Structure Of Zinc Oxide Research Articles

Effect of solutions acidity on Haacke’s Figure of Merit of ZnO and ZnO:F thin films deposited by ultrasonic spray pyrolysis

Fluorine-doped zinc oxide (ZnO:F) thin films are valued for their potential as transparent conductive materials, particularly in optoelectronic applications. In this work, the deposition of highly conductive and transparent fluorine-doped ZnO thin films, deposited by chemical spray on glass substrates is reported. The effect of acetic (AcAc) in the initial fresh solution on Haacke’s Figure of Merit (Φ) of both zinc oxide (ZnO) and fluorine-doped zinc oxide (ZnO:F) thin films was studied. The substrate temperature was fixed to 450°C, and two deposition times (8 and 14 min) were tested. Accordingly, the optical and transport properties, as well as the structural and morphological characteristics of the films were measured. The results indicate that the samples are polycrystalline in all cases and exhibit a wurtzite-type structure of ZnO. The variation of AcAc in the starting solution causes a switch in preferential growth from (002) to (001). As the AcAc content increases, the surface morphology of the films reveals the formation of well-defined hexagonal grains, and the grain size increases. Conversely, the transmittance decreases as the acetic acid increases, which can attributed to carbon incorporation into the film. In addition, the band gap values of the films varied from 3.2 to 3.4 eV. Also, as the acetic acid concentration increased, a drop in the electrical resistivity of ZnO thin films on the order of 0.016 Ω⋅ cm was found for the ZnO:F films deposited with fresh solution for 14 min. This can be ascribed to a dense acetic cloud formed during the synthesis process, trapping volatile F species that incorporate into the ZnO lattice. This enhances Haacke’s Figure of Merit of ZnO:F films deposited with a fresh solution, demonstrating their potential use for application as transparent conductive films. This contrasts with other synthesis methods that require longer aging time in the precursor solution, making these findings useful for large-scale and more efficient production of transparent conductive films.

Zinc oxide-based sensor prepared by modified sol–gel route for detection of low concentrations of ethanol, methanol, acetone, and formaldehyde

Abstract We4 4 We received the acceptance date as 26 September 2024. Could you please update it to reflect this exact date for our project, instead of 1 October 2024? This is very important for our project funding. successfully synthesized zinc oxide (ZnO) nanoparticles using the sol–gel method, followed by their application onto alumina substrates for sensor testing. Comprehensive characterization of the nanomaterials was carried out utilizing XRD, SEM, TEM, UV–VIS-IR, and Photoluminescence (PL) techniques. The nanoparticles displayed a hexagonal wurtzite crystal structure, typical of ZnO. UV–Vis-IR spectroscopy revealed significant absorption in the UV region, with the band gap energy calculated to be 3.22 eV. PL spectra indicated the presence of various defects, such as oxygen vacancies and zinc interstitials, within the ZnO structure. SEM analysis of the deposited film surface showed spherical agglomerates, confirming the nanoscale dimensions, while energy-dispersive x-ray spectroscopy spectra affirmed the high purity of the ZnO films, rich in Zn and O elements. Sensor tests demonstrated the ZnO sensor’s high sensitivity to low concentrations of volatile organic compounds such as ethanol, formaldehyde, methanol, and acetone. Notably, at an operational temperature of 300 °C, the sensor exhibited a remarkable response to 5 ppm of each gas, with the following response and response/recovery times: for methanol, 11.47 and 36 s/57 s; for acetone, 11.54 and 25 s/52 s; for formaldehyde, 0.79 and 53 s/58 s; and for ethanol, 3.88 and 9 s/59 s.

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.

On the Piezoelectric Properties of Zinc Oxide Thin Films Synthesized by Plasma Assisted DC Sputter Deposition

AbstractThis work presents a study of piezoelectric zinc oxide (ZnO) thin films deposited by a novel post‐reactive sputtering method. The process utilizes a rotating drum with DC magnetron sputtering deposition onto substrates with subsequent DC plasma‐assisted oxidation of the deposited metal to metal oxide. The paper analyzes the influence of plasmaassisted magnetron sputtering (PA‐MS) deposition parameters (O2 plasma source power, O2 flow, and Ar flow) on the morphological, structural, optical, and piezoelectric properties of ZnO thin films. Design of experiments has been utilized to evaluate the role of these parameters on the growth rate (rg) and the properties of resulting films. Results indicate a predominant influence of the plasma power on the rg over other parameters. Among the eight tested samples, three of them show high crystal quality with high intensity (0001) diffraction peak, characteristic of the wurtzite crystalline structure of ZnO, and one of them exhibits piezoelectric coefficient values of ≈11pC N−1. That sample corresponding to a ZnO film deposited at the lowest rg of 0.075 nm s−1, confirmed the key role of the deposition parameters on the piezoelectric response of films, and demonstrated PA‐MS as a promising technique to produce high‐quality piezoelectric thin films.

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.

Effect of Electron Irradiation on the Optical Properties of Zinc Oxide Powder Modified by Magnesium Oxide Nanoparticles

The effect of modifying ZnO powders with MgO nanoparticles (with a concentration of 0.1–10 wt. %) on their diffuse reflectance spectra in the region of 0.2–2.5 μm before and after irradiation with 30 keV electrons was studied. Modification of ZnO powder was carried out by MgO nanopowder with concentrations from 0.1 to 10 wt. % using a solid-state method at 650°C heating temperature. X-ray diffraction analysis showed that this method of modification there is no formation of additional phases. It has been established that zinc oxide structure symmetry belongs to the P63mc space group, magnesium oxide – to the Fm–3m space group. The spectral reflectance of such powders in the visible region is over 90%. Under irradiating by 30 keV electrons of initial and modified ZnO powders, as well as MgO nanopowder, a decrease in their reflectance recorded in the entire studied region of the spectrum. It has been established that modification with MgO nanoparticles at a concentration of 3 wt. % leads to an increase in radiation resistance by a factor of 1.32 compared to unmodified samples. This effect is determined by the sink of radiation defects on the large specific surface area of nanoparticles.

Correlating Cu dopant concentration, optoelectronic properties, and photocatalytic activity of ZnO nanostructures: experimental and theoretical insights

The photocatalytic activity of photocatalysts can be enhanced by cation doping, and the dopant concentration plays a key role in achieving high efficiency. This study explores the impact of copper (Cu) doping at concentrations ranging from 0% to 10% on the microstructural, optical, electronic, and photocatalytic properties of zinc oxide (ZnO) nanostructures. The x-ray diffraction analysis shows a non-linear alteration in the lattice parameters with increasing the Cu content and the formation of CuO as a secondary phase at the Cu concentration of >3%. Density functional theory calculations provide insights into the change in the electronic structures of ZnO induced by Cu doping, leading to the formation of localizeddelectronic levels above the valence band maximum. The modulation of the electronic structure of ZnO by Cu doping facilitates the visible light absorption via O 2p → Cu 3d and Cu 3d → Zn 2p transitions. Photoluminescence spectroscopy reveals a quenching of the defect-related emission peak at approximately 570 nm for all Cu-doped ZnO nanostructures, indicating a reduction in the structural and other defects. The photocatalytic activity tests confirm that the ZnO nanostructures doped with 3% Cu exhibit the highest efficiency compared to other samples due to the suitable band-edge position and visible light absorption.

Zinc oxide behavior in CO detection as a function of thermal treatment time

Gas sensors are crucial for safety and well-being in various environments. Zinc oxide (ZnO) gas sensors are notable for their broad gas detection capabilities. In this study, ZnO structures were synthesized by optimized chemical precipitation method with urea, followed by a thermal treatment at 500 °C for 5, 10, 13, and 15 h. The microstructural, morphological, and CO sensing properties were examined. X-ray Diffraction analysis confirmed the hexagonal wurtzite phase. Crystallite size increased from 17.28 to 18.95 nm with longer thermal treatment times. Scanning Electron Microscopy revealed spherical and semi-spherical agglomerates with middle distribution of particle sizes ranging from 140 to 445 nm. The synthesized ZnO structures were evaluated as gas sensors for CO detection. Response time, recovery time, and sensor response were analyzed in a CO atmosphere at 100, 200, and 300 °C. The sample with thermal treatment for 13 h exhibited the lowest Tr of 2.43 s at a concentration of 166 parts per million and 300 °C. The Tr reduction correlated with a ZnO decrease particle size observed with longer thermal treatment times, highlighting the influence of particle size on sensor performance.

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.

Eco-friendly synthesis of indole-4-hydroxy-chromen-2-ones using green zinc oxide nanocatalyst and its assessment of anti-cancer studies against A549 cells

Zinc oxide (ZnO) nanoparticles have significant attention in the field of photocatalyst, super capacitor, battery and biomedicine due to their versatile potential and diverse applications. In the present study, ZnO was synthesized using Celastruspaniulatus leaf extract as a green fuel through combustion method. The morphological and structural studies of ZnO were characterized using XRD, FTIR, UV–Vis, SEM and TEM analysis. The PXRD pattern of ZnO as shown diffraction peaks of ZnO planes (100), (002), (102), (110), (103) and (112) are hexagonal Wurtzite ZnO structure. ZnO is formed in a discrete irregular hexagonal shape was confirmed by SEM analysis. The application of ZnO is achieved for the synthesis of (4-hydroxy3-(1H-indol-3-yl)-phenyl-methyl-chromen-2-one) and its derivatives via Knoevenagel/Michael addition reaction. All synthesized compounds showed good yield and are characterized using 1H NMR, 13C NMR and ESI-MS spectral studies. The reusability of the ZnO catalyst is tested and documented. Some of the synthesized chromenone compounds show promising anticancer activity against A549 cells with less concentration.

3D printing flexible Ga-doped ZnO films for wearable energy harvesting: thermoelectric and piezoelectric nanogenerators

The 3D printing of energy harvesters using earth-abundant and non-toxic elements promotes energy sustainability and market competitiveness. The semiconducting behavior and non-centrosymmetric wurtzite crystal structure of gallium-doped zinc oxide (GZO) films make them attractive for thermoelectric and piezoelectric nanogenerators. This study investigates the thermal, structural, mechanical, thermoelectric, and piezoelectric properties of 3D-printed GZO nanocomposite films. Thermal analysis demonstrates the stability of the nanocomposite film up to 230 °C, making it suitable for wearable energy harvesters. The crystalline structure of the nanocomposite film aligns with the hexagonal wurtzite structure of ZnO and displays a bulk-like microstructure with a uniform distribution of elements. The presence of Ga 2p, Zn 2p, O 1 s, and C 1 s core levels confirms the development of the nanocomposite film, characterized by a fine granular structure and a conductive domain compared to the neat resin film. The inclusion of GZO nanofillers tailors the stress–strain behavior of the nanocomposite film, enhancing flexibility. The 3D-printed GZO nanocomposite films demonstrate a promising thermoelectric power factor and piezoelectric power densities, along with mechanical flexibility and thermal stability. These advancements hold significant potential for wearable and hybrid energy generation technologies.

The figure of merit improvement of (Sn, Co)–ZnO sprayed thin films for optoelectronic applications

Nanocrystalline zinc oxide (ZnO) has garnered significant attention from researchers and industries due to its superior properties as an optoelectronic material, particularly in solar cells as a transparent electrode. Doping, especially with tin (Sn) and co-doping with tin and cobalt (Co), can refine its optoelectronic properties. In this manuscript, we report on the optoelectronic properties of undoped ZnO thin films, as well as those doped with Sn and/or Co, elaborated using a simple chemical pneumatic spray pyrolysis method on glass substrates. A 1 % Sn doping concentration was used, with Co doping concentrations of 0 %, 0.5 %, and 1 %. The effects of Sn and/or Co doping concentration on the structure, morphology, optical, and electrical properties of nanocrystalline ZnO were studied using X-ray diffractometer (XRD), Raman spectroscopy, Field emission scanning electron microscopy (FESEM), UV–Vis–NIR spectroscopy and Hall effect measurements. All the films studied exhibit wurtzite ZnO structures with a predominant (002) orientation and no secondary phase, as confirmed by X-ray diffraction (XRD) analysis. The Raman spectroscopy also reveals the presence of a wurtzite structure in all the films. The FESEM images reveal the kind and concentration of the dopants significantly influenced the surface morphology of the films. The elemental analysis with energy dispersive X-ray analysis (EDS) analysis successfully detected the doping of Sn and Co. The analysis of UV–Vis spectroscopy provide that the optical band gap for the undoped ZnO film is 3.25 eV. This band gap increases upon doping and co-doping, reaching a peak value of 3.30 eV for the Sn:Co (1 %:0.5 %) co-doped ZnO film. The ZnO film shows an improvement in the electrical resistivity upon doping and co-doping with low resistivity value of 1.95 × 10−2 Ω cm for the film (1%Sn, 0.5 % Co)–ZnO. The highest figure of merit (FOM) achieved is 1.41 × 10−4 Ω−1 for a ZnO thin film co-doped with (1 % Sn, 0.5 % Co). The existence of (1 % Sn, 0.5 % Co) film with improved optical gap, low electrical resistivity and high FOM supports its use in transparent conductive oxide applications.

Green-synthesized CuO and ZnO nanoparticles derived from Calotropis gigantea (Apple of Sodom): enhancing plant growth, efficient dye removal, and potent antibacterial applications.

Nanoparticles, owing to their unique physicochemical properties, have garnered significant attention in various scientific disciplines, including materials science, chemistry, biology, and environmental engineering. In recent years, the synthesis of metal oxide nanoparticles, such as NiO, Fe2O3, ZnO, SnO2, and CuO via green routes, has gained attraction due to their diverse applications in fields ranging from catalysis and electronics to medicine and environmental remediation. This study focuses on the green synthesis of copper oxide (CuO) and zinc oxide (ZnO) nanoparticles using Calotropis gigantea (Apple of Sodom) leaf extract as a reducing agent and stabilizer, with zinc nitrate (ZnNO3.6H2O) and copper nitrate (CuNO3.3H2O) as precursors. The hexagonal phase of ZnO and monoclinic plan structure of CuO with high crystallinity was confirmed by XRD and elemental composition by EDX analysis. With the help of an SEM image, particle size measured for CuO and ZnO using ImageJ software was found to be 56.08nm and 46.49nm, respectively. This study investigates the efficacy of nanoparticles in wastewater treatment, particularly focusing on methylene blue dye decolorization using the statistical processing of response surface methodology (RSM) using the Box-Behnken method. Additionally, it explores the impact of synthesized nanoparticles on seed growth enhancement, using Vigna radiata (green gram) seeds immersed in various doses of nanoparticles (0, 0.5, 1, 1.5, 2mg/30mL). Furthermore, the antibacterial activity of the nanoparticles against both gram-positive and gram-negative bacteria is evaluated. The results confirm the effectiveness of the materials for methylene blue dye removal, achieving 80.53% with CuO and 78.25% with ZnO. Significant seed growth was observed with a low nanoparticle dosage of 1.5mg/30mL, resulting in the highest seedling vigour index and germination percentage. This reduces the need for fertilizers and lessens environmental impact.

Long Electrical Stability on Dual Acceptor p-Type ZnO:Ag,N Thin Films.

p-type Ag-N dual acceptor doped ZnO thin films with long electrical stability were deposited by DC magnetron reactive co-sputtering technique. After deposition, the films were annealed at 400 °C for one hour in a nitrogen-controlled atmosphere. The deposited films were amorphous. However, after annealing, they crystallize in the typical hexagonal wurtzite structure of ZnO. The Ag-N dual acceptors were incorporated substitutionally in the structure of zinc oxide, and achieving that; the three samples presented the p-type conductivity in the ZnO. Initial electrical properties showed a low resistivity of from 1 to 10-3 Ω·cm, Hall mobility of tens cm2/V·s, and a hole concentration from 1017 to 1019 cm-3. The electrical stability analysis reveals that the p-type conductivity of the ZnO:Ag,N films is very stable and does not revert to n-type, even after 36 months of aging. These results reveal the feasibility of using these films for applications in short-wavelength or transparent optoelectronic devices.

Fluorine-free approaches to impart photovoltaic systems with self-cleaning and anti-icing features

AbstractDust deposition on photovoltaic systems has a significant impact on the transmittance, temperature, and roughness, causing reductions in their power generation efficiency and lifetime. A promising approach to deal with this problem relies on the use of superhydrophobic coatings to impart the surfaces of these devices with self-cleaning properties. In this work, materials with different chemistry and morphology were added to an acrylic dispersion to create hydrophobic surfaces using a non-fluorinated coating simple strategy for glass substrates. Results showed that materials with more complex morphology, namely the spherical shape of silica nanoparticles, and the needle-like and prism-like structures of zinc oxide, imparted the glass with higher water contact angles. All coatings prepared displayed self-cleaning features and good adhesion to the glass substrate. Coatings comprising silica nanoparticles, zirconia and alumina modified with HDMTS were the best ones to prevent ice formation. In terms of chemical stability, all the coatings resisted acidic conditions close to acid rain pH and solvents with mild polarity. Therefore, the coatings proposed hold great potential to expel dust contaminants and prevent ice formation of photovoltaic devices, increasing their lifetime and power generation efficiency.

Rapidly chemical preparation of Mn doped ZnO nanostructures for photocatalysis efficiency based on UV light system and mechanism insights

Through a facile chemical precipitation process, pure zinc oxide (ZnO) and various ratio of Mn-doped zinc oxide (Zn1-xMnxO) nanostructured materials were synthesized. The degradation of an azo dye acid orange 2 (AO-2) solution under UV light was investigated using the synthesized materials as photocatalysts. XRD, FTIR, DLS, FESEM, EDS, PL, BET, magnetic, TGA and UV–vis techniques were used to elucidate the structural, functional, particle, elemental, morphological, and optical aspects of the catalysts. The XRD and FESEM analysis showed the hexagonal ZnO structure and spherical shape of the ZnO nano-photocatalyst, respectively. The crystal sizes of Zn1-xMnxO are 27.40–38.31 nm. The optical band gap energy of Zn1-xMnxO are 2.53–3.10 eV. Under UV irradiation for 60 min, MZ-25 NPs demonstrated better degradation (100.0%) of AO-2 dye. The effect of various factors such as catalyst quantity, and pH of the dye solution on the rate removal was investigated. After 60 min of UV light irradiation, dye removal was obtained under ideal conditions (with catalyst loading of 3 mgL−1, and pH 4). The rate constant values of MZ-25 sample are determined to be 0.0219 min−1. The scavenging test reveals that ∙O2 − and ∙OH are responsible for the photo-degradation of AO-2 dye.

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.

Detection performance of flower-like hydrothermally synthesized ZnO in silicon-type photodetector

Zinc oxide (ZnO) is a versatile compound or metal oxide with a wide range of applications across various industries such as electronics, optoelectronics, and gas sensors, etc. A simple hydrothermal method was used to synthesize ZnO flower-like structures in this study. The synthesized ZnO structures were analyzed by x-ray diffractometer (XRD) and scanning electron microscope (SEM). We used ZnO structures as an interfacial layer for a Schottky-type silicon-based photodetector. While Au and Al metals were employed as metallic and ohmic contacts, respectively, p-Si was utilized as a semiconductor and substrate. Thus, Au/ZnO/p-Si sandwich was successfully fabricated and tested by current–voltage (I–V) measurements under dark and various light power illumination densities from 10 mW cm−2 to 150 mW cm−2 as well as the various wavelengths in the case of same power. The I–V characteristics were used to determine the diode and photodetection parameters. The fabricated heterostructure exhibited 77.51 mA W−1 responsivity, 1.30 × 1010 Jones specific detectivity, and 26.33% external quantum efficiency (EQE) values.

Tailoring the Electronic Structures and Spectral Properties of ZnO with Irradiation Defects Generated Under Intense Electronic Excitation: A Combined Experimental and DFT Approach

AbstractThe relationship between the composition of the internal defect states, spectral properties, and correlated electronic structures of wurtzite zinc oxide (ZnO) crystals under 645 MeV Xe35+ irradiation is systematically investigated, employing experimental characterizations combined with first‐principle calculations. Based on the ion irradiation‐induced thermal expansion and relaxation processes, the high concentration of vacancy/interstitial defects produced from the transient disordered phase in molten track states trigger photoelectric changes, as follows: i) the generation of internal defect states effectively reduces the intrinsic bandgap (3.25 eV → 2.66 eV); ii) a large number of defective active sites inhibits the recombination between electron–hole pairs, causing dark conductance and photoconductance to increase with increasing damage levels until optimal fluence is achieved. Based on the density functional theory (DFT) with the GGA + U (GGA = generalized gradient approximation) method, the defective models associated with the different electronic structures, density of states, formation energy, and the nature of the chemical bonding are established. The narrowing of the bandgap observed experimentally and the enhancement of carrier concentration originating from the internal electron defect states are qualitatively verified, therefore laying the foundation for designing future nanoscale photoelectronic devices and microelectronics applications.

Synergistic effect of ZnO/Ag2O@g-C3N4 based nanocomposites embedded in carrageenan matrix for dye degradation in water

This research achieved success by synthesizing innovative nanocomposite composed of zinc oxide (ZnO), graphitic carbon nitride (g-C3N4) and silver oxide (Ag2O) nanomaterials incorporated into a carrageenan matrix, thus creating an environmentally friendly and stable support structure. The synthesis process involved hydrothermal and chemical precipitation methods to create photocatalytic g-C3N4, ZnO, and Ag2O nanocomposites. The success is evident through the characterization results, which unveiled distinctive peaks corresponding to Zn–O (590-404 cm−1) and Ag–O (2072 cm−1) stretching in the Fourier transform infrared (FTIR) and X-ray diffraction (XRD) analyses, conclusively confirming the successful synthesis of g-C3N4, ZnO, Ag2O, and their respective nanocomposites. Further validation through a scanning electron microscope coupled with an energy dispersive spectrometer (SEM-EDX) and elemental mapping affirmed the presence of Zn, O, Ag, C, and N. Additionally, transmission electron microscope (TEM) imaging unveiled the nanosheet morphology of g-C3N4, the nanorod structure of ZnO, and the spherical form of Ag2O nanomaterials. ZnO and Ag2O nanomaterials demonstrated a consistent 10–20 nm size range. To underscore their ability to harness visible light, the nanomaterials were excited at 380 nm, emitting visible light emission within the 400–450 nm range. The synthesized nanocomposites showcased outstanding adsorption and photocatalytic properties, achieving efficiency ranging from 80 % to 98 %, attributed to the synergistic interactions between the various components. These findings culminate in a confirmation of the research's success, validating the exceptional potential of these nanocomposites for various applications.