Morphology Of ZnO Nanostructures Research Articles

Synergistic bifunctionality of ZnO nanowalls: Antibacterial activity and photocatalysis through integrated in silico and in vitro approaches

This research investigation delves into the versatile attributes of ZnO nanowalls, specifically probing into their dual functionality encompassing antibacterial and photocatalytic properties. The synthesis of ZnO was achieved by employing a microwave-mediated co-precipitation technique. The resulting sample underwent thorough characterization through diverse analytical methodologies. X-ray diffraction analysis disclosed the prevalence of the hexagonal wurtzite phase, as confirmed by JCPDS card No. 36–1451, with an average crystallite size determined as 23.48 nm. Tauc plot extrapolation method was applied to the UV absorption spectrum to ascertain the bandgap energy. The ZnO nanostructure morphology, featuring multi-directional nano-walls, was unveiled through scanning electron microscopy (SEM). The BET nitrogen adsorption technique quantified the surface area of the ZnO sample as 6.69 m2/g. In antibacterial evaluation, the in vitro (disk diffusion) method showcased the remarkable efficacy of ZnO against both gram-positive Staphylococcus sp. and gram-negative E. coli bacteria. Complementing these experimental findings, in silico molecular docking studies exposed both nano ZnO ligands with standard and corrected lattice parameter values exhibiting favorable binding energy. Moreover, the synthesized ZnO nanoparticles exhibited remarkable photocatalytic activity, particularly demonstrated in the decolorisation of Azure A and Azure B dyes, following the first-order Langmuir–Hinshelwood kinetic model. The collective findings underscored a synergistic effect within the fabricated ZnO nanoparticles, showcasing their dual prowess in both antibacterial and photocatalytic activities. The observed phenomenon can be chiefly ascribed to the presence of lattice strain and dislocation density. This intriguing dual functionality positions them as promising candidates for potential applications in wastewater treatment.

Antioxidant and Anti-inflammatory Applications of Aerva persica Aqueous-Root Extract-Mediated Synthesis of ZnO Nanoparticles.

In the present study, ZnO nanoparticles were synthesized by using aqueous extracts of Aerva persica roots. Characterization of as-prepared ZnO nanoparticles was carried out using different techniques, including powder X-ray diffraction (XRD), UV-vis diffuse reflectance spectroscopy (DRS), Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and BET surface area analysis. Morphological analysis confirmed the small, aggregated flake-shaped morphology of as-synthesized ZnO nanostructures. The as-prepared ZnO nanoparticles were analyzed for their potential application as anti-inflammatory (using in vivo inhibition of carrageenan induced paw edema) and antioxidant (using in vitro radical scavenging activity) agents. The ZnO nanoparticles were found to have a potent antioxidant and anti-inflammatory activity comparable to that of standard ascorbic acid (antioxidant) and indomethacin (anti-inflammatory drug). Therefore, due to their ecofriendly synthesis, nontoxicity, and biocompatible nature, zinc oxide nanoparticles synthesized successfully from roots extract of the plant Aerva persica with potent efficiencies can be utilized for different biomedical applications.

Surface parametric influences on the photocatalytic behaviour of zinc oxide nanoparticles

Zinc oxide nanoparticles were chemically synthesised and characterised by UV-DRS spectroscopy, FTIR, scanning electron microscopy with energy-dispersive X-ray diffraction, and X-ray powder diffraction. In order to evaluate the impact of the synthesis process on the structural parameters, Rietveld refinement was done using the GSAS-II programme on experimentally acquired XRD data. ZnO was found to have a hexagonal structure with lattice parameters of a = b =3.247 Å; c = 5.205Å and an average size of about 20-40 nm, as determined by Rietveld refinement of XRD and SEM data. FTIR and EDX analysis was used to confirm the functional group and elemental composition of ZnO NPs. The UV-DRS spectra revealed that the synthesised ZnO had an optical band gap of 3.05 eV. Parametric investigations of the surface morphology of ZnO nanostructures were conducted using the Gwyddion programme. Pseudo-first-order rate kinetics were observed for the photodegradation of two cationic dyes, MB (87.87%) and RhB (74.79%), in the presence of UV light.

Towards carbon monoxide detection based on ZnO nanostructures

In this work, we investigated how the morphology of ZnO nanostructures influenced their CO detection. ZnO nanoparticles and nanorods were synthesized using the MAH method. XRD confirmed the formation of wurtzite ZnO without secondary phases. Raman spectroscopy revealed that oxygen vacancies, zinc interstitial, and their free carriers are the dominant defects. The nanorod morphology enhanced the performance towards CO when compared with the nanoparticles. The ZnO nanorods have a higher specific surface area and are more sensitive to CO. The CO detection performance of the ZnO nanorods highlights how the CTAB employed in the synthesis changed the structural defects or states localized inside the bandgap. Moreover, the use of the MAH method with CTAB is important due to the short treatment time, low temperature, and the possibility to control the morphologies of the ZnO nanostructures. Also, the ZnO nanorods response to CO shows their potential as a gas-sensing component.

Understanding the effect of morphological change on photocatalytic activity of ZnO nanostructures and reaction mechanism by molecular dynamics

The photocatalytic activity of photocatalysts is often influenced by their particle morphology, dimension, size, exposed facets, porosity, etc. This work aims at gaining insights into the influence of the particle morphology of ZnO nanostructures on their photocatalytic activity. Under hydrothermal conditions, the Zn(NO3)2∙6 H2O:KOH (Zn:KOH) ratio is changed to 1:2, 1:8, and 1:12 to modulate the morphology of ZnO nanostructures. Particularly, the ZnO nanostructures with a nanostar-like morphology, synthesized at the Zn:KOH ratio of 1:8, exhibit the highest photocatalytic activity in comparison to ZnO nanoparticles and nanorods synthesized at the Zn:KOH ratios of 1:2 and 1:12, respectively. The enhanced photocatalytic activity for the degradation of methylene blue (MB) of ZnO nanostructures with a nanostar-like morphology is due to the presence of a large number of oxygen vacancy-related defects, which are preferably formed on the (1 0 1) facet of ZnO. The results from X-ray diffraction and photoluminescence spectroscopy analyses confirm it. Further, molecular dynamics (MD) simulation is involved to explore the interaction of oxygen atoms (as a representative of hydroxyl radical) with methylene blue molecules to understand the mechanism of enhanced MB degradation at the atomic level. The results of the computational study indicate the formation of hydroxyl radicals and the cleavage and the formation of some bonds in the side and central aromatic rings of MB molecules, which ultimately leads to the degradation of MB. Our findings reveal that it is important to control the morphology and facets of nanostructures for achieving high efficiency in the photocatalytic processes to be applied in practical application.

Morphology Effects on Electro- and Photo-Catalytic Properties of Zinc Oxide Nanostructures.

Environmental problems are among the most pressing issues in the modern world, including the shortage of clean drinking water partially caused by contamination from various industries and the excessive emission of CO2 primarily from the massive use of fossil fuels. Consequently, it is crucial to develop inexpensive, effective, and environmentally friendly methods for wastewater treatment and CO2 reduction, turning them into useful feedstocks. This study explores a unique method that addresses both challenges by utilizing ZnO, which is recognized as one of the most active semiconductors for photocatalysis, as well as a cost-effective electrocatalyst for the CO2 reduction reaction (CO2RR). Specifically, we investigate the influence of the morphology of various ZnO nanostructures synthesized via different low-cost routes on their photocatalytic properties for degrading the rhodamine-B dye (RhB) and on their electrocatalytic performance for the CO2RR. Our results show that the ZnO lamella morphology achieves the best performance compared to the nanorod and nanoparticle structures. This outcome is likely attributed to the lamella's higher aspect ratio, which plays a critical role in determining the structural, optical, and electrical properties of ZnO.

Laser-Induced Au Catalyst Generation for Tailored ZnO Nanostructure Growth.

ZnO nanostructures, semiconductors with attractive optical properties, are typically grown by thermal chemical vapor deposition for optimal growth control. Their growth is well investigated, but commonly results in the entire substrate being covered with identical ZnO nanostructures. At best a limited, binary growth control is achieved with masks or lithographic processes. We demonstrate nanosecond laser-induced Au catalyst generation on Si(100) wafers, resulting in controlled ZnO nanostructure growth. Scanning electron and atomic force microscopy measurements reveal the laser pulse's influence on the substrate's and catalyst's properties, e.g., nanoparticle size and distribution. The laser-induced formation of a thin SiO2-layer on the catalysts plays a key role in the subsequent ZnO growth mechanism. By tuning the irradiation parameters, the width, density, and morphology of ZnO nanostructures, i.e., nanorods, nanowires, and nanobelts, were controlled. Our method allows for maskless ZnO nanostructure designs locally controlled on Si-wafers.

Hydrophilic ionic liquid assisted hydrothermal synthesis of ZnO nanostructures with controllable morphology.

Nanostructured ZnO with controllable morphology was prepared by a hydrothermal method in the presence of three different hydrophilic ionic liquids (ILs), 1-ethyl-3-methylimidazolium methylsulfate, ([C2mim]CH3SO4), 1-butyl-3-methylimidazolium methylsulfate, ([C4mim]CH3SO4) and 1-ethyl-3-methylimidazolium ethylsulfate, ([C2mim]C2H5SO4) as soft templates. The formation of ZnO nanoparticles (NPs) with and without IL was verified using FT-IR and UV-visible spectroscopy. X-ray diffraction (XRD) and selected area electron diffraction (SAED) patterns indicated the formation of pure crystalline ZnO with a hexagonal wurtzite phase. Field emission scanning electron microscopic (FESEM) and high-resolution transmission electron microscopic (HRTEM) images confirmed the formation of rod-shaped ZnO nanostructures without using IL, whereas the morphology varied widely following addition of ILs. With increasing concentrations of [C2mim]CH3SO4, the rod-shaped ZnO nanostructures transformed into flower-shaped nanostructures whereas with rising concentrations of [C4mim]CH3SO4 and [C2mim]C2H5SO4 the morphology changed into petal- and flake-like nanostructures, respectively. The selective adsorption effect of the ILs could protect certain facets during the formation of ZnO rods and promote the growth in directions other than [0001] to yield petal- or flake-like architectures. The morphology of ZnO nanostructures was, therefore, tunable by the controlled addition of hydrophilic ILs of different structures. The size of the nanostructures was widely distributed and the Z-average diameter, evaluated from dynamic light scattering measurements, increased as the concentration of the IL increased and passed through a maximum before decreasing again. The optical band gap energy of the ZnO nanostructures decreased when IL was added during the synthesis which is consistent with the morphology of the ZnO nanostructures. Thus, the hydrophilic ILs serve as self-directing agents and soft templates for the synthesis of ZnO nanostructures and the morphology and optical properties of ZnO nanostructures are tunable by changing the structure of the ILs as well as systematic variation of the concentration of ILs during synthesis.

The Effect of Al-Cu Co-Dopants on Morphology, Structure, and Optical Properties of ZnO Nanostructures

The Effect of Al-Cu Co-Dopants on Morphology, Structure, and Optical Properties of ZnO Nanostructures

Decay emission study of ZnO nanostructures obtained by low-pressure vapor transport technique

Currently, the search for inexpensive, non-toxic, and environmentally friendly materials for optoelectronic applications has led to an increased interest in one-dimensional ZnO materials. Attributes such as their high surface area, crystalline phase purity, and high photoexcited response make them attractive for light emission, biosensing, and energy harvesting applications. However, there is still a need for studies that correlate the optical and structural properties of these materials, so they can be integrated as functional building blocks in practical devices. In this work, we report the growth of 1D ZnO nanostructured films using a low-pressure vapor transport technique. Gold-plated substrates allowed us to achieve different types of homogeneous films composed of nanowires/nanorods. Through scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-Ray diffraction (XRD) the high-crystalline structure and morphological properties of the materials were determined. The presented methodology also offers control over the growth direction of the nanostructures, as both random and highly aligned matrixes were obtained. Finally, the optical properties of the system were studied by photoluminescence spectroscopy (PL). Along with the excitonic emission, a significant role of defect-related luminescence was found, allowing us to interpret the emission mechanism for the different morphologies of ZnO nanostructures. Time-resolved PL experiments determined decays between 1.9-0.3 ns where an enhancement in the carrier's lifetime was observed as the size of the nanostructure increased. The present study could help us to design efficient ZnO nanostructures with control over their morphology and controllable optoelectronic properties for modern device fabrication.

Fabrication of Carbon/Zinc Oxide Nanocomposites as Highly Efficient Catalytic Materials for Application in Dye-Sensitized Solar Cells

Different nanostructured semiconducting ZnO photoanodes were prepared by Hydrothermal (HT), Co-precipitation (CoP) and Chemical Bath Deposition (CBD) methods for their use in the Dye Sensitized Solar Cells (DSSCs) in the present study. Additionally, different ZnO nanocomposites were synthesized by mixing the Carbon Nanotubes (CNTs), Graphene Oxide (GO) and their combination with the ZnO nanostructures. Scanning electron microscopy (SEM) revealed various morphologies of ZnO nanostructures and nanocomposites such as nanoflowers, nanorods, rhombohedral, cubic, and cauliflower-like nanorods, and nanorods with hexagonal symmetry. Energy Dispersive X-ray (EDX) spectra confirmed the purity of the synthesized samples. X-ray Diffraction (XRD) demonstrated the hexagonal wurtzite phase of ZnO and a minor presence of CNTs and graphene. The UV-Visible, transmittance and diffuse reflectance spectra demonstrated that the ZnO synthesized through the CBD method exhibits the highest transmittance as 70–71% in the UV-Vis range and reduced % R. Optical band gaps of the samples were determined with the help of Tauc plots. Comparison of J-V characteristics showed that the ZnO synthesized via the HT method exhibits the highest conversion efficiency of 1.45%. Comparison among pristine ZnO synthesized via CBD and ZnO nanocomposites revealed that ZnO/CNTs possesses the highest energy conversion efficiency of 1.23% with enhanced JSC of 4.49 mA/cm2.

Surface defect-rich ZnO nanostructures with high yellow-orange luminescence

ZnO nanostructures such as nanoislands, nanosheets, microflowers and nanoparticles were obtained successfully using a facile and rapid solution route employing low temperatures and reduced molar concentrations from precursor without using any surfactant agent or additional procedures. In this route, we use ZnCl2 as precursor ranging from 0.05 to 0.4 M and two hydrothermal times (2 and 4 h) to obtain different ZnO morphologies. According to SEM micrographs, the morphology of ZnO nanostructures showed a strong dependence on the ZnCl2 concentration and hydrothermal synthesis time. ZnO microflowers were obtained at 0.05 M during 2 h, while ZnO nanoislands, nanoparticles and nanosheets were observed at 0.05, 0.2 and 0.4 M, respectively, in 4 h. X-Ray diffraction and Raman results showed the wurtzite-type ZnO structure and good crystallinity in all cases. In addition, both techniques confirmed the best crystalline quality in ZnO nanoparticles followed by ZnO nanosheets. Finally, according to photoluminescence measurements, all samples exhibit a high yellow-orange emission, associated to a large number of surface defect states, such as oxygen and zinc interstitials. The largest amount of zinc interstitials and zinc vacancies were observed in ZnO nanoislands, while ZnO microflowers have the highest visible emission (followed by ZnO nanoparticles) which in turn, offered the lowest excitonic recombination from the conduction band to the valence band, which may result in a higher photocatalytic efficiency.

Flower-like ZnO Nanostructures Local Surface Morphology and Chemistry

This work presents the results of comparative studies using complementary methods, such as scanning electron microscopy (SEM), X-ray photoemission spectroscopy (XPS), and thermal desorption spectroscopy (TDS) to investigate the local surface morphology and chemistry of flower-like ZnO nanostructures synthesized by the thermal oxidation technique on native Si/SiO2 substrates. SEM studies showed that our flower-like ZnO nanostructures contained mostly isolated and irregular morphological low-dimensional forms, seen as rolled-up floss flowers, together with local, elongated, complex stalks similar to Liatris flowers, which contained joined short flosses in the form of nanodendrites. Beyond this, XPS studies showed that these nanostructures exhibited a slight surface nonstoichiometry, mostly related to the existence of oxygen-deficient regions, combined with strong undesired C surface contamination. In addition, the TDS studies showed that these undesired surface contaminations (including mainly C species and hydroxyl groups) are only slightly removed from the surface of our flower-like ZnO nanostructures, causing an expected modification of their nonstoichiometry. All of these effects are of great importance when using our flower-like ZnO nanostructures in gas sensor devices for detecting oxidizing gases because surface contamination leads to an undesired barrier for toxic gas adsorption, and it can additionally be responsible for the uncontrolled sensor aging effect.

Dependence of Cu doping on structure, morphology, magnetic and biomedical properties of ZnO nanostructures

We report the dependency of Cu doping on the structure, morphology, magnetic properties and the regulation of cytotoxicity and biocompatibility in macrophages (RAW 264.7) of ZnO nanostructures. A viable chemical bath deposition technique has been explored for the synthesis of undoped and Cu-doped ZnO nanostructures, using the precursor’s mixture of Zinc nitrate hexahydrate, Hexamethylenetetramine and Copper (II) acetate monohydrate. The structural and morphological studies confirms the incorporation of Cu 2+ ion into ZnO matrix hinders the nanorod growth and the nanorod morphology disappears at higher doping. Cu ions substitute Zn 2+ sites in its divalent state as confirmed from X-ray photoelectron spectroscopy studies. Magnetic measurement ensures a dramatic change in the magnetic features due to doping, which is directly reflected in the temperature- and field-dependent magnetization curves. From the cytotoxicity assessment with RAW 264.7 macrophage cell lines, the Cu doped ZnO samples are non-toxic. Our study exhibits the potential usefulness of the materials in spintronic/ magnetic media device applications as well as Cu doping as a promising approach for new functional biomaterials for bio-medical applications.

Selected organic dyes (carminic acid, pyrocatechol violet and dithizone) sensitized metal (silver, neodymium) doped TiO2/ZnO nanostructured materials: A photoanode for hybrid bulk heterojunction solar cells

A photoactive nanohybrid material consisting of pyrocatechol violet, carminic acid and dithizone dyes functionalized silver and neodymium-doped TiO2/ZnO nanostructured materials is reported here, as photoactive blend, for solid-state dye sensitized solar cell. First of all we synthesized metals (silver, neodymium) doped (TiO2) Titanium oxide nanoparticles and their nanocomposites (TiO2/ZnO, M−TiO2/ZnO) using the sol–gel and reflux technique, respectively. The synthesized samples were then characterized by UV–Visible spectroscopy, X-Ray diffraction Analysis (XRD), Scanning electron microscopy (SEM), Energy dispersive X-Ray Analysis (EDX), and Fourier Transform infrared spectroscopy (FTIR). Optical studies were done through UV–Visible spectroscopy and the absorption spectra were used to calculate band gaps. The value of the energy gap for TiO2 nanoparticles is 3.10 eV which was gradually tuned to 2.47 eV after incorporating metals (Ag and Nd) and forming respective nanocomposites. X-Ray diffraction Analysis (XRD) patterns revealed the purity and crystallinity in samples. Scanning electron microscopy (SEM) confirmed the irregular morphology (nanorods and spherical shaped) of ZnO and TiO2 nanostructures respectively. The elemental composition of nanomaterials was successfully investigated using energy dispersive X-ray analysis (EDX). In the absence of any impurities, Fourier Transform infrared spectroscopy (FTIR) was used to identify the functional groups in synthesized material. For device fabrication, a solid-state electrolyte, P3HT, a hole conducting polymer was used. Characterization of fabricated solar cells was done using I-V measurements. Under simulated solar irradiation, the DSSC based on pyrocatechol violet sensitized neodymium doped TiO2/ZnO nanohybrid materials exhibited the best PCE (power conversion efficiency) of 2.38 % and significantly improved Jsc (short circuit current density) of 15.68 mA/cm2 as compared to carminic acid and dithizone in photovoltaic measurements. The improved power conversion efficiency of this device is ascribed to the particle size, increased dye adsorption, increased surface area and thus improved short circuit current density (Jsc).

Branches of ZnO nanostructure grown on sub-microrod template with seed layer coated by ultrasonic-assisted immersion technique: effect of surface energy on the growth of branches

Branches of ZnO nanostructure were hydrothermally grown on seed layer coated on sub-microrod template by ultrasonic-assisted immersion technique. Zinc acetate, monoethanolamine, and isopropanol were used as a precursor, stabilizer, and solvent for coating seed layer, respectively. The crystallization of seed layer, which was confirmed by x-ray diffractometer (XRD) and x-ray photoelectron spectrometer (XPS), was facilitated by ultrasonic irradiation. The sol concentration was adjusted to be 20 and 50 mM with the coating cycles of 8 and 16 for controlling the uniformity and surface energy of seed layer. The increase of sol concentration and coating cycles led to the increase of crystal orientation in (002) plane causing the improvement of seed layer’s surface energy which was estimated from water contact angle of the template. Atomic force microscope (AFM) was revealed that the seed layer did not cover the template only at the lowest condition of both sol concentration and coating cycles. However, the roughness and maximum peak-to-valley value tended to be increased for other conditions and dropped for the last condition which was suitable to vertically grow branches. After the growth of branches, the morphology of hierarchical ZnO nanostructure was investigated by field-emission scanning electron microscope (FESEM). It was found that the branches were vertically grown on the surface of rod template in every condition except the lowest sol concentration and coating cycles. Moreover, when the sol concentration and coating cycle of seed layer were increased, the branch density was also increased.

Highly efficient ZnO nanostructures for enhanced photocatalytic degradation of organic contaminants under simulated solar light: An efficient industrial approach

The increasing demand for uncontaminated and affordable water is now the biggest challenge worldwide. Therefore, there is an urgent need to remove the soluble organic effluents from wastewater and make water reusable. In this aspect, two different morphologies of ZnO nanostructures (NPs and NRs) were developed by a soft-chemical approach and their photocatalytic activity for degradation of organic dyes were investigated. TEM micrographs confirm the formation of nanoparticles (NPs: 20 ± 3 nm) and nanorods (NRs: length of 60 ± 5 nm and width of ∼ 10 nm) of ZnO. XRD and Raman spectra show the formation of single-phase hexagonal wurtzite for both the ZnO nanostructures. The UV–visible absorption and photoluminescence studies confirm that ZnO nanostructures show a change in bandgap and defect concentration as morphology changes from particles to rods. Both the morphologies of ZnO nanostructures show the excellent photocatalytic degradation of methylene blue (MB), rhodamine B (RhB), methyl orange (MO) (under UV and simulated solar light) as well as an industrial dye (under simulated solar light). TheZnO NPs and NRs degrade MB, RhB and MO with 100 % efficiency under UV and solar light at the appropriate time. Moreover, ZnO nanostructures show good photostability and reusability which make them useful for industrial applications.

Rapid synthesis of ZnO nanostructures on woven carbon fiber using microwave treated chemical bath deposition and their characterization

Microwave-assisted chemical bath deposition (MACBD) is a new method for synthesizing metal-oxide layers and nanostructures efficiently. The fast synthesis of ZnO nanostructures (NSs) on woven carbon fiber (WCF) is reported in this study employing the MACBD technique. An aqueous solution of tetra ammonium zinc complex was used to create several morphologies of ZnO NSs on WCF fabric, including nanopetals, twinned nanospheres, nanoflowers, and nanoflakes. Under microwave heating, plain WCF fabric samples were treated with several precursor solutions. When compared to conventional CBD, the development time of ZnO NSs is lowered to roughly 2–4 min. Field-emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), and an X-ray diffractometer were used to evaluate as-developed ZnO NSs morphologies on WCF. The processing of ZnO NSs on the strands of carbon fibers was interpreted using FESEM, and it was discovered that variations in microwave duration and precursor solution are the primary causes of ZnO morphology development. With the formation of nanostructures, the crystalline peak height of the nanostructures increases. For the fabrication of high performance ZnO nanostructured WCF hybrid polymer composites vacuum bagging technique were used along with resin transfer system. Epoxy resin was applied as a matrix material with the five layers of ZnO grown WCF for varied applications.

Effect of calcination temperature on the morphology and catalytic properties of ZnO nanostructures fabricated from a chiral precursor for photodegradation of both cationic and anionic dyes

A chiral Zn MOF is fabricated into ZnO microflowers, polyhedrons and nanorods at three different temperatures and these are utilized for the photodegradation of methylene blue and Congo red.

Morphology control of ZnO nanostructures using Zn and W electrodes in solution plasma process

The morphology of ZnO nanostructures was controlled by the type of electrodes used, without chemical additives in the solution plasma process. Nanorod and nanosheet-type ZnO were synthesized using Zn and W electrodes, respectively. In the solution plasma process, the ZnO nanostructure can be fabricated because of the unique reaction between ions and radicals at the plasma/liquid interface. During this reaction, ions generated from the metal electrode influence the morphology of ZnO by adsorption on the (001) facet. Zn(OH)42− ions promoted crystal growth in the [001] direction, resulting in a rod structure. In contrast, the sheet structure was formed owing to the inhibition of growth in the [001] direction by WO42− ions.