Hexagonal Wurtzite Structure Of Zinc Oxide Research Articles

Low-cost fabrication methods of ZnO nanorods and their physical and photoelectrochemical properties for optoelectronic applications

Zinc Oxide (ZnO) nanorods have great potential in several applications including gas sensors, light-emitting diodes, and solar cells because of their unique properties. Here, three low cost and ecofriendly techniques were used to produce ZnO nanorods on FTO substrates: hydrothermal, chemical bath deposition (CBD), and electrochemical deposition (ECD). This study explores the impact of such methods on the optical, structural, electrical, morphological, and photoelectrochemical properties of nanorods using various measurements. XRD analysis confirmed the hexagonal wurtzite structure of ZnO nanorods in all three methods, with hydrothermal showing a preferred orientation (002) and CBD and ECD samples showing multiple growth directions, with average particle sizes of 31 nm, 34 nm, and 33 nm, respectively. Raman spectra revealed hexagonal Wurtzite structure of ZnO, with hydrothermal method exhibiting higher E2 (high) peak at 438 cm−1 than CBD and ECD methods. SEM results revealed hexagonal ZnO nanorods became more regular and thicker for the hydrothermal method, while CBD and ECD led to less uniform with voids. UV-vis spectra showed absorption lines between 390 nm and 360 nm. Optical bandgap energies were calculated as 3.32 eV, 3.22 eV, and 3.23 eV for hydrothermal, CBD, and ECD samples, respectively. PL spectra revealed UV emission band with a small intensity peak around 389 nm and visible emission peaks at 580 nm. Temperature dependent PL measurements for ZnO nanorods indicated that the intensities ratio between bound exciton and free exciton decreases with temperature increases for the three methods. Photocurrent measurements revealed ZnO nanorod films as n-type semiconductors, with photocurrent values of 2.25 µA, 0.28 µA, and 0.3 µA for hydrothermal, CBD, and ECD samples, and photosensitivity values of 8.01, 2.79, and 3.56 respectively. Our results suggest that the hydrothermal method is the most effective approach for fabricating high-quality ZnO nanorods for optoelectronic applications.

Effect of various processing parameters on the properties of ZnO thin films

Zinc oxide (ZnO) thin films are essential in opto-/piezo-electronics due to their transparency, high electron mobility, wide bandgap (∼3.37 eV), and high excitonic binding energy (60 meV). Effects of processing parameters on ZnO thin films, such as the molarity, ageing, thickness, and calcination temperature, on the microstructural and optical properties deposited by sol-gel spin-coating are investigated under one roof. X-ray diffraction (XRD) confirmed the polycrystalline nature of all films, along with a dominant orientation (002) plane, indicating the formation of a c-axis oriented hexagonal wurtzite structure of ZnO regardless of the processing parameters. Peak intensities varied for all samples and exhibited the highest peak intensity annealed at 500 °C, which correlates with the increase in crystallite size from 15.93 to 16.41 nm due to a decrease in defect density via the thermal expansion. 0.4 M aged solution over 70 h showed the variation in the crystallite size and dislocation density, indicating the improvements in the thin film quality. Thickness-dependent ZnO thin films also improved the crystallinity, which was confirmed by high peak intensities. Decreasing the Urbach energy (Eu) of 0.4 M solution indicates reduced lattice imperfections/defects and high electronic quality of thin-film materials. Deposited ZnO films with an ageing time of 70 h and thickness of 109 nm exhibit the highest refractive index of 3.9 and 2.6, indicating light interaction and optimal density. The optimized conditions of sol-gel derived ZnO thin films augment the ease of development of economic devices for practical implications in opto-/piezo-electronics.

ZnO nanostructures grown from spent batteries: Ambient catalytic aspects and novel mechanistic insights

The present work includes a facile and economic microwave assisted hydrothermal synthesis of Zinc Oxide (ZnO), Diethylene Triamine Pentaacetic Acid (DTPA) stabilized Zinc Oxide (ZD) and DTPA stabilized Silver doped Zinc Oxide (ZAD) nanostructures using Zn from spent alkaline batteries. The synthesised nanostructures were well characterised using electronic, vibrational and X-Ray spectroscopic techniques as well as thermal and microscopic techniques revealing the successful stabilisation of DTPA in ZD and doping of Ag in ZAD. The Fourier Transform Infrared Spectroscopy (FTIR) spectra showed peaks characteristic to the presence of ZnO in the fingerprint region and those to the presence of DTPA. The X-Ray Diffraction Spectroscopy (XRD) pattern of ZnO, ZD and ZAD indicated the hexagonal wurtzite structure of ZnO and face centred cubic metallic Ag in ZAD. The Transmission Electron Microscopy (TEM) images revealed rod shaped morphology for ZnO and spherical morphologies for ZD and ZAD. The nanostructures proved to be efficient catalysts to achieve 100 % degradation of Malachite Green, Crystal Violet and Reactive Blue-21 and their binary mixtures under ambient conditions in presence of Hydrogen peroxide (H2O2). ZAD exhibited relatively rapid degradation with rate constants 0.754 min−1, 0.187 min−1 and 0.0150 min−1 for MG, CV, and RB-21 respectively as well as 99 % reduction in Chemical Oxygen Demand (COD) value of the dye solutions. Scavenging studies and Electron Paramagnetic Resonance (EPR) studies using different spin trapping agents revealed the involvement of singlet oxygen species, hydroxyl radicals (OH.) and superoxide radicals (O2.-) in the degradation process. This work aligns with Sustainable Development Goals 6, 12 and 13.

Green synthesis and studies on citrus medica leaf extract-mediated Au–ZnO nanocomposites: A sustainable approach for efficient photocatalytic degradation of rhodamine B dye in aqueous media

Abstract Incorporating narrow band gap oxide semiconductors and metals into zinc oxide (ZnO) nanostructures broadens the range of light sensitivity to include visible wavelengths. In this study, the photocatalytic degradation of rhodamine B (RhB) dye was studied as a model for environmental pollution in aqueous media. This study describes the use of photodegradation catalysts, including gold (Au), ZnO, and Au–ZnO nanocomposites (prepared in ratios of 90:10 and 95:5) using the extract of Citrus medica leaves. X-ray diffraction (XRD) findings have shown that ZnO nanoparticles (NPs) have a hexagonal wurtzite structure. Field emission-scanning electron microscopy findings have depicted that ZnO NPs have diverse shapes, including spherical, quasi-spherical, hexagonal, and anisotropic, with some clumping. Au exhibits consistent spherical shapes and sizes with even distribution. Au–ZnO (90:10) shows quasi-spherical NPs with interconnected spherical Au, forming a porous and uneven surface. Au–ZnO (95:5) has spherical gold nanoparticles (Au NPs) dispersed on a textured ZnO surface, with some clustering and size variation as evident from the transmission electron microscopy, atomic force microscopy, and diffuse reflectance UV-visible spectroscopy analysis. The characterization results have demonstrated the uniform distribution of Au across the ZnO lattice. Additionally, the XRD patterns confirmed the hexagonal wurtzite structure of ZnO. Furthermore, energy-dispersive analysis of X-ray (EDX)-mapping verified the inclusion of zinc, oxygen, and Au in the hybrid Au–ZnO nanocomposites and their effective distribution. The topological analysis revealed a rough surface for the generated nanostructures. By comparing the results of various techniques, EDX analysis using atomic and weight ratios confirmed the presence of oxygen and Au in the nanocomposite. Additionally, the surface area analysis (BET) test has reported that the adsorption and desorption of nitrogen follow a Type III isotherm. The presence of an H3-type hysteresis loop further confirms the mesoporous nature of the composites, which reports the presence of wedge-shaped pores. The Au–ZnO (90:10) nanocomposite exhibits a higher surface roughness compared to other composites. In addition, this UV-visible diffuse reflectance spectroscopy has enumerated the band gaps of various nanomaterials using UV-visible spectroscopy. Moreover, the analysis has unveiled that combining ZnO with Au NPs (doping) improved the photocatalytic performance of ZnO. This improvement is attributed to the formation of additional energy levels within the ZnO band gap due to the presence of Au ions. Experimental investigation of the breakdown of RhB dye under visible light irradiation revealed superior photocatalytic activity for the Au–ZnO (90:10) nanocomposite compared to both Au–ZnO (95:5) and pure ZnO and Au counterparts. Multiple experiments confirmed the effective photodegradation and removal of RhB dye from the aqueous medium using the nanocatalyst under visible light irradiation. Under optimal conditions (1.0 g·L−1 photocatalyst, 10 ppm RhB, and pH 10), 99% photodegradation efficiency was reached within 50 min of irradiation. Investigation of reactive species revealed that the increased effectiveness of photodegradation in Au–ZnO (90:10) stems from the presence of photogenerated holes and hydroxyl radicals. The study also analyzed the reaction kinetics and order, and the reusability of the best photocatalyst Au–ZnO (90:10)) was confirmed through five consecutive cycles, demonstrating its sustained effectiveness in photodegradation. These findings highlight the potential of Au–ZnO (90:10) nanocomposite as a promising material for photocatalytic degradation of organic dyes.

Synthesis and characterization of P3HT:ZnO-FWCNTs for possible application in organic solar cells

Zinc oxide (ZnO) and few-walled carbon nanotubes (FWCNTs) mixed in poly(3-hexylthiophene-2,5-diyl) (P3HT) were prepared for application in organic solar cells (OSCs) as photoactive materials. ZnO was synthesized by microwave-assisted sol-gel method. Improved properties were found for the nanocomposite with 3 wt% of FWCNTs concentration. XRD revealed the hexagonal wurtzite structure of ZnO and the nanocomposites (ZnO-FWCNTs) showed both hexagonal wurtzite and carbon structure. UV/Vis/NIR and PL studies revealed a relatively higher photon absorption efficiency and emission intensity from the ZnO-3% FWCNTs. PL intensity of P3HT was quenched from the sample P3HT:ZnO-3% FWCNTs with the ratio of 1:1, indicating charge transfer phenomena between the electron donor (P3HT) and an acceptor (ZnO-FWCNTs) materials. FESEM showed well-mixed ZnO nanorods with P3HT. Current-voltage measurements indicated an improved electrical conductivity for P3HT:ZnO-3% FWCNTs (ratio 1:1). The obtained results suggest that this sample can potentially improve the photoelectrical conversion efficiency of the OSCs.

New insights into the photocatalytic mechanism of pristine ZnO nanocrystals: From experiments to DFT calculations

Zinc oxide (ZnO) has been regarded as a promising photocatalytic candidate for the purification of wastewaters containing organic contaminants. In this study, six ZnO nanocrystals with the shapes of granule, flake, rod, porous flake, nanosheet-assembled flower, and nanorod-assembled flower were designed and synthesized to investigate the relationship between their photocatalytic activities and morphological features. All these different morphological samples had high-degree of crystallization and belonged to the hexagonal wurtzite structure of ZnO. The morphology had little effect on the light absorption threshold and band gap of these samples, but showed great effect on their adsorption performance, photocatalytic activity, and separation efficiency of photogenerated electrons and holes. The main reactive radicals generated during the photocatalytic process were O2–, OH, and holes. The theoretical calculations revealed that the polar crystal plane could facilitate the separation of charge carriers. The adsorption and distortion energies for O2 adsorbed onto different crystal planes were found to be much higher than those for H2O. These findings theoretically confirmed why O2– was the dominant group of reactive radicals.

Simultaneous removal of Cu (II) and Cr (VI) ions from petroleum refinery wastewater using ZnO/Fe3O4 nanocomposite

The presence and removal of heavy metals such as Cu(II) as well as Cr(VI) in petroleum refinery wastewater calls for concerted efforts due to their mobility, toxicity, bioaccumulation, and non-biodegradability in the environment. In this present work, zinc oxide (ZnO), iron oxide (Fe3O4) nanoparticles and ZnO/Fe3O4 nanocomposites were synthesized via simple sol-gel and chemical reduction methods; characterized using different analytical tools and then applied as nanoadsorbent to sequester Cu(II) and Cr(VI) ions from Petroleum Refinery wastewater via batch adsorption process. Cu(II) and Cr(VI) adsorption processes were examined with respect to contact time (kinetic effect), nanoadsorbent dosage, isotherm equilibrium, and thermodynamic parameters. ZnO/Fe3O4 nanocomposites with higher surface area (39.450 m2/g) have a mixture of rod-like and spherical shapes as compared to ZnO and Fe3O4 nanoparticles with spherical shape only and surface areas of 8.62 m2/g and 7.86 m2/g) according to the high-resolution scanning electron microscopy (HRSEM) and Brunauer–Emmett–Teller (BET) analysis. The X-ray diffractometer (XRD) results revealed the formation of hexagonal wurtzite structure of ZnO and the face-centered cubic structure phase of Fe3O4 nanoparticles, after the formation of the ZnO/Fe3O4 nanocomposites the phases of the nanoparticles were not affected but the diffraction peaks shifted to higher 2θ degree. The average crystallite size of ZnO and Fe3O4 nanoparticles and ZnO/Fe3O4 nanocomposites were 20.12, 26.36 and 14.50 nm respectively. The maximum removal efficiency of Cu (II) (92.99%) and Cr (VI) (77.60%) by ZnO/Fe3O4 nanocomposites was higher than 85.83%; 65.19% for Cu (II) and 80.57%; 62.53 for Cr (VI) using ZnO and Fe3O4 nanoadsorbents individually under the following conditions: contact time (15), dosage (0.08 g) and temperature (30 °C). The experimental data for Cu (II) and Cr (VI) ion removal fitted well to the pseudo-second-order kinetic and Langmuir isotherm models. The thermodynamic study suggested that the removal of the two metal ions from petroleum wastewater was endothermic. The reusability study after the fourth adsorption-desorption cycle indicated the stability of ZnO/Fe3O4 nanocomposites with 85.51% and 69.42% removal efficiency of Cu (II) and Cr (VI). The results showed that ZnO/Fe3O4 nanocomposite achieves higher performance than ZnO and Fe3O4 alone in the removal of Cu (II) and Cr (VI) ions from the petroleum refinery wastewater.

Hydrothermal growth and ultraviolet sensing performance of well-aligned Ga-doped ZnO nanowire arrays

Herein, gallium (Ga)-doped zinc oxide (ZnO) nanowire arrays (GZNWAs) with different Ga doping concentrations (Ga/Zn = 0–4 atom%) were grown on the interdigital patterned fluoro-doped tin oxide glass substrates by a hydrothermal technique, their crystalline structure, morphology and ultraviolet (UV) sensing performance were focused on investigating. The results showed that all the as-grown samples were hexagonal wurtzite structure of ZnO. When the Ga doping concentration was below 4%, well-aligned GZNWAs were achieved. Furthermore, five UV photodetectors (PDs) were prepared using the GZNWAs as photoactive layers, all the devices were found to be excellent responses towards 365 nm light. Among these devices, the GZNWAs UV PD (1% Ga) maintained the optimal performance, its responsivity, sensitivity, detectivity, external quantum efficiency, response time and decay time were 72.8 A/W at 5 V, 747.8 at 0 V, 5.5 × 1012 Jones, 2.5 × 104%, 10.6 s and 45.6 s, respectively.

Ultraviolet photoconductivity and photoluminescence properties of spray pyrolyzed ZnO nanostructure: Effect of deposition temperature

The current investigation focuses on the influence of substrate temperature on Zinc Oxide (ZnO) thin films synthesized on glass substrates using 0.1 M precursor solution by low-cost spray pyrolysis technique. The x-ray diffraction peaks matched the hexagonal wurtzite structure of ZnO with the highest intensity along the (1 0 1) plane. Estimated the crystallite size, dislocation density, micro-strain, and the number of crystallites in the deposits using X ray diffraction (XRD) data. The crystallinity of the films deposited at 450 °C was maximum. Fibrous surface morphology is altered by varying the deposition temperature. The enhancement of optical transmittance and energy bandgap of the deposits with deposition temperature. The reduction of Urbach energy with an increase in the substrate temperature confirmed the improvement of crystallinity. The photoluminescence study revealed peaks associated with electron-hole pair recombination, zinc, and oxygen-related defects. The samples deposited at 450 °C showed minimum defects. Commission Internationale de l'éclairage (CIE) chromaticity diagram showed white light emission for sample deposited at 450 °C with the color temperature equal to 5378 °C which is agreeing with the temperature of a normal white light source. Improvement of free carrier concentration and n-type conductivity due to the enhancement of crystallinity was observed. ZnO thin films deposited at 450 °C showed maximum photocurrent when illuminated with UV light and faster rise and fall of photo resistance due to the improvement in the crystallinity and carrier concentration. The maximum photosensitivity was observed for the samples synthesized at 450 °C. Hence the ZnO thin films deposited at 450 °C can be used as ultraviolet photodetector material.

Structural, optical and electrical conductivity studies of pure and Fe doped ZincOxide (ZnO) nanoparticles

The Co-precipitation method (CPM) was used to make pure and Fe doped Zinc Oxide (ZnO) nanoparticles (Nps) in this study. X-ray diffractometer (XRD), UV–vis absorption spectroscopy and Fourier transform infrared spectroscopy (FTIR) were used to describe the sample's structural, optical, and electrical properties. The hexagonal wurtzite structure of ZnO was verified by the X-ray diffraction pattern. The Debye Scherrer formula was used to measure the average crystallite size. The pure and Fe doped ZnO sample absorbs the radiations in the UV ranges up to 327.27, 324.74 and 323.5 nm and almost all the visible spectrum radiations are transmitted by the synthesized Nps. FTIR analysis was used to identify the functional frequencies of pure and Fe doped ZnO Np. The electrical conductivity of ZnO Nps decreases with Fe doping concentration due to increase in deep donor concentration.

Structural, electrical, and optical properties of Si-doped ZnO thin films prepared via supercycled atomic layer deposition

Si-doped zinc oxide (ZnO) thin films were fabricated via atomic layer deposition (ALD) using diethylzinc, Tris(dimethylamino)silane, and H2O as Zn, Si, and O sources, respectively. The ALD cycle of the (Zn-O) step and the (Zn-Si-O) step were separated and the Si concentration was controlled via changing the (Zn-Si-O) pulse cycle compared to the (Zn-O) step. This Si source pulse sequence (Zn-Si-O) is different from the conventional (O-Si) pulse sequence and was specially selected in this study to maximize the properties of the thin film. All of the films showed the hexagonal wurtzite structure of ZnO with the (100) plane producing the main diffraction peak when ALD was performed at 200 ℃. As the Si-doping concentration increased, the crystallinity of the films deteriorated and the Scherrer size was reduced from 29.69 to 28.10 nm, there were improvements in the electrical characteristics, the carrier concentration increased up to 8.10 × 1020 cm−3, and the resistivity decreased to 5.15 × 10-4 Ω·cm, which is lower than the lowest previously reported result for Si-ZnO thin films fabricated via ALD (9.29 × 10-4 Ω·cm). Moreover, the carrier mobility increased at first (Si-ZnO 1:29 supercycles) and then decreased with increasing Si concentration. The average transmittance of all of the films was above 80% and the optical band gap increased from 3.29 to 3.47 eV. The increased carrier concentration according to the Burstein-Moss effect was linearly related to the band gap shift while up-shifting the EF (Fermi level) toward the conduction band. We expect that our approach in this study will provide an experimental basis to optimize ZnO thin-film characteristics via modification of Si pulsing sequence.

Enhanced physical characteristics of ZnO thin films through Sr and Mg co-doping

ABSTRACT In this study, undoped ZnO, (Sr, Mg) co-doped ZnO (SMZO) thin films were synthetised on heated glass substrates at a temperature of 250°C by using ultrasonic spray technique. Doping strontium (Sr) and magnesium (Mg) into zinc oxide (ZnO) offers an important way to modify various properties. X-ray diffraction (XRD) confirmed that the films exhibited the hexagonal wurtzite structure of ZnO with a favored orientation along (002) plane . Scanning electron microscope (SEM) showed a strong change in the surface morphology while Energy dispersive X-ray spectrometer (EDX) and mapping confirmed the purity of the films . UV-Visible studies demonstrated that the optical transmittance was improved to an average value above 94% and that Mg-doping induces an increase of the band gap indicating high optical quality of the films. From the fabricated films, SMZO3 is the most appropriate for optoelectronic applications where a low resistivity and high figure of merit were obtained.

A novel and highly efficient Ag and GO co-synthesized ZnO nano photocatalyst for methylene blue dye degradation under UV irradiation

Heterogeneous photocatalysis is an effective and promising treatment technology for the removal of organic dye compounds in textile wastewater. Hybrid nanostructured semiconductor materials have been extensively applied and received greater attention in the last few decades. In this study, nano structured zinc oxide (ZnO) was doped by silver (Ag) and graphene oxide (GO) nanoparticles to synthesize Ag/GO/ZnO using the sol–gel technique followed by the heat treatment method. The hexagonal wurtzite structure of ZnO as observed by SEM was changed to lump/flake shape after doping with Ag and GO onto the ZnO crystal surface. FTIR confirms the stretching vibration of broad O–H groups with adsorbed H2O molecules. The broad absorption edge of Ag/GO/ZnO nanocomposite shifted to the visible-light region with the reduced band gap energy of 3.22 eV as compared to 3.34 for ZnO. The photocatalytic degradation of methylene blue (MB) dye (15 mgL−1) under 100 W UV irradiation was84.67%, 88.13%, and 97.53%, for ZnO, Ag/ZnO, and Ag/GO/ZnO nanocomposites, respectively, at the same dose of photocatalyst (0.300 g) and pH 11.0for3 h UV irradiation. The best fitted kinetic of photocatalytic studies were showed a pseudo-first-order reaction model and the respective rate constants were found to be 0.0129 min−1, 0.0149 min−1, and 0.5198 min−1, for ZnO, Ag/ZnO, and Ag/GO/ZnO nanocomposites, respectively. The enriched photodegradation activity of Ag/GO/ZnO nanocomposite indicates the potential of the nanocomposite for the treatment of organic pollutants from the textile wastewater.

Opto-electronic properties of solution-processed zinc oxide thin films: role of solvents and doping

Undoped zinc oxide (ZnO) and nitrogen-doped zinc oxide (NZO) thin films were prepared on transparent conducting oxide-coated glass substrates by employing sol–gel technique. The effect of different solvents and nitrogen doping on the optical, structural, and electrical properties was investigated by UV–visible absorption spectroscopy, atomic force microscopy (AFM), X-ray diffraction (XRD), profilometry, and Hall effect studies. ZnO films yielded transmittance above 85% and the bandgap of ZnO thin films decreased with doping. XRD pattern confirmed hexagonal wurtzite structure of ZnO. NZO thin films were found to be in the nano-thin film phase with thickness of 40 nm. Hall effect studies yielded carrier concentration of 1.2 × 1015 cm−3 and 2.03 × 1014 cm−3, respectively, for undoped and doped ZnO thin films. The changes in vibrational modes of ZnO due to nitrogen doping were detected using Fourier transform infrared (FTIR) analysis. It was found that p-type doping, leading to an improved surface morphology, led to a reduction in optical bandgap and an increased charge carrier mobility. The choice of the solvent was found to have a profound influence on the surface morphology, optical bandgap, tail states distribution, and charge carrier mobility.

Strontium doping effect on characteristics of ultrasonically sprayed zinc oxide thin films

In the present work, Sr-doped ZnO (SZO) thin films were grown on heated glass substrates (250 °C) by the ultrasonic spray technique. The effect of strontium concentration on the structural and physical characteristics was studied. The molar ratio of strontium in the ultrasonically sprayed solution was varied from 0 to 5 at.%. Several characterization techniques have been investigated to analyze the SZO thin films. The X-ray diffraction results showed that the SZO thin films exhibited the hexagonal wurtzite structure of ZnO with a preferential orientation along (002) plane. Scanning electron microscope indicated that the surface morphology of the SZO thin films changed with the increase in Sr concentration. No impurity was present in all the SZO films which was confirmed by the elemental composition analysis. Moreover, Fourier transform infrared spectroscopy showed the chemical bonding of zinc oxide (ZnO) and confirmed the incorporation of the dopant into the ZnO lattice. From the UV–Vis studies, it was found that the optical band gap decreased from 3.34 to 3.04 eV by increasing Sr doping concentration. Measurements of the Hall Effect indicated that all the elaborated samples exhibited n type conductivity. From all the films studied, SZO (1 at.%) was the most suitable for applications in optoelectronic devices, where a large figure of merit was required.

Bright red luminescence emission of macroporous honeycomb-like Eu3+ ion-doped ZnO nanoparticles developed by gel-combustion technique

The impact of europium (Eu3+) ion doping has been outlined in improving the structure and optical properties of macroporous honeycomb-like zinc oxide (ZnO) nanoparticles, produced by the gel-combustion technique by changing the quantity of dopant. The X-ray diffraction (XRD) research verified that the hexagonal wurtzite structure of ZnO was not disturbed by Eu3+ substitution. Scherrer method, Scherrer plots (SP), Williamson-Hall (W–H) plots and Size-Strain plots (SSP) were used to estimate the crystallite size. Decreased crystallite size in ZnO:Eu3+ was noticed along with lower angle shift of XRD peaks and increased lattice parameters such as unit cell volume that can be described as replacement result of Eu3+ at Zn sites. Fourier transform infrared (FTIR) spectroscopy analysis confirmed the Eu3+ dopant by moving the peak from 474 cm−1 to 525 cm−1. Field-emission scanning electron microscopy (FESEM) pictures verified macroporous honeycomb-like structures. UV–Visible (UV–Vis) absorption spectroscopic studies show that the ability of ZnO:Eu3+ nanoparticles concerning the absorption of visible light increased upon Eu3+ doping with a red shift compared to ZnO nanoparticles. Photoluminescence (PL) emission spectra of Eu3+ doped ZnO nanoparticles exhibited five intense band emissions at 579, 591, 617, 652, and 706 nm ascribed to 5D0 → 7F0, 5D0 → 7F1, 5D0 → 7F2, 5D0 → 7F3, and 5D0 → 7F4 transitions of Eu3+ ions when excited at 465 nm wavelength, originated from intra-4f transition of Eu3+ ions, respectively. ZnO:Eu3+ nanoparticles intensified with concentration progression and revealed as nanoparticles emitting red under 465 nm excitation.

Effect of Benzalkonium Chloride on Properties of Zinc Oxide Nanoparticles Synthesized through Sol-Gel Technique

In the present study, to synthesize controllable sized metal oxide particles, benzalkonium chloride (BAK) as cationic surfactant was added to zinc oxide (ZnO) nanostructures synthesis at room temperature using sol–gel method. The effect of cationic surfactant BAK concentrations, on the optical properties, size, and morphology of ZnO nanoparticles synthesized through sol–gel method was studied. The characterization of ZnO nanostructures was occurred using transmission electron microscopy (TEM), X-ray diffraction (XRD), ultraviolet–visible near infrared (UV-Vis) spectrophotometer, Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). ZnO nanostructures shape and size were revealed by SEM and TEM. The hexagonal (wurtzite structure) of ZnO was confirmed by an X-ray diffractogram. The bandgap energy of the prepared ZnO samples was determined by UV-Vis spectrophotometer. FTIR analyzed the presence of functional groups.

Zinc oxide nanoparticles prepared by thermal decomposition of zinc benzenepolycarboxylato precursors: Photoluminescent, photocatalytic and antimicrobial properties

Zinc oxide (ZnO) nanoparticles were obtained by thermal decomposition of one-dimensional zinc?benzenepolycarboxylato complexes as single- -source precursors at 450 ?C in an air atmosphere. The mechanism and kinetics of thermal degradation of zinc?benzenepolycarboxylato complexes were analyzed under non-isothermal conditions in an air atmosphere. The results of X-ray powder diffraction and field emission scanning electron microscopy revealed hexagonal wurtzite structure of ZnO with an average crystallite size in the range of 39?47 nm and similar morphology. The band gap and the specific surface area of ZnO nanoparticles were determined using UV?Vis diffuse reflectance spectroscopy and the Brunauer, Emmett and Teller method, respectively. The photoluminescent, photocatalytic and antimicrobial properties of the ZnO nanoparticles were also examined. The best photocatalytic activity in the degradation of C. I. Reactive Orange 16 dye was observed for the ZnO powder where the crystallites form the smallest agglomerates. All ZnO nanoparticles showed excellent inhibitory effect against Gram-positive bacterium Staphylococcus aureus and Gram-negative bacterium Escherichia coli.

Effect of Cationic Surfactants on Properties of Zinc Oxide Nanoparticles Synthesized through Sol-gel Technique

Zinc oxide (ZnO) is an important metal oxide which participates in lots of applications, including gas sensors, catalysis, and optoelectronic devices. For nanostructured materials, agglomeration is problematic in the chemical production processes. In surfactant-free chemical reactions, aggregation occurs immediately as particles are generated. Therefore, the synthesis of controllable size nanoparticles is of great fundamental and technological interest. In the present study, the effect of cationic surfactants such as cetyltrimethylammonium bromide and benzalkonium chloride concentrations, on the optical properties, size, and morphology of ZnO nanoparticles synthesized through sol-gel method were studied. The characterizing tools were X-ray diffraction, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and ultraviolet-visible (UV-Vis-near-infrared) spectrophotometer. X-ray diffractogram confirmed the hexagonal (wurtzite structure) of ZnO. FTIR analyzed the presence of functional groups. The shape and size of the ZnO nanostructures were revealed by SEM and TEM. The band gap energy of the prepared ZnO samples was determined by UV-Vis spectrophotometer.

UV–visible photoresponse properties of self-seeded and polymer mediated ZnO flower-like and biconical nanostructures

Nano-sized zinc oxide (ZnO) flowers and bicones have been prepared by a co-precipitation method using ZnO-seed for flowers and polyethylene glycol (PEG) for bicones to study their photoconductivity under UV–vis illumination. As-synthesized ZnO samples were characterized by various techniques. XRD spectra show that both samples exhibit hexagonal wurtzite structure of ZnO. FESEM images show the morphology of ZnO as that of flower-shaped structures and bicone-shaped structures respectively. UV–visible absorption spectra of both samples have two absorption band edges due to bicone-like structure. ZnO bicones exhibit high photosensitivity as compared to ZnO flowers. However, vacuum is found enhancing the photosensitivity of ZnO bicones as compared to that in air.