Growth Of Zinc Oxide Nanorods Research Articles

Growth of well-arrayed ZnO nanorods on single-mode silica fiber and evaluation of its light scattering

Light scattering by zinc oxide (ZnO) nanorods at different growth duration is investigated. Synthesis of ZnO nanorods was done using hydrothermal techniques on the surface of bare silica optical fiber at different growth duration ranging from 4 to 10 hours. Both physical and optical characterizations were accomplished to investigate the morphology of ZnO and light scattering effect, respectively. The samples with different growth times were analyzed using the field emission scanning electron microscopy (FESEM) image to estimate the length, diameter and density of nanorods grown on the curve surface of bare fiber. At growth duration of 10 hours, the length, diameter, and density of nanorods are 928.85 nm, 185.77 nm, and 43.33 × 1012 nanorods/m2, respectively. Optical characterization was performed by measuring the output spectrum of the transmission light, the result indicates that the scattering effect increases with the growth durations.

A Simple, One-step, Seedless Hydrothermal Growth of ZnO Nanorods on Printed Circuit Board Substrate

Abstract: High quality, high density, and well-aligned zinc oxide (ZnO) nanorods have been synthesized on cost-effective printed circuit board (PCB) substrates via a simple, seedless, one-step, low-temperature hydrothermal method based galvanic cell structure. It was found that the outer diameters of the ZnO nanorods range from 50 nm to 400 nm. The as-grown ZnO nanorods prefer to grow along the c axis. The morphologies of the ZnO nanorods were investigated by scanning electron microscope (SEM) and X-ray diffraction (XRD). The crystallinity properties were characterized by Raman spectroscopy and photoluminescence (PL) spectroscopy.

Nonlinear piezoelectric dual sensor for the detection of angle and radius of a bending deformation

A non-linear piezoelectric dual sensor consisting of one-directionally and randomly aligned bi-axially grown zinc oxide nanorods was introduced for simultaneous detection of the bending radius and angle of bending deformation. The tendency of the voltage peak according to the bending radius and angle was experimentally measured and theoretically calculated using COMSOL Multiphysics®. For the sensing measurements, the bending radius was set as the independent variable, and both the average voltage peak and the rate of change of the voltage peak value with respect to the bending angle were set as dependent variables. Based on these variables, an algorithm was designed to simultaneously recognize the bending radius and angle. Finally, a two-channel nonlinear piezoelectric dual sensor was fabricated and the bending radius and angle were successfully identified through the proposed algorithm with various bending deformations.

Zinc oxide nanorods functionalized paper for protein preconcentration in biodiagnostics

Distinguishing a specific biomarker from a biofluid sample containing a large variety of proteins often requires the selective preconcentration of that particular biomarker to a detectable level for analysis. Low-cost, paper-based device is an emerging opportunity in diagnostics. In the present study, we report a novel Zinc oxide nanorods functionalized paper platform for the preconcentration of Myoglobin, a cardiac biomarker. Zinc oxide nanorods were grown on a Whatman filter paper no. 1 via the standard hydrothermal route. The growth of Zinc oxide nanorods on paper was confirmed by a combination of techniques consisting of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS,) scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDX) analysis. The Zinc oxide nanorods modified Whatman filter paper (ZnO-NRs/WFP) was further tested for use as a protein preconcentrator. Paper-based ELISA was performed for determination of pre-concentration of cardiac marker protein Myoglobin using the new ZnO-NRs/WFP platform. The ZnO-NRs/WFP could efficiently capture the biomarker even from a very dilute solution (Myoglobin < 50 nM). Our ELISA results show a threefold enhancement in protein capture with ZnO-NRs/WFP compared to unmodified Whatman filter paper, allowing accurate protein analysis and showing the diagnostic concept.

Growth of high-density ZnO nanorods on wood with enhanced photostability, flame retardancy and water repellency

Zinc oxide (ZnO) nanorod arrays were successfully assembled on the wood surface in situ via a two-step process consisting of formation of ZnO seeds and subsequent crystal growth under hydrothermal conditions at a low temperature. The morphology and crystalline structure of the formed ZnO nanorods were studied by field-emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD). Highly dense and uniform arrays of ZnO nanorods with well-defined hexagonal facets were generated on the wood surface by tuning the concentration of the ZnO growth solution during the hydrothermal treatment. Accelerated weathering tests indicated that the assembled ZnO nanorod arrays were highly protective against UV radiation and greatly enhanced the photostability of the coated wood. Meanwhile, the ZnO nanorod-coated wood can withstand continuous exposure to flame with only minor smoldering in contrast with the pristine wood catching fire easily and burning rapidly. Moreover, when further modified with low-surface-energy stearic acid, the ZnO nanorod decorated wood surface can be transformed into a superhydrophobic surface, with a water contact angle (CA) of ∼154°. Such ZnO nanorod-modified woods with enhanced photostability, flame retardancy and water repellency offer an interesting alternative to conventional wood preservation strategies, highlighting their potential applications in some novel wood products.

Solution-processed hybrid light emitting and photovoltaic devices comprising zinc oxide nanorod arrays and tungsten trioxide layers

The goal of this research is to prepare inverted optoelectronic devices with improved performance by combining zinc oxide (ZnO) nanorod arrays and tungsten trioxide (WO3) layer. ZnO seed layers with thickness of 52 nm were established, followed by growth of ZnO nanorods with length of 300 nm vertical to the ITO substrates in the precursor bath. The ZnO nanorod arrays possess high transmittance up to 92% in the visible range. Inverted light-emitting devices with the configuration of ITO/ZnO nanorods/ionic PF/MEH-PPV/PEDOT:PSS/Au were constructed. The best device achieved a max brightness and current efficiency of 10,620 cd/m2 and 0.25 cd/A at 10 V, respectively, revealing much higher brightness compared with conventional devices using Ca/Al as cathode, or inverted devices based on ZnO thin film. By inserting a WO3 thin layer between PEDOT:PSS and Au electrode, the max brightness and current efficiency were further improved to 21,881 cd/m2 and 0.43 cd/A, respectively. Inverted polymer solar cells were also fabricated with the configuration of ITO/ZnO nanorods/ionic PF/P3HT:PC61BM/PEDOT/WO3/Au. The best device parameters, including the open-circuit voltage, short-circuit current density, fill factor, and power conversion efficiency, reached 0.54 V, 14.87 mA/cm2, 41%, and 3.31%, respectively

Fabrication of a robust and highly sensitive nitrate biosensor based on directly grown zinc oxide nanorods on a silver electrode

This article reports the fabrication of a robust and highly sensitive nitrate biosensor based on directly-grown ZnO NRs on an electrode surface.

Development and characterization of a hydrophobic treatment for jute fibres based on zinc oxide nanoparticles and a fatty acid

This work aims at developing a hydrophobic treatment for jute fibres based on the grafting and growth of zinc oxide (ZnO) nanorods on the fibre surface. The first step consists in removing impurities from the fibre surface with a scouring treatment. In the second step, the jute fibres are coated with a layer of ZnO nanoseeds. A hydrothermal process is carried out as a third step to ensure a uniform growth of ZnO nanorods on the surface of the jute fibres. Finally, a hydrophobic treatment is performed on the ZnO nanorod-covered jute fibres using stearic acid (SA), i.e., a typical fatty acid. A large improvement in the fibre hydrophobicity was obtained without any negative effect on thermal stability and limited reduction in strength. Complementary measurements by scanning electron microscopy and X-ray diffraction were also performed and revealed a hexagonal system for the ZnO nanorods.

Growth of zinc oxide nanorod structures: pressure controlled hydrothermal process and growth mechanism

Zinc oxide (ZnO) nanorods of various morphologies are grown on zinc substrate by pressure-assisted hydrothermal process and the growth mechanism is investigated with the help of molecular dynamics (MD) simulation results. Hydrothermally reacted ZnO2 nanostructure bottom-up formation from Zn substrate is a useful process employed here. A systematic study on the role of process control parameters such as pressure and temperature on nanorod growth has been carried out. Correlation among the process parameters to form ordered nanostructures is established. The effect of pressure on the diameter and length of the grown ZnO nanorod structures is studied, which is precisely tunable. With a decrease in pressure from 500 to 400 kPa, the nanorod diameter is reduced by 22.2 %, while its length is increased by 24.8 %. At lower vapor pressure, the nanorod tips are sharper, whereas at higher vapor pressure they are flat. These variations along with a detailed analysis of MD simulations helps us hypothesize that pressure plays an important role in governing the diffusion of oxygen atom onto zinc surface and generating wurtzite phase. Simulation results clearly show that ZnO nanorods lift off due to their interaction with the Zn atoms on the substrate and the resulting forces.

Nucleation and growth of zinc oxide nanorods directly on metal wire by sonochemical method

ZnO nanorods were directly grown on four different wires (silver, nickel, copper, and tungsten) using sonochemical method. Zinc nitrate hexahydrate and hexamethylenetetramine (HMT) were used as precursors. Influence of growth parameters such as precursors’ concentration and ultrasonic power on the grown nanorods were determined. The results demonstrated that the precursor concentration affected the growth structure and density of the nanorods. The morphology, distribution, and orientation of nanorods changed as the ultrasonic power changed. Nucleation of ZnO nanorods on the wire occurred at lower ultrasonic power and when the power increased, the formation and growth of ZnO nanorods on the wires were initiated. The best morphology, size, distribution, and orientation of the nanorods were observed on the Ag wire. The presence of single crystal nanorod with hexagonal shaped was obtained. This shape indicates that the ZnO nanorods corresponded to the hexagonal wurtzite structure with growth preferential towards the (002) direction.

Effect of Growth Temperature on ZnO Nanorod Properties and Dye Sensitized Solar Cell Performance

&lt;p&gt;Nanostructure of semiconductor materials zinc oxide (ZnO) is widely used in fabrication of solar cell devices. The performance of such devices is strongly depending on the nanostructures of the thin films used. In this paper reports the effect of growth temperature during synthesis of one-dimensional (1-D) anatase ZnO nanorod arrays through hydrothermal process facing their structure, morphology, and optical properties. The ZnO nanorod was first synthesized use the solution concentration and time fixed at 0.04M and 1 hour. The growth temperature were varied from 70, 80, 90 and 100 &lt;sup&gt;°&lt;/sup&gt;C. The effect of growth temperature on the structural, morphology, and optical absorption of ZnO nanorod were studied by using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and UV–vis spectroscopy. The regularity, diameters, heights, and surface densities of the ZnO nanorods were increased with the growth temperature.The optimum results of FESEM characterizations showed that the grown ZnO nanorods have diameters of 64.14 ± 8.3 nm, heights of 363.72 ± 34 nm and surface densities of 182 numbers/µm&lt;sup&gt;2&lt;/sup&gt; which was obtained at temperature of 90 ˚C. The optimum ZnO nanorod film was utilized as photo anode in dye sensitized solar cells. The DSSC yielded Jsc of 0.86 mA/cm&lt;sup&gt;2&lt;/sup&gt;, Voc of 0.49 V, and FF of 38 %, resulting in PCE of 0.16 %.&lt;/p&gt;&lt;p&gt; &lt;/p&gt;

Effect of Growth Temperature on ZnO Nanorod Properties and Dye Sensitized Solar Cell Performance

&lt;p&gt;Nanostructure of semiconductor materials zinc oxide (ZnO) is widely used in fabrication of solar cell devices. The performance of such devices is strongly depending on the nanostructures of the thin films used. In this paper reports the effect of growth temperature during synthesis of one-dimensional (1-D) anatase ZnO nanorod arrays through hydrothermal process facing their structure, morphology, and optical properties. The ZnO nanorod was first synthesized use the solution concentration and time fixed at 0.04M and 1 hour. The growth temperature were varied from 70, 80, 90 and 100 &lt;sup&gt;°&lt;/sup&gt;C. The effect of growth temperature on the structural, morphology, and optical absorption of ZnO nanorod were studied by using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and UV–vis spectroscopy. The regularity, diameters, heights, and surface densities of the ZnO nanorods were increased with the growth temperature.The optimum results of FESEM characterizations showed that the grown ZnO nanorods have diameters of 64.14 ± 8.3 nm, heights of 363.72 ± 34 nm and surface densities of 182 numbers/µm&lt;sup&gt;2&lt;/sup&gt; which was obtained at temperature of 90 ˚C. The optimum ZnO nanorod film was utilized as photo anode in dye sensitized solar cells. The DSSC yielded Jsc of 0.86 mA/cm&lt;sup&gt;2&lt;/sup&gt;, Voc of 0.49 V, and FF of 38 %, resulting in PCE of 0.16 %.&lt;/p&gt;&lt;p&gt; &lt;/p&gt;

Resonant-cavity-enhanced a-Ge:H nanoabsorber solar cells for application in multijunction devices

A resonant-cavity-enhanced solar cell with a 25nm thick amorphous germanium nanoabsorber is demonstrated. The device is specifically designed for use as bottom cell in multijunction devices. In this case, instead of relying on broadband absorption, only red light needs to be absorbed in the bottom cell. This allows exploiting the narrow resonance patterns of long Fabry-Pérot cavities to achieve efficient absorption inside the nanoabsorber. It is shown that this approach can only be integrated into multijunction devices when suppressing inter-subcell coherence. To achieve this, the intermediate reflector of the tandem device is textured using electrochemically grown zinc oxide nanorods.

Role of hexamethylenetetramine concentration on structural, morphological, optical and electrical properties of hydrothermally grown zinc oxide nanorods

Zinc oxide (ZnO) nanorods were grown on the glass substrates using hydrothermal method. Influence of hexamethylenetetramine (HMTA) concentration on the morphological, structural, optical and electrical properties of ZnO was investigated. Increasing HMTA concentration produces dense growth of nanorods and decreases the diameter from ~450 to ~150 nm and also modified the hexagonal shape of ZnO nanorods to circular shape. X-ray diffraction spectra revealed that the synthesized ZnO nanorod exhibits wurtzite structure. Shifting of absorbance edge from 3.30 to 3.36 eV with increasing concentration of HMTA was observed in the UV–Vis spectra. Photoluminescence studies showed the presence of defect related peaks such as zinc interstitial and oxygen vacancies. The observed blue shift in UV emission peak from 387 to 361 nm in photoluminescence spectrum also confirmed the decrease in the size of nanorods. Electrical studies showed the increase in the resistance with the increase in the HMTA concentration from 1.17 to 16.9 kΩ due to dense and reduced size of nanorod networks.

Metal-Semiconductor-Metal Near-Ultraviolet (~380nm) Photodetectors by Selective Area Growth of ZnO Nanorods and SiO2 Passivation.

Metal-semiconductor-metal near-ultraviolet (NUV) photodetectors (PDs) based on zinc oxide (ZnO) nanorods (NRs), operating at λ ~ 380 nm, were fabricated using conventional photolithography and hydrothermal synthesis processes. The vertically aligned ZnO NRs were selectively grown in the channel area of PDs. The performance of ZnO NR-based NUV PDs was optimized by varying the solution concentration and active channel width (Wch). For the fabricated samples, their electrical and photoresponse properties were investigated under the dark state and the illumination at wavelength of ~380 nm, respectively. For the device (Wch = 30 μm) with ZnO NRs at 25 mM, the highest photocurrent of 0.63 mA was obtained with the on/off ratio of 1720 at the bias of 5 V. The silicon dioxide passivation was also carried out to improve the photoresponse properties of PDs. The passivated devices exhibited faster rise and reset times rather than those of the unpassivated devices.

Effect of Zinc Nitrate Concentration on the Optical and Morphological Properties of ZnO Nanorods for Photovoltaic Applications.

We report the effect of zinc nitrate (ZN) concentration on the growth of zinc oxide (ZnO) nanorods and their optical and morphological properties. As prepared ZnO nanorods on glass substrate were characterized using field emission scanning electron microscopy (FE-SEM), ultra violet-visible (UV-Vis), Raman and Photo-luminescence (PL) spectroscopy. FE-SEM results show that the nanorods were obtained for the 0.033 and 0.053 M concentration of ZN. As the ZN concentration increased from 0.033 M to 0.053 M, the diameter of the nanorods was increased. It indicated that the diameter of the nanorods was affected by the ZN concentration. The Raman spectra of nanorods show only one peak at 438 cm(-1) corresponding to E2(high) high mode, which means that ZnO nanorods grown perpendicularly on the glass substrate, i.e., the ZnO nanorod arrays are highly c-axis oriented. Room-temperature PL spectrum of the as-grown ZnO nanorods reveals a near-band-edge (NBE) emission peak and defect induced green light emission. The green light emission band at -579 nm might be attributed to surface oxygen vacancies or defects. The UV-visible measurements reflect that the total transmittance for the as grown ZnO nanorods is over 80%. The simple technique presented in this study to grow ZnO nanorods on a glass substrate can be helpful for making the cost effective photovoltaic devices.

Side coupling of multiple optical channels by spiral patterned zinc oxide coatings on large core plastic optical fibers

Improved optical side coupling efficiency was demonstrated for spiral patterned zinc oxide (ZnO) nanorods coated large core plastic optic fibers (POFs) as opposed to unpatterned continuous coatings. ZnO nanorods were grown by the hydrothermal method directly onto POF surfaces. Nanorods coating enhanced coupling inside the fiber by scattering light but were also capable of causing leakage. Structuring the growth to specific regions allows scattering from different segments along the fiber to contribute to the total coupled power. ZnO nanorods growth time of 12 h and temperature of 90 °C provided the best coupling voltage. Side coupling was measured to be a factor of 2.2 times better for spiral patterned coatings as opposed to unpatterned coatings. The formation of multiple segments was as well used for multiple-wavelength channels excitation where different bands were side coupled from different segments.

Synthesis, Characterization of ZnO Nanorods and its Interaction with Albumin Protein

A simple wet chemical method has been successfully used to grow zinc oxide nanorods (ZnO NRs). The structural characteristics were investigated through XRD and TEM. The crystal unit cell of the NRs was found to be hexagonal and the size of the ZnO NR ≈27nm. The interaction as well as the formation of bio-conjugate of Bovine Serum Albumin (BSA) and ZnO NRs is investigated using optical spectroscopy, zeta potential, TEM analysis. UV–VIS and fluorescence spectra show that a spontaneous binding process occurred between BSA and ZnO NRs. The binding constant and the number of binding sites were also calculated.

Efficiency Enhancement of Dye-Sensitized Solar Cells' Performance with ZnO Nanorods Grown by Low-Temperature Hydrothermal Reaction.

In this study, aligned zinc oxide (ZnO) nanorods (NRs) with various lengths (1.5–5 µm) were deposited on ZnO:Al (AZO)-coated glass substrates by using a solution phase deposition method; these NRs were prepared for application as working electrodes to increase the photovoltaic conversion efficiency of solar cells. The results were observed in detail by using X-ray diffraction, field-emission scanning electron microscopy, UV-visible spectrophotometry, electrochemical impedance spectroscopy, incident photo-to-current conversion efficiency, and solar simulation. The results indicated that when the lengths of the ZnO NRs increased, the adsorption of D-719 dyes through the ZnO NRs increased along with enhancing the short-circuit photocurrent and open-circuit voltage of the cell. An optimal power conversion efficiency of 0.64% was obtained in a dye-sensitized solar cell (DSSC) containing the ZnO NR with a length of 5 µm. The objective of this study was to facilitate the development of a ZnO-based DSSC.

Characteristics of controllable‐shape well‐aligned zinc oxide nanorods synthesised by microwave‐assisted heating

A microwave-assisted heating method for growing well-aligned zinc oxide (ZnO) nanorods on the ZnO/silicon (Si) substrate is developed. For ZnO nanorods growth, a thin ZnO seed layer was deposited on an Si substrate by sputtering technique. The ZnO nanorods grown on the ZnO/Si substrate were synthesised in aqueous solution mixed with zinc nitrate hexahydrate and hexamethylenetetramine (HMTA) under microwave heating. The scanning electron microscopy (SEM) images and X-ray diffraction results exhibit that the ZnO nanorods with hexagonal phase, single crystalline, and highly oriented along (002) plane are obtained successfully. SEM images also show that the morphology and diameter of the synthesised ZnO nanorods can be controlled by adjusting the molar ratio of Zn(NO3)2·6H2O to HMTA. The Raman scattering results evidence the vertical well-aligned ZnO nanrods with larger diameter are strain-free. The investigations of the photoluminescence spectra suggest that the ultraviolet emission peak of the synthesised ZnO nanorods depending on its controllable diameter would be applicable for various nanodevice fabrications.