Nanohybrid Films Research Articles

Ultrasensitive immunoassay for free prostate-specific antigen based on ferrocenecarboxylate enhanced cathodic electrochemiluminescence of peroxydisulfate

The catalytic effect of ferrocenecarboxylate (FCC; in the form of nanocrystals) on the cathodic electrochemiluminescence (ECL) of peroxodisulfate was studied and applied to an ECL immunoassay to quantify free prostate-specific antigen (fPSA). The nanocrystals were entrapped in graphene previously functionalized with poly(dimethyldiallylammonium chloride) to give a solid-state nanohybrid referred to as FCC-Gr-PDDA. When cast onto a glassy carbon electrode (GCE), the ECL of peroxodisulfate is strongly enhanced. An immunoelectrode was then constructed by coating the positively charged nanohybrids matrix of FCC-Gr-PDDA with negatively charged gold nanoparticles and then immobilizing antibody against fPSA on the Au-NPs. The resulting electrode is then incubated with samples containing fPSA. An immunocomplex is formed in the presence of fPSA, and this prevents the solid-state nanohybrid film to enhance the ECL of the peroxodisulfate luminophor. The observed decrease in ECL intensity is directly related to the concentration of fPSA antigen in the range from 0.005 to 5 ng mL−1, and the detection limit is as low as 1.7 pg mL−1. The method is deemed to provide a widely applicable and general platform for ECL-based immunoassays.

Architectured Morphologies of Chemically Prepared NiO/MWCNTs Nanohybrid Thin Films for High Performance Supercapacitors

The preparation of nanostructured metal oxide decorated on multiwalled carbon nanotubes (MWCNTs) nanohybrid films through simple, scalable, additive-free, binderless, and cost-effective route has fascinated significant attention not only in fundamental research areas but also its commercial applications, in order to reduce the growing environmental pollution and the cost of electrode fabrication. Here, we report the fabrication of highly flexible electrode with NiO/MWCNTs nanohybrid thin films directly on stainless steel substrate using successive ionic layer adsorption and reaction (SILAR) method. The impact of ratio of adsorption and reaction cycles on structural, surface areas and electrochemical properties of NiO/MWCNTs nanohybrids was investigated. X-ray diffraction measurements confirm the hybridization and face centered cubic (FCC) crystal structure of NiO in NiO/MWCNTs nanohybrids. In addition, these nanohybrids exhibit excellent surface properties such as uniform surface morphology, good surface area, pore volume, and uniform pore size distribution. The electrochemical tests demonstrate the highest specific capacitance of 1727 F g(-1) at 5 mA cm(-2) of current density with 91% capacitance retention after 2000 cycles. In addition, the Ragone plot confirms the better power and energy densities for all NiO/MWCNTs nanohybrids. The attractive electrochemical capacitive activity revealed by NiO/MWCNTs nanohybrid electrode proposes that it is an auspicious respondent for future energy storage application.

Investigation of the antibacterial effects of silver-modified TiO2 and ZnO plasmonic photocatalysts embedded in polymer thin films

Nanosilver-modified TiO2 and ZnO photocatalysts were studied against methicillin-resistant Staphylococcus aureus on the surface and against naturally occurring airborne microorganisms. The photocatalysts/polymer nanohybrid films were prepared by spray coating technique on the surface of glass plates and on the inner surface of the reactive light source. The photoreactive surfaces were activated with visible light emitting LED light at λ = 405 nm. The optical properties of the prepared photocatalyst/polymer nanohybrid films were characterized by diffuse reflectance measurements. The photocatalytic properties were verified with the degradation of ethanol by gas chromatography measurements. The destruction of the bacterial cell wall component was examined with transmission electron microscope. The antibacterial effect of the photocatalyst/polymer nanohybrid films was tested with different methods and with the associated standard ISO 27447:2009. With the photoreactive coatings, an extensive disinfectant film was developed and successfully prepared. The cell wall component of S. aureus was degraded after 1 h of illumination. The antibacterial effect of the nanohybrid films has been proven by measuring the decrease of the number of methicillin-resistant S. aureus on the surface and in the air as the function of illumination time. The photocatalyst/polymer nanohybrid films could inactivate 99.9 % of the investigated bacteria on different thin films after 2 h of illumination with visible light source. The reactive light source with the inner-coated photocatalyst could kill 96 % of naturally occurring airborne microorganisms after 48 h of visible light illumination in indoor air sample. The TEM results and the microbiological measurements were completed with toxicity tests carried out with Vibrio fischeri bioluminescence bacterium.

Improving compression-after-impact performance of carbon–fiber composites by CNTs/thermoplastic hybrid film interlayer

Abstract Multi-walled carbon nanotubes (MWCNTs) have been effectively dispersed with polyetherketone cardo (PEK-C)/dichloromethane by ball milling technique. Pure PEK-C film and MWCNTs hybrid PEK-C (MWCNTs/PEK-C) films with different MWCNTs content were made employing an solvent casting technology. Transmission electron microscope (TEM) showed the MWCNTs shortened by ball milling. The neat and nano-hybrid films were used as interleaves for carbon fiber/bismaleimide (BMI) composite laminates. C-scan results showed that impact damage area decreased for PEK-C film interleaved laminates and further reduced by modification of MWCNTs. The compression after impact (CAI) strength was significantly improved for interleaved composite laminates when compared to baseline composite laminate. Maximum improvement (∼33%) of CAI value was achieved by interlayer of hybrid film with 10 wt% MWCNTs. The toughening micromechanism of enhanced resistance to low-energy impact with the incorporation of MWCNTs were investigated based on scanning electron microscopic (SEM) images of the fracture surfaces of the tested specimens. It is suggested that thermoplastics, BMI particles and MWCNTs had combined action to reduce interlaminar impact damage and thus to improve CAI strength.

Integrating porphyrin nanoparticles into a 2D graphene matrix for free-standing nanohybrid films with enhanced visible-light photocatalytic activity

Organic nanostructures in terms of porphyrin building blocks have shown great potential in visible-light photocatalytic applications because of their optical, electrical, and catalytic properties. Graphenes are known to provide a high-quality two-dimensional (2D) support for inorganic semiconductor nanostructures to increase the adsorption capability of the photocatalysts and an electron-transfer medium with attractive potential to enhance photogenerated charge separation. A combination of porphyrin nanostructures with graphene sheets, particularly in the form of free-standing films, is highly desirable due to its photocatalysing feasibility and convenience. Toward this aim, we demonstrate a facile method to integrate porphyrin (meso-tetra(p-hydroxyphenyl)porphyrin, p-THPP) nanoparticles (NPs) into macroscopic graphene (reduced graphene oxide, rGO) films through vacuum filtration of the co-colloids of graphene oxide (GO) and p-THPP nanoparticles (NPs) followed by gaseous reduction. The obtained p-THPP/rGO nanohybrid film exhibits enhanced visible-light photocatalytic activity compared to each moiety of the hybrid, and this photocatalyst can be easily separated and recycled for successive use with excellent stability. The results show that this facile fabrication of the p-THPP/rGO nanohybrid film makes it available for high-performance optoelectronic applications, as well as for device integration.

Transparent graphene–platinum nanohybrid films for counter electrodes in high efficiency dye-sensitized solar cells

A dispersion of platinum-on-graphene was prepared essentially by a two-step process, involving uniform distribution of graphene nanoplatelets in a cosolvent of ethanol–water in the presence of a polymeric dispersant and subsequent in situ reduction of dihydrogen hexachloroplatinate to metallic platinum on the graphene surface. The process generated platinum nanoparticles (PtNPs) of ca. 4.0–10 nm in diameter on the graphene surface. The platinum-on-graphene dispersion was coated on an FTO glass to prepare a counter electrode (CE) for a dye-sensitized solar cell (DSSC). The hybrid film of platinum nanoparticles and graphene nanoplatelets (PtNP/GN) showed a transparency of 70% at 550 nm, indicating its suitability as a CE material for a rear-illuminated DSSC. The DSSC with the CE having the film of PtNP/GN exhibited a power conversion efficiency (η) of 8.00%, superior to 7.14% of the DSSC with a conventional sputtered platinum (s-Pt) CE. In the case of rear-illumination the DSSC showed an η of 7.01%, while the DSSC with the conventional s-Pt showed an η of only 2.36%. HRTEM and FE-SEM were used to observe the dispersion of the hybrid material in the solvent, UV-vis spectroscopy and cyclic voltammetry were used to characterize the films, and IPCE spectra and electrochemical impedance spectra were used to explain the photovoltaic parameters of the DSSCs.

Fabrication of wafer-scale free-standing quantum dot/polymer nanohybrid films for white-light-emitting diodes using an electrospray method

Wafer-scale free-standing quantum dot (QD)/polymer nanohybrid (NHB) based down-conversion (DC) phosphor films for remote-type white-light-emitting diodes (W-LEDs) are developed.

An electrochemical sensor for honokiol based on a glassy carbon electrode modified with MoS2/graphene nanohybrid film

An electrochemical sensor for the sensitive determination of honokiol was successfully constructed based on MoS2/graphene nanohybrid.

Preparation and characterization of polyimide/titania nanohybrid films

Thermally stable polyimide/titania (PI/TiO2) hybrid nanocomposite films have been successfully synthesized through the in situ formation of TiO2 within a PI matrix via sol-gel process. Poly(amic acid) (PAA) solution is prepared from 3,5-diamino benzoyl amino phenyl-14H-dibenzo[a,j]xanthene and 4,4′-(hexaflouroisopropylidene)diphthalic anhydride in N-methyl-2-pyrrolidinone solvent. The different amounts of tetraethyl orthotitanate and actylacetone are incorporated into PAA matrix, and then thermally imidized to form PI/TiO2. The chelating agent, acetylacetone, was applied to reduce the gelation rate of titanium alkoxide. Thermal decomposition temperatures of nanocomposites with a 10% weight loss were in excess of 500°C, and char yields higher than 63% at 800°C in nitrogen. The chemical and morphological structures of the hybrid nanocomposites were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, and transmission electron microscopy. The results show that the TiO2 particles are well dispersed in the PI matrix with particle size between 10 and 30 nm in diameter. POLYM. COMPOS., 35:1486–1493, 2014. © 2013 Society of Plastics Engineers

Immobilization of Urease on TiO<SUB>2</SUB>-Chitosan Nanohybrid Film for Development of Urea Biosensor

Immobilization of Urease on TiO<SUB>2</SUB>-Chitosan Nanohybrid Film for Development of Urea Biosensor

Nickel hydroxide nanoparticles-reduced graphene oxide nanosheets film: Layer-by-layer electrochemical preparation, characterization and rifampicin sensory application

Electrochemical deposition, as a well-controlled synthesis procedure, has been used for subsequently layer-by-layer preparation of nickel hydroxide nanoparticle-reduced graphene oxide nanosheets (Ni(OH)2-RGO) on a graphene oxide (GO) film pre-cast on a glassy carbon electrode surface. The surface morphology and nature of the nano-hybrid film (Ni(OH)2-RGO) was thoroughly characterized by scanning electron and atomic force microscopy, spectroscopy and electrochemical techniques. The modified electrode appeared as an effective electro-catalytic model for analysis of rifampicin (RIF) by using linear sweep voltammetry (LSV). The prepared modified electrode exhibited a distinctly higher activity for electro-oxidation of RIF than either GO, RGO nanosheets or Ni(OH)2 nanoparticles. Enhancement of peak currents is ascribed to the fast heterogeneous electron transfer kinetics that arise from the synergistic coupling between the excellent properties of RGO nanosheets (such as high density of edge plane sites, subtle electronic characteristics and attractive π-π interaction) and unique properties of metal nanoparticles. Under the optimized analysis conditions, the modified electrode showed two oxidation processes for rifampicin at potentials about 0.08 V (peak I) and 0.69 V (peak II) in buffer solution of pH 7.0 with a wide linear dynamic range of 0.006-10.0 µmol L(-1) and 0.04-10 µmol L(-1) with a detection limit of 4.16 nmol L(-1) and 2.34 nmol L(-1) considering peaks I and II as an analytical signal, respectively. The results proved the efficacy of the fabricated modified electrode for simple, low cost and highly sensitive medicine sensor well suited for the accurate determinations of trace amounts of rifampicin in the pharmaceutical and clinical preparations.

Ammonia gas sensing properties of CSA doped PANi-SnO2 nanohybrid thin films

The polyaniline (PANi)-SnO2 nanohybrid based thin films doped with 10–50wt % camphor sulfonic acid (CSA) were deposited on the glass substrates using spin coating technique. The crystallinity, chemical structure and morphology of the films were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and Field emission scanning electron microscopy respectively, which proved that there is a strong synergetic interaction between the CSA and PANi-SnO2 nanohybrid. The sensor response was estimated by the change in the electrical resistance of the film in the absence and presence of ammonia (NH3) gas. The sensor response and selectivity in relation to the CSA doping concentration and the gas concentration has been systematically studied. A significant sensitivity (91%) and fast response (46s) toward 100ppm NH3 operating at room temperature is observed for the 30wt % CSA doped PANi-SnO2 nanohybrid film. The sensing mechanism of CSA doped PANi-SnO2 nanohybrid film to NH3 was presumed to be the synergism of PANi and SnO2 or the effect of p–n heterojunctions.

Polyaniline-iron oxide nanohybrid film as multi-functional label-free electrochemical and biomagnetic sensor for catechol

Polyaniline-iron oxide magnetic nanohybrid was synthesized and characterized using various spectroscopic, microstructural and electrochemical techniques. The smart integration of Fe3O4 nanoparticles within the polyaniline (PANI) matrix yielded a mesoporous nanohybrid (Fe3O4@PANI) with high surface area (94m2g−1) and average pore width of 12.8nm. Catechol is quasi-reversibly oxidized to o-quinone and reduced at the Fe3O4@PANI modified electrodes. The amperometric current response toward catechol was evaluated using the nanohybrid and the sensitivity and detection limit were found to be 312μAμL−1 and 0.2nM, respectively. The results from electrochemical impedance spectroscopy (EIS) indicated that the increased solution resistance (Rs) was due to elevated adsorption of catechol on the modified electrodes. Photoluminescence spectra showed ligand-to-metal charge transfer (LMCT) between p-π orbitals of the phenolate oxygen in catechol and the d-σ* metal orbital of Fe3O4@PANI nanohybrid. Potential dependent spectroelectrochemical behavior of Fe3O4@PANI nanohybrid toward catechol was studied using UV/vis/NIR spectroscopy. The binding activity of the biomagnetic particles to catechol through Brownian relaxation was evident from AC susceptibility measurements. The proposed sensor was used for successful recovery of catechol in tap water samples.

Photopatternable and refractive-index-tunable sol–gel-derived silica–titania nanohybrid materials

Silica–titania nanohybrid materials were synthesized using functionalized organosilanes and organically chelated titanium alkoxide in a simple sol–gel process. The synthesized silica–titania nanohybrid materials exhibited good solution processability and homogeneous dispersion without any phase separation regardless of the ratio of the mixture of the two components. The silica–titania nanohybrid materials exhibited good photoinitiator solubility and effective photocurability with a high degree of degree under ultraviolet (UV) exposure. Because of their high photocurability and solution processability, the silica–titania nanohybrid materials were readily converted into silica–titania nanohybrid films and were used for direct photopatterning without requiring the developing process used in the photomask method. In particular, the refractive indices of the silica–titania nanohybrid materials could be decreased by decreasing the content of chelated titanium alkoxide in the materials. Moreover, the silica–titania nanohybrid films exhibited high transmittance in the visible wavelength range, and their surface roughnesses were very smooth, exhibiting values <1 nm. On the basis of these observations, the fabricated silica–titania nanohybrid materials can be used in solution-processable materials for producing optical and electro-optical elements.

Linear Assembly of Oxidized Surface Treated Nanodiamonds in Polymer-Based Nanohybrids by Electric Field Inducement

Linear assembly of densely packed oxidized nanodiamonds (OxNDs) was achieved in polyepoxide-based nanohybrid films. A homogeneous suspension of pre-polymer of polyepoxide and OxNDs was cast onto a polyamide-spacer and subjected to an electric field in order to induce relocation and stretched-assembles of the fillers before the mixture became cross-linked. The OxNDs suspended readily, forming linear assemblies of OxNDs (LAOxNDs) of varying thicknesses, and aligned vertical to the film surfaces. Nanohybrid films with assemblies of LAOxNDs led to a significant enhancement in thermal conductivity while maintained the electrical insulation property of the polyepoxide. Mechanisms for the formation and structural variation of LAOxNDs in the matrix are elaborated regarding the improvement in physical properties. The present ambient-oxidation process and field-induced application are simple, but effective in enhancing the thermal properties of the polymer-based hybrids, and hence, promising for applications in the semiconductor industry, such as thermal interface materials.

Enhanced dielectric permittivity of fluorine polyimide matrix with embedded graphene

AbstractA polymer nanohybrid material with enhanced dielectric permittivity was prepared using the fluorine‐containing polyimide (PI) 4,4′‐(hexafluoroisopropylidene)diphthalic anhydride/4,4′‐oxydianiline (6FDA/ODA) as matrix and graphene as conductive filler in our present work. Studies on the dielectric properties of the 6FDA/ODA–graphene nanohybrid films show that the dielectric permittivity (ε) can be significantly enhanced by the layer‐by‐layer structure of graphene and the presence of fluorine also has an important influence on the improvement of ε. The percolation theory and microcapacitor model are used to explain the change of dielectric properties and a percolation threshold fc = 0.0152 (2.45 wt%) was obtained by a linear‐fit calculation.magnified image(© 2013 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

Facile Route for the Synthesis of a Vertically Aligned ZnO–PANI Nanohybrid Film for Polyphenol Sensing

Vertically aligned zinc oxide (ZnO) nanorods have been fabricated on a polyaniline (PANI) film template after electrochemical seeding and hydrothermal growth in a nutrient medium at a low temperature of 65 °C. Dense c-oriented [0001], hexagonal-shaped, vertically aligned ZnO nanorods are obtained on the PANI film surface, which is confirmed by X-ray diffraction and scanning electron microscopy studies. The nanohybrid film used as the working electrode has been characterized for sensing catechin polyphenol in different tea varieties through cyclic voltammetry. Principal component analysis shows enhancement in the classification ability of the nanohybrid film for various concentrations of catechin standard and tea infusions.

Thermal anisotropy of epoxy resin-based nano-hybrid films containing BN nanosheets under a rotating superconducting magnetic field

We demonstrated that the orientation of unmodified BN nanosheets can be controlled in a polymer matrix either perpendicular or parallel to the nanocomposite film surface with high anisotropy triggered by a rotating superconducting magnetic field (10T) while the prepolymer suspension of polyepoxide was cross-linked. The resulting polymer nanocomposite had outstanding thermal anisotropy, and the increased thermal diffusivity was proportional to the anisotropic orientation of the BN nanosheet. This research provides a method to effectively control diamagnetic 1D or 2D nanofiller particles in polymer-based nanocomposites, and may provide enhanced dielectric thermal interface materials for the semiconductor industry.

Oxidation of nanodiamonds and modulation of their assembly in polymer-based nanohybrids by field-inducement

Linear assembly of densely packed oxidized nanodiamonds (OxNDs) was performed in polymer-based nanohybrid films. A homogeneous suspension of the pre-polymer polyepoxide and OxNDs was placed onto a polyamide spacer and subjected to an electric field in order to induce the relocation and assembly of the fillers before the mixture became cross-linked. The OxNDs suspended readily, forming linear assemblies of OxNDs (LAOxNDs) of varying thicknesses, aligned perpendicular to the film surfaces. Nanohybrid films with linear assemblies of LAOxNDs exhibited a moderate increase in thermal conductivity while maintaining the electrical insulation properties of the polyepoxide. Mechanisms for the field-induced fabrication and the structural variation of LAOxNDs in the pre-polymer matrix are elucidated in relation to the variations in physical properties. The present air oxidation process and field-induced application are simple but effective in enhancing the physical properties of polymer-based hybrids, and hence, has the potential for applying in the fabrication and modulation of nanocomposite materials.

Transparent Graphene-Platinum Films for Advancing the Performance of Dye-Sensitized Solar Cells

ABSTRACTTransparent films of platinum nanoparticles on graphene nanohybrids were synthesized in a two-step process. Reduction of homogeneously dispersed Pt precursor and graphene in water and solution coating/annealing afforded thin films with high catalytic performance as counter electrodes in dye-sensitized solar cells (DSSC). The requisite dispersant consisting of poly(oxyethylene)-(POE) segments and cyclic imide functionalities allowed the in-situ reduction of dihydrogen hexachloroplatinate by ethanol and the formation of nanohybrids of graphene-supported Pt nanoparticles at 4.0 nm diameter. Characterizations of polymeric dispersants by Fourier-transform infrared spectroscopy, thermogravimetric analysis, and nanohybrids by transmission electron microscope were performed. After screening various compositions of Pt/graphene, the nanohybrid film at the specific ratio of 5/1 by weight was fabricated into a counter electrode (CE) for DSSC by the solution casting method. The evaluation of cell performance demonstrated the most improved power conversion efficiency of 8.00%. This is significant achievement in comparison with 7.14% for the DSSC with the conventional platinum sputtered CE. Furthermore, the solution casting method allows the preparation of transparent CE films that are suitable for using as rear-illuminated DSSC. The approach was proven to be feasible by measuring the cell efficiency under rear light illumination. The power efficiency up to 7.01%, comparable to 8.00% by a normally front illumination, has been accomplished. In contrast, the rear illumination at merely 2.36% efficiency was obtained for the DSSC with sputtered platinum CE. Analyses of cyclic voltammetry, electrochemical impedance spectra were well correlated to the high efficiency of the performance caused by this nanohybrid film.