Surface Morphology Of Nanostructures Research Articles

Design of an FPGA-Based Controller for Fast Scanning Probe Microscopy.

Atomic-scale imaging using scanning probe microscopy is a pivotal method for investigating the morphology and physico-chemical properties of nanostructured surfaces. Time resolution represents a significant limitation of this technique, as typical image acquisition times are on the order of several seconds or even a few minutes, while dynamic processes-such as surface restructuring or particle sintering, to be observed upon external stimuli such as changes in gas atmosphere or electrochemical potential-often occur within timescales shorter than a second. In this article, we present a fully redesigned field programmable gate array (FPGA)-based instrument that can be integrated into most commercially available standard scanning probe microscopes. This instrument not only significantly accelerates the acquisition of atomic-scale images by orders of magnitude but also enables the tracking of moving features such as adatoms, vacancies, or clusters across the surface ("atom tracking") due to the parallel execution of sophisticated control and acquisition algorithms and the fast exchange of data with an external processor. Each of these measurement modes requires a complex series of operations within the FPGA that are explained in detail.

Synthesis, characterization and photoelectrochemical performance of Bi2Fe4O9 thin films

Mullite-type Bi2Fe4O9 has been little explored in thin film form as a photoanode for photoelectrochemical water splitting. In this study, Bi2Fe4O9 thin films have been prepared using the sol-gel technique from a simple precursor solution based on the corresponding metal salts, acetic acid, and polyvinyl alcohol. The films were deposited by dip-coating onto fluorine-doped tin oxide substrates and dried at 350 °C, repeating the dipping-drying cycle six times, and finally sintered at 600 °C. The films were characterized by GIXRD, revealing the formation of the material in its orthorhombic phase. Raman spectroscopy showed the Ag and B1g vibrational modes, validating the formation of the bismuth iron oxide. UV–Vis transmittance measurements revealed that the material exhibits two optical transitions: a direct band gap of 2.86 eV and an indirect band gap of 1.98 eV. FESEM micrographs and AFM images showed a uniform nanostructured surface morphology. The photoelectrochemical properties of the Bi2Fe4O9 films were studied using cyclic voltammetry and chronoamperometry with front side illumination, demonstrating the stability of the material in aqueous media and the generation of photocurrent in the presence of H2O2. Furthermore, results from intensity-modulated photocurrent spectroscopy (IMPS) revealed that the photocurrent is limited by both bulk and surface recombination and a short hole diffusion length.

Surface parametric influences on the photocatalytic behaviour of zinc oxide nanoparticles

Zinc oxide nanoparticles were chemically synthesised and characterised by UV-DRS spectroscopy, FTIR, scanning electron microscopy with energy-dispersive X-ray diffraction, and X-ray powder diffraction. In order to evaluate the impact of the synthesis process on the structural parameters, Rietveld refinement was done using the GSAS-II programme on experimentally acquired XRD data. ZnO was found to have a hexagonal structure with lattice parameters of a = b =3.247 Å; c = 5.205Å and an average size of about 20-40 nm, as determined by Rietveld refinement of XRD and SEM data. FTIR and EDX analysis was used to confirm the functional group and elemental composition of ZnO NPs. The UV-DRS spectra revealed that the synthesised ZnO had an optical band gap of 3.05 eV. Parametric investigations of the surface morphology of ZnO nanostructures were conducted using the Gwyddion programme. Pseudo-first-order rate kinetics were observed for the photodegradation of two cationic dyes, MB (87.87%) and RhB (74.79%), in the presence of UV light.

NEW ZINC-BONE APATITE FILMS SHOW ANTI-TUMOUR EFFICACY AGAINST BONE METASTASES IN VITRO

Decreasing the chance of local relapse or infection after surgical excision of bone metastases is a main goals in orthopedic oncology. Indeed, bone metastases have high incidence rate (up to 75%) and important cross-relations with infection and bone regeneration. Even in patients with advanced cancer, bone gaps resulting from tumor excision must be filled with bone substitutes. Functionalization of these substitutes with antitumor and antibacterial compounds could constitute a promising approach to overcome infection and tumor at one same time. Here, for the first time, we propose the use of nanostructured zinc-bone apatite coatings having antitumor and antimicrobial efficacy. The coatings are obtained by Ionized Jet Deposition from composite targets of zinc and bovine-derived bone apatite. Antibacterial and antibiofilm efficacy of the coatings is demonstrated in vitro against S. Aureus and E. Coli. Anti-tumor efficacy is investigated against MDA- MB-231 cells and biocompatibility is assessed on L929 and MSCs.A microfluidic based approach is used to select the optimal concentration of zinc to be used to obtain antitumor efficacy and avoid cytotoxicity, exploiting a custom gradient generator microfluidic device, specifically designed for the experiments. Then, coatings capable of releasing the desired amount of active compounds are manufactured. Films morphology, composition and ion-release are studies by FEG- SEM/EDS, XRD and ICP. Efficacy and biocompatibility of the coatings are verified by investigating MDA, MSCs and L929 viability and morphology by Alamar Blue, Live/Dead Assay and FEG-SEM at different timepoints. Statistical analysis is performed by SPSS/PC + Statistics TM 25.0 software, one-way ANOVA and post-hoc Sheffe? test. Data are reported as Mean ± standard Deviation at a significance level of p <0.05.Results and Discussion. Coatings have a nanostructured surface morphology and a composition mimicking the target. They permit sustained zinc release for over 14 days in medium. Thanks to these characteristics, they show high antibacterial ability (inhibition of bacteria viability and adhesion to substrate) against both the gram + and gram – strain.The gradient generator microfluidic device permits a fine selection of the concentration of zinc to be used, with many potential perspectives for the design of biomaterials. For the first time, we show that zinc and zinc-based coatings have a selective efficacy against MDA cells. Upon mixing with bone apatite, the efficacy is maintained and cytotoxicity is avoided. For the first time, new antibacterial metal-based films are proposed for addressing bone metastases and infection at one same time. At the same time, a new approach is proposed for the design of the coatings, based on a microfluidic approach. We demonstrated the efficacy of Zn against the MDA-MB-231 cells, characterized for their ability to form bone metastases in vivo, and the possibility to use nanostructured metallic coatings against bone tumors. At the same time, we show that the gradient-generator approach is promising for the design of antitumor biomaterials. Efficacy of Zn films must be verified in vivo, but the dual-efficacy coatings appear promising for orthopedic applications.

Fractal and structural analysis of the different sculptured Mn-based nanostructures

Surface morphology and fractal properties of 3D nanostructures of the circular helical, square helical, and chevron were investigated. The nanostructures were deposited on the glass substrate using the oblique angle deposition technique. The surface properties of the nanostructures were investigated by atomic force microscopy (AFM) and field emission scanning electron microscopy (FESEM). The autocorrelation function (ACF), height-height correlation function (H(r)), power density function (PSDF), and Minkowski function are used for fractal characterization. The results showed that the circular helical nanostructure has more surface roughness, roughness exponent, and grain size compared to the square helical and chevron nanostructures. The fractal dimension of the surface of all three nanostructures showed that the chevron nanostructure with Df=2.88 has higher spatial complexity. The Minkowski functionals showed similar behavior for all three nanostructures. However, more negative and positive Minkowski connectivity was obtained for the circular helical nanostructure compared to the other two nanostructures.

Fast One-Step Fabrication of Highly Regular Microscrolls with Controllable Surface Morphology.

Although rolling origami technology has provided convenient access to three-dimensional (3D) microstructure systems, the high yield and scalable construction of complex rolling structures with well-defined geometry without impeding functionality has remained challenging. The straightforward, one-step fabrication that uses external mechanical stress to scroll micrometer thick, flexible planar films with centimeter lateral dimensions into tubular or spiral geometry within a few seconds is demonstrated. The method allows controlling the scrolls' diameter, number of windings and nanostructured surface morphology, and is applicable to a wide range of functional materials. The obtained 3D structures are highly promising for various applications including sensors, actuators, microrobotics, as well as energy storage and electronic devices.

Cerium Ion-Incorporated Titanium Metal Implants of Enhanced Bioactivity for Biomedical Applications.

The enhancement in the performance of metallic bone implants based on commercially pure titanium (CP-Ti) by incorporation of cerium (Ce) ions onto the surface was evaluated. The incorporation of Ce ions onto the CP-Ti surface was carried out by a simple two-step chemical treatment method, where an initial NaOH treatment and then a subsequent treatment with different molar concentrations of ceric nitrate solution followed by heat treatment at 600 °C were carried out. The modified surfaces were observed using field emission scanning electron microscopy (FE-SEM), scanning electron microscopy-energy dispersive X-ray analysis (SEM-EDX), X-ray photoelectron spectroscopy (XPS), the laser Raman spectroscopic technique, high-resolution transmission electron microscopy (HR-TEM), and atomic force microscopy (AFM). The formation of a nanonetwork structure by the initial NaOH treatment and the replacement of Na ions with Ce ions along with different phases of TiO2 was evident from the surface characterization results. The transition of rutile TiO2 to anatase TiO2 in the modified surface is evident from the Raman spectra with respect to the treatment of higher to lower concentrations of ceric nitrate solution. The presence of two different oxidation states of Ce (Ce3+ and Ce4+) and improvement in the surface wettability were also distinct in the modified samples. Thus, the incorporated Ce ions over the nanostructured titania network showed low cytotoxicity, good cell adhesion, and enhanced extracellular mineralization on MG-63 cells with better protein adsorption in BSA medium. Taken together, the thus-improved nanostructured surface morphology with the anatase TiO2 phase and distinct extracellular mineralization in the Ce-incorporated Ti metal with good biocompatibility make it a promising candidate for bone implant applications.

Light Extraction of Near-Infrared AlGaAs-Based LED Enhanced by Nanostructured Surface Morphology

To improve the light extraction efficiency of a planar AlGaAs-based light emitting diode (LED) (Device A), three novel LEDs with nanostructured surface morphologies are prepared using a surface texturing approach. We describe the fabrication of a nanostructured light extraction enhancement layer via the annealing of an evaporated Ag layer. Thermal annealing is used to induce the restructuring of a 15–25 nm layer of electron beam evaporated Ag into “nanoparticles”, which are used as an etch mask to transfer a nanopattern into the n-AlGaAs layer. Then, the Ag is removed, and the remaining nanostructured n-AlGaAs surface improves the extraction of light from the device. The novel LEDs have three different nanostructured thicknesses, namely 15 nm (Device B), 20 nm (Device C), and 25 nm (Device D). The morphologies of the Devices B–D are analyzed by an atomic force microscope and a scanning electron microscope. Compared to the planar LED (Device A), the light output powers of the Devices B–D increases by 112.6%, 91.4%, and 63.5%, respectively. The nanopatterns can mitigate the abrupt change of the refractive indexes between the air and the semiconductor to increase the LEDs’ light extraction efficiency. The surface texturing approach can be applied to commercial high-power LEDs.

Photocatalytic degradation of methylene blue at nanostructured ZnO thin films

The photocatalytic degradation of the wastewater dye pollutant methylene blue (MB) at ZnO nanostructured porous thin films, deposited by direct current reactive magnetron sputtering on Si substrates, was studied. It was observed that over 4 photocatalytic cycles (0.3 mg · l−1 MB solution, 540 minUV irradiation), the rate constant k of MB degradation decreased by ∼50%, varying in the range (1.54 ÷ 0.78) · 10–9 (mol·l−1·min−1). For a deeper analysis of the photodegradation mechanism, detailed information on the nanostructured ZnO surface morphology and local surface and subsurface chemistry (nonstoichiometry) were obtained by using scanning electron microscopy (SEM) and x-ray photoelectron spectroscopy (XPS) as complementary analytical methods. The SEM studies revealed that at the surface of the nanostructured ZnO thin films a coral reef structure containing polycrystalline coral dendrites is present, and that, after the photocatalytic experiments, the sizes of individual crystallites increased, varying in the range 43 ÷ 76 nm for the longer axis, and in the range 28 ÷ 58 nm for the shorter axis. In turn, the XPS studies showed a slight non-stoichiometry, mainly defined by the relative [O]/[Zn] concentration of ca. 1.4, whereas [C]/[Zn] was ca. 1.2, both before and after the photocatalytic experiments. This phenomenon was directly related to the presence of superficial ZnO lattice oxygen atoms that can participate in the oxidation of the adsorbed MB molecules, as well as to the presence of surface hydroxyl groups acting as hole-acceptors to produce OH· radicals, which can be responsible for the generation of superoxide ions. In addition, after experiments, the XPS measurements revealed the presence of carboxyl and carbonyl functional groups, ascribable to the oxidation by-products formed during the photodegradation of MB.

Aminosilica-Functionalized Co3O4 Nanostructures in Proton Exchange Mixed Matrix Membranes for Enhanced Separation Efficiency of Direct Methanol Fuel Cells

This work reports the alterations in the performance and morphology of a Nafion-based proton exchange membrane in the presence of three nano-Co3O4 morphologies (nanorod (R), nanosphere (S), and nanooctahedral (O)) modified by tetraethylorthosilicate (TEOS, T) and 3-aminopropyltriethoxysilane (APTES, A). The effects of surface chemistry and morphology of Co3O4 nanostructures on the properties of the as-prepared nanocomposite membranes were investigated by water uptake, proton conductivity, methanol permeability, and selectivity measurements. The methanol barrier properties of all nanocomposite membranes improved compared to the control Nafion membrane. The Nafion membranes embedded with aminosilica-functionalized Co3O4 also showed higher proton conductivity and improved methanol barrier properties compared to silica-functionalized Co3O4 and unmodified nanoparticles owing to the strong interaction between amino functionals on the surface of Co3O4 nanostructures and sulfonic moieties of the Nafion matrix. In particular, the incorporation of 5 wt % octahedral aminosilica-functionalized Co3O4 into the Nafion matrix provided the highest selectivity (15.2 × 104 S s–1 cm–3) and the lowermost methanol permeability (5 × 10–7 cm2 s–1), which were 3.6-fold higher and four times lower than that of the control Nafion membrane, respectively.

Durable Hydrophobic Polymer Coating on Silk Surface by Surfactant-aided Fluoro-monomer Polymerization Through Admicellar Technique

Inspired by the lotus-leaf water repellent attribute, the ‘queen of textiles’, silk has been modified through the simple admicellar polymerization technique. Thin polymer coatings were successfully designed and fabricated on silk surfaces using surfactant-aided polymerization of 1H, 1H, 2H, 2H-Perfluorodecyl acrylate. The nanostructured surface morphology was studied by SEM and EDX. The structural changes of the surface due to new bond formation after surface modification were studied by FTIR technique. The water drop stay time test and water contact angle (WCA) measurement indicated that a substantial degree of hydrophobicity has been imparted to the silk surface. The best WCA of the polymer-coated silk was found to be 140.1°. The modified (cured at 60 °C) silk was studied to check the durability and quality of the polymer coating. The thermal stability of the coating was also found to be remarkably good. The modified hydrophobic surface showed enthralling durability against multiple washing cycles and abrasion cycles.

Investigation of biochemical properties of flash sintered ZrO2–SnO2 nanofibers

ZrO2–SnO2 nanocomposition were produced in nanofibers (NFs) form with three various mixing volume ratio by electrospinning technique. The microstructure and morphological characterization of NFs reveals the ternary system of ZrO2–SnO2–ZrSnO4. Furthermore, Band gap structure of NFs was varied with the composition ratio which consequently affect the Flash sintering (FS) event. The FS experiments were utilized under thermal (844–878 °C) and electric field (420 V/mm) with 3.77 mA/mm2 current cutoff. Highly dense nanocomposition were obtained in less than 80secs with a max power absorption of 1.58 W/mm3. Thanks to low sintering temperature and time, nanostructured surface morphology were acquired which is crucial for biochemical properties of nanocompositions. Drosophila melanogaster food was covered with sintered nanocompositions and the control food. The toxicity of the nanomaterial in the insect, survival rate(%), development time(days) were investigated. In order to support the results, biochemical analyzes (total oxidative level-TOS, total antioxidant level-TAS and oxidative stress index-OSI) were performed in adults. In addition, antimicrobial activity was evaluated with Escherichia coli and Staphylococcus aureus. It was determined that the nanomaterials had an antimicrobial effect along with non-toxic effect on the insect. Besides, it did not change the survival rate of the insect in all groups. Although there was a one-day difference in development times, it did not cause a statistical change in the OSIs of female and male individuals. We believe that the synthesized nanocompositions can be used as a valid candidate in the healthcare system, such as dental implants, due to its antimicrobial effect and non-toxicity in the model organism.

Flower-like ZnO Nanostructures Local Surface Morphology and Chemistry

This work presents the results of comparative studies using complementary methods, such as scanning electron microscopy (SEM), X-ray photoemission spectroscopy (XPS), and thermal desorption spectroscopy (TDS) to investigate the local surface morphology and chemistry of flower-like ZnO nanostructures synthesized by the thermal oxidation technique on native Si/SiO2 substrates. SEM studies showed that our flower-like ZnO nanostructures contained mostly isolated and irregular morphological low-dimensional forms, seen as rolled-up floss flowers, together with local, elongated, complex stalks similar to Liatris flowers, which contained joined short flosses in the form of nanodendrites. Beyond this, XPS studies showed that these nanostructures exhibited a slight surface nonstoichiometry, mostly related to the existence of oxygen-deficient regions, combined with strong undesired C surface contamination. In addition, the TDS studies showed that these undesired surface contaminations (including mainly C species and hydroxyl groups) are only slightly removed from the surface of our flower-like ZnO nanostructures, causing an expected modification of their nonstoichiometry. All of these effects are of great importance when using our flower-like ZnO nanostructures in gas sensor devices for detecting oxidizing gases because surface contamination leads to an undesired barrier for toxic gas adsorption, and it can additionally be responsible for the uncontrolled sensor aging effect.

A symmetry-based approach to the characterization of complex surface morphologies: Application in CuO and NiO nanostructures

In recent years, bottom-up nanofabrication techniques and especially solution-based ones have gained significant popularity due to their relatively facile implementation, low-cost and design flexibility that allows the development of a plethora of three-dimensional nanostructures and nanoarchitectures. Nonetheless, despite the apparent simplicity of the methods, the resulting nanostructures are often morphologically and hierarchically complex with no apparent way of appropriately describing their features in a quantifiable and methodological way. In this work, we propose a symmetry-based approach for the quantitative characterization of the morphology of nanostructured surfaces. The key idea is to characterize the morphology of nanostructures by means of the fundamental spatial symmetry metrics and the deviations from the fully symmetrical counterparts. The focus of the proposed methodology is on the translational and scaling symmetry, which are investigated through the mathematical tools of Fourier and (multi)fractal analysis, respectively. The calculated metrics characterizing these symmetries are the period and the fractal dimension of surfaces while the deviations are quantified by the disorder parameter ω d related to the FWHM of Fourier peak and by the asymmetry of the multifractal spectrum for the translational and scaling symmetry respectively. As an initial study case and in order to demonstrate its suitability, the developed symmetry-based methodology was applied to nickel oxide (NiO) and copper oxide (CuO) nanostructures hydrothermally-grown on silicon substrates. The results show that even in the cases where the surfaces display similar symmetry metrics (period, fractal dimension) the symmetry-based approach reveals subtle, but quantifiable differences in the deviations from full symmetries which are not easily identified by other approaches. • A symmetry-based method for nanometrological analysis of complex nanomorphologies is developed and implemented. • It detects and quantifies the spatial symmetries in surfaces and the deviations from these (surface disorder). • Fourier, correlation and (multi) fractal analysis are used. • The method is successfully applied in CuO and NiO nanostructures hydrothermally grown on silicon substrates. • It captures subtle differences in nanosurface translational and scaling disorder and evaluates material/process origins.

Surface modified Ni wire supported flexible asymmetric supercapacitor of Mn3O4// PEDOT-PSS-MWCNT and its solar charging for self-powered Cu-doped ZnO nanorods-based UV photodetector

Recently, wire-shaped supercapacitors (WSCs) with the benefits of being flexible, lightweight, and wearable, have attracted great attention as portable and wearable power sources, though still, they face critical challenges of inadequate energy density and electrochemical stability under mechanical deformations. Therefore, we report the fabrication of the asymmetric WSC constituting surface-modified Ni wire as current collectors, PVA-KOH electrolyte, and hydrothermally grown Mn3O4 nanoflakes and dip-coated PEDOT: PSS-MWCNT nanocomposites as positive and negative electrode active materials, respectively. Owing to surface modification of Ni wire and active materials with approximate mass matching, mesoporous nanostructured surface morphology, and improved surface areas, the twisted asymmetric WSC exhibits excellent volumetric capacitance of 7.55 F/cm3, 2.69 mWh/cm3 energy density, and 95 mW/cm3 power density at 25 μA with a 1.6 V voltage window. In addition, considering the recent trend of developing multi-functional self-powered systems integrating energy harvesters, storage entities, and functional components, ultraviolet photodetector (UV PD) in metal-semiconductor-metal (MSM) configuration was fabricated by hydrothermal growth of Cu-doped ZnO nanorods onto interdigitated electrode printed glass substrate, and hence for the first time a self-powered UV-light detection system with a fast response and high on/off ratio were successfully demonstrated by connecting solar-charged parallel asymmetric WSCs and UV PD.

Corrosion resistance and surface microstructure of Mg3 N2 /SS thin films by plasma focus instrument.

Utilizing a plasma focus (PF) instrument, magnesium nitride (Mg3 N2 ) thin films were synthesized on stainless steel substrates. Twenty five optimum focus shots at 8 cm distance from the anode tip were used to deposit the films at different angular positions regarded to the anode axis. Scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray diffraction (XRD) analyses were performed to assess the surface morphology and structural characteristics of Mg3 N2 films. Based on AFM images, these films were studied to understand the effect of angular position variation on their surfaces through morphological and fractal parameters. By increasing the angle, we verify that the grain size decreased from 130(0) nm to 75(5) nm and also the mean quadratic surface roughness of the films reduced in its average values from (28.97 ± 3.24) nm to (23.10 ± 1.34) nm. Power spectrum density analysis indicated that films become more self-affine at larger angles. Furthermore, the corrosion behavior of the films was investigated through a potentiodynamic polarization test in H2 SO4 solution. It was found that the ion energy and flux, varying with the angular positions from the anode tip, directly affected the nanostructured roughness and surface morphology of the samples. The electrochemical studies of films show that the uncoated sample presented the lowest corrosion resistance. The highest corrosion resistance was obtained for the sample deposited with 25 optimum shots and at 0° angular position reaching a reduction in the corrosion current density of almost 800 times compared to the pure stainless steel-304 substrate. HIGHLIGHTS: Mg3 N2 /SS films have been deposited at different angles by plasma focus (PF) instruments. The effect of angular position on the surface microtexture, morphological parameters, and corrosion features of the films was studied. The RBS measurement and X-ray diffraction are utilized to identify the crystalline phases and thickness of films.

Electrochemically obtained Al2O3 nanoporous layers with increased anticorrosive properties of aluminum alloy

The nanoporous layers of aluminum oxide obtained by means of the anodic oxidation process, in 1 M H2SO4 in which 1 g/L Al2(SO4)3 × 18H2O was added, at constant potential and three oxidation times, are subjected to corrosion tests in 3.5% NaCl solution, pH = 5.75, to evaluate their anticorrosive properties compared to the unmodified surface of the Al1050 aluminum alloy. Electron microscopy and EDX compare the morphology of nanostructured aluminum oxide surfaces with their composition and layer thicknesses. Also, by analyzing the X-ray diffraction, the aluminum oxide is highlighted by the specific diffraction peaks. The evaluation of the corrosion resistance is performed by the electrochemical methods like evolution of the free potential depending on the immersion time and electrochemical impedance spectroscopy. From the analysis of the obtained results, a uniform and size distribution of the nanopores is observed, between 17.8 nm and 47 nm, depending on the anodic oxidation time. All nanoporous layers of aluminum oxide obtained have improved anticorrosive properties compared to untreated aluminum alloy.

Au Nanoparticles Decorated Graphene-Based Hybrid Nanocomposite for As(III) Electroanalytical Detection

Electrochemical sensors integrating hybrid nanostructured platforms are a promising alternative to conventional detection techniques for addressing highly relevant challenges of heavy metal determination in the environment. Hybrid nanocomposites based on graphene derivatives and inorganic nanoparticles (NPs) are ideal candidates as active materials for detecting heavy metals, as they merge the relevant physico-chemical properties of both the components, finally leading to a rapid and sensitive current response. In this work, a hybrid nanocomposite formed of reduced graphene oxide (RGO) sheets, surface functionalized by π-π interactions with 1-pyrene carboxylic acid (PCA), and decorated in situ by Au NPs, was synthesized by using a colloidal route. The hybrid nanocomposite was characterized by cyclic voltammetry and electrochemical impedance spectroscopy with respect to the corresponding single components, both bare and deposited as a layer-by-layer junction onto the electrode. The results demonstrated the high electrochemical activity of the hybrid nanocomposite with respect to the single components, highlighting the crucial role of the nanostructured surface morphology of the electrode and the PCA coupling agent at the NPs-RGO interphase in enhancing the nanocomposite electroactivity. Finally, the Au NP-decorated PCA-RGO sheets were tested by anodic stripping voltammetry of As(III) ion—a particularly relevant analyte among heavy metal ions—in order to assess the sensing ability of the nanocomposite material with respect to its single components. The nanocomposite has been found to present a sensitivity higher than that characterizing the bare components, with LODs complying with the directives established by the U.S. EPA and in line with those reported for state-of-the-art electrochemical sensors based on other Au-graphene nanocomposites.

Effect of ambient temperature and cathode-anode separation on electron field emission property of carbon nanofibers thin films

Carbon nanofibers (CNFs) thin films were prepared by using Radio frequency assisted plasma enhanced chemical vapor deposition (RF-PECVD) technique. Nickel thin films have been used for preparation of CNFs thin films, which stimulates the growth. The identification and confirmation of the graphitic phase of CNFs thin films were confirmed by using X-Ray Diffractometer. Nanostructure surface morphology of the CNFs thin films have been investigated by an Atomic Force Microscope, which reveals that the typical diameter of the CNFs was ∼ 180 nm with length of several micrometers. The electron field emission properties of CNFs thin films have been carried out for different cathode–anode separation and for various ambient temperatures. It was observed that with the extent of cathode–anode separation from 70 to 210 μm, the turn-on field was reduced to 3.5 V/μm from 4.4 V/μm respectively. Temperature dependent electron field emission measurement showed that the turn-on field was reduced to 2.3 V/μm from 4.2 V/μm, as ambient temperature of CNFs thin films was increased from 30 °C to 250 °C respectively. The field enhancement factor and turn-on field were calculated and demonstrate the electron emission procedure.

Tailoring of band gap, dielectric and antimicrobial properties of silver iodide nanoparticles through Cu doping

This work reports facile chemical synthesis of Cu doped silver iodide (AgI) nanostructures with 0.0, 0.5, 1.0, 2.5 and 5.0 wt% concentrations. As grown nanostructures crystals structures were investigated, using X-ray diffraction and surface morphology of nanostructures were analyzed as a function of Cu doping concentration using scanning electron microscope (SEM). Impact of Cu doping on electronic structure of AgI nanostructures were examined using diffuse reflectance spectra and photoluminescence spectroscopy. The band gap of nanostructures were calculated to be between 2.74 and 2.87 eV and decreases systematically as Cu doping concentration increases. Dielectric studies and electrical conductivity of nanostructures were also investigated as a function of Cu doping concentrations. Dielectric constant shows the significant improvement as Cu doping concentration rise. Antimicrobial activity of Cu:AgI nanostructures were analyzed against various bacteria. Optimum antimicrobial activity was observed against Streptococcus pyogenes and Enterococcus faecalis.