ZnO Nanopowders Research Articles

Mn-doped ZnO nanopowders prepared by sol-gel and microwave-assisted sol-gel methods and their photocatalytic properties.

Although the microwave-assisted sol-gel method is quite frequently used for the preparation of oxide nanostructures, the synergism of the reaction pathways is not fully explained. However, state-of-the-art theoretical and practical results of high novelty can be achieved by continuously evaluating the as-synthesized materials. The present paper presents a comparative study of Mn-doped ZnO nanopowders prepared by both sol-gel and microwave-assisted sol-gel methods. The structural, morphological, and optical properties of the as-obtained powders were established and correlated with their newly proved functionality, namely, the ability to photogenerate distinct reactive oxygen species (·OH or O2 -) and to act as photoactive materials in aqueous media. The solar light-induced mineralization of oxalic acid by Mn-doped ZnO materials was clearly observed while similar amounts of generated CO2 were measured for both catalysts. These inexpensive semiconductor materials, which proved to be light-responsive, can be further used for developing water depollution technologies based on solar light energy.

Al-Doped ZnO/SiO2 Nano-glass Ceramic System: A New Composite System for Improvement in Thermal Stability and Mechanical Properties of Dental Resins

AbstractThis study aims to enhance dental resins' mechanical and thermal properties by reinforcing them with Al-doped ZnO/SiO2 nano-glass ceramic. The synthesis of the nano-glass ceramic involved the addition of Al-doped ZnO nano-powders to a diluted aqueous solution of liquid glass (25 mL) in ethanol (50 mL) at room temperature. The synthesized samples were characterized using TEM, EDS, FE-SEM, and XRD techniques. Various concentrations of the nano-glass ceramic (2, 5, 8, 10, and 15 wt.%) were then integrated with Bis-GMA and TEGDMA. The mechanical properties, including flexural strength (FS), compressive strength (CS), diameter tensile strength (DTS), and flexural modulus (FM), were evaluated. Thermal stability was assessed through TGA analysis, which indicated polymer degradation occurring between 300 and 450 °C. An increase in filler content correlated with enhanced thermal stability. The optimal mechanical properties were observed at a 7.5 wt.% filler content, showing significant improvements in FS (124.652 MPa), FM (9.87GPa), DTS (33.87 MPa), and CS (178.47 MPa).

Experimental studies on insulating oils for power transformer applications

Abstract In recent days, ester-based alternatives like natural and synthetic oils are preferred as an alternative to mineral oil by the power industry due to its higher bio-degradability, superior thermal conductivity, and fire resistance than mineral oil. In addition to this, blended oils are quite attractive because of its low dielectric loss and a low ratio of degradation. The present research deals with the experimental studies on different insulating oils like mineral oil, synthetic ester oil, coconut oil, blended oils, and nanofluids, which are developed from ZnO and TiO2 nanoparticle doped at 0.01 vol% in different insulating oils through ultrasonication process. In this experiment, the critical properties like electrical and physicochemical properties are examined according to International Electrotechnical Commission and American Society for Testing and Materials standards. Results show that ZnO and TiO2 nano-powder enhances the AC breakdown voltage (BDV), dielectric permittivity, and DC resistivity properties of different insulating oils with improved flash and fire resistance. Remarkably, it is found that mineral oil-based TiO2 nanofluid shows an enhancement of 55.8 % in AC BDV, 9.1 % in permittivity, and 15 % in flash resistance. Moreover, mineral oil based ZnO and TiO2 nanofluid results exhibit remarkable decrement in loss tangent with increased DC resistance property. Finally, it is observed that the influence of TiO2 nano-powder at 0.01 vol% remarkably enhances the electrical and physicochemical properties in different insulating oils compared to ZnO nanofluids. Hence, mineral oil and green insulating based synthetic ester oil (which is based on TiO2 nanofluids) have been considered as a potential candidate to make alternatives to traditional insulating oil for power transformer applications. The findings offer critical insights for the future of transformer insulation systems, guiding industry standards and fostering innovation in material science.

Structure, Spectral and Photocatalytic Properties of Porous ZnO Nanopowders Modified by Oxide Compounds of Manganese

Structure, Spectral and Photocatalytic Properties of Porous ZnO Nanopowders Modified by Oxide Compounds of Manganese

The impact of lithium concentration on the optical properties of colloidal ZnO nanocrystals

In this work, Li-doped ZnO nanocrystals (LZO) were synthesized via the sol–gel method. The concentration of zinc acetate has been set at 2 M in order to prepare the highly concentrated Li-doped ZnO sol. The generated LZO sol’s optical characteristics were assessed using UV–visible absorption and photoluminescence spectroscopy, while the ZnO nanopowders’ lithium doping process was assessed using XRD and Raman spectroscopy. The experimental findings indicate that the concentration of Li+ ions in the synthesized zinc oxide nanocrystals has reached the maximum solid solubility limit. The inclusion of Li+ ions results in a reduction in the size of ZnO nanocrystals, accompanied by a notable increase in violet-blue emission, distinguishing them from other materials reported in the literature. As can be found, Li+ ions cannot change the type of conductivity in thin ZnO films, and they have n-type conductivity.

Eco-friendly green synthesis of (Cu, Ce) dual-doped ZnO nanoparticles with Colocasia esculenta plant extract using microwave assisted technique for antioxidant and antibacterial activity

In the realm of biomedical applications, the inclusion of plant-derived components stands out as a critical consideration due to their non-toxic nature and antioxidant properties. In our research, we opt for Colocasia esculenta plant extract, utilizing microwave technology to create dually doped ZnO nanopowder with copper (Cu) and cerium (Ce). Authors employ XRD analysis to explore the structural attributes and crystallite size of the nanoparticles, which are found to be within the range of 16–19 nm. The surface and internal characteristics of these nanoparticles are precisely scrutinized using SEM-EDS and TEM characterization techniques. Additionally, ultraviolet-visible spectroscopy is utilized to determine the forbidden energy gap of the samples, providing insights into their potential applications in UV-protected devices. The synthesized nanoparticles exhibit significant antibacterial and antioxidant properties, highlighting their adaptability for various biomedical uses.

Crystalography and the behavior of optical band gap in transition metal-doped (Al+Mn) ZnO nanopowder

Crystalography and the behavior of optical band gap in transition metal-doped (Al+Mn) ZnO nanopowder

Green Valorization of Waste Plastics to Graphene as an Upcycled Eco-Friendly Material for Advanced Gas Sensing

The valorization technique successfully transformed waste polyethylene terephthalate (PET) into valuable carbon nanomaterial (CN)/graphene, while doped and undoped ZnO nanopowders were synthesized via sol–gel methods. Utilizing XRD, BET, TEM, EDX, FTIR, and TGA analyses, the synthesis of sp2 2D sheet, pristine, and doped ZnO nanostructures was confirmed. Solid-state gas sensor devices, tested under 51% relative humidity (RH), 30 °C ambient temperature, and 0.2 flow rate, exhibited a 3.4% enhanced response to H2 gas compared to CO2 at 50 ppm concentrations over time. Notably, the ZnO/CN sensor surpassed CN and ZnO alone, attributed to CN dopant integration with decreasing order of response performance as ZnO/CN > CN > ZnO. This study underscores the efficacy of valorization techniques in generating high-value carbon nanomaterials and their efficacy in bolstering gas sensor performance, with ZnO/CN demonstrating superior response capabilities.

Effect of Ga doping on the structural, optical, and electrical properties of ZnO nanopowders elaborated by sol-gel method

Nanostructured ZnO has received a considerable amount of interest, owing to its unique physical and chemical characteristics, as well as its remarkable performance in the fields of electronics, optics, and photonics. This work aims to study the influence of Ga dopant on the structural, optical, and electrical properties of ZnO nanopowders. Undoped and Ga-doped ZnO (GZO) nanopowders were successfully synthesised with the soft chemical sol-gel method. The solution was prepared using zinc acetate dihydrate and gallium (III) nitrate hydrate as precursors. The ethylene glycol is used as solvent. The X-ray diffractometer, scanning electronic microscope (SEM), UV–Vis, FTIR, and four-point probe method are used to analyse the properties of the synthesised powders. XRD and FTIR measurements show the growth of pure and Ga-doped ZnO crystals, which have a hexagonal wurtzite structure, and the average crystallite size varies from 9.09 nm to 24.8 nm. The nanospherical morphology of the nanopowders synthesised can be seen in the SEM images. The UV–visible spectroscopy shows that the optical gap energy increases with Ga concentration, from 3.59 eV to 3.67 eV. The I-V electrical measurements indicate that the breakdown voltage and the non-linear coefficient increase with Ga doping. This study will open the way for the investigation of a relationship between the electrical and nanostructural features of ZnO-based varistors for future device applications.

Interfacial charge transfer complexes between ZnO and benzene derivatives: Characterization and photocatalytic hydrogen production

The interfacial charge transfer (ICT) complex formation is a simple procedure to bring optical absorption of wide-bandgap oxide materials in the visible spectral range, crucial for enhancing their use in photo-driven reactions. The optical absorption of the prepared ICT complexes between ZnO and five different colorless benzene derivatives is red-shifted compared to pristine ZnO nanopowder. The density functional theory (DFT) calculations provided realistic energy level alignment in hybrid systems. Also, the DFT-calculated infrared spectra support the binding structures derived based on experimental measurements of free and adsorbed ligands onto ZnO surfaces. The photocatalytic performance of prepared hybrids was evaluated using photocatalytic hydrogen generation in the water-splitting reaction. The ZnO nanopowders modified with catechol and caffeic acid have over 50% higher hydrogen production rate than pristine ZnO, displaying steady hydrogen production under long-run working conditions.

Synthesis of ZnO nanopowder using zinc Zamak dross and adsorption of Pb

In this study, zinc oxide nanopowder (ZnONPDs) was successfully recovered from zinc die casting alloys’ (ZAMAK) dross using a facile dissolution and pH-controlled precipitation approach for removal of lead (II) ions from aqueous solutions. XRD patterns showed that ZnONPDs, calcined at 240°C, exhibited a hexagonal unit cell structure with an average crystallite size of 36.46 nm. FE-SEM micrographs revealed that the ZnONPDs are spherical and hexagonal in shape. TEM images showed the morphology and particle size of synthesized ZnONPDs with an average size of 23.81 nm. XRF and EDS analyses confirmed the high purity of the prepared ZnONPDs. The BET surface area of ZnONPDs was 33.85 m²/g. Adsorption experiments exhibited the maximum removal of Pb2+ ions 100% at the optimal conditions (25 ppm Pb2+ ions, 20 min contact time, 30 mg adsorbent per 100 ml of solution). The pH and zeta potential confirmed that a pH range from 5 to 9 was optimal for the adsorption study. The zeta potential within this range indicated a high level of stability for the particles in the suspensions, effectively preventing flocculation and agglomeration. XPS results conclusively demonstrated the successful adsorption of Pb onto the surface of ZnONPDs. The ZnONPDs synthesized in this study were shown to be promising candidates for use in adsorption processes, indicating that they could be highly useful in wastewater treatments removing toxic metal ions.

Electrical Modulation of Random Lasing Emission from ZnO Nanopowder and Liquid Crystal Hybrid Polymer Film

Electrical Modulation of Random Lasing Emission from ZnO Nanopowder and Liquid Crystal Hybrid Polymer Film

Analysis of Mg and Ni co-doped ZnO nanopowder for supercapacitor applications

Analysis of Mg and Ni co-doped ZnO nanopowder for supercapacitor applications

Synthesis, characterization, and photoluminescence investigations of Al/Co-doped ZnO nanopowder

Present research describes the use of solution combustion to create ZnO nanoparticles doped with Co and Al. The studies revealed that the synthesized Al/Co-doped ZnO nanopowder has a narrower size distribution, controllable shape, and high crystallinity. Powder X-Ray diffraction (XRD), Scanning Electron Microscopy (SEM), Fourier Transform Infrared spectroscopy (FTIR), and photoluminescence (PL) spectral techniques were utilized to characterize the as-prepared materials. Interestingly, Al-doped ZnO nanoparticles' UV emission peak location showed greater intensity than Co-doped ZnO, which is explained by an increase in non-radiative recombination. The energy gap plot calculates the Tauc gap, along with the color information defined by the CIE. The doping components were combined through mechanical mixing, and their impact on the effectiveness of the electromagnetic interference (EMI) shielding was examined.

Antibacterial Evolution of ZnO Nanoparticles Synthesized via Wet-Chemical Method

In present days the essentiality of antibiotics is a big challenge for public health because of the spreading of infections severely. Nano metal oxides show effective antibacterial activity and are non-toxic compared to organic anti-microbes because of their high surface area to volume ratio. Nano ZnO is one of the most emerging nano metal oxides that has been used in various applications such as fire retard, anti-microbe, anti-wrinkle, etc. Nano zinc oxide was synthesized by the wet chemical process using zinc nitrate hexahydrate as a precursor. The synthesized nano ZnO powder was subjected to characterization to know the morphology and physical properties. FTIR analysis was employed for the identification of functional group, X-ray diffraction is to identify the crystalline structure, SEM-EDX analysis is employed to determine the morphological structure and size of the synthesized nanoparticles and elemental confirmation, and TEM is used to determine the particle size and shape of synthesized nanoparticles. The synthesized nano ZnO is screened for its antibacterial activity against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Bacillus subtilis by disc diffusion method.

Single-step in situ synthesis of bimetallic catalysts via a gas-phase route: the case of PdZn–ZnO

In this study, we explore the catalytic activity of highly pure PdZn–ZnO nanopowder, synthesized via an innovative metal–organic chemical vapor synthesis (MOCVS) method.

GAD plasma-assisted synthesis of ZnO nanoparticles and their photocatalytic activity

In this study we present an efficient method for synthesizing highly pure ZnO nanoparticles using a Gliding Arc Discharge (GAD) plasma system as a non-thermal plasma source. This approach offers distinct advantages over conventional techniques, including simplicity, a short synthesis time, utilization of readily available air as the source gas, and potential scalability, rendering it a promising alternative for sustainable ZnO nanoparticle production. The synthesized nanoparticles physicochemical properties were characterized using various techniques, such as scanning electron microscopy (SEM), energy dispersive x-ray analysis (EDAX), UV-visible spectroscopy (UV–vis), Fourier-transform infrared spectroscopy (FTIR), x-ray diffraction (XRD), Thermogravimetric Analysis (TGA), and Differential Scanning Calorimetry (DSC). Furthermore, we evaluated the effectiveness of the synthesized ZnO nanoparticles for wastewater treatment by assessing their photocatalytic activity against methylene blue (MB), Brilliant Cresyl Blue (BCB), and Congo Red (CR) under UV light irradiation for 2 h and 30 min. The results confirmed the successful synthesis of highly pure ZnO nano-powder with an average size of 27.18 nm and a band gap energy of 3.28 eV in an exceptionally brief duration and through straightforward steps. Additionally, GAD plasma-assisted ZnO nanoparticles exhibited a significant dye removal rate, showcasing their potential as highly effective materials for photocatalytic wastewater treatment. This study contributes new insights into the application of GAD plasma for nanoparticle synthesis.

Influence of a binary phase ZnO–CuO on the structural and reflectance properties of poly-ε-caprolactone based nanocomposites

The binary phase metal oxide of ZnO and CuO (BPMO-ZC) nanopowders were synthesized by the chemical bath deposition. The BPMO-ZC nanopowders were distributed through the poly-ε-caprolactone (PCL) matrix by solution casting. The effect of the BPMO-ZC on the structure, thermal and reflectance properties of PCL was investigated. The X-ray diffraction (XRD) confirmed the combined hexagonal wurtzite and cubic forms of the respective ZnO and CuO nanomaterials as well as an orthorhombic form of the semi-crystalline PCL nanocomposite films. Morphology included aggregated particles with heterogeneous distribution. Differential scanning calorimetry (DSC) showed that the degree of crystallinity of nanocomposites films increased in the presence of the nanopowders. Nanocomposites displayed poor thermal stability compared to PCL, but improved residue. Reflectance measurement revealed that the absorption edges of PCL shifted to higher wavelength with the addition of ZnO–CuO.

Investigation of Cd and Co co-doped ZnO nanopowder for supercapacitor applications

Investigation of Cd and Co co-doped ZnO nanopowder for supercapacitor applications

Flexible Ultraviolet Sensor Based on Zinc Oxide Nanoparticle Powder

Zinc oxide nanopowder was synthesized by the coprecipitation method. FT-IR and EDS analyses were performed to qualitatively determine the composition of the nanopowder. FE-SEM images revealed the morphology of the nanopowder formed by clusters of nanoparticles. An XRD analysis confirmed the wurtzite structure with a crystallite size of ~21.2 nm. UV–Vis measurements were performed to determine the ZnO bandgap (~3.05 eV) using the Tauc plot method in the absorbance spectra. The ZnO nanopowder and two comb-like metal contacts were confined and compacted between two polymeric layers by a low-temperature thermal lamination method, resulting in a flexible Polymer/ZnO/Metal/ZnO/Polymer structure. Part of each comb-like metal was kept uncovered by a polymeric layer in order to be used for electrical characterization. I-V measurements of the flexible structure were performed in the dark and under UV illumination, showing the capacity to detect UV radiation and its potential application as a visible-blind UV sensor. A facile and low-cost flexible optoelectronic device is presented, avoiding using high-vacuum or high-temperature technology. This new and novel approach to developing optoelectronic devices proposes using powder materials as semiconducting active regions instead of thin films; this could eliminate the cracking and delamination problems of flexible devices based on thin film technology.