Formation Of Zinc Oxide Research Articles

Oxidizing methanol at cubic-hexagonal junction of NiO-ZnO at low onset potential

A bimetallic, low-cost electrocatalyst consisting of non-noble nickel (Ni) and zinc (Zn) metal was synthesized for the effective oxidation of methanol (CH3OH). The formation of cubic NiO (nickel oxide) and hexagonal ZnO (zinc oxide) was confirmed by various spectrophotometric analyses. NiO-ZnO modified with -COOH functionalized MWCNT, NiO-ZnO-f-MWCNT exhibited significant methanol oxidation reaction (MOR) activity without any substantial oxygen evolution reaction (OER). At a lower onset potential value of 1.33 V versus RHE (reversible hydrogen electrode), the catalyst NiO-ZnO-f-MWCNT demonstrated a high current density of 3.88 × 103 Am-2 in 1 M KOH and 1 M CH3OH. The catalyst NiO-ZnO-f-MWCNT, with the lowest Tafel slope value compared to the other synthesized catalysts, was found to be stable without significantly losing current density, for about 500 cycles and 25000s. Density functional theory (DFT) calculation unveiled that all the steps involved during the interaction of CH3OH and the catalyst surface for oxidation of CH3OH were exergonic indicating a thermodynamically feasible and favourable process of MOR. The electrocatalytic activity was found to be dependent on the concentration of both Ni and Zn. An increase in Ni concentration hampered the MOR by favouring the OER.

Studies of optoelectrical properties of Mn-doped ZnO nanostructure for supercapacitor and photodetector applications

The transition metal Manganese (Mn)-doped Zinc Oxide (ZnO) nanoparticles were synthesized using the sol-gel method. The nanomaterials ZnO and Zn1-xMnxO (x=0–0.15) formation, their crystal structure, and morphological properties were confirmed by X-ray Diffraction (XRD) and Scanning Electron Microscope (SEM) analysis of the materials. All the studied materials show hexagonal wurtzite structure with the particle size in nanometres. The optical properties of transition metal Mn-doped ZnO nanomaterials were explored by the absorption and transmission spectra. The band gap of the nanomaterials decreases with the increase of Mn doping concentration from 3.01 to 3.26 eV. The mobility and electrical conductivity of the Mn-doped ZnO thin films show a decreasing trend with the increase of Mn doping concentration in ZnO. The Mn-doped materials were investigated for supercapacitor and photodiode applications. The Zn0.90Mn0.10O nanomaterials show the maximum specific capacitance, power and energy density of ∼ 220 F/g, 2202 W/kg and 1.15 Wh/kg, respectively. The electrochemical properties confirm that the doping of ZnO opens a new window for its application in energy storage devices. The ZnO and Mn-doped ZnO were used as an electron transport layer in perovskite MAPbI3 photodiodes. Under the Illumination of blue (465 nm) light, the highest detectivity of undoped ZnO perovskite photodiode is ∼4.5×1010 Jones and doped ZnO perovskite photodiode is 0.7×1010 Jones, respectively. The low mobility of charges and unfavorable energy level alignment of Mn-doped ZnO with MAPbI3 thin films is the reason for the decrease in photo detectivity. Our studies demonstrate that the Mn-doped ZnO nanomaterials and their thin films have avenues for potential application in energy storage devices and photodiodes of perovskite MAPbI3.

Unlocking antimicrobial activity of gamma irradiated iron-zinc nanoparticles

Waterborne and foodborne diseases are generated by spoilage microorganisms with severe consequences for public health. Therefore, it is imperative to develop a way forward for their growth inhibition. In this contribution, iron-zinc (Fe-Zn) nanoparticles (NPs) were induced by gamma radiolysis as potential antimicrobial agents. X-ray diffraction (XRD) showed the formation of cubic iron oxide and hexagonal zinc oxide as mixed phases in accordance with microscopic observations. Energy dispersive X-ray spectroscopy (EDS) depicted the presence of Fe, Zn, and O within the sample. Photoluminescence (PL) revealed the existence of oxygen vacancies, which were consistent with the ferromagnetic behavior of the vibrating sample magnetometer (VSM). Besides, the antimicrobial activity was more pronounced against Dekkera bruxellensis.

Corrosion of Zinc Cold Spray Coatings in a Wet Sweet and Sour Gas Environment

Internal corrosion is a problem for steel pipelines transporting natural gas or CO2 containing water and partial pressures of H2S higher than 0.3 kPa (0.05 psi). This work aims to mitigate internal corrosion in steel pipelines transporting natural gas containing H2S using cold spray coatings. Two types of the cold spray binary metallic coatings (zinc chromium [ZnCr]. zinc niobium [ZnNb]) were studied using electrochemical techniques: potentiodynamic polarization, linear polarization resistance, and electrochemical impedance spectroscopy. The corrosion resistance of cold spray coatings (ZnCr, ZnNb) was evaluated in an environment containing 4 bar CO2 pressure, simulating the partial pressures found in gas transmission lines over a solution of 3.5 wt% NaCl heated to 40°C. A concentration of 0.003 M Na2S2O3·5H2O, corresponding to H2S partial pressures around 0.079 bar (1.146 psi), was used to simulate sour conditions. Postcorrosion surface characterization was performed using a scanning electron microscope (SEM) equipped with an energy-dispersive x-ray spectroscope (EDS) and x-ray diffraction analysis. The data showed that the presence of 0.003 M Na2S2O3·5H2O shifted the corrosion potential to more anodic values and decreased the corrosion current density. Both coatings showed similar behavior after 1 h of exposure in the CO2/H2S environment, indicating that similar electrochemical reactions were occurring on ZnNb and ZnCr. SEM images and EDS surface analyses for specimens showed a significant change in the surface chemical composition of carbon steel coated with ZnNb and ZnCr after 24 h of immersion. In the presence of thiosulfate (under sour conditions), the formation of corrosion product layers (ZnCO3 and ZnS) on top of ZnNb and ZnCr coatings increased their corrosion resistance, which helped to reduce their corrosion by a factor of 2. Under a sweet environment, the corrosion rates for steel coated with cold spray coatings after 14 d of exposure are lower than that for galvanized steel by a factor of 5 due to the ZnCO3 layer formed on top of the coatings. The ZnCO3 layer formed on the steel surface acts as a physical barrier against corrosion by blocking the diffusion of corrosive species to the surface. No localized attack was observed. ZnCr Cold spray coating with defect showed promising corrosion protection against CO2 corrosion (sweet corrosion) after 14 d of exposure to a CO2 environment. The scratch on the coating simulated damage created in service, and it was deep enough to expose the substrate material (steel). The formation of zinc oxide (ZnO) and zinc carbonate (ZnCO3) on the scratch confirmed the cathodic protection of the steel by ZnCr and ZnNb coatings.

Degradation of rhodamine B dye under visible and solar light on zinc oxide and nickel-doped zinc oxide thin films

The kinetic investigation of rhodamine B dye's photocatalytic degradation, chosen as a model pollutant, was conducted at room temperature using Zinc oxide (ZnO) and nickel-doped zinc oxide (Zn0.97Ni0.03O) photocatalysts synthesized through the spray pyrolysis method. XRD analysis confirmed the formation of hexagonal ZnO and Zn0.97Ni0.03O films, with crystallite sizes ranging from 19 to 29 nm and varying in mean average grain size from 72 nm to 88 nm. The surface morphology of the Ni-doped ZnO films was influenced by nickel doping, observed through SEM and TEM micrographs, revealing a dense structure of spherical-shaped crystals. Light transmission and optical band gap energy of the films ranged between specified values, ranging from 3.27 to 3.24 eV. The degradation process was assessed under various conditions, including different light sources (UV lamp and solar irradiation), pH levels, and substrate concentrations. Degradation followed a pseudo-first-order kinetic model, with rate constants (k) and half-life times (t1/2) calculated accordingly. The degradation efficiency of undoped ZnO and ZnO doped with nickel decreased with increasing concentration under UV irradiation from (0.1–0.5 M) under UV irradiation decreased from (34.29–45.02) (49.61–56.61), while under visible light are (40–45.07 %) (58.46–60.24 %), removal rates ranged within specific percentages. The porous Zn0.97Ni0.03O synthesized at 0.5 M exhibited the highest photocatalytic efficiency due to its enhanced crystallinity, resulting in degradation rates of 9.22 and 11.22 × 10−3 min−1 and half-life times of 75.18 and 61.77 min at 90 min specified for both UV and solar light irradiations, respectively. Acidification of the reaction medium accelerated the photocatalytic degradation kinetics, while alkalization slowed it down. These findings mark a significant advancement in the utilization of oxide semiconductors for water pollutant degradation under natural sunlight.

Physical Properties of ZnO-NPs Induced by the Thermal Annealing of Hydrozincite Derived from Adansonia Digitata Leaves Extract

In this study, we investigated the effects of the annealing temperatures on the physical properties of zinc oxide nanoparticles produced by the decomposition of the hydrozincite obtained from Adansonia digitata leaves. The results of the X-ray diffraction revealed the formation of well-crystallised hexagonal zinc oxide with an average crystallite size of 11.80 nm, 11.90 nm, 11.97 nm and 15.28 nm for the samples annealed at 400 °C, 500 °C, 600 °C and 700 °C, respectively. The crystallite size of the hydrozincite constituting the unannealed sample was 22 nm. In the spectra of the Fourier transform infrared spectroscopy, the appearance of the peaks at 520 cm-1 for all synthesised materials confirms the formation of pure wurtzite zinc oxide. The band gap determined from diffuse reflectance ultraviolet-visible spectroscopy was found to be 3.19 eV, 3.21 eV, 3.23 eV and 3.24 eV for the samples annealed at 400 °C, 500 °C, 600 °C and 700 °C, respectively. These values increase with the annealing temperature and are still lower than the band gap of pure bulk zinc oxide (3.3 eV) owing to the structural defects as confirmed by the broad emission bands in the visible depicted from the photoluminescence analysis.

Effect of doping on the structural properties of ZnO nanowires synthesised by ultrasonic-assisted immersion technique

Various procedures for producing high-quality zinc oxide (ZnO) nanowires (ZnO NWs) have been developed. Nevertheless, most of it rely on harsh circumstances such as high temperature, high pressure, costly materials, and complicated procedures. As a result, this study introduces an alternative ultrasonic-assisted immersion technique due to its many advantages such as low cost, ease of handling, and low energy consumption, as well as studying the effect of different precursors on the morphological, structural, and optical properties of the ZnO NWs, thus supporting and consolidating previous discoveries and providing a clearer understanding of the mechanism of ZnO formation. The most promising desirable features have been demonstrated for chromium doped ZnO NWs. Field emission scanning electron microscopy (FESEM) was used to examine the surface morphology of the samples, and x-ray diffraction (XRD) and UV-visible (UV-Vis) were utilised to investigate the structural and optical characteristics of the ZnO NWs. It was discovered that inserting Cr as a dopant for ZnO enhanced ZnO NWs by preventing quick electron-hole recombination, revealing it as the best dopant. This id due to reduced band gap (3.231 eV), relax strain (−0.2383%) and stress (0.560 GPa), and near zero porosities

Effect of Hexamethylenetetramine of Zinc Oxide Nanowires Using Chemical Bath Deposition Method

AbstractIn this study, zinc oxide (ZnO) nanowires are grown by chemical bath deposition (CBD) using aqueous solutions with [Zn (NO3)2]: [HMTA] ratios of 1:2/5, 1:1/2, 1:2/3, 1:1, 1:2, and 1:3. The effects of hexamethylenetetramine (HMTA) on the formation of Zinc oxide (ZnO) nanowires are investigated. The XRD results reveal that the dominant peak observed at 2θ = 36.25° indicates preferential growth along the (101) crystal plane, and the ZnO nanowires have a larger crystallite size than the others. The length of the ZnO nanowires, grows with a ZnO seed in the thickness of one and three layers, gets increased from 256.16 ± 15.15 to 497.80 ± 7.84 nm, while the diameter decreases from 497.80 ± 7.84 to 50.34 ± 4.23 nm. The ZnO nanowires deposited by one layer show a similar pattern with the three layers, in which the length is increased from 8.44 ± 0.31 to 14.60 ± 0.51 µm, and the diameter has decreased from 1.95 ± 0.09 to 0.49 ± 0.06 µm. These results support the role of HMTA as a capping agent for the production of ammonia (NH3). This study can control the dimensions of ZnO nanowires using the HMTA concentration to obtain extra‐long nanowires desired for piezoelectric applications.

Prunus dulcis-mediated zinc oxide nanoparticles: synthesis, characterization, and an evaluation of their biocidal properties

Use of plant extracts for synthesizing zinc oxide (ZnO) nanoparticles is gaining importance due to their easy, eco-friendly, cost effective and non-toxic nature. In this study, an economical biosynthetic approach of ZnO formation was delineated where aqueous extract of Prunus dulcis (almond) leaves has been used as reducing/capping agent followed by their characterization studies. The present study has successfully synthesized pure, highly crystalline in nature, predominantly spherical ZnO nanoparticles within the size range 71–214 nm for nanocystallites and 526 nm-2.37 μm for aggregated flower-shaped ZnO nanoparticles. Microbicidal properties of uncalcined and calcined ZnO nanoparticles were evaluated using test microbes (bacteria: E. coli, S. aureus, P. aeruginosa, B. subtilis; fungi Penicillium spp., F. oxysporum, A. flavus, R. solani). Lack of microbicidal potential was observed against all four bacteria and fungi. When tested for toxicity against HCT-116 carcinoma cells, these nanoparticles displayed non-toxic nature. This biocompatibility is influenced by physico-chemical properties of ZnO nanoparticles as well as biological properties of living cells. Thus, these ZnO nanoparticles can serve as an innocuous machinery in disease therapeutics due to the presence of their non-microbicidal and non-antineoplastic activities.

Green Synthesis of Zinc Oxide Nanoparticles Using Cymbopogon citratus Extract and Its Antibacterial Activity.

Excessive use of antimicrobial medications including antibiotics has led to the emerging menace of antimicrobial resistance, which, as per the World Health Organization (WHO), is among the top ten public health threats facing humanity, globally. This necessitates that innovative technologies be sought that can aid in the elimination of pathogens and hamper the spread of infections. Zinc oxide (ZnO) has multifunctionality owing to its extraordinary physico-chemical properties and functionality in a range of applications. In this research, ZnO nanoparticles (NPs) were synthesized from zinc nitrate hexahydrate, by a green synthesis approach using Cymbopogon citratus extract followed by characterization of the NPs. The obtained X-ray diffraction peaks of ZnO NPs matched with the standard JCPDS card (no. 89-510). The particles had a size of 20-24 nm, a wurtzite structure with a high crystallinity, and hexagonal rod-like shape. UV-Vis spectroscopy revealed absorption peaks between 369 and 374 nm of ZnO NPs synthesized from C. citratus extract confirming the formation of ZnO. Fourier transform infrared confirmed the ZnO NPs as strong absorption bands were observed in the range of 381-403 cm-1 corresponding to Zn-O bond stretching. Negative values of the highest occupied molecular orbital-lowest unoccupied molecular orbital for ZnO NPs indicated the good potential to form a stable ligand-protein complex. Docking results indicated favorable binding interaction between ZnO and DNA gyrase subunit b with a binding energy of -2.93 kcal/mol. ZnO NPs at various concentrations inhibited the growth of Escherichia coli and Staphylococcus aureus. Minimum inhibitory concentration values of ZnO NPs against E. coli and S. aureus were found to be 92.07 ± 0.13 and 88.13 ± 0.35 μg/mL, respectively, at a concentration of 2 mg/mL. AO/EB staining and fluorescence microscopy revealed the ability of ZnO NPs to kill E. coli and S. aureus cells. Through the findings of this study, it has been shown that C. citratus extract can be used in a green synthesis approach to generate ZnO NPs, which can be employed as alternatives to antibiotics and a tool to eliminate drug-resistant microbes in the future.

Eco-Friendly Synthesis of Ag-ZnO Nanocomposite and its Anti-Bacterial Activity, Photocatalysis Toward Degradation of (CB) Dye and Removal Wastewater Pollution

The zinc oxide, silver particles and the nanocomposite Ag-ZnO were prepared in an easy, fast and environmentally friendly nanoscale method, where these nanomaterials were prepared from nitrates using plant leaf extract Albizia lebbeck, and this environmentally friendly method is safe, nontoxic and nonharmful to the environment, it is a system that is not only cost-effective, but also simple to use and efficient. The reduction reaction can regulate the features and qualities of the resultant chemicals. The researchers used a variety of methods to diagnose and investigate the properties of these nanomaterials, including scanning electron microscopy (FE-SEM), X-ray diffraction (XRD) and atomic force microscopy (AFM). The results showed the formation of zinc oxide and silver in the form of nanoparticles with good properties, as well as the formation of the nanocomposite Ag-ZnO, and element analysis EDX, and infrared FT-IR, and the results showed the formation of zinc oxide and silver in the form of nanoparticles with good properties, and the results also showed the growth of Ag particles on the surface of the reduced zinc oxide and formation of nanocomposite Ag-ZnO. The photocatalytic degradation of Cibacron Brilliant Yellow 3G-P (CB) dye in the presence of visible light was investigated using Ag-ZnO nanostructures as a photocatalyst. About 1[Formula: see text]g/L of Ag-ZnO with 20[Formula: see text]ppm of the dye produces a greater efficiency in the photocatalysis of the dye in its aqueous solution. The influence of the catalyst amount was explored within the quantities (0.2–0.4–0.6–0.8–1.0–1.2–1.4[Formula: see text]g/L) of the components affecting the photo-smashing process to evaluate the best weight which was 1(g). A photosynthesis ratio was calculated using HCL and NaOH to modify the pH of solutions at a concentration of 5[Formula: see text]ppm, [Formula: see text], 4, 6, 8 and 10. It was also discovered that the acidic function 10 was the best function for breaking down the dye with a 99.1% success rate, and that the shattering reaction followed the kinetics of the first order (Pseudo first), with five consecutive reuses of the best catalyst agents in breaking down the dye Ag-ZnO, was also investigated. After 120[Formula: see text]min, Ag doping ZnO with 10% loading showed photocatalytic elimination of about 93%. and the impact of Ag-ZnO nanocomposite on Staphylococcus aureus and Escherichia coli bacteria was investigated, which were utilized as illustrative examples of the cream-negative bacterium and the positive bacteria, respectively. The findings indicated that the Ag-ZnO nanocomposite had a high rate of success in eradicating and destroying these germs, demonstrating the viability of using a nanoscale solution to sanitize and eradicate microorganisms.

Enhanced ethanol vapor sensing by 2D CuO-ZnO composite at ambient conditions

Gas sensors find application in the fields of food packaging, medical, agriculture, industries, transport, storage, and warehousing, etc. An efficient gas sensor should be sensitive and selective towards analyte, have fast response and recovery time and operate under moderate conditions. The commercial sensors have an in-built heating element. Thus, there is scope for finding materials that can function as room temperature ethanol sensors. Here, a composite of two-dimensional copper oxide (CuO) with zinc oxide (ZnO) nanoparticles is reported as a potential ethanol (EtOH) vapor sensor under ambient conditions. CuO is synthesized with the help of liquid–liquid phase separation technique yielding architecturally aligned 2D structures. ZnO nanoparticles are synthesized via microwave assisted wet chemical route separately. X-ray diffraction studies show the phase formation of pure CuO and ZnO individually. The CuO and ZnO samples are ground mechanically in 1:1 wt ratio to form a composite referred to as CZC. The optical absorption studies show bandgap of CuO structures as 1.41 eV, ZnO as 3.13 eV, and of CZC as 1.24 eV. A slurry of the composite is then coated on a glass substrate to study the resistance changes after ethanol vapor exposure. It is observed that while pure CuO is almost unresponsive to EtOH vapors, ZnO has sluggish response, the CZC samples responded fast. The best average response time is observed to be ∼ 4 sec while recovery time is ∼ 12 sec. The sensors show good reversibility as they return to their initial state without applying any heat treatment. The change in EtOH sensing in composites is attributed to the formation of heterojunction between CuO-ZnO which facilitates faster electron transfer across the heterojunction and the presence of large surface area renders an increased number of adsorption sites.

Preparation and Investigation of Structural and Surface Morphology Properties of ZnO Nanorods for Possible Environmental Applications

In the present work, Zinc oxide Nanorods (ZnO NRs.) was prepared by using the chemical bath method and separating the resulting precipitate by centrifugation. The most important physical properties of nanorods such as optical, morphological and structural properties were diagnosed and studied by "X-ray diffraction (XRD), field-emission scanning electron microscope (FE-SEM), energy dispersive X-ray (EDX), as well as UV-visible spectroscopy". The results of XRD showed that the prepared material has a hexagonal crystal structure and is of high purity, as there are no peaks due to impurities. The formation of zinc oxide was also proven by means of EDX, the weight ratio of zinc and oxygen was 85% and 15%, respectively. The energy gap of prepared rods was equal 3.3 eV.

Single-step laser ablation synthesis of ZnO–Ag nanocomposites for broad-spectrum dye photodegradation and bacterial photoinactivation

We present the single-step production of zinc oxide (ZnO)–silver (Ag) nanocomposites using a second harmonic nanosecond laser. The Ag concentration was controlled using various concentration of AgNO3 solution as the medium. The evaluation of the structural and optical characteristics indicated the formation of ZnO–Ag nanocomposites. The resulting nanocomposites exhibited photocatalytic activity in broad-spectrum light, both UV and visible light, for the degradation of rhodamine 6G. Furthermore, the nanocomposites were assessed as antibacterial agents, and the addition of Ag improved the antibacterial activity of pure ZnO against Escherichia coli and Staphylococcus aureus. Under light exposure, Ag greatly increased S. aureus degradation through a simultaneous antibacterial process. Eventually, the nanocomposites could be anticipated as photoactivation antibacterial agent and water purification nanocatalyst applications.

Cu/CuO-Doped ZnO Nanocomposites via Solution Combustion Synthesis for Catalytic 4-Nitrophenol Reduction.

The synthesis of optoelectrically enhanced nanomaterials should be continuously improved by employing time- and energy-saving techniques. The porous zinc oxide (ZnO) and copper-doped ZnO nanocomposites (NCs) were synthesized by the time- and energy-efficient solution combustion synthesis (SCS) approach. In this SCS approach, once the precursor-surfactant complex ignition point is reached, the reaction starts and ends within a short time without the need for any external energy. The TGA-DTA analysis confirmed that 500 °C was the point at which stable metal oxide was obtained. The doping and heterojunction strategy improved the optoelectric properties of the NCs more than the individual constituents, which then enhanced the materials' charge transfer and optical absorption capabilities. The porosity, nanoscale crystallite size (15-50 nm), and formation of Cu/CuO-ZnO NCs materials were confirmed from the XRD, SEM, and TEM/HRTEM analyses. The obtained d-spacing values of 0.275 and 0.234 nm confirm the formation of ZnO and CuO crystals, respectively. The decrease in photoluminescence intensity for the doped NCs corroborates a reduction in electron-hole recombination. On the Mott-Schottky analysis, the positive slope for ZnO confirms the n-type character, while the negative and positive slopes of the NCs confirm the p- and n-type characters, respectively. A diffusion-controlled type of charge transfer process on the electrode surface was confirmed from the cyclic voltammetric analysis. Thus, the overall analysis shows the applicability of the less expensive and more efficient SCS for several applications, such as catalysis and sensors. To confirm this, an organic catalytic reduction reaction of 4-nitrophenol to 4-aminophenol was tested. Within three and a half minutes, the catalytic reduction result showed the great potential of NCs over ZnO NPs. Thus, the energy- and time-saving SCS approach has a great future outlook as an industrial pollutant catalytic reduction application.

Zinc hydroxystannate dripped on magnesium hydroxide flower for enhancing smoke suppression and toxicity reduction properties of epoxy resin

AbstractIn order to reduce the emission of smoke and toxic gases during the combustion of epoxy resin (EP), inspired by the structure of “flowers after rain,” a novel low‐cost flame retardant (FMH@ZHS) was prepared by using flower‐like magnesium hydroxide (FMH) as the flower and zinc hydroxystannate (ZHS) as the raindrop. The tensile strength of EP/3FMH@ZHS increased by 13.7% compared with EP/3FMH. Moreover, the 3 wt% FMH@ZHS hybrid material increased the limited oxygen index value of the EP composite to 27.6% while suppressing the dripping phenomenon during combustion, achieving self‐extinguishing characteristic. Meanwhile, compared with pure EP, peak heat release rate, peak smoke production rate, total smoke production, and peak carbon monoxide production rate of EP/3FMH@ZHS decreased by 34.6%, 55.6%, 41.8%, and 50.0%, respectively. The flame retardant mechanism showed that during the combustion process, the catalytic char formation of magnesium oxide, zinc oxide, and stannic oxide generated from FMH@ZSH can promote the formation of a denser and continuous char layer, inhibiting the transport of flammable gases, toxic gases and heat and improving the fire safety of EP composites. In conclusion, this biomimetic material provided a good approach for the industrial application of EP.

Effect of Carrier Gas Flow Rates on the Structural and Optical Properties of ZnO Films Deposited Using an Aerosol Deposition Technique

Aerosol deposition (AD) is a simple, dry raw-powder deposition process in which the targeted film is formed by direct bombardment of accelerated starting powder onto the substrate surface at room temperature. Despite the increased interest in AD film formation, no work has been completed to systematically investigate the formation of dense zinc oxide (ZnO) films using the AD method and their optical properties. Therefore, this study was carried out to investigate the effect of AD gas flow rate on the formation of AD films and the optical properties of aerosol-deposited ZnO films. ZnO films with nanosized (<40 nm) crystallites were successfully deposited on FTO substrates at room temperature. A dense and uniform layer of aerosol-deposited ZnO films with a roughened surface was obtained without subsequent heat treatment. With the increase in the AD gas flow rate, the crystal size and the AD film’s thickness were reduced. The Raman spectroscopy verified that the thin film was of a ZnO wurtzite structure. The room temperature photoluminescence of the ZnO thin film produced strong visible emissions. The findings of this work demonstrated that AD can be an alternative technique for the rapid deposition of dense and thick ZnO films for optoelectronic applications.

Ultra-low Concentration of Cellulose Nanofibers (CNFs) for Enhanced Nucleation and Yield of ZnO Nanoparticles.

Cellulose nanofibers (CNFs) were used in aqueous synthesis protocols for zinc oxide (ZnO) to affect the formation of the ZnO particles. Different concentrations of CNFs were evaluated in two different synthesis protocols producing distinctly different ZnO morphologies (flowers and sea urchins) as either dominantly oxygen- or zinc-terminated particles. The CNF effects on the ZnO formation were investigated by implementing a heat-treatment method at 400 °C that fully removed the cellulose material without affecting the ZnO particles made in the presence of CNFs. The inorganic phase formations were monitored by extracting samples during the enforced precipitations to observe changes in the ZnO morphologies. A decrease in the size of the ZnO particles could be observed for all synthesis protocols, already occurring at small additions of CNFs. At as low as 0.1 g/L CNFs, the particle size decreased by 50% for the flower-shaped particles and 45% for the sea-urchin-shaped particles. The formation of smaller particles was accompanied by increased yield by 13 and 15% due to the CNFs’ ability to enhance the nucleation, resulting in greater mass of ZnO divided among a larger number of particles. The enhanced nucleation could also be verified as useful for preventing secondary morphologies from forming, which grew on the firstly precipitated particles. The suppression of secondary growths' was due to the more rapid inorganic phase formation during the early phases of the reactions and the faster consumption of dissolved salts, leaving smaller amounts of metal salts present at later stages of the reactions. The findings show that using cellulose to guide inorganic nanoparticle growth can be predicted as an emerging field in the preparation of functional inorganic micro/nanoparticles. The observations are highly relevant in any industrial setting for the large-scale and resource-efficient production of ZnO.

Fabrication of polyhedral Cu–Zn oxide nanoparticles by dealloying and anodic oxidation of German silver alloy for photoelectrochemical water splitting

A significant effort has been dedicated to the synthesis of Cu–Zn oxide nanoparticles as a robust photocathode material for photoelectrochemical water splitting. Cu–Zn oxide nanoparticles were formed by controlled anodization of German silver (Cu–Zn–Ni) alloy in an aqueous electrolyte. Scanning electron microscopy (SEM) demonstrates the dependence of the obtained nanostructures on the anodization time. The X-ray diffraction (XRD) patterns showed the formation of copper oxide (CuO) and zinc oxide (ZnO) nanoparticles with good stability. This was also confirmed by the compositional X-ray photoelectron spectroscopy (XPS) analysis. The obtained polyhedral nanoparticles showed high optical activity with adequate bandgap energy. These optimized nanoparticles achieved boosted photocurrent of − 0.55 mA/cm2 at − 0.6 V vs. SCE under AM 1.5 illumination, confirming the role of the optimized dealloying and thermal treatment in tuning the photoelectrochemical performance of the material.

Zinc oxide decorated titania nanostructured layer over Ti metal as a biocompatible and antimicrobial surface for biomedical application

The present study is an attempt to develop a zinc oxide (ZnO) decorated titania (TiO2) nanostructured layer over Ti metal by a simple chemical and thermal treatment method. Ti metal upon sequential chemical treatment with sodium hydroxide and zinc nitrate solution generated a nanostructured network layer enfolded with Zn2+ ions. Subsequent heat treatment up to 500 °C favoured the formation of ZnO and anatase TiO2 while increasing the temperature to 600 °C resulted in the formation of ZnO and ZnTiO3 along with anatase TiO2. This nanostructured layer showed significant improvement in the hardness after heat treatment at 600 °C as measured by the nano-indentation technique. ZnO formed over the anatase TiO2 layer showed excellent antibacterial activity against both gram positive Staphylococcus aureus and gram negative Escherichia coli and was also found to be non-toxic towards MG-63 osteosarcoma cells. Hence, ZnO/ZnTiO3 modified anatase TiO2 over Ti metal is anticipated to reduce the risk of bacterial infection and enhance the proper functionalisation through its metabolic and cellular signalling and can be useful in dental and orthopaedic fields.