Hybrid Nanorods Research Articles

Syntheses and photocatalytic performances of vertically grown Fe2O3 and TiO2/Fe2O3 nanorods on coated glass substrates

Fe2O3 nanorods vertically grown on α-Fe2O3 (hematite) coated glass substrate have been successfully synthesized first time through hydrothermal technique. The influences of process parameters on the morphologies of Fe2O3 nanorods were investigated in detail also. The synthesized samples were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectroscopy, and UV–vis absorption spectroscopy. Vertically grown Fe2O3 nanorods exhibited a hematite-type crystal structure and a size of around 100nm diameter and around 500nm length. The rutile-TiO2/α-Fe2O3 hybrid nanorods were successfully synthesized as well. The photocatalytic experiments showed that either single hematite nanorods or mixture rutile with hematite nanorods exhibited a high photodegradation capability for methyl blue organic pollutant. This clearly means that Fe2O3-based nanorods can have an extended application such as waste water treatment.

Liquid Crystalline Polymer–Co Nanorod Hybrids: Structural Analysis and Response to a Magnetic Field

This work deals with the structural analysis of side-chain liquid crystalline polysiloxanes, doped with magnetic cobalt nanorods, and their orientational properties under a magnetic field. These new materials exhibit the original combination of orientational behavior and ferromagnetic properties at room temperature. Here we show that, within the liquid crystal polymer matrix, the cobalt nanorods self-assemble in bundles made of nanorod rows packed in a 2-dimensional hexagonal lattice. This structure accounts for the magnetic properties of the composites. The magnetic and orientational properties are discussed with respect to the nature of the polymer matrix.

The development, fabrication, and material characterization of polypropylene composites reinforced with carbon nanofiber and hydroxyapatite nanorod hybrid fillers

This study focuses on the design, fabrication, microstructural and property characterization, and biocompatibility evaluation of polypropylene (PP) reinforced with carbon nanofiber (CNF) and hydroxyapatite nanorod (HANR) fillers. The purpose is to develop advanced PP/CNF–HANR hybrids with good mechanical behavior, thermal stability, and excellent biocompatibility for use as craniofacial implants in orthopedics. Several material-examination techniques, including X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, differential scanning calorimetry, tensile tests, and impact measurement are used to characterize the microstructural, mechanical, and thermal properties of the hybrids. Furthermore, osteoblastic cell cultivation and colorimetric assay are also employed for assessing their viability on the composites. The CNF and HANR filler hybridization yields an improvement in Young’s modulus, impact strength, thermal stability, and biocompatibility of PP. The PP/2% CNF–20% HANR hybrid composite is found to exhibit the highest elastic modulus, tensile strength, thermal stability, and biocompatibility.

Hydrothermal synthesis of carbon- and reduced graphene oxide-supported CoMoO4 nanorods for supercapacitor

Hybrid CoMoO4 nanorods with carbon (C) and graphene oxide (rGO) are successfully synthesized via one-step hydrothermal process. Hybrid α-CoMoO4 nanorods have shown excellent electrochemical performances compared to pristine CoMoO4 in alkaline electrolyte. Specifically, CoMoO4/C nanorod exhibits a maximum specific capacitance of 451.6 F g−1 at the current density of 1 A g−1, whereas CoMoO4/rGO shows high specific capacitance of 336.1 F g−1 at the same current density. Both the hybrid nanorods show good rate capability even at high current density of 20 A g−1 and long-term cyclic stability. The observed electrochemical features of the hybrid CoMoO4 nanostructure could be attributed to the presence of highly conductive carbonaceous material on unique one-dimensional nanorod microstructure which enhances the electrical conductivity of the nanorods thereby allowing faster electrolyte ion diffusion during the redox process.

Synthesis and Optical Properties of Linker-Free TiO2/CdSe Nanorods

Linker-free TiO2/CdSe hybrid nanorods (NRs) were prepared by growing CdSe QDs in the presence of TiO2 NR seeds using seeded–growth type colloidal injection approach. TEM studies revealed the abundant formation of anatase TiO2 NRs with different lengths. We found that the as-prepared TiO2 seeds determined the morphology of TiO2/CdSe NRs. The photophysics of these materials were studied by photoluminescence (PL) and femtosecond transient absorption spectroscopy. While we observed the efficient PL quenching in TiO2/CdSe NRs, the bleach dynamics of TiO2/CdSe NRs is similar to that of CdSe NRs. It suggests that while surface traps that arise from the lattice mismatch between CdSe and TiO2 are mainly observed in transient absorption measurements the ultrafast exciton dissociation over the experimental time resolution occurs in TiO2/CdSe NRs.

Three-dimensional MnO2 nanowire/ZnO nanorod arrays hybrid nanostructure for high-performance and flexible supercapacitor electrode

Pure MnO2 nanowires and MnO2 nanowire/ZnO nanorod array hybrid nanostructure grown on carbon cloth are synthesized through a low temperature solution method for flexible and high performance supercapacitor applications. The MnO2 nanowire/ZnO nanorod hybrid nanostructured electrodes exhibit more than two times higher specific capacitance, and better capacitance retention than those of pure MnO2 nanowire electrodes. For the three-dimensional MnO2 nanowire/ZnO nanorod array hybrid electrode, a high specific capacitance of 746.7 F g−1 (areal capacitance ∼41.5 mF cm−2) is obtained at a scan rate of 2 mV s−1, while the specific capacitance of pure MnO2 nanowire electrode is 319.6 F g−1. The electrochemical impedance spectroscopy measurements also confirm MnO2 nanowire/ZnO nanorod array hybrid electrode has better electrochemical character. The MnO2 nanowire/ZnO nanorod array hybrid electrode shows great cycle stability, it only losses 6.5% of the initial capacitance after 1000 cycles. The energy density and power density of the hybrid electrode at 2 A g−1 are 63.1 Wh kg−1 and 950 W kg−1, respectively. It is illustrated that the electrochemical performance of MnO2 nanowire electrode has been greatly enhanced with the supporting of ZnO nanorod arrays.

A hybrid of CoOOH nanorods with carbon nanotubes as a superior positive electrode material for supercapacitors

A hybrid of CoOOH nanorods with MWCNTs has been synthesized by hydrothermal method, exhibiting high reversible capacitance, good high-rate capability and excellent cycling performance.

Characterization of the antioxidant activity of gold@platinum nanoparticles

Gold@platinum (Au@Pt) nanostructures exhibit desirable catalytic abilities and unique optical properties, which are not seen in single-component metal nanoparticles (NPs). To date, however, there is only limited information available in the literature on the integrated approach to investigate the antioxidant activities of Au@Pt NPs. The aim of the present study, was to evaluate the antioxidant activities of hybrid nanorods, i.e., Au@Pt NPs. Specifically, the free radical scavenging effect, hydroxyl radical scavenging activity, and superoxide dismutase (SOD)-like activity of Au@Pt NPs were examined. Furthermore, the in vitro antioxidant ability of Au@Pt NPs was assessed by measuring the cell viability of V79-4 (Chinese hamster lung fibroblasts), PC-3 (human prostate cancer), and MCF-7 (human breast cancer) cells under oxidative stress induced by hydrogen peroxide (H2O2). The results showed that Au@Pt NPs exhibited high DPPH radical scavenging activity, non-site specific hydroxyl radical scavenging activity, linoleic acid peroxidation inhibitory ability by TBA tests in a low Au@Pt NP concentration range. Furthermore, in vitro experiments revealed that Au@Pt NPs showed cellular protection against oxidative stress induced by H2O2.

Hybrid poly(3-hexyl thiophene)–TiO2 nanorod oxygen sensor

Conjugated polymers are promising materials for oxygen sensing owing to their specific interaction with oxygen molecules and also advantages of low cost, easy processing and room temperature operation. The present work for the first time demonstrates an oxygen sensing material of poly(3-hexylethiophene) (P3HT)–TiO2 nanorod hybrid thin film which reveals considerable improvement of sensing response as compared to the pristine P3HT film. The effects of hybrid composition and film thickness on sensing performance were systematically investigated. Kelvin probe force microscopy (KPFM) was employed to understand the mechanism of oxygen sensing including the control of surface morphologies and electronic properties by TiO2 incorporation. The hybrid material developed in this study is helpful in the advancement of room temperature oxygen sensing technology.

Graphene oxide modified ZnO nanorods hybrid with high reusable photocatalytic activity under UV-LED irradiation

In this work, graphene oxide/zinc oxide (GO/ZnO) hybrid was prepared through a facile hydrothermal process. Transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectra and N2 adsorption and desorption isotherms were used to investigate the morphology, crystal structure, optical properties and specific surface area of GO/ZnO hybrid. It was shown that the well-dispersed ZnO nanorods were deposited on GO homogeneously. Photocatalytic properties of GO/ZnO nanorods hybrid were evaluated under 375 nm light-emitting diode light irradiation for photodegradation of methylene blue (MB). The synergic effect between GO and ZnO was found to lead to an improved photo-generated carrier separation. An optimal GO content has been determined to be 3 wt%, and corresponding the apparent pseudo-first-order rate constant kapp is 0.0248 min−1, 4.3 times and 2.5 times more than that of pure ZnO nanorods and commercial P25 photocatalyst, respectively. Moreover, the cyclic photocatalytic test indicated that GO/ZnO hybrid can be reused for degradation of MB, suggesting the possible application of GO/ZnO hybrid as excellent candidate for water treatment.

Photo-responsive spiropyran monolayer protected gold nanorod

The spiropyran monolayer covalently protected gold nanorod (GNR) hybrid was prepared and well characterized for the first time, which was stable, soluble and photo-responsive under certain light irradiation in organic solvent. The photochromism of the densely packed spiropyran monolayer on the surface of GNRs was found having effect on the surface plasmonic resonance (SPR) absorption of gold nanorods, namely inducing the intensity change of the two plasma absorption peaks at 786 and 551 nm of the GNR hybrids. The functionalization of this organic-inorganic GNR hybrid and the photo-tuning of its SPR absorption properties, especially in the not only UV–Vis range but also near-infrared (NIR) spectral area would make important and interesting sense in the area of functional hybrid nanomaterial.

Light transmission enhancement from hybrid ZnO micro-mesh and nanorod arrays with application to GaN-based light-emitting diodes

A hybrid ZnO micro-mesh and nanorod arrays (MMNR) was fabricated as a light output window for GaN-based light-emitting diodes (LEDs) to enhance the light extraction efficiency. The light output power of GaN-based LEDs with the ZnO MMNR is improved by 95% compared to the original planar LEDs. The ZnO MMNR is manufactured by photolithography techniques and a two-step wet chemical growth process. The incident angle-resolved light transmission of the ZnO MMNR beyond the critical angle of total internal reflection is greatly enhanced. The light diffraction pattern of the ZnO MMNR shows that it possesses both the two-dimensional diffraction grating effect of a ZnO micro-mesh and the light scattering effect of a ZnO nanorod array. LEDs with the ZnO MMNR have greater light extraction efficiency than those with only a ZnO micro-mesh or a ZnO nanorod array. The local optical field patterns of the ZnO micro-mesh and the ZnO MMNR are investigated using confocal scanning electroluminescence microscopy. The microscopic light extraction mechanism of the ZnO MMNR is analyzed in-depth.

Novel mesoporous g-C3N4 and BiPO4 nanorods hybrid architectures and their enhanced visible-light-driven photocatalytic performances

BiPO4 nanorods covered with mesoporous graphitic C3N4 (mg-C3N4) with highly visible-light-driven photocatalytic activity have been synthesized by using a in situ growth strategy. X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectra (XPS) and UV–vis diffusive reflectance spectra have been employed to characterize the hybrid materials. The as-prepared composite photocatalyst show the outstanding activity for degradation of Methyl Orange Dye (MO) under visible light (λ>420nm). The enhanced photocatalytic activity for BiPO4 coupled with mg-C3N4 comes from the high migration efficiency of photoinduced electrons on the interface of mg-C3N4 and BiPO4. As a result, the optimum photocatalytic activity of BiPO4/mg-C3N4 with BiPO4 weight ratio of 15% under visible irradiation is above 2.5 times as high as that of pure mg-C3N4.

Light Extraction Enhancement of GaN LEDs by Hybrid ZnO Micro-Cylinders and Nanorods Array

A hybrid patterned ZnO micro-cylinders and nanorods array (MCNR) was fabricated to improve the light extraction efficiency for high brightness GaN-based light-emitting diodes (LEDs). The light extraction efficiency of the LEDs with the ZnO MCNR is increased by 86.4% compared with conventional planar LEDs. LEDs with ZnO MCNR have greater light extraction efficiency than those only with ZnO micro-cylinders or ZnO nanorods array. The optical-electrical characteristics and far-field radiation patterns are measured and analyzed. The local optical field distribution patterns of the LEDs with ZnO micro-cylinders, ZnO nanorods, and ZnO MCNR are investigated using confocal scanning electroluminescence microscopy. The higher light extraction enhancement effect of ZnO MCNR is attributed to that it combines the light outputting effect from side walls of ZnO micro-cylinders and the light scattering effect of ZnO nanorods array.

Epoxy/polyaniline–ZnO nanorods hybrid nanocomposite coatings: Synthesis, characterization and corrosion protection performance of conducting paints

The objective of this research is the production of an epoxy coating blended with organic–inorganic hybrid nanocomposite as a corrosion inhibiting pigment applied over carbon steel grade ST37. A series of conducting polyaniline (PANI)–ZnO nanocomposites materials has been successfully prepared by an in situ chemical oxidative method of aniline monomers in the presence of ZnO nanorods with camphorsulfonic acid (CSA) and ammonium peroxydisulfate (APS) as surfactant and initiator, respectively. The synthesized polymers were characterized by X-ray diffraction pattern (XRD), Fourier transform infrared (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermal gravimetric analysis (TGA) and electrical conductivity techniques. Synthesized nanocomposites were solved in tetraethylenpentamine (TEPA), and then prepared solution was mixed with epoxy and then was applied as a protective coating on carbon steel plates. The anti-corrosion behavior of the epoxy binder blended with PANI–ZnO nanocomposites were studied in 3.5% NaCl solution at a temperature of 25°C by electrochemical techniques including electrochemical impedance spectroscopy (EIS) and chronopotentiometry at open circuit potential (OCP). It was observed that the epoxy coating containing conducting PANI–ZnO nanocomposites exhibited higher corrosion resistance and provided better barrier properties in the paint film in comparison with pure epoxy and epoxy/PANI coatings. In the case of conducting coatings, the OCP was shifted to the noble region due to presence of PANI pigments. Additionally, the possibility of formation of a passive film in the presence of PANI was reinforced at the substrate–coating interface. SEM studies taken from surface of the coatings showed that epoxy/PANI–ZnO hybrid nanocomposite coating systems (EPZ) are crack free, uniform and compact. Furthermore, it was found that the presence of ZnO nanorods beside PANI can significantly improve the barrier and corrosion protection performance of the epoxy coating due to the flaky shaped structure of the PANI–ZnO nanocomposites.

Cover Picture: Tailoring Copper Oxide Semiconductor Nanorod Arrays for Photoelectrochemical Reduction of Carbon Dioxide to Methanol (ChemPhysChem 10/2013)

CuO/Cu2O hybrid nanorod arrays are prepared on a Cu substrate by K. Rajeshwar, N. R. de Tacconi et al. (p. 2251). The procedure involves the initial thermal growth of CuO nanorods followed by controlled electrodeposition of p-type Cu2O crystallites on their walls. Photoelectrosynthesis of methanol from CO2 is conducted under simulated solar irradiation at Faradaic efficiencies up to 95%. The hybrid nanoarchitectures, ensuring a double pathway for photoelectron injection to CO2, along with the high surface area are key to the excellent performance of these films.

Cu/ZnO nanorods′ hybrid showing enhanced photoluminescence properties due to surface plasmon resonance

Cu/ZnO nanorods (NRs) hybrids have been synthesized for various concentrations of Cu nanoparticles (NPs). X-ray diffraction patterns and X-ray photoelectron spectroscopy show the phase purity of the hybrids. A detailed study on the photoluminescence (PL) properties of Cu/ZnO NRs hybrids show that the near band edge emission (NBE) of ZnO is enhanced eight times after Cu loading over that of pristine ZnO NRs. The mechanism behind luminescence enhancement has been analyzed by the surface plasmon dispersion relations of Cu/air and Cu/ZnO systems. It has been confirmed that the enhanced emission is due to the surface plasmon resonance coupling of the NBE emission between Cu and ZnO.

Silver Cholesteric Liquid Crystalline: Shape-Dependent Assembly and Plasmonic Chiroptical Response

A novel silver cholesteric liquid crystalline (CLC) colloidal suspension has been fabricated by a shape-dependent self-assembly process via van der Waals and electrostatic interactions. The circular dichroism (CD) spectra show that the cysteine molecules have a strong effect on the as-obtained silver CLC structure, albeit it is very stable in the presence of many other kinds of amino acid molecules. The original silver CLC structure can be completely dissociated as soon as the concentration of cysteine solution arrives at a critical value. Furthermore, the cysteine molecules can translate their chirality to the silver nanorods (NRs) and silver nanoplates (NPs) by strong S–Ag bonds to form two novel chiral silver–cysteine nanocrystals, respectively. The colloidal suspension of silver–cysteine hybrid nanorods shows a much stronger CD intensity than the colloidal suspension of silver–cysteine hybrid nanoplates do, which can be attributed to its unique anisotropy of geometry and superficial constitution.

Controlled synthesis of MoO3 microcrystals by subsequent calcination of hydrothermally grown pyrazine–MoO3 nanorod hybrids and their photodecomposition properties

We present our results on successful synthesis of pyrazine–MoO3 nanorod hybrids by using pyrazine and MoO3 nanorods. On the first stage, MoO3 nanorods were grown hydrothermally and, on the second stage, their mixture with pyrazine was again involved in a hydrothermal reaction to produce organic–inorganic hybrids. To understand the growth mechanism of the hybrids we varied time and temperature of the hydrothermal process. Intercalation of pyrazine was confirmed through X-ray diffraction analysis, X-ray photoelectron spectroscopy, X-ray emission spectroscopy, scanning electron microscopy methods. Upon calcinations, pyrazine was deintercalated, i.e. removed from the MoO3 hybrid system, and the MoO3 nanorods were found to bind together resulting in formation of MoO3 microslabs with increased surface area. Photodecomposition performance of the MoO3 nanorods, pyrazine–MoO3 hybrids and MoO3 microcrystals was studied against Procion Red MX-5B textile dye. A high photodecomposition performance was found to decrease when going from MoO3 nanorods to MoO3 microcrystal and, further, to pyrazine–MoO3 hybrids.

A sensitive NADH and ethanol biosensor based on graphene–Au nanorods nanocomposites

In this paper, a simple strategy for the synthesis of graphene–Au nanorods hybrid nanosheets (GN–AuNRs) through electrostatic interaction has been demonstrated. Due to the synergistic effect between AuNRs and GN, the hybrid nanosheets exhibited excellent performance toward dihydronicotinamide adenine dinucleotide (NADH) oxidation, with a low detection limit of 6µM. The linear GN–AuNRs also served as a biocompatible and electroactive matrix for enzyme assembly to facilitate the electron transfer between the enzyme and the electrode. Using alcohol dehydrogenase (ADH) as a model system, a simple and effective sensing platform was developed for ethanol assay. The response displayed a good linear range from 5 to 377µM with detection limit 1.5μM. Furthermore, the interference effects of redox active substances, such as uric acid, ascorbic acid and glucose for the proposed biosensor were negligible.