Doped ZnO Research Articles

Effect of Ozone Aging and ZnO Doping on the Mechanical, Thermal, and Chemical Properties of Glass‐Epoxy Composites

ABSTRACTThis study explores the effects of ozone exposure and ZnO doping on the mechanical, thermal, and chemical properties of glass‐epoxy composites. Composite samples were subjected to ozone aging under controlled conditions and were modified with 1%, 2%, and 4% ZnO contents. Tensile testing, FTIR, TGA, and DSC analyses were conducted to assess performance changes. Results showed that 700 parts per hundred million (pphm) ozone exposure enhanced tensile strength by ~12%, likely due to improved matrix–fiber interaction. In contrast, high ozone exposure led to polymer degradation and reduced mechanical performance. The highest tensile strength was observed in samples containing 2% ZnO under high ozone exposure, showing a 13.5% improvement over the unmodified composite, which indicates a clear synergistic effect between ZnO and ozone. Thermal analyses confirmed that ZnO improved thermal stability and increased glass transition temperature. FTIR results revealed that ZnO effectively reduced oxidative modifications induced by ozone, as indicated by the decreased intensity of –OH and C=O absorption bands. These findings suggest that tuning ZnO content and ozone exposure can improve the durability of glass‐epoxy composites.

Dynamical Characteristics of Isolated Donors, Acceptors, and Complex Defect Centers in Novel ZnO.

Novel wide-bandgap ZnO, BeO, and ZnBeO materials have recently gained considerable interest due to their stellar optoelectronic properties. These semiconductors are being used in developing high-resolution, flexible, transparent nanoelectronics/photonics and achieving high-power radio frequency modules for sensors/biosensors, photodetectors/solar cells, and resistive random-access memory applications. Despite earlier evidence of attaining p-type wz ZnO with N doping, the problem persists in achieving reproducible p-type conductivity. This issue is linked to charging compensation by intrinsic donors and/or background impurities. In ZnO: Al (Li), the vibrational features by infrared and Raman spectroscopy have been ascribed to the presence of isolated AlZn(LiZn) defects, nearest-neighbor (NN) [AlZn-NO] pairs, and second NN [AlZn-O-LiZn;VZn-O-LiZn] complexes. However, no firm identification has been established. By integrating accurate perturbation models in a realistic Green's function method, we have meticulously simulated the impurity vibrational modes of AlZn(LiZn) and their bonding to form complexes with dopants as well as intrinsic defects. We strongly feel that these phonon features in doped ZnO will encourage spectroscopists to perform similar measurements to check our theoretical conjectures.

An acetylacetone gas sensor based on transition-metal doped ZnO double hexagonal prism structure with UV excitation

An acetylacetone gas sensor based on transition-metal doped ZnO double hexagonal prism structure with UV excitation

Photocatalytic Degradation of Malachite Green Dye by Using Microwave Synthesized ZnO and Sr Doped ZnO Nanoparticles: A Comparative Study

Photocatalytic Degradation of Malachite Green Dye by Using Microwave Synthesized ZnO and Sr Doped ZnO Nanoparticles: A Comparative Study

The Design and Fabrication of Shear-Mode Piezoelectric Accelerometers with High Bandwidth Using High Piezoelectric g-Coefficient NKN-Based Ceramics.

In this work, lead-free (Na0.475K0.475Li0.05)NbO3 + x wt.% ZnO (NKLN, x = 0 to 0.3) piezoelectric ceramics with high piezoelectric g-coefficients were prepared by conventional solid-state synthesis method. By adding different concentrations of ZnO dopants, we aimed to improve the material properties and enhance their piezoelectric properties. The effects of the ZnO addition on the microstructure, dielectric, piezoelectric and ferroelectric properties of the proposed samples are investigated. Adding ZnO reduced the dielectric constant and improved the g-value of the samples. The properties of the samples without ZnO doping were g33 = 31 mV·m/N, g15 = 34 mV·m/N, kp = 0.39, Qm = 92, εr = 458, d33 = 127 pC/N and dielectric loss = 3.4%. With the preferable ZnO doping of 1 wt.%, the piezoelectric properties improved to g33 = 40 mV·m/N, g15 = 44 mV·m/N, kp = 0.44, Qm = 89, εr = 406, d33 = 139 pC/N and dielectric loss = 2.4%. Finally, ring-shaped shear mode piezoelectric accelerometers were fabricated using the optimum ZnO-doped samples. The simulated resonant frequency using ANSYS 2024 R1 software was approximately 23 kHz, while the actual measured resonant frequency of the devices was 19 kHz. The sensitivity was approximately 7.08 mV/g. This piezoelectric accelerometer suits applications requiring lower sensitivity and higher resonant frequencies, such as monitoring high-frequency vibrations in high-speed machinery, robotic arms or scientific research and engineering fields involving high-frequency vibration testing.

Influence of ZnO doping on the band gap energy of TiO2 thin films for solar energy applications

Influence of ZnO doping on the band gap energy of TiO2 thin films for solar energy applications

Synthesis and Characterization of Zn(1-x-y)MnxCoyO NPs for Liver Cancer Treatment.

In this study, pure and cobalt manganese-doped ZnO nanoparticles (Zn(1-x-y)MnxCoyO NPs) at varying concentrations were synthesized through sol-gel method, and zinc acetate dihydrate, manganese nitrate, cobalt acetate, and diethyl amine were used as precursors, with samples finally calcined at 700oC. The hexagonal wurtzite structure of pure and co-doped ZnO NPs was confirmed by X-ray diffraction (XRD). The computed grain sizes of pure and co-doped ZnO NPs, according to Scherrer's formula, were 32 nm, 32.5 nm, 36.3 nm, and 36.5 nm, respectively. SEM was used to observe the morphology of nanoparticles. FTIR spectroscopy was used to examine the chemical make-up and vibrational modes of pure and co-doped ZnO NPs. The bandgaps of pure and doped ZnO were examined using UV-Vis spectroscopy. It was found that the optical bandgap of ZnO was lowered by 3.21 eV by manganese and cobalt doping. Elemental composition analysis was performed by using EDX analysis. Finally, anticancer activity of pure and co-doped ZnO NPs was assessed by employing MTT assay, which indicated that Zn0.8 Mn0.1 Co0.1O NPs showed significant anticancer results against liver cancer (HepG-2) cells as compared to ZnO, Zn0.98 Mn0.01Co0.01O and Zn0.90 Mn0.05 Co0.05O NPs. Moreover, Zn0.8 Mn0.1 Co0.1O NPs showed low toxicity and good biocompatibility comparable to doxorubicin (DOX). Comprehensive experimental findings have demonstrated an authentic way of obtaining feasible in vivo liver cancer therapy.

Photocatalytic, antibacterial and antioxidant capabilities of (Fe, Al) double doped ZnO nanoparticles with Murraya Koenigii leaf extract synthesized by using microwave assisted technique

Photocatalytic, antibacterial and antioxidant capabilities of (Fe, Al) double doped ZnO nanoparticles with Murraya Koenigii leaf extract synthesized by using microwave assisted technique

Annealing Effect on the Photocatalytic Activity of Samarium Doped ZnO Prepared by Aqueous Precipitation Route

Annealing Effect on the Photocatalytic Activity of Samarium Doped ZnO Prepared by Aqueous Precipitation Route

High-sensitivity creatine detection using doped ZnO nanoribbon biosensors: A density functional theory approach

High-sensitivity creatine detection using doped ZnO nanoribbon biosensors: A density functional theory approach

Structural Research of Li Doped ZnO Powders

Structural Research of Li Doped ZnO Powders

Modification of structure and electrical properties of K0.5Na0.5NbO3-BiMnO3 single crystals by adding ZnO dopant

Modification of structure and electrical properties of K0.5Na0.5NbO3-BiMnO3 single crystals by adding ZnO dopant

First Principles Study of Undoped and Halogen Doped ZnO Monolayer

This study reports the structural, electronic, and magnetic properties of undoped and halogen (F, Cl, and Br) doped ZnO monolayers (3 × 3 × 1) by replacing one Zn-atom. Using spin polarized Density Functional Theory (DFT) in VASP code and a projected augmented wave basis set, we employed GGA-PBE and PBE+U exchange correlation functionals. The band gap of pristine ZnO was measured to be 1.67 eV and 2.61 eV for PBE and PBE+U, respectively, whereas band gap decreased significantly upon addition of halogen atom. Likewise, doped ZnO shows semimetallic behavior, whereas undoped ZnO exhibits semiconducting behaviour. Further, the magnetic moments of about 1 µB for Cl and Br-doped ZnO, and 1.02 µB & 2.98 µB for F-ZnO utilizing PBE and PBE+U functionals, respectively were observed. These findings suggest that halogen-doped ZnO might carry huge potential for next-generation spintronic nanodevices.

Structural, Optical, and Electronic Properties Analysis of Praseodymium Doped ZnO: Insights from Density Functional Theory with GGA+U Approach

ZnO is widely used as a semiconductor material due to its wide bandgap, high exciton binding energy, and excellent transparency in the visible range, which make it suitable for optoelectronic applications. Doping in ZnO is important because it allows for controlling its electrical properties, enables the tuning of conductivity, and enhances its functionality for specific applications. Doping can introduce new energy levels within the bandgap. Moreover, it improves the performance of ZnO-based devices. This study explored the structural, optical, and electronic properties of pure and Praseodymium ion (Pr3+) doped ZnO using GGA+U based DFT. Results agreed with prior research, showing compatible lattice parameters and band gap for pure ZnO. Increasing Pr concentration expanded lattice parameters and volumes while reducing the energy band gap. Pr doping shifted the Fermi level to the upper conduction band, causing an overlap between the conduction and valence bands. This indicated a transition from a semiconductor to an n-type degenerate semiconductor with metal-like characteristics. Higher doping concentrations led to a shift in density of states towards lower energies. Computed optical properties exhibited red shifts in absorption peaks and increased absorption in the near and far ultraviolet regions following Pr doping. Similar red shifts were observed in the reflectivity spectrum and other optical properties. The real dielectric constant (ε1 (ω)) displayed negative values, signifying metallic behavior at specific photon energies, consistent with band structure optimization.

Sonocatalytic degradation of RB-5 dye using ZnO nanoparticles doped with transition metals

In this study, ZnO was doped and co-doped with rhodium and tungsten to assess the impact of these transition metals on the sonocatalytic degradation of reactive black 5 azo dye (RB-5). Structural analysis revealed that doping ZnO with 1% Rh and W does not alter its wurtzite hexagonal structure, although minor changes in cell parameters were observed due to differences in electronic density. Interestingly, co-doping resulted in lower degradation efficiency than single doping, with W-ZnO emerging as the most effective catalyst, achieving 100% RB-5 degradation within 60 min, likely due to a higher density of oxygen vacancies and hydroxyl groups. Moreover, a 2k factorial design identified optimal sonocatalytic conditions for W-ZnO, including a catalyst concentration of 0.75 g/L, a power tip of 225 W, and a hydrogen peroxide volume of 27 μL. The findings highlight the potential for doped ZnO nanoparticles in advanced oxidation processes and green chemistry applications, making this method an environmentally friendly alternative for wastewater treatment.

Effects of cadmium doping on thermo-physical properties of ZnO nanoparticles and nanofluids for heat transfer applications

The most common method of improving the thermal performance of the conventional fluids is adding the solid particles to the base fluid. This even though increases the thermal conductivity, but in turn increases the viscosity and the risk of sedimentation. Hence alternative methods are required to enhance the thermal performance of the base fluids. One such promising method is doping. In this regard, in this work it is aimed to study the effects of cadmium doping ZnO nanoparticles, which were then analyzed using X-ray Diffraction (XRD), Energy Dispersive X-ray (EDX), and Scanning Electron Microscopy (SEM). Their elemental composition was determined using SEM. XRD was utilized to ascertain the average size of the crystallite. All particles were found to be spherical and the average particle size ranged from 17 to 20 nm. Their thermal features were determined for various temperatures (20°C–60°C) and concentrations (0.1%–0.3%). Outcomes depict that at the highest concentration of the doped ZnO NPs, the thermal conductivity (TC) of the cadmium doped ZnO NFs for the concentration of 0.05% has enhanced by 42% than the base fluid. The TC of the Cadmium doped NFs was also found to be 7% higher than the TC of pure ZnO NFs. Density and viscosity has showed an increasing trend with the rise in the loading of the nanoparticles(NPs) whereas the specific heat has decreased. Doped nanofluids outperformed the ZnO nanofluids in their properties.

Effect of Acetylene Properties on its Gas Sensing by NiO Doped ZnO Clusters: A Transition State Theory Model

The sensitivity of nickel oxide doped zinc oxide to industrial gas acetylene was calculated and compared to available experimental data. The adsorption of C2H2 on the NiO-doped ZnO surface and the activation transition states formed afterward were studied computationally. B3LYP version of density functional theory with 6-311G** basis set, including dispersion correction (GD3BJ) was performed for the calculations with the help of Gaussian 09 software. Thermodynamic quantities of the reaction of C2H2 with NiO-doped ZnO surfaces, such as Gibbs free energy, enthalpy, and entropy, were used to interpret the reaction at the temperature range 25–325 °C. Response and response time variation with different NiO doping percentages were calculated. The calculations took into account the combustion of acetylene as it approached its autoignition temperature, which was not considered in previous works. The results show that the optimum response operating temperature of the C2H2 gas sensor is below the autoignition temperature of acetylene at 300 °C. A good agreement of theoretical response and response time with variation of temperature and acetylene concentration was obtained with the experiment. This study was the first to take into account the autoignition of C2H2 in gas sensor calculations and noted that gases can be easily distinguished by their autoignition temperature.

Improving the Gas Detection Abilities of ZIF-8 Coated ZnO through Titanium Metal Doping

Worldwide atmospheric pollution is one of the biggest and deadliest issues as the effect of prolonged exposure to gases such as nitrogen oxides (NOx), carbon dioxide (CO2), carbon monoxide (CO) and volatile organic compounds (VOC) cause severe adverse effects towards environmental and human well-being [1]. Significant research efforts were made for the development of gas sensors that can precisely detect the amount of toxic gases present in air. Metal oxide semiconductors (MOS) are being intensively developed due to their inherent properties like high sensitivity to toxic gases, ability to be incorporated into small, miniaturized devices capable of high mobility and ease of usage [2]. ZnO is at the forefront of MOS based gas sensors, becoming increasingly popular over the years for several suitable properties like wide band gas energy, high binding energy and high electron mobility [3]. Regardless, further improvement through the addition of doping elements and the creation of a heterostructure is necessary. This study investigates the effects of titanium (Ti) element doping of ZnO and the encapsulation strategy by zeolitic imidazolate framework-8 (ZIF-8). ZIFs are a part of metal organic frameworks (MOFs) that have attracted considerable attention due to their supremely porous structure that is quite suitable for gas sensing purposes [4]. It was reported that the encapsulation of ZnO core by ZIF-8 increases the selectivity via the molecular sieving mechanism common for MOFs, meaning that the gas particles smaller than the aperture sizes of the ZIF-8 shell may pass through to the ZnO core, while the same isn’t viable for bigger particles. This study focuses on the combination of both doping by Ti element and the encapsulation by ZIF-8 shell for the synergistic effect on base ZnO material for gas sensing applications that has not been reported yet.Initially, zinc nitrate hexahydrate was chosen as zinc source, while titanium isopropoxide was added for the doping purpose. Both the doping and encapsulation synthesis processes took place in a controlled temperature and pressure environment in a Teflon-lined stainless-steel autoclave, further aiding the formation of crystalline nanoparticles. Figure 1 shows the XRD, FTIR, and TEM characterization results for the synthesized products. The difference in FTIR spectra between the ZnO@ZIF-8 and doped/undoped ZnO samples is the presence of peaks characteristic to ZIF-8 such as 1146, 1311, 992, 759, 692 cm-1. Peak 425 cm-1 corresponds to Zn-N stretching vibration band and indicates the presence of nitrogen characteristic to methylimidazole ligands present in ZIF-8. The peaks in range 400-500 cm-1 are jointly attributable to Ti-O and Zn-O vibrational stretching modes, while weak peaks from 1100 to 1600 are due to OH bending vibrational mode that is likely to be present due to the precursor nature of the doping element.The structural modification of ZnO is evident from the XRD graph in Fig. 1a. The peaks (100), (002), (101), (102), (110), (103), (112) correspond to hexagonal ZnO structure. Ti element has a smaller ionic radius that Zn and therefore the substitution to Zn site leads to a decrease in the size of the crystals, from 39.68 to 33.61 nm, and the increase in stress and strain, 6.356 * 10-6 Å-2 to 8.862 * 10-6 Å-2 and 2.93 * 10-3 to 3.44*10-3, respectively, as compared to before. Moreover, the shift in the angle of diffraction greatly hints at the optimized structure. Peaks (110), (200), (211), (220), (310), (222) are attributable to ZIF-8 that constitute the shell and is seen from the TEM image presented in Fig. 1d. The reported results are expected to alter the base sensitivity and selectivity of ZnO sensing material towards NO2.Gas sensing performance and further characterization of prepared Ti-doped ZnO@ZIF-8 sensing material will be presented at the conference.

MOF-derived La-doped ZnO dodecahedron nanostructures for efficient detection of NO2 gas

MOF-derived La-doped ZnO dodecahedron nanostructures for efficient detection of NO2 gas

Enhancement of Photocatalytic Removal of 4-Chlorophenol from Aqueous Solutions by Manganese Oxide Doped ZnO Nanoparticles Using RSM

Background: Phenol and its derivatives as a toxic and dangerous substance produce by many industries. This pollutant must be removed from contaminated streams or fluids before discharging. The aim of this study was to enhancement of nano-photocatalytic removal of 4-chlorophenol (4- CP) from aqueous solutions applying manganese oxide doped ZnO nanoparticle (MnO₃-doped ZnO) catalyst via experimental designing of surface-response method. Methods: In this study, MnO₃-doped ZnO NPs were fabricated using hydrothermal technique and ratio of Mn-doped ZnO NPs consisted of 0 (pure), 0.5, 1 and 1.5%. The characteristics of the synthesized NPs was studied by scanning electron microscopy (SEM), Fourier transform infrared spectra (FTIR), X-ray diffraction (XRD) and atomic force microscopy (AFM) analyses. For determined the doped ZnO quality, variables such as pH, initial 4-CP concentration, NPs dose and contact time were probed in 4-CP removal. Results: Results demonstrate that the removal efficiency are significantly affected by the varied Mn-doped ZnO ratio. The ratio of 1% was optimal. The hexagonal shape of NPs confirmed by XRD and SEM analysis. The SEM indicated that no agglomeration of NPs observed. The sharp edges peaks in XRD indicate a proper crystallized ZnO NPs. Regression analysis showed a quadratic polynomial model was obtained for efficiency prediction. The data providing an acceptable model assumption for analyzing the variance. It was also realized that increasing the nanoparticles dose and the contact time led to reduce the removal rat. Conclusion: Comparing the 4-CP removal efficiency of bare ZnO and Mn-doped ZnO showed that the Mn-doped ZnO have larger efficiency and improve up to 84%.