Ag-ZnO Nanocomposites Research Articles

New Composite Nanomaterials with Antimicrobial and Photocatalytic Properties Based on Silver and Zinc Oxide

Herein we report the synthesis of composites containing nanobio silver, ZnO and phytochemicals in different Ag/Zn molar ratios. First, Ag nanoparticles were prepared using red cabbage extract and then they are covered with zinc oxide obtained also in the same extract by precipitation method. The antimicrobial activity of synthesized nanocomposites was tested against Staphylococcus aureus, Streptococcus, Escherichia coli, Pseudomonas and Candida clinical isolates and compared with that of ZnO functionalized with anthocyanins. The presence of nanobio silver into the nanocomposites enhanced the bactericidal properties demonstrated by slightly larger diameters of growth inhibition zone and lower minimal inhibitory concentrations. S. aureus and Streptococcus strains were more sensitive than the other strains and fungi both for Ag–ZnO nanocomposites and ZnO functionalized with anthocyanins. Also, the presence of silver in the nanocomposites leads to an improved photocatalytic activity (PA) confirmed in the bleaching of Congo red solution. The PA increases with silver content when Ag content is low (up to 1/12 Ag/Zn molar ratio), but decreases significantly for high silver concentration (1/7 Ag/ZnO molar ratio) in the Ag–ZnO nanocomposites.

Facile synthesis and investigation of NiO–ZnO–Ag nanocomposites as efficient photocatalysts for degradation of methylene blue dye

Abstract In the present study, NiO–ZnO–Ag photocatalytic nanocomposites were synthesized using two-stage precipitation method. The synthesized composite powders were investigated and characterized using different techniques including XRD, FESEM, FT-IR, TGA and UV–Vis. XRD results showed that by increasing the Ag content, the crystallite size of ZnO decreased. FESEM micrographs showed that addition of Ag could lead to formation of more uniform particles in the size range of 30–500 nm. Diffuse reflectance spectroscopy results confirmed that addition of Ag nanoparticles led to the increase of light absorption, which was attributed to the plasmon surface resonance of Ag. Band gap energies of NiO–ZnO, NiO–ZnO–5%Ag, NiO–ZnO–3%Ag, NiO–ZnO–1%Ag and ZnO–1%Ag were estimated to be 3.13, 3.14, 3.147, 3.19 and 3.17 eV, respectively. Investigation of degradation process showed that by adding up to 1 wt% Ag to NiO–ZnO composite led to the increase of methylene blue degradation from 67% to 94%, but further addition resulted in decrease of degradation.

Effects of Ag Doping Content and Dispersion on the Photocatalytic and Antibacterial Properties in ZnO Nanoparticles

ZnO nanoparticles(NPs) with different contents of Ag dopants were obtained by one-step solvothermal method. The crystalline structures of the prepared composites were characterized by means of X-ray diffraction (XRD). The morphology and composition of the samples were studied by means of scanning transmission electron microscopy(TEM), X-ray photoelectron spectroscopy(XPS) and electron microscopy(SEM). Photoluminescence(PL) spectra have been used to investigate pure ZnO, Ag-ZnO and Ag-ZnO-PVP NPs to determine the effect of composition on PL properties. It was found that the Ag-ZnO samples showed stronger emissions than pure ZnO. The catalytic activity of samples was measured by the degradation rate of R6G, which exhibited that Ag-ZnO nanocomposite demonstrated enhanced photocatalytic activity compared to the pure ZnO NPs. The possible influence factors to the photocatalytic and antibacterial activities of the sample were explored, including Ag contents and dispersion. It was presented that the photocatalytic activity of Ag-ZnO-PVP was better than that of Ag-ZnO and it showed the highest photocatalytic activity with 7% of Ag content. The Ag-ZnO-PVP can kill the Escherichia coli(E. coli) cells.

One-step synthesis of hexylresorcinol calix[4]arene-capped ZnO–Ag nanocomposites for enhanced degradation of organic pollutants

In this study, hexylresorcinol calix[4]arene (HRCA) is introduced into the reaction system, and HRCA-capped ZnO–Ag nanocomposites are prepared via a simple one-step reflux method. HRCA is used not only as a reducing agent for deoxidizing Ag+ to Ag, but also as a protectant for wrapping around the microstructure of the formed ZnO–Ag. The prepared samples are characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy (TEM), high-resolution TEM, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, and water contact angle. The Ag nanoparticles and ZnO adhere to each other and HRCA molecules encapsulate on the surface of ZnO–Ag nanocomposites. HRCA-capped ZnO–Ag nanocomposites with different Ag contents are investigated for use in photodegradation of organic pollutants (rhodamine B (RhB) and levofloxacin hydrochloride). The sample with 10.20 mol% Ag, denoted as ZA3, exhibits the highest catalytic activity for photodegradation of RhB and levofloxacin hydrochloride. Moreover, ZA3 exhibits high stability during photodegradation of organic pollutants even after multiple reuses. The possible photocatalytic mechanism is discussed. We believe that O2− and h+ are the chief active species responsible for the photocatalytic activity of HRCA-capped ZnO–Ag nanocomposite system. HRCA-capped ZnO–Ag nanocomposite is expected to be an effective photocatalyst with potential application to sewage treatment under sunlight.

ZnO rod decorated with Ag nanoparticles for enhanced photocatalytic degradation of methylene blue

Silver-zinc oxide nanocomposite (Ag-ZnO nanocomposite) were synthesised with different concentrations of Ag doped to the ZnO for enhance photocatalytic degradation of methylene blue. The structures, morphologies, and optical properties of synthesised nanocomposites were characterized by UV-Visible spectroscopy (UV-vis) scanning electron microscopy (SEM), X-ray diffraction (XRD), Dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FRIR), and photoluminescence spectroscopy (PL). The average size of the synthesized Ag nanoparticles was around 40 nm and ZnO nanorod were 2 μm in length and 200 nm in width. The morphological characterization revealed that Ag nanoparticles were well doped with the ZnO rod surface. The performance and stability of the nanocomposites for the photocatalytic degradation of methylene blue under ultraviolet (UV) light irradiation were evaluated. The overall results suggested that, 6% of Ag nanoparticles achieved better degradation than compare to the other concentrations and bare ZnO. This work provides a simple and effective route to prepare Ag-ZnO nanocomposite for effective degradation of methylene blue. Therefore, Ag-ZnO nanocomposite can be regarded as a potential candidate for application in the treatment of waste water.

Surface plasmonic effect of Ag enfold ZnO pyramid nanostructured photoanode for enhanced dye sensitized solar cell application

A green approach to synthesize three dimensional pyramid structured ZnO and Ag decorated ZnO nanoparticles were developed by one pot hydrothermal method and they were successfully applied as photoanode for DSSC. Neem extract was utilized to control the size of Ag particles. The structural and morphological properties of synthesized samples of ZnO and Ag-ZnO nanocomposites have been investigated by XRD, FESEM, and HRTEM analysis respectively. The XPS studies were performed for scrutinizing the binding energy of ZnO and Ag-ZnO nanostructured materials. The UV–VIS absorption spectrum of Ag-ZnO nanostructure displaced absorption towards visible region than the pristine ZnO. The electrochemical properties of both ZnO and Ag-ZnO nanostructure were studied using EIS (Electrochemical impedance spectra). The photoconversion efficiency of Ag-ZnO based DSSC cell showed an efficiency of 3.51% which has higher conversion efficiency than pristine ZnO (2.62%).

Synthesis and characterization of hybrid Ag-ZnO nanocomposite for the application of sensor selectivity

Facile, rapid, and environmentally benign hybrid Ag-ZnO nanocomposites were synthesized by two steps from green synthesis approach at room temperature. The absence of an impurity peak in X-ray diffraction (XRD) pattern confirmed the formation of polycrystalline nanocomposite material. An additional peak (111) of Ag was detected along with ZnO crystalline wurtzite structure. The surface area electron diffraction (SAED) pattern further confirmed the crystallinity of nanocomposites. The compositional analysis of hybrid Ag-ZnO was determined by EDS-mapping and confirmed the presence of Zn, O and Ag in the composite. The room-temperature photoluminescence (PL) spectra of hybrid Ag-ZnO depict a weak ultraviolet (UV) emission at 385 nm, and the strong visible emission at ∼600 nm, while increasing the Ag concentration in to ZnO matrix, the UV peak was completely disappeared and major visible peak was moved to ∼500 nm indicated to the best optimal detection peak for sensors. The fluorescence spectra were measured with respect to Ag concentrations of Ag-ZnO nanocomposite at room temperature to investigate the functionality and the selectivity of nanomaterials. This work opens a notable way to fabricate Ag-ZnO nanohybrids, and makes a significant contribution to the fluorescence based sensor applications.

Thermal-induced SPR tuning of Ag-ZnO nanocomposite thin film for plasmonic applications

The formation of silver (Ag) nanoparticles in a ZnO matrix were successfully synthesized by RF-magnetron sputtering at room temperature. As prepared Ag-ZnO nanocomposite (NCs) thin films were annealed in vacuum at three different temperatures of 300 °C, 400 °C and 500 °C, respectively. The structural modifications for as-deposited and annealed films were estimated by X-ray diffraction and TEM techniques. The crystalline behavior preferably along the c-axis of the hexagonal wurtzite structure was observed in as-deposited Ag-ZnO film and improved significantly with increasing the annealing temperature. The crystallite size of as-deposited film was measured to be 13.6 nm, and increases up to 28.5 nm at higher temperatures. The chemical composition and surface structure of the as-deposited films were estimated by X-ray photoelectron spectroscopy. The presence of Ag nanoparticles with average size of 8.2 ± 0.2 nm, was confirmed by transmission electron microscopy. The strong surface plasmon resonance (SPR) band was observed at the wavelength of ∼565 nm for as-deposited film and a remarkable red shift of ∼22 nm was recorded after the annealing treatment as confirmed by UV-visible spectroscopy. Atomic force microscopy confirmed the grain growth from 60.38 nm to 79.42 nm for as-deposited and higher temperature annealed film respectively, with no significant change in the surface roughness. Thermal induced modifications such as disordering and lattice defects in Ag-ZnO NCs thin films were carried out by Raman spectroscopy. High quality Ag-ZnO NCs thin films with minimum strain and tunable optical properties could be useful in various plasmonic applications.

Facile synthesis of ZnO–Ag nanocomposite and its photocatalytic activity

The evolution of photoactive hybrid materials (e.g. noble metal-semiconductor) has resulted in heterogeneous photocatalysis. We report a facile route for the synthesis of ZnO–Ag nanocomposites with varying percentage of loading of the noble metal, expecting a great boost in the photocatalytic behavior of ZnO. The as prepared material was thoroughly characterized by UV–Vis, FTIR, TEM, FESEM, XRD, XPS analyses. The photocatalytic activities of the nanocomposites have been assessed from the ability to degrade methylene blue dye in aqueous solution. The results suggest that incorporation of Ag nanoparticles on the surface of ZnO particles can enhance catalytic activity in comparison to pure ZnO particles under visible light by minimizing the recombination of photogenerated electron–hole pairs.

Precipitation dispersion of Ag–ZnO nanocatalyst over functionalized multiwall carbon nanotube used in degradation of Acid Orange from wastewater

A series of Ag–ZnO/CNT nanophotocatalysts with different multiwall carbon nanotubes loadings were prepared by precipitation–decomposition method. The samples properties were well-characterized by XRD, FESEM, EDX, BET, FTIR and DRS measurements. The results indicated that the loading of multiwall carbon nanotubes to nanocomposites has significant influences on morphology, surface area, hydroxyl and carboxylic functional groups and the absorption of visible light region. The catalytic performance was evaluated by the photocatalytic degradation of Acid Orange 7 dye under visible light. The results revealed that the Ag–ZnO/CNT(5) nanophotocatalyst with 5 wt.% loading of functionalized multiwall carbon nanotubes possessed superior photocatalytic activity than that of Ag–ZnO nanocomposite and the pure ZnO. The enhanced photocatalytic activity was attributed to the effective separation of electron–hole pairs on Ag–ZnO/CNT. The effect of operational parameters such as the initial pH, amount of photocatalyst and dye concentration on photo mineralization of AO7 dye has been analyzed, which efficient degradation was observed at pH 3–9. Furthermore, Ag–ZnO/CNT(5) nanophotocatalyst exhibited good recycling stabilities over several separation cycles in photocatalytic reaction system. Finally, a mechanism for photocatalytic degradation of AO7 dye is suggested.

Effect of leavening agent on structural and photocatalytic properties of ZnO nanorods

In the present work, we have demonstrated a simple, facile, one-step, rapid and cost effective synthesis of ZnO nanorods through the thermal decomposition of zinc acetate and leavening agent (NaHCO3). The silver nanoparticles (AgNPs) were deposited on the surface of ZnO nanorods by photocatalytic reduction of Ag (I) to Ag(0). As synthesized ZnO nanorods and Ag–ZnO nanocomposites were characterized by using X-ray Diffraction, field emission scanning electron microscope, high-resolution transmission electron microscope and diffuse reflectance spectroscopy. The photocatalytic activities of the ZnO nanorods and Ag–ZnO nanocomposites were evaluated for the photodegradation of Methyl Orange (MO) under UV and sunlight irradiation. The use of common leavening agent helps to prevent the aggregation of ZnO nanorods, further it hinders crystallite growth and narrowing the diameter of nanorods by the evolution of carbon dioxide during calcination. The ZnO nanorods and Ag–ZnO nanocomposite exhibited an enhanced photocatalytic activity and separation of photogenerated electron and hole pairs. Due to effect of leavening agent and AgNPs deposited on surface of ZnO nanorods finds best catalyst for the 99% degradation of MO within 30 min compared to ZnO.

Silicate sol–gel matrix stabilized ZnO–Ag nanocomposites materials and their environmental remediation applications

A facile preparation method was employed to decorate the zinc oxide nanoparticles by aminosilicate sol-gel supported silver nanoparticles (TPDT/(ZnO-Ag) NCMs). The nanocomposite photocatalyst materials were characterized by UV–vis absorption spectra, DRS, XRD, SEM and EDX techniques. The absorption spectral studies showed that the Ag nanoparticles (Ag NPs) were deposited on the ZnO nanoparticles (ZnO NPs) (represented as TPDT/(ZnO-Ag) NCMs) and the NCMs are highly stable. The photocatalytic oxidation and reduction reactions at the TPDT/(ZnO-Ag) NCMs photocatalysts were evaluated by using the toxic methylene blue (MB) dye and hexavalent chromium (Cr(VI)), respectively under visible light irradiation. The photocatalytic activity of the NCMs showed that the MB dye was completely decolorized at TPDT/(ZnO-Ag) 0.1 NCMs photocatalyst when compared to the controlled photocatalyst materials. The photocatalytic reduction of highly toxic Cr(VI) to less toxic Cr(III) was studied at the photocatalyst TPDT/(ZnO-Ag) 0.5 NCMs in the presence of hole scavengers such as oxalic acid. The Ag NPs deposited on the ZnO NPs and dispersed in silicate sol-gel matrix (TPDT/(ZnO-Ag) NCMs) improved the photocatalytic activity of the ZnO NPs photocatalyst with effective interfacial electron transfer processes at the ZnO by minimizing the charge recombination process when compared to the bare ZnO NPs. The TPDT/(ZnO-Ag) NCMs showed promising environmental remediation and water purification processes through the synergistic photocatalytic activity by advanced oxidation-reduction processes.

Study on swift heavy ions induced modifications of Ag-ZnO nanocomposite thin film

In the present work, swift heavy ion (SHI) irradiation induced modifications in structural and optical properties of Ag-ZnO nanocomposite thin films have been investigated. Ag-ZnO nanocomposite (NCs) thin films were synthesized by RF magnetron sputtering technique and irradiated with 100 MeV Ag7+ ions at three different fluences 3 × 1012, 1 × 1013 and 3 × 1013 ions/cm2. Rutherford Backscattering Spectrometry revealed Ag concentration to be ∼8.0 at.%, and measured thickness of the films was ∼55 nm. Structural properties of pristine and irradiated films have been analyzed by X-ray diffraction analysis and found that variation in crystallite size of the film with ion irradiation. X-ray photoelectron spectroscopy (XPS) indicates the formation of Ag-ZnO nanocomposite thin film with presence of Ag, Zn and O elements. Oxidation state of Ag and Zn also estimated by XPS analysis. Surface plasmon resonance (SPR) of Ag nanoparticle has appeared at ∼475 nm in the pristine thin film, which is blue shifted by ∼30 nm in film irradiated at fluence of 3 × 1012 ions/cm2 and completely disappeared in film irradiated at higher fluences, 1 × 1013 and 3 × 1013 ions/cm2. A marginal change in the optical band gap of Ag-ZnO nanocomposite thin film is also found with increasing ion fluence. Surface morphology of pristine and irradiated films have been studied using Atomic Force Microscopy (AFM). Raman and Photo-luminance (PL) spectra of nanocomposite thin films have been investigated to understand the ion induced modifications such as lattice defects and disordering in the nanocomposite thin film.

Controllable Ag nanoparticle coated ZnO nanorod arrays on an alloy substrate with enhanced field emission performance

Ag–ZnO nanocomposites are conveniently prepared on alloy substrates, leading to much improved field emission performances.

Synthesis, characterization of polyindole/Ag[sbnd]ZnO nanocomposites and its antibacterial activity

Polyindole/SilverZinc Oxide (PIND/AgZnO) nanocomposites were synthesized by loading ZnO and Ag nanoparticles on the surface of polyindole. Polyindole and PIND/AgZnO were prepared using chemical oxidative polymerization and co-precipitation method in nitrogen (N2) atmosphere. The functional groups, crystalline structure, morphology, elemental composition and shapes of the nanocomposites were characterized by Fourier transform spectrophotometer (FT-IR), X-ray diffraction study (XRD), scanning electron microscope with energy dispersive X-ray diffraction studies (SEM-EDAX) and transmission electron microscope with selected area diffraction (TEM-SEAD). The results were obtained from the characterization techniques reveals the formation of nanocomposites consist of polyindole, Ag and ZnO nanoparticles. Prepared nanocomposites were evaluated for the antibacterial activity against selected gram negative and gram positive bacteria. PIND/AgZnO nanocomposites with different shapes such as spherical, cylindrical and hexagonal were reported. This is the first report on the simple chemical synthesis of polyindole based AgZnO nanocomposites, which exhibits good antibacterial activity.

Investigation of optical, structural, morphological and antimicrobial properties of carboxymethyl cellulose capped Ag-ZnO nanocomposites prepared by chemical and mechanical methods

This study reports on preparation and investigation of novel Ag-ZnO nanocomposites with antimicrobial activity. Carboxymethyl cellulose (CMC) capped Ag-ZnO nanoparticles (NPs) were synthesized by chemical (CD) and mechanical deposition (MD) of Ag NPs on ZnO NPs. The samples were investigated by UV–Vis spectroscopy, FTIR, XRD, DLS, SEM, EDX, WDXRF and TEM analyses. The antimicrobial activity was assessed against a wide range of pathogenic microorganisms in planktonic and adherent state. Ag-ZnO nanocomposites exhibited maximum 0.64wt.% spherical Ag NPs deposited on hexagonal prism ZnO NPs with single surface plasmon absorption band ranging 398–424nm. The mechanism for obtaining CMC capped Ag-ZnO NPs by chemical synthesis was proposed. Ag-ZnO nanocomposites yielded average crystallite size of 56.1–64nm, mean effective diameter of 388–427nm, polydispersity of 0.193–0.286, and a bimodal volume-weighted particle size distribution. All nanomaterials exhibited good antimicrobial activity against planktonic and biofilm growing bacteria.

ZnO-Ag core shell nanocomposite formed by green method using essential oil of wild ginger and their bactericidal and cytotoxic effects

In this paper, a novel green method for fabrication of zinc oxide-silver (ZnO-Ag) core-shell nanocomposite using essential oil of ginger (EO-G) is reported. The EO-G played two significant roles in the synthesis process: it could act as a reaction media for the formation of ZnO and reduce Ag+ to Ag0. The bioformed ZnO-Ag nanocomposite was compared with pure biosynthesized ZnO-NPs and characterized by UV–vis spectroscopy, TEM, EDX, XRD and FTIR. The characterization results confirmed that Ag-NPs had been embedded in ZnO hexagonal nanoparticles. Six Gram positive and negative pathogens were used to investigate the antibacterial effects of these samples. Ag-doping improves the bactericidal activity of ZnO-NPs. In vitro cytotoxicity studies on Vero cells, a dose dependent toxicity with non-toxic effect of concentration below 100μg/mL was shown for ZnO-Ag nanocomposite. The biosynthesized ZnO-Ag nanocomposites were found to be comparable to those obtained from the conventional methods using hazardous materials which can be an excellent alternative for the synthesis of ZnO-Ag using biomass.

Synthesis, characterization and application of ZnO-Ag as a nanophotocatalyst for organic compounds degradation, mechanism and economic study

The current work deals with ZnO-Ag nanocomposites (in the wide range of x in the Zn1−xO-Agx chemical composition) synthesized using microwave assisted solution combustion method. The structural, morphological and optical properties of the samples were characterized by XRD (X-ray diffraction), FTIR (Fourier transform infrared spectrometry), SEM (scanning electron microscopy technique), EDX (energy dispersive X-ray spectrum), ICP (inductively coupled plasma technique), TEM (transmission electron microscopy), BET (Brunauer–Emmett–Teller method), UV–Vis (ultraviolet–visible spectrophotometer) and photoluminescence spectrophotometer. The photocatalytic activity of the ZnO-Ag was investigated by photo-degradation of Acid Blue 113 (AB 113) under UV illumination in a semi-batch reactor. This experiment showed that ZnO-Ag has much more excellent photocatalytic properties than ZnO synthesized by the same method. The enhanced photocatalytic activity was due to the decrease in recombination of photogenerated electron-holes. The results showed the improvement of ZnO photocatalytic activity and there is an optimum amount of Ag (3.5mol%) that needs to be doped with ZnO. The effect of operating parameters such as pH, catalyst dose and dye concentration were investigated. The reaction byproducts were identified by LC/MS (liquid chromatography/mass spectrometry) analysis and a pathway was proposed as well. Kinetic studies indicated that the decolorization process follows the first order kinetics. Also, the degradation percentage of AB 113 was determined using a total organic carbon (TOC) analyzer. Additionally, cost analysis of the process, the mechanism and the role of Ag were discussed.

Selective synthesis of different ZnO/Ag nanocomposites as surface enhanced Raman scattering substrates and highly efficient photocatalytic catalysts

Different ZnO–Ag nanocomposites with controlling SERS and photocatalytic performance were obtained only by adjusting solvents.

Distinct spatial profiles and antibacterial effects of 20-nm Ag nanoparticles dripped on ZnO nanorods grown on a polished Ti substrate

Abstract Ag nanoparticles (NPs) were spread by dropping them on hexagonal-shaped ZnO nanorods (NRs) to obtain nanocomposites. ZnO NRs were grown on a polished Ti substrate. The Ag-ZnO nanocomposites were characterized using field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, Fourier-transform infrared spectroscopy and optical imaging. The experimental results indicated that Ag NPs tend to aggregate at the tip of ZnO NR surfaces. Furthermore, antibacterial tests confirmed that adding Ag NPs enhances antibacterial effects. The findings regarding the distinct behaviors of Ag NPs may facilitate the development of future biomedical devices.