ZnO Nanowires Research Articles

A high thermal conductive BN-ZnO NWs/PVA composite based on the oriented structure construction using ice template method

The increasing demand for effective thermal management in electronic devices has highlighted the crucial importance of researching composite materials with exceptional thermal conductivity in the field of electronics. A novel hybrid filler consisting of hexagonal boron nitride (BN) and needle-like zinc oxide nanowires (ZnO NWs) was designed and synthesized in this work, then used to prepare thermally conductive composites by mixing it with polyvinyl alcohol (PVA) using the ice template method and hot-pressing process. The results demonstrated that a filler loading of 20 wt% yielded the highest thermal conductivity for the composite, reaching an impressive in-plane thermal conductivity of 1.77 Wm−1 k−1, which was 3.4 times higher than that of the conventional frozen pure PVA. This substantial improvement in thermal conductivity is mainly attributed to the synergistic effect achieved through the ice template method to construct a conventional orientation structure combined with the presence of BN-ZnO NWs hybrid filler. In addition, this composite also has good mechanical properties and thermal stability, etc. Our study shows that the BN-ZnO NWs/PVA thermally conductive composite demonstrates excellent potential as a thermal interface material for various applications in the field of thermal management of electronic devices.

A Zinc Oxide Nanowire-Modified Mineralized Collagen Scaffold Promotes Infectious Bone Regeneration.

Bone infection poses a major clinical challenge that can hinder patient recovery and exacerbate postoperative complications. This study has developed a bioactive composite scaffold through the co-assembly and intrafibrillar mineralization of collagen fibrils and zinc oxide (ZnO) nanowires (IMC/ZnO). The IMC/ZnO exhibits bone-like hierarchical structures and enhances capabilities for osteogenesis, antibacterial activity, and bacteria-infected bone healing. During co-cultivation with human bone marrow mesenchymal stem cells (BMMSCs), the IMC/ZnO improves BMMSC adhesion, proliferation, and osteogenic differentiation even under inflammatory conditions. Moreover, it suppresses the activity of Gram-negative Porphyromonas gingivalis and Gram-positive Streptococcus mutans by releasing zinc ions within the acidic infectious microenvironment. In vivo, the IMC/ZnO enables near-complete healing of infected bone defects within the intricate oral bacterial milieu, which is attributed to IMC/ZnO orchestrating M2 macrophage polarization, and fostering an osteogenic and anti-inflammatory microenvironment. Overall, these findings demonstrate the promise of the bioactive scaffold IMC/ZnO for treating bacteria-infected bone defects.

The interface structural, electronic and optical properties of ZnO nanowires/Graphene nanohybrid (ZnO NWs/G): Experimental and theoretical DFT investigations

In this work, a ZnO nanowires/graphene nanohybrid was synthesized by a three steps approach. Copper substrates were covered with graphene by chemical vapor deposition, further ZnO nanowires were electrochemically deposited on the as grown graphene on copper and finally a transfer process was employed for moving the heterostructure onto a different substrate. A comprehensive structural analysis which included scanning electron microscopy, X-ray diffraction and Raman measurements revealed that the ZnO nanowires crystallize in wurtzite structure perpendicular to graphene, the process leading to the formation of a nanohybrid heterostructure. The band gap energy of the ZnO nanowires deposited on graphene was estimated to be 3.11 eV, as calculated from the reflectance spectrum analysis. The GGA-PBE+U within Grimme (DFT-D) approach was used to provide an accurate description of the interface structure in terms of electronic and optical properties, confirming that the decrease in the band gap energy of ZnO nanowires is caused by the interaction with the graphene surface. The findings of this study could serve as an experimental and theoretical reference for upcoming studies on ZnO NWs/Graphene nanohybrid-based optoelectronic applications.

PVDF Nanofiber Modified with ZnO Nanowires/Polydopamine for the Treatment of Sewage Containing Heavy Metals, Organic Dyes, and Bacteria.

In various countries worldwide, the issue of wastewater contamination poses a significant threat due to its intricate composition of heavy metals, organic dyes, and microorganisms, thereby complicating the purification process. Consequently, researchers have expressed considerable interest in materials capable of eliminating organic, heavy metal, and microbial pollutants. This study focuses on the fabrication of a water purification membrane (PDA/ZnO-NWs/PVDF) with a hierarchical structure and the ability to remove multiple pollutants. The membrane was created by modifying poly(vinylidene fluoride) (PVDF) nanofiber with zinc oxide nanowires (ZnO-NWs) and reinforcing it with polydopamine (PDA). The experimental results demonstrate that the PDA/ZnO-NWs/PVDF membrane exhibits a range of functionalities, including long-lasting superhydrophilicity, Cu(II) adsorption, photocatalytic degradation, and antibacterial ability. The manipulation of the DA synthesis procedure allows for the adjustment of the wettability, adsorption, and photocatalytic and antibacterial activities of the PDA/ZnO-NWs/PVDF composite. According to the Langmuir isotherm, the maximum Cu(II) adsorption capacity of the PDA/ZnO-NWs/PVDF membrane is determined to be 65.75 mg/g, which is significantly higher (27.26 mg/g) than that of the ZnO-NWs/PVDF membrane (38.49 mg/g). The PDA/ZnO-NWs/PVDF composite exhibited a notable degradation capacity toward rhodamine B under natural sunlight, reaching a maximum of 5.97 mg/g. Additionally, the degradation rate achieved during daylight hours was as high as 90.42%. Furthermore, the antibacterial efficacy of the PDA/ZnO-NWs/PVDF composite against both Gram-positive and Gram-negative bacteria approached 100%. This work presents a promising approach for the treatment of wastewater containing various coexisting contaminants.

Nanostructured Channel for Improving Emission Efficiency of Hybrid Light-Emitting Field-Effect Transistors.

We report on the mechanism of enhancing the luminance and external quantum efficiency (EQE) by developing nanostructured channels in hybrid (organic/inorganic) light-emitting transistors (HLETs) that combine a solution-processed oxide and a polymer heterostructure. The heterostructure comprised two parts: (i) the zinc tin oxide/zinc oxide (ZTO/ZnO), with and without ZnO nanowires (NWs) grown on the top of the ZTO/ZnO stack, as the charge transport layer and (ii) a polymer Super Yellow (SY, also known as PDY-132) layer as the light-emitting layer. Device characterization shows that using NWs significantly improves luminance and EQE (≈1.1% @ 5000 cd m-2) compared to previously reported similar HLET devices that show EQE < 1%. The size and shape of the NWs were controlled through solution concentration and growth time, which also render NWs to have higher crystallinity. Notably, the size of the NWs was found to provide higher escape efficiency for emitted photons while offering lower contact resistance for charge injection, which resulted in the improved optical performance of HLETs. These results represent a significant step forward in enabling efficient and all-solution-processed HLET technology for lighting and display applications.

Oil/water separation copper membranes modified by laser induced ZnO nanowires growth with enhanced catalytic function

Oil/water separation is a significant area of scientific study, and also has significant practical applications in the treatment of industrial oily wastewater and oil spill pollution. In this study, the high-flux copper mesh is fabricated by laser in a Zn2+ precursor solution at room temperature. The copper mesh processed inside the solution has a higher flux than that processed in the air. The heat absorbed by the liquid promotes the growth of ZnO nanowires on the copper mesh surface. The copper mesh's underwater oil contact angle (OCA) is as high as 150°. Compared with conventional copper mesh, it has a higher stability and can maintain a contact angle of 150° in acid-base environments and high-temperature environments. It has hydrophilic and oleophobic properties and can be used for oil/water separation. After 50 oil/water separation cycles, the separation efficiency can keep higher than 97%. This new method exhibits excellent potentials for oil/water separation and oil purification attributed to its simple and ecologically friendly processing.

H2 generation from aqueous ethanol over ZnO nanowires, the photo-transformation of surface species

ZnO nanowires (NWs) with wurzite structure and a very high [0001] preferred orientation were grown on a ZnO thin film, from a gas-solid process, in the absence of catalyst. ZnO NWs were characterized by FESEM, XRD, HRTEM, XPS, PL and Raman spectroscopy and used as photocatalysts for the photo-transformation of ethanol(aq) in the gas phase. The existence of different defects such as oxygen vacancies was evidenced. The photocatalytic process was followed by in-situ diffuse reflectance infrared spectroscopy (DRIFTS) coupled to on-line mass spectrometry (MS) analysis. The surface species determined during the irradiation (λ = 365 nm) of ZnO NWs under ethanol/water vapor flow at room temperature are related with the hydrogen production and carbon-containing products evolved.

Investigation of highly efficient self-powered photo-detector performance of all inorganic lead-free halide perovskites (CsSnCl3) nanocrystals (NCs) decorated Er: ZnO nanowires (NWs)/Si heterojunctions

In this study, a zero-biased or self-powered heterojunction photodetector is fabricated by using the combination of lead-free halide-based inorganic perovskite (CsSnCl3) and erbium (Er)-doped ZnO nanowires (NWs) on Si platform. The main advantages of such types of heterojunctions are cost-effective fabrication procedure, highly stable and responsive photoresponse, and, such devices exhibit low dark current and high photo-to-dark current ratio of >102. The HRTEM images confirm that CsSnCl3 perovskites nanocrystals (NCs) are randomly decorated over the ZnO NWs. The UV–visible spectroscopy shows the absorption edges and bandgaps of perovskites NCs, ZnO NWs, and combined heterojunctions. The structural, chemical compositional, and defect-related optical transitions are studied in detail by employing XRD, XPS, and PL results. The highest zero-biased photo-response at 374 nm is achieved for the 1%Er: ZnO–CsSnCl3 NWs/Si heterojunction and corresponding calculated responsivity and detectivity values are obtained to be 0.196 A/W and 2.48 × 1011 Jones, respectively. Along with it, such selective Er-doped NWs perovskites heterojunction exhibits relatively superior linear dynamic range (LDR) (51.76 dB) and rapid response speed (rise time: fall time = 83 ms:63 ms) as compared to reported values. Hence, current work demonstrates that Er-doped oxide-perovskite heterojunctions can be a promising candidate for developing high-performance UV/Visible photodetector under self-powered mode.

Diameter-dependent ultra-high thermoelectric performance of ZnO nanowires

Zinc oxide (ZnO) shows great potential in electronics, but its large intrinsic thermal conductivity limits its thermoelectric applications. In this work, we explore the significant carrier transport capacity and diameter-dependent thermoelectric characteristics of wurtzite-ZnO 〈0001〉 nanowires based on first-principles and molecular dynamics simulations. Under the synergistic effect of band degeneracy and weak phonon–electron scattering, P-type (ZnO)73 nanowires achieve an ultra-high power factor above 1500 μW⋅cm−1⋅K−2 over a wide temperature range. The lattice thermal conductivity and carrier transport properties of ZnO nanowires exhibit a strong diameter size dependence. When the ZnO nanowire diameter exceeds 12.72 Å, the carrier transport properties increase significantly, while the thermal conductivity shows a slight increase with the diameter size, resulting in a ZT value of up to 6.4 at 700 K for P-type (ZnO)73. For the first time, the size effect is also illustrated by introducing two geometrical configurations of the ZnO nanowires. This work theoretically depicts the size optimization strategy for the thermoelectric conversion of ZnO nanowires.

Voltage-assisted selective growth of ZnO nanowires on metal/semiconductor surfaces employing hydrothermal double-step CBD/CBD growth technique

Voltage-assisted selective growth of ZnO nanowires on metal/semiconductor surfaces employing hydrothermal double-step CBD/CBD growth technique

Enhanced thermoelectric properties of self-assembling ZnO nanowire networks encapsulated in nonconductive polymers

The near-room temperature thermoelectric properties of self-assembling ZnO nanowire networks before and after encapsulation in nonconductive polymers are studied. ZnO nanowire networks were synthesized via a two-step fabrication technique involving the deposition of metallic Zn networks by thermal evaporation, followed by thermal oxidation. Synthesized ZnO nanowire networks were encapsulated in polyvinyl alcohol (PVA) or commercially available epoxy adhesive. Comparison of electrical resistance and Seebeck coefficient of the ZnO nanowire networks before and after encapsulation showed a significant increase in the network's electrical conductivity accompanied by the increase of its Seebeck coefficient after the encapsulation. The thermoelectric power factor (PF) of the encapsulated ZnO nanowire networks exceeded the PF of bare ZnO networks by ~ 5 and ~ 185 times for PVA- and epoxy-encapsulated samples, respectively, reaching 0.85 μW m−1 K−2 and ZT ~ 3·10–6 at room temperature, which significantly exceeded the PF and ZT values for state-of-the-art non-conductive polymers based thermoelectric flexible films. Mechanisms underlying the improvement of the thermoelectrical properties of ZnO nanowire networks due to their encapsulation are discussed. In addition, encapsulated ZnO nanowire networks showed excellent stability during 100 repetitive bending cycles down to a 5 mm radius, which makes them perspective for the application in flexible thermoelectrics.

Chemical bath deposited ZnO nanowires for $$\hbox {H}_{2}$$ gas sensing: Effect of deposition duration

Chemical bath deposited ZnO nanowires for $$\hbox {H}_{2}$$ gas sensing: Effect of deposition duration

Direct detection of dopamine using zinc oxide nanowire-based surface plasmon resonance sensor

This study uses an angle interrogation approach to propose an SF11 Prism- Ag– ZnO nanowires-CeO2-Sensing layer-based surface plasmon resonance sensor. The proposed multilayer structure has been used for the concentration measurement of dopamine in human blood. The thicknesses of the ZnO nanowire (ZnO-NW) and cerium oxide (CeO2) layer have been taken as 50 nm and 0.5 nm, respectively, and the thickness of the metal layer is 50 nm considered. The characteristics and parameters are also measured for the proposed sensor. The sensitivity, full width at half maximum (FWHM), detection accuracy (DA), and quality factor (QF) are obtained as 95 deg/RIU, 14.34 deg, 0.06578 deg−1, and 6.24 RIU−1, respectively. Numerous neurological illnesses are brought on by abnormalities of dopamine (D. A.), a crucial neurotransmitter in the brain's neural circuits. Quick and sensitive sensors for D. A. detection are needed to diagnose these illnesses early. The significance of this sensor in the biomedical field.

Synthesis, characterization, and photoluminescence of zinc oxide ultra-thin nanowires

Ultra-thin Zinc oxide nanowires were prepared by a simple thermal evaporation method using a suitable amount of lead sulfide as an additive. It has been found that the nanowires are single crystalline of zincate grown along [1 0 1] direction. The transmission electron microscopy images show that nanowires consist of smooth ultra-thin cantilever-like with a diameter in the range of 10–20 nanometer (nm) and length of few microns. At room temperature, the photoluminescence spectra exhibit unusual strong broad peaks extending from the visible to near infrared (∼500–800 nm). The synthesized nanowires can serve as a novel platform for electrochemical and nano-biomolecular applications.

Piezoelectric properties of ZnO nanowire arrays/DAST-PDMS flexible nanogenerators

The piezoelectric properties of 4-(4-dimethylaminostyryl) methylpyridine p-toluene sulfonate (DAST)-polydimethylsiloxane (PDMS) composite thin film was investigated. Flexible nanogenerators based on zinc oxide (ZnO) nanowire (NW) arrays/DAST-PDMS were fabricated. DAST holds organic crystal structure, and it can possess piezoelectric properties, and it can enhance the piezoelectric properties of ZnO NW arrays. PDMS can not only mix DAST powder with a liquid to prepare a thin film but also protect ZnO NW arrays and DAST from deterioration. When applying pressure with a balance weight of 100 g, the flexible nanogenerator based on ZnO NW arrays/DAST-PDMS can generate an output voltage of 2.3 V, which is much larger than that of the nanogenerator based on ZnO NW arrays. The effect of the strength of vertical external force, frequency of vertical external force, and degree of bending deformation on the ZnO NW arrays/DAST-PDMS flexible nanogenerators were investigated in this Letter. In our experiments, the output voltage of the ZnO NW arrays/DAST-PDMS flexible nanogenerators can reach 3.3 V. After bending the nanogenerator 20 times, the energy collection device based on the ZnO NW arrays/DAST-PDMS flexible nanogenerator was able to light an LED bulb.

Fabrication of Piezoelectric ZnO Nanowires on Laser Textured Copper Substrate to Enhance Catalytic Properties

In this work, 3D periodic “grid-type” CuO/Cu2O layers were fabricated on a copper sheet using laser processing techniques, and the laser processing parameters were optimized for favorable ZnO nanowire growth. It was found that ZnO nanowires could be successfully prepared to form a CuO-Cu2O-ZnO heterojunction structure without an extra catalyst or seed layer coating, which could be attributed to the copper oxide active sites induced via laser texturing. ZnO nanowires on laser textured “grid-type” copper substrates demonstrated an effective piezocatalytic performance with different morphologies and the generation of abundant reactive oxygen species in the CuO-Cu2O-ZnO catalytic system, providing a fundamental mechanism for the degradation of organic dye in water. This simple and low-cost method could provide a useful guide for the large-scale efficient and versatile synthesis of immobilized piezoelectric catalysts.

Enhanced photoresponse of self-powered ZnO-based photoelectrochemical-type UV photodetectors via Ga-doping for optical communication application

Wide-bandgap metal-oxide semiconductors hold promise for self-powered photoelectrochemical (PEC) type UV photodetectors (PDs) due to their inherent photoelectric properties and durability. However, inadequate charge carrier separation and transport remain a fundamental challenge for practical applications. Herein, the extraordinary efficacy of introducing gallium (Ga) into ZnO nanowire to design high-performance PEC-type PDs is demonstrated. The obtained Ga-doped ZnO (ZnO:Ga) PEC-type photodetectors exhibit superior UV photoresponse performance, featuring an exceptionally high responsivity of 233.26mA/W, an excellent detectivity of 4.18 × 1012 Jones, and a fast response/recovery time of 159/150 ms under 365nm illumination without external bias voltages. These accomplishments outperform the majority of previously reported PEC-type UV PDs. It is found that the unique properties of ZnO:Ga nanowires, including improved donor density and steeper band bending at solid-liquid interface, significantly enhance the generation, transfer, and separation of photoexcited charge carriers, thus contributing to the superior photodetector’s performance. In addition, a secure UV communication system using international Morse code is set to demonstrate the feasibility of ZnO:Ga nanowires PEC-PD as a self-powered optical receiver. This study introduces a promising approach to develop self-powered photodetectors that are highly stable, cost-effective, and poised for integration into future multifunctional optoelectronic devices.

Interfacial reinforcement strategy of basalt fiber/polymer composite constructed by interlocking interface composed of ZnO nanowires

Basalt fiber (BF) as a promising reinforcing material, is used widely to prepare polymer composite, but poor interfacial interaction with polymer matrix deteriorates the reinforcement effect. Here, a biomimetic “root-like” BF with laterally-grown zinc oxide (ZnO) nanowires was prepared via dopamine surface modification and two-step hydrothermal method. By virtue of the coordination of catechol groups with Zn2+ ions, the polydopamine coating layer provided the strong affinity with the ZnO seeds layer and facilitated the direction growth of ZnO nanowires, with firm immobilization on the BF surface. Accordingly, the robust interlocking interface was successfully constructed in the root-like BF/polymer composite by penetrating laterally-grown ZnO nanowires into polymer matrix, greatly reinforcing the interfacial adhesion. Compared to conventional surface chemical treatment only suitable for a single specific system, the interfacial interlocking effect mainly depended on the formation of the laterally-grown ZnO nanowires, rather than intrinsic properties of polymer components, so as to be applied to a wide range of polymer composites. This can be exemplified by 265% and 197% increases in interfacial strength of the root-like BF-filled polypropylene (PP) and polydimethylsiloxane (PDMS) composite over that of the corresponding pristine BF ones.

Zno Nanorod From Structure, Properties to Applications

This paper aims to review current understandings of ZnO Nanorods (NRs) and summarizes them into a clear pathway from structure to properties and to applications. The crystal structure of ZnO NRs is a hexagonal wurtzite structure with asymmetry giving rise to its prominent piezoelectric property. Using methods such as AFM, researchers have confirmed and modeled the piezoelectric potential generated by ZnO NRs in deformation, and the intensity of the potential is strongly correlated with resistivity and dimensions of NRs. Several techniques, such as doping, are invented to enhance the piezoelectric intensity of ZnO NRs, suppressing the screening effect of ZnO NRs. Recent research has shown potential applications based on the piezoelectric property of ZnO NRs or nanowires (NWs) as nanogenerators (NGs) or nanosensors for self-powered devices in a range of areas.

Silicon-Based Nanoelectronic Semiconductor Material and Its Surface-Enhanced Raman Image Signals

One-dimensional Zinc Oxide (ZnO) nanomaterials have important applications in devices, such as solar energy, sensors, and piezoelectric materials due to surface effects and quantum size effects. As a semiconductor material, Si has good thermal conductivity and low resistivity. A layer of n-type ZnO nanowires is grown on P-type monocrystalline silicon by transferring the Anodic Aluminum Oxide (AAO) template. The enhanced Raman effect on the surface is attempted by preparing n-type ZnO-P-type Si heterojunction nanostructures. This paper uses Si-based AAO as a template and uses electrochemical deposition method to prepare silicon-based nano-electronic semiconductor material ZnO/AAO/Si. According to SEM analysis, there are uniform pores on the surface of the material, and the cross-section shows that ZnO nanowires have been assembled into the AAO/Si structure. XRD analysis shows that ZnOn nanowires have a hexagonal wurtzite structure. In optoelectronic testing, through PL spectral analysis, the semiconductor material ZnO/AAO/Si has a strong yellow green emission peak near 574 nm. Field emission analysis shows that the β value of the ZnO field enhancement factor in the ZnO/AAO/Si structure is relatively high. The Surface-Enhanced Raman Spectroscopy (SERS) image signal experiment shows that the silicon-based nano-electronic semiconductor material prepared by electrochemical deposition method has good SERS characteristics. The SERS spectral intensity increases with the increase of the concentration of the detected substance and can be used as a SERS substrate to achieve Raman spectral image signal detection of chemical substances with low concentration.