Formation Of Zinc Oxide Research Articles

The Effects of Deposition Time and Seed Layer on Morphological Properties of Zinc Oxide by Chemical Bath Deposition

In this work, chemical bath deposition (CBD) method is used to form zinc oxide (ZnO) thin film nanostructures. Three types of zinc (Zn) precursors, namely Zn (NO3)2, ZnSO4 and ZnCl2, were used and the deposition time in water bath were controlled for 20, 40 and 60 minutes at 85 °C respectively. The effect of seed layer, by using potassium permanganate (KMnO4) solution, on the formation of zinc oxide (ZnO) thin films on glass substrates has been determined. It was found that the presence of the seed layer promote better adhesion of the films which allows ZnO to form with a higher growth rate on the substrate with only little or no loss by precipitation in the solution. The enhancement of the thin film adhesion is due to the in situ nucleation centres formation of hydrated oxide colloids of Mn (O)OH, acting as metal ion binding centres on the glass substrates surface. Meanwhile, in the absence of a seed layer, only scattered ZnO deposits are formed on substrates. By varying the deposition time, ZnO nanostructures with different length and diameter can be formed.

High Reversibility of Zinc Metal Anode for High-Energy Aqueous Batteries

Since the invention of the first battery by Volta in 1796, metallic zinc has been regarded as an ideal anode material for the aqueous batteries systems for its high theoretical capacity (820 mAh/g), low negative potential (-0.762 V vs. SHE), abundance, low toxicity and the intrinsic safety advantages that arise from nonflammable aqueous electrolytes. Recently, rechargeable batteries using zinc metal anode have been investigated extensively. However, an important barrier of the Zn-based batteries is the poor cycle life, which mainly derives from the drawbacks of the Zn metal anode and the electrolyte. The cyclability of the traditional alkaline Zn-based batteries is mainly restricted by dendrite growth, high solubility of discharge product (i.e. zincate) in the electrolytes, water loss from the liquid electrolyte, electrolyte depletion caused by the narrow electrochemical window. In most previous studies, the zinc-based aqueous batteries suffered from low columbic efficiency (CE) even using the high rate to minimize the side reaction, which means the Zn-based batteries usually require regular topping up with electrolyte. Significant excessive zinc has to been used to keep the cycle stability, results in sub-optimal utilization of the zinc theoretical capacity, as in the case of the lithium metal anode. The goal of achieving high CE in aqueous zinc metal batteries remained allusive. The poor reversibility and low CE of the Zn metal anode is closely related with the Zn (II) cation solvate structure in the aqueous electrolyte. The hydration effects of the Zn (II) cation in water is so significant that the zinc hydroxide is easily forms. The slight but non-ignorable water decomposition caused by the narrow stability window produces more hydroxyl ion and certainly aggravates the formation of zinc hydroxide. Zinc hydroxide converts into insoluble zinc oxide (ZnO) when the solubility limit of the hydroxide species is reached. Formation of solid ZnO can be a difficult process to reverse during recharge, as it relies on the resolubilization of the Zn species back into the electrolyte prior to reduction. We report the development of a highly concentrated neutral electrolyte that alters Zn(II) solvation structure resulting in the dendrite-free plating of Zn metal with high CE. The suppression of the zinc hydration was achieved through the formation of [Zn-TFSI] solvation structure instead of the [Zn-6H2O]2+ solvation structure. The solvation structure change is ascribed to the introduction of the TFSI- anion, which has strong coordination to the Zn (II) cation in concentrated electrolytes. The solvation structure change was investigated via a combination of IR spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, density functional theory (DFT) calculations and molecular dynamics (MD) simulations using polarizable force fields. We demonstrate an exceptional performance of zinc metal cells containing Zn-based aqueous electrolyte that delivered an unprecedented high practical energy density of 300Wh/kg (based on both the cathode and anode electrodes). This study opens an avenue for the highly efficient utilization of zinc metal electrodes for advanced energy storage applications while the fundamental knowledge gained can also be applied to other metal anodes.

Structural, optical and photocatalytic study of ZnO and ZnO–ZnS synthesized by chemical method

Zinc oxide (ZnO) and ZnO–ZnS nanocomposite materials have been prepared by simple chemical co-precipitation method. The X-ray diffraction analysis revealed formation of ZnO and ZnO–ZnS crystalline materials. FESEM and HRTEM analyses indicated the formation of flake-like ZnO and sheet-like ZnO–ZnS structures. Energy dispersive X-ray (EDS) study further established formation of ZnO and ZnO–ZnS materials. In the FTIR spectrum the presence of Zn-O symmetric stretching vibration at 442cm−1 and 809cm−1, due to weak vibration of ZnO, while the other peak at 687cm−1 due to Zn-S symmetric bending vibration proved the formation of ZnO–ZnS composite material. Optical absorption spectrum showed that the band gap energy decreased for ZnO–ZnS composite compared to the pure ZnO NPs. The photoluminescence spectral analysis shows that the broad emissions spectrum caused due to several different bands, owing to presence of zinc vacancies, oxygen vacancies, and surface defects. The photocatalytic performance of these samples were tested for degradation of a dye methylene blue under UV light exposure. ZnS–ZnO composite shows the higher dye degradation efficiency (93%) than that of pure ZnO (55%).

Green Synthesis Nanoparticle ZnO Sargassum sp. Extract and The Products Charactheristic

The synthesis of zinc oxide (ZnO) nanoparticles is an emerging research area due to its wide range of applications, such as electronics, pharmaceuticals, optics and food packaging. In this study, described <br />the green synthesis of ZnO nanoparticles and their characteristics using Sargassum sp. extract and 0.1 M zinc nitrate as the precursors. The variations include Sargassum sp. extracts volume of 5, 10, and 20<br />mL and the calcination temperature of 400, 500, and 600 oC. The characterization had been done such as the role of Sargassum sp. extract as a reducing agent for Zn2+ → Zn0 confirmed by Fourier Transform <br />Infrared Spectroscopy (FTIR) spectra due to 450-4000 cm-1 wavelength, the size of particles using Particle Size Analyzer (PSA), image and chemical composition using Scanning Electron Microscopy with X-ray microanalysis (SEM-EDS) and crystallinity using ray powder diffraction (XRD) with Cu anode at 1.54187 Å. Analysis with PSA instrument showed that ZnO particle size increased from 607 up to 649 nm along with increasing of extract concentration from 5 up to 20% (v/v). SEM imaging showed the formation of ZnO to be predominantly spherical and EDS data confirmed the existence of zinc and oxygen in the particles obtained. XRD analysis revealed hexagonal crystal system of ZnO nanoparticles and decreased in crystallite size was observed from 31.4 to 14.7 nm with increased in calcination temperature from 400 to 600 oC.

Optimization of AZO films for integrating optically transparent antennas with photovoltaics

The importance of having an optimal material for fabricating Optically Transparent Antennas (OTAs) is crucial for designing highly efficient antennas that can be integrated with photovoltaics. Transparent Conductor Oxides are promising for OTA fabrication due to their capability of being simultaneously transparent at optical frequencies and conductive within the radio frequency (RF) range. Here in this study, thin aluminum and zinc oxide layers were co-sputtered onto Si and a polycrystalline photovoltaic cell and then annealed between 350 °C and 450 °C for 24 and 48 h in a N2 ambient. The annealing process ensured the formation of Aluminum Zinc Oxide (AZO) with low resistivity ≈10−5 Ω cm and a transparency of 86% between 350 and 750 nm. The material was tested by performing RF characterization and by fabricating and testing two different OTAs. The results of the optimization process and characterization show that the AZO material is feasible for OTA fabrication.

Vitis labruska skin extract assisted green synthesis of ZnO super structures for multifunctional applications

Abstract The formation of unique morphologies of zinc oxide (ZnO) super structured frameworks were reported via a simple and eco-friendly route employing Vitis labruska fruit Black Grape Skin (BGS) extract as a fuel. XRD, FTIR, UV–vis, PL, SEM and TEM studies are performed to analyse the formation and characterization of ZnO. XRD confirmed the crystalline nature of the material with hexagonal Wurtzite structure having average crystallite size of ~50 nm. FTIR spectrum shows a band at 532 cm−1 due to the vibrational mode of Zn-O bending. The band gap of the ZnO was found to be 3.26 eV. SEM images confirm the formation of different morphologies like Mysore pak (a popular Indian dessert), canine teeth, hollow pyramids and gems were obtained by varying the weight of BGS. These superstructures were obtained due to the interaction of Zn2+ with BGS extract. TEM images clearly shows lattice spacing of 0.29 nm corresponding to the (002) plane of ZnO. Photoluminescence (PL) spectrum shows strong yellow light emission upon excitation at 320 nm due to the Zn-O defects. Synthesized ZnO nanoparticles (Nps) exhibited good photocatalytic activity for the degradation of Methylene blue (MB) dye. The photocatalytic activity was due to the production of OH˙ radicals during photo irradiation on ZnO Nps. ZnO Nps also exhibited superior antibacterial activity against Staphylococcus aureus and Escherichia coli bacteria. Further, ZnO Nps were also used in the development of novel electrochemical sensing platform towards the electrochemical detection of hydrazine as a model system at very low concentrations having a detection limit of 0.3 µM.

Green synthesis of zinc oxide nanoparticles using arabic gum and photocatalytic degradation of direct blue 129 dye under visible light

In this work, zinc oxide (ZnO) nanoparticles were synthesized using arabic gum as a biotemplate source by the sol–gel method and its photocatalytic dye degradation ability from aqueous solution was studied. This method has many advantages such as nontoxic, economic viability, ease to scale up, less time consuming and environmental friendly approach for the synthesis of ZnO nanoparticles without using any organic chemicals. Direct blue 129 (DB129) was used as model dye. The synthesized ZnO nanoparticles were characterized by powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy, scanning electron microscopy and UV–Visible spectroscopy. The X-ray powder diffraction (XRD) analysis revealed the formation of wurtzite hexagonal phase ZnO with average crystallite size of 10 nm. Photocatalytic dye degradation by ZnO nanoparticles was studied using UV–Vis spectrophotometer. The effects of process parameters like, catalyst dosage, initial dye concentration, and visible light irradiation on dye degradation have been investigated.

Eco –friendly flame retardant via self assembly coating

Limiting oxygen index (LOI) of the most of the textiles in use have lower than 21%, while cotton has 18.4%, which means that they can burn easily once the fire has started. Currently, there is some difficulty in making durable flame retardant (DFR) treatments for cotton fabric using an ordinary one step wet process, which is nontoxic to the humans and the environment. This research has also aimed to investigate the optimum treatment conditions that allow controlled deposition of zinc oxide onto carboxymethylated cotton fabric using sodium hypophosphite (SHP) /citric acid (CA). In this regards, the influence of the process parameters on the physicochemical and performance properties of treated cotton fabric will elucidate. The treated fabric was monitored for carboxylic content, LOI, char length, char residue, whiteness index, retained tensile strength and elongation at break. The formation of zinc oxide was verified using UV-Visible spectrum at wavelength of 325nm. Also, the zinc oxide in nano scale was monitored and observed in the range of 19-41nm by transition electron microscope (TEM). The treated cotton fabrics show LOI value and char length 25.3%, 3cm respectively, compared with 18.4 and 11cm for untreated fabric. The existence of zinc oxide particle interaction and other functional groups introduced into cotton fabrics were promoted by Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and X-ray diffraction (XRD).

Zinc oxide hierarchical nanostructures as potential NO2 sensors

A superficial thermal evaporation method has been employed for the fabrication of hierarchical zinc oxide (ZnO) nanostructured films, composed of nanorods (NR's) and bunch of nanowires (BNW's), on glass substrate and the diverse atmospheric annealing effect on their structural, morphological, compositional, and gas sensing properties has been systematically studied and reported. Structural investigation corroborates the formation of crystalline hexagonal wurtzite ZnO. The arrays of vertically aligned nanorods and bunch of nanowires of ZnO were observed on the substrate surface. As-prepared ZnO NR's and BNW's are utilized as a sensing material for detection of toxic nitrogen dioxide (NO2). The ZnO sensors exhibit high response to NO2 along with rapid response and recovery time values @200°C. In addition, ZnO sensors respond to a very small exposure of NO2 gas i.e. 1ppm. Furthermore, the developed sensors attain excellent stability and reproducibility in response. Finally, the interaction of NO2 gas molecules with hierarchical nanostructured ZnO sensors has successfully been studied and discussed by employing an electrochemical impedance spectroscopy measurement.

Fabrication of PANI–ZnO nanocomposite thin film for room temperature methanol sensor

In the recent past, polymer–metal oxide nanocomposites have been identified as one of the key and new class of materials for fabricating gas sensors owing to their swift redox characteristics. In this line of thought, chemical oxidative process was employed to synthesize zinc oxide (ZnO) and polyaniline (PANI) nanocomposite thin films with different mass concentrations of ZnO to explore their gas sensing signatures. X-ray diffraction patterns and Fourier transform infrared spectra confirmed the formation of pure ZnO and PANI–ZnO composites. Field emission scanning electron micrographs revealed the leaf like structure of ZnO, porous nature of PANI and the uniformly distributed blend of these two structures for the composite films. Further, the room temperature gas/vapour sensing characteristics revealed the selective nature of nanocomposite films towards methanol vapour in the presence of other vapours with better response, swift response and recovery times of 7 and 20 s respectively.

ZnO nanoparticles: hydrothermal synthesis and 4-nitrophenol sensing property

In this paper reports a facile hydrothermal synthesis, characterization and sensing application of zinc oxide (ZnO) nanostructures. ZnO nanostructures were synthesized by mixing triethylamine (TEA) with zinc nitrate at 60 °C followed by calcination at 650 °C for 6 h. The detailed characterizations conformed the synthesized ZnO nanostructures. Powder X-ray diffraction (XRD), Fourier transform infrared (FT-IR) and Raman spectral analysis confirmed the formation of hexagonal ZnO. Band gap of the ZnO nanoparticles was determined by UV–visible absorption spectroscopy. Morphology and size of the sample was examined by field emission scanning electron microscopy (FE-SEM) and high resolution transmission electron microscopy (HR-TEM). It shows that the sample has rod and hexagonal morphology. Elemental composition was determined by energy dispersive X-ray (EDX) spectroscopy. The ZnO was coated on glassy carbon electrode (ZnO/GCE) and it was utilized as an electrochemical sensor for 4-nitrophenol (4-Np). Sensitivity and detection limit of ZnO/GCE towards 4-Np was found to be 0.04 µA/mM and 2.09 × 10−5 M. The result suggests that ZnO has suitable sensor detection of 4-Np.

Solvothermal Preparation of Zinc Oxide/Reduced Graphene Oxide Composites for Rapid Removal of Methylene Blue.

Zinc oxide/reduced graphene oxide composites with various morphologies and properties were prepared via a one-step solvothermal process. The formation of zinc oxide and reduction of graphene oxide were simultaneously accomplished. These as-obtained samples showed high performance in removing methylene blue from aqueous solution. Solvent could play an important role in tuning the morphologies of the zinc oxide and the efficiency of the final composites. Composites prepared in acetone showed the highest removal efficiency, compared with those prepared in water and ethanol. Loading content of the reduced graphene oxide could affect the performance as well. With the increase in the content of the reduced graphene oxide, the as-prepared samples showed enhanced performance gradually. The as-prepared composite showed certain stability, with a maximum recyclability of 5 times for efficient removal. The effective removal of target dye turned out to be the result of the combination of physical adsorption and photo-catalysis.

Electrochemical Deposition of Zinc Oxide on the Surface of Composite Membrane Polysulfone-Graphene-Polystyrene in the Presence of Water Soluble Polymers

The aim of this study consisted in the development of an alternative synthesis procedure for hybrid ultrafiltration membranes for water purification. The membranes were obtained by wet-phase inversion method based on aliquots of polysulfone (PSF) and graphene nanoplatelets modified with poly(styrene) (G-PST). The hybrid materials were modified by electrochemical deposition of zinc oxide (ZnO) on one side of the membranes in the presence of water soluble polymers. Raman, XPS, and TGA analyses were used to characterize the chemical and thermal characteristics of the PST-G. SEM analysis showed the formation of asymmetric porous configuration in all cases and the generation of ZnO with different shapes/structures on the bottom surface of the membrane or inside the porous channels. EDS analysis confirmed the formation of ZnO.

Antimicrobial activity of ZnO/silica gel nanocomposites prepared by a simple and fast solid-state method

The formation of Zinc oxide (ZnO) nanoparticles on silica gel (SG) is achieved through a new- one stage solid state method. The only precursor used was ZnCl2. The preparation of nanocomposite is accomplished by heating a mixture of ZnCl2 and silica gel at 450°C, leading to the formation of ZnO particles on the surface. The structure, morphology, absorption spectrum and homogeneity of the ZnO/Silica gel nanocomposites (ZnO/SG) were characterized. The absorption spectra of the nanocomposites show the change of state from silica gel to ZnO/SG. X-Ray Diffraction (XRD) patterns prove the formation of the ZnO/SG. Micro-EDXRF (energy dispersive X-ray fluorescence) analysis of the composites showed good homogeneity. The antibacterial test of the samples against Escherichia coli and Staphylococcus aureus shows the strong antibacterial activity of nanocomposites when confronted by these bacteria.

A New Precursor Route to Semiconducting Zinc Oxide

We demonstrate a new precursor route toward solution-processed films of the II–VI semiconductor zinc oxide (ZnO). Spray pyrolysis of aqueous solutions of the zinc salt zinc chloride (ZnCl2) onto a substrate heated to at least 250 °C gives films that are insoluble in water, display an absorption edge at 365 nm, and when electrically gated display thin film transistor characteristics similar to ZnO films derived via the established zinc acetate (ZnAc) precursor route; we, therefore, identify it as ZnO. Control experiments attempting spray pyrolysis of aqueous zinc sulfate solutions, and delayed pyrolysis of cold-sprayed and dried ZnCl2 films, do not lead to semiconducting films. Formation of ZnO from an aqueous Zinc salt requires the simultaneous presence of zinc ions, chloride ions, and water, at the time of pyrolysis. We, therefore, suggest that the actual ZnO precursor is the ZnCl x H2O(4– x ) species that forms when ZnCl2 dissolves in water [The Journal of Chemical Physics 39, 3436 (1963)]. The reported process is easy to upscale for large area ZnO coatings, e.g., on window panes for thermal control, as no organic solvent vapors are released.

Selective Ion Transporting Polymerized Ionic Liquid Membrane Separator for Enhancing Cycle Stability and Durability in Secondary Zinc-Air Battery Systems.

Rechargeable secondary zinc-air batteries with superior cyclic stability were developed using commercial polypropylene (PP) membrane coated with polymerized ionic liquid as separators. The anionic exchange polymer was synthesized copolymerizing 1-[(4-ethenylphenyl)methyl]-3-butylimidazolium hydroxide (EBIH) and butyl methacrylate (BMA) monomers by free radical polymerization for both functionality and structural integrity. The ionic liquid induced copolymer was coated on a commercially available PP membrane (Celguard 5550). The coat allows anionic transfer through the separator and minimizes the migration of zincate ions to the cathode compartment, which reduces electrolyte conductivity and may deteriorate catalytic activity by the formation of zinc oxide on the surface of the catalyst layer. Energy dispersive X-ray spectroscopy (EDS) data revealed the copolymer-coated separator showed less zinc element in the cathode, indicating lower zinc crossover through the membrane. Ion coupled plasma optical emission spectroscopy (ICP-OES) analysis confirmed over 96% of zincate ion crossover was reduced. In our charge/discharge setup, the constructed cell with the ionic liquid induced copolymer casted separator exhibited drastically improved durability as the battery life increased more than 281% compared to the pure commercial PP membrane. Electrochemical impedance spectroscopy (EIS) during the cycle process elucidated the premature failure of cells due to the zinc crossover for the untreated cell and revealed a substantial importance must be placed in zincate control.

Enhancement of Cycle Stability and Durability in Secondary Zinc-Air Batteries By Optional Ion-Transporting Separator

Highly durable secondary zinc air batteries were developed using polypropylene (PP) membrane (Celguard 5550) coated with polymerized ionic liquid as separators. The anionic exchange polymer was synthesized copolymerizing 1-[(4-ethenylphenyl)methyl]-3-butyl-imidazolium hydroxide (EBIH) and butyl methacrylate (BMA) monomers by free radical polymerization for both functionality and structural integrity. The ionic liquid induced copolymer was coated on a commercially available PP membrane. The coat allows anionic transfer through the separator and minimizes the migration of zincate ions, which causes the loss of active sites by the formation of zinc oxide on the surface of the catalyst layer. Electrochemical Impedance Spectroscopy (EIS) during the cycle process elucidated the premature failure of cells due to the zinc cross over for the untreated cell and revealed a substantial importance must be placed in zincate control. Scanning electron microscopy (SEM) revealed significant decrease in the porosity of the coated film without large cell performance sacrifice. Energy dispersive x-ray spectroscopy (EDS) data revealed the copolymer coated separator showed less zinc element in the cathode electrolyte, indicating lower zinc permeation through the membrane. Ion Coupled Plasma Optical Emission Spectroscopy (ICP-OES) analysis confirmed over 96% of zinc ion cross over was reduced. In our charge/discharge setup, the constructed cell with the ionic liquid induced copolymer casted separator exhibited drastically improved durability as the battery life increased more than 281% compared to the pure commercial PP membrane.

Boosting Responsivity of Organic–Metal Oxynitride Hybrid Heterointerface Phototransistor

Amorphous metal oxides are attractive materials for various sensor applications, because of high electrical performance and easy processing. However, low absorption coefficient, slow photoresponse, and persistent photoconductivity of amorphous metal oxide films from the origin of deep-level defects are obstacles to their use as photonic applications. Here, we demonstrate ultrahigh photoresponsivity of organic-inorganic hybrid phototransistors featuring bulk heterojunction polymers and low-bandgap zinc oxynitride. Spontaneous formation of ultrathin zinc oxide on the surface of zinc oxynitride films could make an effective band-alignment for electron transfer from the dissociation of excitons in the bulk heterojunction, while holes were blocked by the deep highest occupied molecular orbital level of zinc oxide. These hybrid structure-based phototransistors are ultrasensitive to broad-bandwidth photons in ultraviolet to near-infrared regions. The detectivity and a linear dynamic range exceeded 10(12) Jones and 122.3 dB, respectively.

Novel Biomimatic Synthesis of ZnO Nanorods Using Egg White (Albumen) and Their Antibacterial Studies.

Zinc oxide (ZnO) is well-recognized as a biocompatible multifunctional material with outstanding properties as well as low toxicity and biodegradability. In this work, a simple and versatile technique was developed to prepare highly crystalline ZnO nanorods by introducing egg white to a bio-inspired approach. X-ray diffraction (XRD) and selected area electron diffraction (SAED) pattern results indicated that the ZnO nanorods have single phase nature with the wurtzite structure. Field emission scanning electron microscopy (FESEM) and Transmission electron microscopy (TEM) results showed the nanometer dimension of the nanorods. Raman, FTIR, and TGA/DTA analyses revealed the formation of wurtzite ZnO. The antibacterial properties of ZnO nanorods were investigated using both Gram-positive and Gram-negative microorganisms. These studies demonstrate that ZnO nanorods have a wide range of antibacterial activities toward various microorganisms that are commonly found in environmental settings. Survival ratio of bacteria decreased with increasing powder concentration, i.e., increase in antibacterial activity. The antibacterial activity of the ZnO nanorods toward Pseudomonas aeruginosa was stronger than that of Escherichia coli and Staphylococcus aureus. Surprisingly, the antibacterial activity did not require specific UV activation using artificial lamps, rather activation was achieved under ambient lighting conditions. Overall, the experimental results suggest that ZnO nanorods could be developed as antibacterial agents against a wide range of microorganisms to control and prevent the spreading and persistence of bacterial infections. This research introduces a new concept to synthesize ZnO nanorods by using egg white as a biological template for various applications including food science, animal science, biochemistry, microbiology and medicine.

DNA Adsorption by ZnO Nanoparticles near Its Solubility Limit: Implications for DNA Fluorescence Quenching and DNAzyme Activity Assays.

Zinc oxide (ZnO) is a highly important material, and Zn(2+) is a key metal ion in biology. ZnO and Zn(2+) interconvert via dissolution and hydrolysis/condensation. In this work, we explore their interactions with DNA, which is important for biointerface, analytical, and bioinorganic chemistry. Fluorescently labeled DNA oligonucleotides were adsorbed by a low concentration (around 5 μg/mL) of ZnO nanoparticles, near the solubility limit. Right after mixing, fluorescence quenching occurred, indicating DNA adsorption. Then, fluorescence recovered, attributable to ZnO dissolution. The dissolution rate followed A5 > T5 > C5. Dissolution was slower with longer DNA. The adsorption affinity was also measured by a displacement assay to be G5 > C5 > T5 > A5, suggesting that tightly adsorbed DNA can retard ZnO dissolution. Electrostatic interactions are important for DNA adsorption because ZnO is positively charged at neutral pH, and a high salt concentration inhibits DNA adsorption. Next, in situ formation of ZnO from Zn(2+) was studied. First, titrating Zn(2+) into a fluorescently labeled oligonucleotide at pH 7.5 resulted in an abrupt fluorescence quenching beyond 0.2 mM Zn(2+). At pH 6, quenching occurred linearly with the Zn(2+) concentration, suggesting the effect of Zn(2+) precipitation at pH 7.5. Second, a Zn(2+)-dependent DNA-cleaving DNAzyme was studied. This DNAzyme was inhibited at higher than 2 mM Zn(2+), attributable to Zn(2+) precipitation and adsorption of the DNAzyme. This paper has established the interplay between DNA, Zn(2+), and ZnO. This understanding can avoid misinterpretation of DNA assay results and adds knowledge to DNA immobilization.