepared Fe3O4@SiO2-Ag showed an potential inhibition activity againstEscherichia coliandStaphylococcus aureuswith an inhibition zone of about 8–10 mm. In addition, an in-vitro MTS assay also revealed that epirubicin (EPI)-loaded Fe3O4@SiO2-Ag nanoparticles has cytotoxic properties against HeLa cells. This indicates that the as-prepared Fe3O4@SiO2-Ag nanoparticles could potentially be used as both an antibacterial agent and an anticancer drug carrier.

Curcumin Sustained Release with a Hybrid Chitosan-Silk Fibroin Nanofiber Containing Silver Nanoparticles as a Novel Highly Efficient Antibacterial Wound Dressing.

Drug loading in electrospun nanofibers has gained a lot of attention as a novel method for direct drug release in an injury site to accelerate wound healing. The present study deals with the fabrication of silk fibroin (SF)-chitosan (CS)-silver (Ag)-curcumin (CUR) nanofibers using the electrospinning method, which facilitates the pH-responsive release of CUR, accelerates wound healing, and improves mechanical properties. Response surface methodology (RSM) was used to investigate the effect of the solution parameters on the nanofiber diameter and morphology. The nanofibers were characterized via Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), zeta potential, and Dynamic Light Scattering (DLS). CS concentration plays a crucial role in the physical and mechanical properties of the nanofibers. Drug loading and entrapment efficiencies improved from 13 to 44% and 43 to 82%, respectively, after the incorporation of Ag nanoparticles. The application of CS hydrogel enabled a pH-responsive release of CUR under acid conditions. The Minimum Inhibitory Concentration (MIC) assay on E. coli and S. aureus bacteria showed that nanofibers with lower CS concentration cause stronger inhibitory effects on bacterial growth. The nanofibers do not have any toxic effect on cell culture, as revealed by in vitro wound healing test on NIH 3T3 fibroblasts.

Microstructure and improved fracture toughness of borosilicate glass reinforced by 1 vol% Ag nanoparticles

Silver (Ag) nanoparticles (1 vol%) were successfully incorporated into borosilicate glass by spark plasma sintering of powder mixtures of borosilicate glass and silver nitrate. Finer glass powder as the starting material led to the coarsening of Ag nanoparticles in the sintered sample, while starting with coarse glass powder led to a high concentration of Ag nanoparticle precipitates at the original interface. The fracture toughness was enhanced by incorporating Ag nanoparticles. The toughness values of the samples starting from coarse and fine glass powders were 1.76 (1.9-fold increase) and 1.31 MPa m1/2 (1.4-fold increase), respectively. The precipitation of Ag nanoparticles in a large number density in a narrow area of the interface results in significant crack deflection and crack bridging, and thus greater toughness improvement by starting with coarse glass powder.

Horizontal and vertical stacked Ag/MoS2 nanostructure enabled excellent carrier mobility and optoelectronic properties

Amongst 2D materials, MoS2 with highly exposed atomic edges and large specific surface area are considered potentially strong candidates for optoelectronic devices such as photogenerated electron transport layer, saturated/reverse saturated light absorber. With these prospects in mind, doped nanohybrid system was employed as a “accelerator” for problems related to conductivity and field emission. Herein, the horizontal-vertical stacked Ag/MoS2 films including horizontal nanolayer and vertical nanosheets (NSs) was firstly presented, which exhibit excellent carrier mobility and luminescence characteristics. We have confirmed that the morphology of the Ag/MoS2 NSs (including microworm-like, worm-like, and sheet-like shape), Ag content, micro strain and crystallinity can be adjusted under the different substrate temperature. Base on anisotropy bonding and ultrafast chemical conversion effect of MoS2, the cross-layer diffusion of sputtered atoms is suppressed, thereby the subsequent deposited atoms preferring to diffuse along the van der Waals gap. The efficient light-matter interaction and surface plasmon resonance (SPR) effect is introduced by the abundant exposed S-edges of horizontal-vertical stacked Ag-MoS2 nanostructure, which lead to excellent Raman signal and linear absorption characteristic. The carrier mobility and concentration of Ag/MoS2 NSs with excellent electrical behavior has reached 4480 cm2 V-1S-1 and 3.272 × 1018 cm−2, which can be regarded as the unique ohmic contact and the electron injection effect. Further, the luminescence performance (visible light region) of horizontal-vertical stacked Ag/MoS2-350 °C NSs is 2.5 times higher than that of the original MoS2 NSs, which is dominated by the hot electron injection effect. Importantly, the carrier relaxation time guided by the nonradiative recombination behavior of Ag/MoS2-350 °C NSs was not significantly changed by the incorporation of Ag nanoparticles. The above phenomenon implies that the hot electron injection effect mainly promotes the photoluminescence behavior induced by radiative recombination. The homogeneous and controllable Ag/MoS2 NSs exhibits excellent multiple optoelectronic properties, which can provide a valuable reference strategy for the application of optoelectronic nano-film materials.

Photo-Induced Preparation of Ag@MOF-801 Composite Based Heterogeneous Nanocatalyst for the Production of Biodiesel

Hybrid materials based on metal-organic frameworks (MOFs) and nanoparticles (NPs) have gained considerable popularity in a variety of applications. Particularly, these types of materials have demonstrated excellent efficiency in heterogeneous catalysis due to the synergistic effect between the components. Herein, we report a simple, eco-friendly, photocatalytic method for the fabrication of Zr containing MOF-801 and a silver (Ag) NPs-based hybrid (Ag@MOF-801). In this method, the photocatalytic property of the central metal ion (Zr) of MOF was exploited to promote the formation and deposition of Ag NPs on the surface of the MOF-801 under the irradiation of visible light. The successful incorporation of Ag NPs was ascertained by powder X-ray diffraction (XRD) and UV-Vis analysis, while the morphology and surface area of the sample was determined by N2 adsorption–desorption and scanning electron microscopy (SEM), respectively. The resulting Ag@MOF-801 hybrid served as a highly efficient catalyst for the transesterification of used vegetable oil (UVO) for the production of biodiesel. The Ag@MOF-801 catalyst exhibited superior catalytic activity compared to its pristine MOF-801 counterpart due to the enhanced surface area of the material.

Investigation of broad-band optical absorption and electrical properties in vacuum annealed CZTS/Ag multi-layered stack structure for plasmonic solar cell application

As there is only a few research work carried out in thin film plasmonic Cu2ZnSnS4 (CZTS) based solar cells, it is exceedingly inspiring to advance the optical and electrical properties through incorporating Ag nanoparticles without affecting its structural properties. In this work, CZTS and Ag were stacked with the help of sequential magnetron sputtering method using RF and DC power supplies. Homogeneous distribution of Ag nanoparticles in CZTS matrix has been achieved via post deposition annealing at 500 °C. The concentration of Ag has been tailored by varying deposition time from 30 to 90 s. The morphological properties of Ag incorporated CZTS thin films has been investigated by using FE-SEM technique. The optical property of CZTS films has been enhanced by increasing the optical path length through multiple scattering due to the localized surface plasmon resonance (LSPR) of Ag nanoparticles. In Hall effect study, a gradual drop in the resistivity is observed with increasing Ag deposition time however it is within the tolerable limit of CZTS film.

Antibacterial and in vivo studies of poly(ɛ-caprolactone)-silver electrospun nanofibers: effect of preparation methods on the properties

Poly(ɛ-caprolactone)-silver nanocomposite were prepared by two main methods of metal-polymer nanocomposite preparation approaches, in situ and ex situ methods, by electrospinning. Effective parameters on electrospun nanofibers were optimized by Design Expert, CCD method. Using in situ and ex situ methods, effect of incorporating silver nanoparticle into Poly(ɛ-caprolactone) on conductivity, average fiber diameter, morphology of nanofiber mats and antibacterial properties were investigated. According to Field Emission Scanning Electron Microscopy (FESEM) and Energy-Dispersive X-ray Spectroscopy (EDX) analysis, average fibers diameters decreased by increasing incorporated Ag nanoparticles. Conductivity results confirmed the higher content of silver nanoparticles in in situ samples. Antibacterial test was performed against two bacteria types: Staphylococcus-aureus and Escherichia-coli. Due to higher content and smaller size of Ag nanoparticles incorporated in nanofibers, silver-loaded PCL electrospun nanofibers obtained by in situ method showed higher antibacterial efficiency in comparison to the ex situ samples. Moreover, Ag particles had more effects on Staphylococcus aureus due to sensitive membrane of this type of bacteria. In vivo study has proved that in situ samples improved the wounds on Wistar rat lateral part of body skin. Antibacterial and in vivo results showed that PCL-Ag nanofiber mats obtained by in situ method are suitable for medical applications.

Non‐Enzymatic Electrochemical Biosensing of Glucose Using Nanocomposites of Polyaniline Nanofibers and Silver

AbstractIn this study silver nanoparticles were dispersed over polyaniline nanofibers (nPANI) by simple chemical reduction of silver nitrate in the presence of nPANI, and the prepared nPANI/Ag nanocomposite was employed for sensitive and cost‐effective non‐enzymatic detection of glucose using a modified carbon paste electrode. Detailed structural, crystallographic and morphological characterization of nPANI/Ag was carried out by means of Fourier‐transform infrared spectroscopy, X‐ray diffractometry and scanning electron microscopy. The enhancement of charge transfer of nPANI upon incorporation of Ag nanoparticles was confirmed by electrochemical impedance spectroscopy, and the electrocatalytic efficacy of the nPANI/Ag nanocomposite towards oxidation of glucose in alkaline medium was proven by cyclic voltammetry. Crucially, chronoamperometry demonstrated a linear response of the nPANI/Ag‐based glucose sensor over a wide range of glucose concentrations from 100 μM to 10 mM with a lowest detection limit of 1,3 μM. The sensor had a good selectivity for glucose in the presence of common interfering biomolecules. The sensor also had a shelf‐life of several days and the response was repeatable for up to nine individual measurements.

Synthesis and structural, optical and photovoltaic characteristics of pure and Ag doped TiO2 nanoparticles for dye sensitized solar cell application

The Pure titanium oxide (TiO2) and Ag doped (0.04 mol%) TiO2nanoparticles (NPs) were prepared by microwave-assisted method, and were characterized by various techniques. The XRD patterns of both samples suggested the presence of anatase tetragonal structure. The Rietveldrefinements on XRD plots of both samples by GSAS package confirmed the proper incorporation of Ag at TiO2 lattice. The SEM-EDS analysis revealed that the presence of spherical-shaped NPs with the expected elements in proper ratio. The Raman spectroscopy analysis also confirmed the incorporation of Ag nanoparticles at TiO2lattice by showing the drastically decreased intensity while comparing with pure TiO2NPs. The UV–Vis spectroscopy results confirmed the presence of direct band gap in both the samples; however Ag doping reduces the optical band gap but increases Urbach energy, which is the clear indication of red shift in Ag doped TiO2 NPs. The Photoluminescence spectra confirmed the presence of the defects like oxygen vacancies, however, these defects are increased in Ag doped TiO2 system. So, as expected, the photovoltaic measurements showed very slight increase in power conversion efficiency of Ag doped TiO2 NPs. These optical and photovoltaic results of Ag doped TiO2 NPs were correlatively discussed to bring the broad understanding for device fabrications successfully.

Photocatalytic CO2 reduction with water vapor to CO and CH4 in a recirculation reactor by Ag-Cu2O/TiO2 Z-scheme heterostructures

A ternary Z-scheme Ag-Cu2O/TiO2 catalyst was prepared by one-step chemical reduction method which was applied in photocatalytic CO2 reduction with water vapor under simulated sunlight in a recirculation reactor. The structure, morphology, photo absorption capacity and optoelectronic properties of the obtained samples were characterized by XRD, TEM, XPS, UV–vis DRS and Photoelectrochemical measurements. The photocatalytic activity tests showed that 0.5Ag-0.5Cu2O/TiO2 exhibited the highest production rate of CO (13.19 μmol/g/h) and CH4 (1.74 μmol/g/h) under simulated sunlight when compared to P25, 1Cu2O/TiO2 and 1Ag/TiO2. Mechanism studies by means of EPR technology testified that the improvement of photocatalytic performance was mainly due to the formation of Z-scheme heterojunctions between P25 and Cu2O, which facilitated the separation of photogenerated charges. The incorporation of Ag nanoparticles further enhanced the transfer of photogenerated carriers and the absorption of visible light, thus preventing the self-reduction of Cu2O and improving the photocatalytic CO2 reduction performance.

The effect of KOH activation and Ag nanoparticle incorporation on rice husk-based porous materials for wastewater treatment

Major agricultural solid waste, rice husk (RH)-based mesoporous materials were prepared by potassium hydroxide (KOH) treatment of RH and RH hydrochar (RHH) produced at 180 °C with 20 min reaction time. In this study, RH was treated with three different methods: RH activation by KOH (KOH-RH), RH activation by KOH-aqueous silver (Ag)-shell nanoparticle (AgNP) incorporation followed calcination at 550 °C for 2 h (AgNP–KOH-RH) and hydrothermally carbonized RH activation by KOH (KOH-RHH). The main objective of this study was to determine the effect of KOH activation with different synthesis approaches and compare the characterization results of RH based porous material to identify the potential adsorbent application for wastewater treatment. Therefore, after activation in different methods, all interactive properties such as elemental, chemical, structural, morphological, and thermal analyses were investigated comprehensively for all samples. The crystallinity peak intensity around 22°λ at the angle of diffraction of 2θ confirmed the presence of silica, higher stability of the material, and removal of organic components during the KOH activation. AgNP–KOH-RH and KOH-RHH presented high porosity on the outer surface. The presence of negligible volatile matter in KOH-RHH by TGA demonstrated the decomposition of organic compound. Very high ratio of aromatic carbon and lignin content by FTIR and XPS analysis in both AgNP–KOH-RH and KOH-RHH showed these two samples have improved stability. Very high negative surface charge (zeta potential) in AgNP–KOH-RH (−43.9 mV) and KOH-RHH (−43.1 mV) indicated the enhanced water holding capacity. Surface area for all experimented porous materials has been enhanced after KOH activation, where KOH-RHH demonstrated the maximum surface area value, 27.87 m2/g. However, AgNP–KOH-RH presented maximum pore diameter, 18.16 nm, and pore volume, 0.12 cm3/g. Hence, it can be concluded that both KOH-RHH and AgNP–KOH-RH have the potential to be implemented as wastewater adsorbents.

Covalent incorporation of Ag nanoparticles into TiO2 nanotubes on Ti6Al4V by molecular grafting for enhancing antibacterial effect

Silver antibacterial composite coatings were prepared on additive manufactured Ti6Al4V substrates by merging anodic oxidation, molecular grafting, and spray deposition methods. The surface microstructure, composition, elemental characteristics, and antibacterial properties of the composite coatings were obtained. When the anodizing time was varied from 0.5 to 4 h, the results revealed that the average inner diameter of TiO2 nanotubes (TNTs) increased from 19.9 nm to 78 nm and the average wall thickness decreased from 22.9 nm to 12.8 nm, concluding the optimized voltage of 40 V and anodizing time of 1 h. X-ray diffraction spectra depicted that the structure of TNTs transformed to the more stable anatase phase with a small amount of rutile phase after annealing. After molecule grafting, silanes are covalently bonding to the TNTs via amino groups and Si-O-Si networks. With the help of the covalent bonding between Ag and TNTs, the Ag+ release has been slowed down significantly from 1.127 ppm to 0.17 ppm. Bare TNTs show a certain antibacterial effect with an antibacterial rate of 57.5% for E. coli and of 50.1% for S. aureus. When the spraying pass for Ag deposition is 10, the prepared AgNPs embedded coatings have significantly improved the antibacterial properties, as the antibacterial efficiencies are 100% for all these silane-modified TNTs surfaces.

Incorporation of dynamic boronate links and Ag nanoparticles into PVA hydrogels for pH-Regulated and prolonged release of methotrexate

In this study, pH-responsive hydrogels based on PVA-boronate crosslinks were prepared via a simple route and used for controlled and targeted delivery of anticancer drug methotrexate. A double network (DN) hydrogel composed of didiol-boronate/PVA complex as the first network and PVA crystallites generated by a freeze-thaw process as the second one was developed. The swelling of PVA-boronate DN hydrogels demonstrated high sensitivity to multiple stimuli including the pH, temperature, and ionic strength of the media thanks to the dynamic boronate links in the first network. Moreover, unlike previously reported hydrogels based on the boronate linkages, the new DN hydrogels preserved their structural stability in acidic media due to the second network and consequently, a sustained drug release was achieved under low pH conditions. Methotrexate release from the hydrogels at pH 5.4 was faster and greater than that at pH 7.4, agreeing with the gels’ swelling behavior under the two pH conditions. Interestingly, with the incorporation of Ag nanoparticles (NPs) for the antibacterial function, PVA-boronate hydrogels showed not only a higher pH responsiveness in drug release but also a more sustained process. These hydrogels can be considered in prolonged cancer therapy with reduced side effects.

Constructing of strawberry-like core-shell structured Al2O3 nanoparticles for improving thermal conductivity of nitrile butadiene rubber composites

In this paper, we have designed strawberry-like core-shell structured aluminum oxide/tannic acid-ferric ion/silver (Al2O3/TA-Fe3+/Ag) nanoparticles (NPs) and incorporated them into nitrile butadiene rubber (NBR) matrix to obtain thermally conductive composites. The tannic acid (TA) provided a strong binding affinity to the surface of Al2O3 NPs and formed a stable octahedral complex with Fe3+. Moreover, the TA layer enhanced interfacial interactions and compatibility between thermally conductive filler and NBR matrix, leading to reduced phonon scattering and decreased interfacial resistance of NBR composites. As a result, the incorporation of Ag NPs on the surface of Al2O3/TA-Fe3+ enhanced the thermal conductivity (λ) of NBR composites. The results revealed that the λ of 50 vol% Al2O3/TA-Fe3+/Ag/NBR composite was 0.90 W/mK, which was 600% of pure NBR (0.15 W/mK). Meanwhile, the dielectric constant (ϵr) of 50 vol% Al2O3/TA-Fe3+/Ag/NBR composite reached up to 12.91 at 102 Hz. However, the volume resistance of all Al2O3/TA-Fe3+/Ag/NBR composites was larger than 1.97 × 1011 Ω mm. Overall, the proposed low-cost and green surface modification method provides novel insights into the design of advanced polymeric composites with high λ for large-scale production.

A novel H2O2photoelectrochemical sensor based on ternary RGO/Ag-TiO2 nanotube arrays nanocomposite

Ternary nanocomposite photoelectrodes composed of Ag nanoparticles, reduced graphene oxide (RGO), and TiO2 nanotube arrays (TNTs) were successfully designed and achieved by a combining technique of cyclic voltammetry and anodic oxidation. Herein, the obtained RGO/Ag-TNTs composites were employed for photoelectrochemical (PEC) monitoring platform of hydrogen peroxide (H2O2) for the first time. Compared to pure TNTs, Ag-TNTs, and RGO-TNTs, the ternary RGO/Ag-TNTs nanocomposites with appropriate loading amount of RGO and Ag show much higher PEC activity, which were contributed to the synergistic effect resulting from the effective incorporation of Ag nanoparticles and RGO onto the TNTs to accelerate the electron transfer, increase the charge carrier density and prolong the electron lifetime demonstrated by electrochemical impedance spectroscopy (EIS), Mott-Schottky (M-S) measurements and open circuit voltage decay (OCVD) measurement. Under the optimal experimental conditions, the as-prepared PEC sensors exhibited an extremely wide dynamic range from 10−7 nM to 10 mM, and in the range of 0.1–10 mM with higher sensitivity and a detection limit of 20 μM. Moreover, the PEC sensors displayed good reproducibility, long-term stability, and selectivity toward the determination of H2O2. These excellent results make the as-developed ternary RGO/Ag-TNTs nanocomposites a promising candidate in PEC detection H2O2.

Polydopamine Ultrathin Film Growth on Mica via In-Situ Polymerization of Dopamine with Applications for Silver-Based Antimicrobial Coatings

The development of polydopamine (PDA) coatings with a nanometer-scale thickness on surfaces is highly desirable for exploiting the novel features arising from the specific structure on the molecular level. Exploring the mechanisms of thin-film growth is helpful for attaining desirable control over the useful properties of materials. We present a systematic study demonstrating the growth of a PDA thin film on the surface of mica in consecutive short deposition time intervals. Film growth at each deposition time was monitored through instrumental techniques such as atomic force microscopy (AFM), water contact angle (WCA) analysis, and X-ray photoelectron spectroscopy (XPS). Film growth was initiated by adsorption of the PDA molecules on mica, with subsequent island-like aggregation, and finally, a complete molecular level PDA film was formed on the surface due to further molecular adsorption. A duration of 60−300 s was sufficient for complete formation of the PDA layer within the thickness range of 0.5−1.1 nm. An outstanding feature of PDA ultrathin films is their ability to act as a molecular adhesive, providing a foundation for constructing functional surfaces. We also explored antimicrobial applications by incorporating Ag nanoparticles into a PDA film. The Ag NPs/PDA film was formed on a surgical blade and then characterized and confirmed by SEM-EDS and XPS. The modified film inhibited bacterial growth by up to 42% on the blade after cutting through a pork meat sample.