Zinc Oxide Nanoarrays Research Articles

Surface Functionalization of 3D-Printed Scaffolds with Seed-Assisted Hydrothermally Grown ZnO Nanoarrays for Bone Tissue Engineering.

Bioactive metal-based nanostructures, particularly zinc oxide (ZnO), are promising materials for bone tissue engineering. However, integrating them into 3D-printed polymers using traditional blending methods reduces the cell performance. Alternative surface deposition techniques often require extreme conditions that are unsuitable for polymers. To address these issues, we propose a metal-assisted hydrothermal synthesis method to modify 3D printed polycaprolactone (PCL) scaffolds with ZnO nanoparticles (NPs), facilitating the growth of ZnO nanoarrays (NAs) at a low-temperature (55 °C). Physicochemical characterizations revealed that the ZnO NPs form both physical and chemical bonds with the PCL surface; chemical bonding occurs between the carboxylate groups of PCL and Zn(OH)2 during seed deposition and hydrothermal synthesis. The ZnO NPs and NAs grown for a longer time (18 h) on the surface of PCL scaffolds exhibit significant proliferation and early differentiation of osteoblast-like cells. The proposed method is suitable for the surface modification of thermally degradable polymers, opening up new possibilities for the deposition of diverse metals.

Facilistic preparation of zinc oxide nanoarrays on nickel foam via a one-step chemical bath method for photocatalysis

One-dimensional ZnO nanoarrays (ZnO NAs) were prepared on nickel foam using a one-step chemical bath deposition method. SEM and XRD confirmed the successful preparation of ZnO nanoarrays. TEM and Raman spectroscopy confirmed the preferential orientation of the ZnO nanorods along the (002) crystal plane. The Ni/ZnO NAs composites exhibited excellent photocatalytic degradation activity for ciprofloxacin (CIP) under UV light. UV–visible diffuse reflectance and transient photocurrent response characterization revealed that compared with ZnO nanorod powder, the Ni/ZnO NA composites increased the light absorption and reduced the complexation rate of photogenerated electron-hole pairs, thus improving the photocatalytic efficiency. In addition, the electron work functions of the two substances were calculated by using the crystal faces of Ni (111) and ZnO (002), and the calculation results confirmed the electron transfer paths. Electron transfer pathways further confirmed the possible reaction mechanism of Ni/ZnO NA degradation of CIP. Finally, Mott–Schottky tests were used to investigate the structure of the energy bands of the material and reveal its photocatalytic mechanism.

Morphology-controlled ZnO nanoarrays in situ grown on the basalt fiber surface for improving the interfacial properties of the high-performance thermoplastic composites

In this work, a biomimetic root-soil-like interfacial phase structure was constructed to improve the weak interfacial bonding of the fibers and resin based on the mechanical interlocking theory. Unidirectional basalt fiber (BF) reinforced high-temperature resistant thermoplastic poly (phthalazinone ether nitrile ketone) (PPENK, Tg = 278 °C) composites with multiscale structures were prepared. By utilizing a whiskerization technique, the zinc oxide nanoarrays (ZnO-NAs) with controllable morphologies grown on the BF surface through a pyrolysis-hydrothermal method. The remarkable field emission properties of the ZnO-NAs allow for visually characterizing the interfacial phase structures. The flexural, interlaminar shear, and interfacial shear strengths of BF-ZnO-PEI-2/PPENK composite were increased by 43 %, 65 %, and 177 %, respectively. Further investigations revealed that the flexural strength retention was 61 % at 250 °C, respectively. This study introduces a novel and viable approach to enhance the interfacial properties of BF-reinforced high-performance thermoplastic composites and expands their applications within high-temperature environments.

Rational design of graphite carbon nitride-decorated zinc oxide nanoarrays on three-dimensional nickel foam for the efficient production of reactive oxygen species through stirring-promoted piezo–photocatalysis

Stirring-promoted piezo–photocatalysis based on a three-dimensional foam architecture has great potential applications in wastewater treatment and water splitting. However, the detailed mechanism of stirring-promoted piezo–photocatalysis has not been quantitatively studied, and the utilization of visible light needs to be further improved. In this work, the high solar-driven piezo–photocatalytic ability of graphite carbon nitride (g-C3N4)-decorated zinc oxide (ZnO) nanoarrays on nickel (Ni) foam is experimentally achieved and first simulated by the finite element method (FEM). The water flow velocity, depending on the stirring rate, is significantly increased by turbulence-induced fluid eddies while flowing through 3D macropores and nanoarrays, resulting in higher piezoelectricity. Reactive oxygen species (ROS) are experimentally examined by the electron spin resonance (ESR) technique and theoretically calculated by density functional theory (DFT) to confirm the configurations of the heterojunction under photocatalysis and piezo–photocatalysis. In particular, the large enhancement of 1O2 generation suggests the potential of piezo–photocatalysis in biological applications. The mechanism of piezo–photocatalysis is proposed in which the S-scheme heterojunction is realized by piezoelectricity to improve photocatalysis by retaining high redox ability and inhibiting recombination. This work provides a possible approach to harvesting energy sources for piezoelectricity and expands the scope of solar-driven piezo–photocatalysis.

Ultraviolet Photodetector Based on Poly(3,4-Ethylenedioxyselenophene)/ZnO Core–Shell Nanorods p-n Heterojunction

In this work, we successfully assembled an organic–inorganic core–shell hybrid p-n heterojunction ultraviolet photodetector by the electropolymerization deposition of poly(3,4-ethylenedioxyselenophene) (PEDOS) on the surface of zinc oxide nanoarrays (ZnO NRs). The structures of composite were confirmed by FTIR, UV–Vis, XRD and XPS. Mott–Schottky analysis was used to study the p-n heterojunction structure. The photodetection properties of ZnO NRs/PEDOS heterojunction ultraviolet photodetector were systematically investigated current–voltage (I–V) and current–time (I–t) analysis under different bias voltages. The results showed that PEDOS films uniformly grew on ZnO NRs surface and core–shell structure was formed. The p-n heterojunction structure was formed with strong built-in electric field between ZnO NRs and PEDOS. Under the irradiation of UV light, the device showed a good rectification behavior. The responsivity, detection rate and the external quantum efficiency of the ultraviolet photodetector reached to 247.7 A/W, 3.41 × 1012 Jones and 84,000% at 2 V bias, respectively. The rise time (τr) and fall time (τf) of ZnO NRs/PEDOS UV photodetector were obviously shortened compared to ZnO UV photodetector. The results show that the introduction of PEDOS effectively improves the performance of the UV photodetector.

Enhancement of the Au/ZnO-NA Plasmonic SERS Signal Using Principal Component Analysis as a Machine Learning Approach

In this work, we modeled a novel approach to enhance surface-enhanced Raman scattering (SERS) signals using principal component analysis (PCA) as a machine learning approach. Zinc oxide nanoarrays (ZnO-NAs) were synthesized using a hydrothermal method followed by zinc oxide nucleation on ITO glass substrates via an oxidation furnace at 500 °C. The surface morphology was improved by short rapid thermal annealing (S-RTA) after deposition of a gold layer via a thermal evaporator to avoid chemical contamination of the sensing surface, which is a suitable plasmonic platform for the generation of “hot spots” for SERS enhancement with fewer defects. The proposed Au/ZnO-NA SERS sensor exhibited an enhancement factor (EF) of 1.15 × 10 7 via the R6G Raman probe and excellent uniformity over the entire surface. The PCA algorithm was used to extract useful features and information from the SERS signal. The algorithm was implemented with MATLAB software (R2019a) by the multivariable analytical tool to find an enhanced signal (~3 times higher) with high uniformity, which has great potential and is applicable to a wide range of probe molecules suitable in medical, safety, and environmental applications.

Acoustofluidics-Assisted Engineering of Multifunctional Three-Dimensional Zinc Oxide Nanoarrays.

The integration of acoustics and microfluidics (termed acoustofluidics) presents a frontier in the engineering of functional micro-/nanomaterials. Acoustofluidic techniques enable active and precise spatiotemporal control of matter, providing great potential for the design of advanced nanosystems with tunable material properties. In this work, we introduce an acoustofluidic approach for engineering multifunctional three-dimensional nanostructure arrays and demonstrate their potential in enrichment and biosensing applications. In particular, our acoustofluidic device integrates an acoustic transducer with a sharp-edge-based acoustofluidic reactor that enables uniform patterning of zinc oxide (ZnO) nanoarrays with customizable lengths, densities, diameters, and other properties. The resulting ZnO nanoarray-coated glass capillaries can rapidly and efficiently capture and enrich biomolecules with sizes ranging from a few nanometers to several hundred nanometers. In order to enable the detection of these biomolecules, silver (Ag) nanoparticles are deposited onto the ZnO nanoarrays, and the integrated ZnO-Ag capillary device functions as a label-free plasmonic biosensing system for surface-enhanced Raman spectroscopy (SERS) based detection of exosomes, DNA oligonucleotides, and E. coli bacteria. The optical sensing enhancement of ZnO-Ag capillary is further validated through finite-difference time-domain (FDTD) simulations. These findings not only provide insights into the engineering of functional micro/nanomaterials using acoustofluidics but also shed light onto the development of portable microanalytical devices for point-of-care applications.

Synthesis and characterization of self-assembled ZnO nanoarrays on hybrid structural fibers

Hybrid carbon fibers with self-assembled and well-aligned zinc oxide (ZnO) nanoarrays can lead to novel structural materials that enable promising applications in multifunctional composites with beneficial properties including enhanced interlaminar mechanical properties and potential load sensing capabilities. In this paper, atomic layer deposition (ALD) and hydrothermal methods were integrated to synthesize ZnO nanoarrays in the shape of aligned nanowires and nanorods on carbon fiber fabrics. The surface morphology of ZnO nanoarrays were controlled by adjusting the reagent concentrations and hydrothermal reaction time. As-synthesized hybrid fibers were characterized to understand their critical properties including nanostructure morphology, crystal structures, ZnO weight concentration, and contact angle between water and ZnO nanoarrays. The results demonstrated that the ZnO nanostructures and morphology can be controlled and optimized for lightweight composite applications.

Durable superhydrophobic and underwater superoleophobic cotton fabrics growing zinc oxide nanoarrays for application in separation of heavy/light oil and water mixtures as need

Based on controlling ZnO nanoarrays morphology and employing fluorine-free modification agent, superhydrophobicity in air and superoleophobicity under water were successfully achieved on the prepared cotton fabric surfaces via a two-step hydrothermal reaction. To increase adhesion between ZnO crystal layer and substrate surface, two kinds of silane coupling agents (hydrophobic TTOP-12 and hydrophilic KH550) were added selectively in the pretreatment process. The as-prepared fabric exhibited great tolerance and durableness towards external harsh environments, such as mechanical abrasion, UV radiation, immersion of acid or alkali, and high temperature. In comparison, superhydrophobic fabrics showed superior separation effect for heavy oil and water mixture, while underwater superoleophobic fabric can also show efficient separation of water and light oil with high separation efficiency and flux. In a word, heavy/light oil and water mixtures can be separated efficiently as need by choosing cotton fabrics with various wettabilities.

Synthesis of ZnO nanoarrays on carbon fibers using combined atomic layer deposition and hydrothermal methods

The paper presents the synthesis and characterization of zinc oxide (ZnO) nanoarrays on carbon fiber fabrics using the combined atomic layer deposition (ALD) and hydrothermal methods. A conformal ZnO seed layer was first synthesized using the ALD method on carbon fiber surfaces, then characterized by field emission scanning electron microscope (FESEM). ZnO nanoarrays were grown on the carbon fibers using the hydrothermal method. The morphology of ZnO nanoarrays in the form of nanowires and nanorods was controlled by adjusting hydrothermal synthesis parameters, including the concentration of chemical reagents and solution temperature. The FESEM characterization showed that the synthesized ZnO nanowires and nanorods had a wurtzite structure and uniformity distributed on the surface of carbon fibers. The length to diameter ratios of the ZnO nanoarrays were controlled between 44 and 270. The thermogravimetric analysis tests showed that the growth of ZnO nanoarrays added about 10% additional weight to the carbon fibers.

N-ZnO/p-CuI barrier heterostructure based on zinc-oxide nanoarrays formed by pulsed electrodeposition and SILAR copper-iodide films

A p-CuI/n-ZnO barrier structure is investigated as a promising base diode structure for a semitransparent near-ultraviolet detector. We analyze the crystal structure and electrical and optical properties of zinc-oxide nanoarrays electrodeposited in the pulsed mode and copper-iodide films formed by the successive ionic layer adsorption and reaction (SILAR) method, which were used as the basis for an n-ZnO/p-CuI barrier heterostructure sensitive to ultraviolet radiation in the spectral range of 365–370 nm. Using the I–V characteristics, a shunting resistance of R sh · S c = 879 Ω cm2, a series resistance of R s · S c = 8.5 Ω cm2, a diode rectification factor of K = 17.6, a rectifying p–n-junction barrier height of Φ = 1.1 eV, and a diode ideality factor of η = 2.4 are established. It is demonstrated that at low forward biases (0 V < U < 0.15 V), the effects of charge-carrier recombination and tunneling are equal. As the bias increases above 0.15 V, the tunneling–recombination transport mechanism starts working. The diode saturation current J 0 is found to be 6.4 × 10–6 mA cm–2 for recombination and tunneling charge-carrier transport and 2.7 × 10–3 mA cm–2 for tunneling–recombination charge-carrier transport.

Application of patterned growth of aligned zinc oxide nanoarrays by mirocontact printing in quantum dots-sensitized solar cells

This paper describes a simple method for patterned growth of ZnO nanoarrays (NAs) that is based on a combination of the microcontact printing process for patterning ZnO seed films and the low-temperature hydrothermal approach for depositing ZnO NAs. The patterned ZnO seed films were achieved via printing patterned TiO2 sol on ZnO seed films. It is found that the pattern quality is mainly affected by the viscosity of TiO2 ink and the pressure including value and direction. To assess the possibility of patterned ZnO NAs applied to devices, the patterned ZnO NAs were used as light scattering layer in CdSe-sensitized solar cells. The diffuse-reflection, absorption and transmission spectra show that the patterned ZnO NAs greatly enhance the light scattering and absorbance in the visible range. The enhancement of cell performance is attributed to the patterned ZnO NAs: 1) multiple-light scattering improves the light absorbance, and 2) NAs with high electron mobility facilitate the electron collection.

In situ growth mechanism and the thermodynamic functions of zinc oxide nano-arrays and hierarchical structure

We report the one-step synthesis of zinc oxide nanomaterials with arrays and hierarchical structure at room temperature. The zinc oxide nanomaterials can be synthesized via a simple method without catalyst. Furthermore, we explained the growth mechanisms of the two systems. In situ growth experiment provided the information of thermodynamics and kinetics, and based on that, growth mechanism was given a further explanation via the curve of in situ growth. Moreover, the relations between thermodynamic functions and the potential difference can be established by the electrochemical method. Take bulk zinc oxide reference. The thermodynamic functions of nano zinc oxide such as standard molar entropy, standard molar Gibbs free energy of formation, and standard molar enthalpy of formation can be calculated. The change rules of thermodynamic functions at different reaction times evidenced the growth mechanism more deeply. This work may contribute to the analysis of growth mechanism for nanostructures and obtain the thermodynamic functions of nanomaterials.

Characterization of Optical- and N&lt;SUB&gt;2&lt;/SUB&gt; Adsorption Properties of Self-Twin Zinc Oxide Nanoarrays Assemblies

Characterization of Optical- and N&lt;SUB&gt;2&lt;/SUB&gt; Adsorption Properties of Self-Twin Zinc Oxide Nanoarrays Assemblies

Robust, High-Density Zinc Oxide Nanoarrays by Nanoimprint Lithography-Assisted Area-Selective Atomic Layer Deposition

Polymer templates realized through a combination of block copolymer lithography (BCL) and nanoimprint lithography (NIL) are used to direct atomic layer deposition (ALD) to obtain high-quality ZnO n...

Nonstoichiometric Zinc Oxide Nanorod Arrays Doped Co or Ni as Effective Antimicrobial Materials

Nonstoichiometric Zinc oxide (ZnO) nanorod arrays doped Co or Ni can be easily obtained by calicining soaked ZnO nanorod arrays. More importantly, the nonstoichiometric doped ZnO nanoarrays have more effective antimicrobial than pure ZnO nanoarrays, which means we can obtain a kind of promising new effective functional nanomaterials.

Nanogenerators Based on ZnO or TiO&lt;SUB&gt;2&lt;/SUB&gt; Oxides

Recently, an approach for converting nanoscale mechanical energy into electrical energy has been suggested by using piezoelectric zinc oxide (ZnO) nanowire arrays. Such devices have been shown to convert ultrasonic energy into electric energy by a deflection of the nanowires via a corrugated electrode operated up and down by the ultrasound. A typical approximately 1 pW output power for a device of a approximately 1 mm2 area and a density of approximately 10(7)/mm2 nanowires can be obtained. In order to reach the approximately 10 nW power needed to operate a nanodevice, nanogenerators of this kind need to be optimized. With the aim of fabricating low cost to efficiency ratio nanogenerators, we have considered ZnO films grown by an electrochemical technique, based on the direct precipitation of Zn hydroxide on a conducting ITO/glass substrate and subsequent heat treatment, and TiO2 films deposited from a colloidal suspension of anatase/rutile commercial powders. These methods allowed us to obtain disordered but quite uniform arrays distributed on the surface of the substrate. Preliminary results on the electrical properties are presented. Under input mechanical strain we find output powers of approximately 10(-9)/cm2 W, which are comparable to those obtained with the ZnO nanoarrays. Possible interpretations of results in terms of piezoelectricity (ZnO) and incipient ferroelectricity (TiO2) are presented and improvements of the devices are discussed.

Fabrication and characterization of In-doped zinc oxide nanoarrays

In-doped ZnO nanoarrays were successfully synthesized by the carbon thermal reduction deposition process, at 850℃ using Au catalyst. The length of legs of T-ZnO nanorods is 2—3 μm and the diameter is ～400 nm, dimensionally uniform and the surface smooth. Energy dispersive spectroscopy and X-ray photoelectron spectroscopy investigations show that the In content of nanorods reaches about 08%. Room temperature photoluminescence spectra of the nanoarrays shows that the ultraviolet emission peak red-shifts and becomes broader after doping. Raman scattering study shows that ZnO peaks have different shift, and a new peak appears, which proved a part of In atoms replacing Zn in the crystal lattice.

Morphology and field emission from ZnO nanowire arrays synthesized at different temperature

Three kinds of ZnO nanowire arrays were fabricated on Au coated (1 1 0)silicon wafer by using of heating the mixture of zinc oxide (ZnO) and graphite powders at various depositing temperature. The synthesized samples were examined by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) analytic technology, respectively. Structural analyses revealed that the morphologies and crystal microstructures of ZnO nanoarrays were related with the substrate temperature. And control to the growth morphologies can be achieved by carefully tuning the depositing temperature. The testing results to different nanowire arrays showed that the properties of field emission follow the Fowler–Nordheim law. The quais-aligned ZnO nanowire array sample synthesized at 750 °C had the lowest turn-on field of 7.4 V/μm, highest β of 1028. This largest emission efficiency is attributed to the clear tip and appropriate coverage density. As well as the nanowires are straight with long length and parallel to each other with good crystal quality. The experimental results could be very useful for field emission materials and other nanoelectronics device applications.

Zinc oxide nanoarrays in nanoporous nickel phosphate with a huge blueshift ultraviolet-visible exciton absorption peak

Zinc oxide (ZnO) nanoarray prepared in the template of nanoporous nickel(II) phosphate Versailles Santa Barbara-1 (VSB-1) crystal exhibits an unusual ultraviolet-visible exciton absorption peak and an absorption shoulder. The exciton absorption peak at 266nm with the largest blueshift of 122nm up to now and narrow absorption peak with a full width at half maximum (FWHM) of about 34nm and the narrow photoluminescence emission peak 380nm with a FWHM of about 30nm, compared with that of bulk ZnO, are due to the quantum-confinement effects and the narrow size distribution of ZnO in the pores of VSB-1. This material presents potential applications in the theoretical research and fabrication of future quantum devices.