Papers by Keyword: Zinc Oxide

Abstract: This research investigated the impact of Ag content supported on ZnO catalysts regarding the oxidation activity of DPM. The catalyst was synthesised through the doping of varying Ag concentrations on ZnO (e.g., 2, 4, 8, and 16 wt%) employing the incipient wetness impregnation technique. Characterisation of the synthesised catalyst was conducted utilising XRD, SEM, TEM, and H₂-TPR. The evaluation of oxidation activity and stability was performed through TGA. The characterisation findings substantiated the successful integration of Ag onto ZnO across all experimental conditions investigated. H₂-TPR profiles revealed two distinct regions of H₂ consumption: 1) at 200-400 °C, and 2) at 400-700 °C. These regions were attributed to the reduction of Ag₂O to Ag⁰ and the liberation of lattice oxygen from ZnO, respectively. An increase in Ag concentrations resulted in enhanced reduction reactions within the temperature spectrum of 400 to 700 °C, demonstrating a favourable trend towards improved reaction efficiency. The oxidation performance of DPM was markedly augmented by the Ag content, particularly at 16 wt%. Stability assessments indicated a consistent capability in facilitating DPM oxidation across five cycles. The concentration of oxygen exhibited a significant influence on the oxidation activity of DPM.

Abstract: Zinc oxide is the most widely used nanomaterial in nanotechnology due to its outstanding properties and characterizations. Enormous attention has arisen due to its unique physical properties consists of a wide energy band gap of 3.37 eV at ambient temperature and large binding energy of 60 meV, which give development to an extensive range of potential applications in many areas such as electronics, solar cells, and biological applications. The size and shape of nanoparticles are significant to ensure the process becomes faster, cheaper and more efficient compared with traditional methods. By having more active area of nanoparticles, the biological and chemical process become more effectives. The biological activity of ZnO Nanoparticles was investigated through the antibacterial activity, anti-microbial activity, as anticancer and antioxidant material. The method used to prepare the ZnO Nanoparticles also take an important part which is to reduce the by-product formation when applied in wastewater treatment. This article summarizes different preparation methods of ZnO Nanoparticles and its application uses. The ZnO nanoparticles can be used the various applications, for example for the antibacterial, anti-cancer, anti-microbial, antioxidant and for wastewater treatment applications.

Abstract: ZnO thin films were deposited on borosilicate glass substrates by confocal radio frequency (RF) magnetron sputtering and subsequently annealed in air at 300 °C and 500 °C for 60 min. The influence of thermal treatment on the structural, morphological, optical, and electrical properties was systematically investigated. X-ray diffraction (XRD) confirmed the formation of a hexagonal wurtzite phase with a pronounced (002) preferential orientation. Rietveld refinement analysis revealed that annealing led to a decrease in the lattice parameter c from 5.344 Å to 5.220 Å, an increase in crystallite size from 9.3 nm to 34.1 nm, and a reduction in microstrain from 0.0265 to 0.0027. Raman spectroscopy exhibited a sharper E₂^high mode at 438 cm^-1 and a suppressed defect-related A₁(LO) mode (583 cm^-1), evidencing enhanced crystallinity and defect passivation. Scanning electron microscopy (SEM) observations revealed grain coalescence and densification with increasing annealing temperature. The average optical transmittance improved from 70.8% to 82.2%, accompanied by a slight widening of the optical band gap from 3.22 eV to 3.27 eV. Hall measurements indicated a marked decrease in resistivity from 2.7 × 10^-2 Ω·cm to 5 × 10^-3 Ω·cm, yielding a maximum figure of merit of 1.68 × 10^-3 Ω^-1 at 500 °C. Overall, post-deposition annealing is shown to significantly enhance crystallinity, reduce structural defects, and improve the optoelectronic performance of ZnO thin films, confirming their suitability for transparent electronics and photovoltaic applications.

Abstract: Pyrolytic technology was developed to grow Zn-based nano- and microstructures. It was based on the application of a mixture of ammonium chloride, Zn and ZnO powders as source materials. Two temperature profiles were used for the synthesis. In the first and second growth processes, the maximum substrate temperatures of 250 and 410°C were reached, respectively. The granular layer of micrometer range ZnO crystals was produced in the first process. By depleting the source with NH₄Cl, the Zn polyhedra, and layered spheres were produced within 50–65 min in the second process. By increasing the NH₄Cl content in the source to 0.9 g, the Zn/ZnO core–shell spheres were synthesized. The further increase of process duration led to the out-diffusion of Zn from the core, its oxidation, and the formation of a thick, dense ZnO spherical shell. Even further annealing in residual gases caused the increase of the Zn vapor pressure inside the shell. As a result, at a certain Zn vapor pressure, the shell bursts, causing the formation of a hollow ZnO microsphere.

Abstract: Zinc oxide (ZnO) is a common photocatalyst for dye degradation, but its efficiency is limited by surface properties, photocorrosion, and pH sensitivity. This study functionalized ZnO with 2-aminophenol (ZnO-AP) to enhance dye adsorption and stability under varying pH. FTIR, XRD, and UV-Vis confirmed successful synthesis, with ZnO-AP showing a reduced band gap for improved visible light absorption. Photodegradation tests using Brilliant Blue G (BBG) revealed that ZnO-AP has the highest efficiency (36.17%) at pH 4, driven by strong electrostatic interactions. Performance decreased at pH 7 and 11 due to reduced dye adsorption, especially at basic pH with electrostatic repulsion. Functionalization also protected ZnO against photocorrosion, improving stability in acidic conditions. These results highlight 2-AP functionalization as a promising strategy to enhance the photocatalytic performance of ZnO across pH ranges.

Abstract: Zinc oxide (ZnO) thin films have attracted considerable attention due to their versatile applications in optoelectronic devices, transparent electrodes and surface acoustic wave devices. In particular, their photocatalytic properties make them interesting for wastewater treatment. In this study, we investigate the influence of substrate and film thickness on the structure and photocatalytic activity of ZnO thin films prepared by atomic layer deposition (ALD). The photocatalytic activity of ZnO films on Si, glass, Al, and porous Al substrates was investigated under UV irradiation, focusing on the decomposition of methylene blue (MB) as a model for an organic pollutant. To understand the mechanism of photodegradation, detailed information on the morphology of the nanostructured ZnO surface and the surface chemistry was obtained by scanning electron microscopy (SEM), secondary ion mass spectrometry (SIMS) and X-ray photoelectron spectroscopy (XPS). We have shown that the photocatalytic activity depends on ZnO film thickness and that it reaches saturation at a film thickness of about 20 nm, independent of the substrate. Furthermore, we compared the photocatalytic activity of ZnO films on flat substrates and porous aluminum (prepared by electrochemical anodization) at an optimal film thickness of 20 nm. Our results show that the ZnO thin film on porous aluminum has a significantly higher photocatalytic activity. After 300 minutes of UV lamp exposure, the ZnO thin film deposited on flat aluminum demonstrated the least photocatalytic activity, leading to a reduction of approximately 35% in the concentration of the MB solution. In contrast, the ZnO film coated on a porous anodic aluminum substrate exhibited the highest photocatalytic efficiency, with a reduction in the MB solution concentration by approximately 85%.

Abstract: Am-241 is an alpha emitting isotope which can be used to fuel a nuclear battery via alphavoltaic effect by using a semiconductor to convert alpha radiation to electricity. The main issue of alphavoltaic battery is the radiation damage due to high energy alpha particle, resulted in a rapid decline in performance. Zinc oxide (ZnO) is known as a semiconductor with high radiation tolerance. In this study, the effect of annealing temperature to ZnO crystal was studied along with its alteration due to Am-241 irradiation overtime. The annealing temperatures were set at 450°C and 650°C. The irradiation process was carried out using Am-241 isotope for 12 days with an activity of 44.85 mCi and approximately 0.0866 MGy of absorbed dose. The crystal structure of fabricated and irradiated ZnO were investigated through X-ray Diffraction (XRD). The XRD diffraction pattern indicates that the crystal structure of ZnO is hexagonal wurtzite and still maintained after irradiation process. Raising the annealing temperature from 450°C to 650°C leads to a reduction in peak intensity. This change correlates with an increase in grain size post-irradiation. After exposure to alpha particle radiation, changes occurred in the diffraction peaks of ZnO. At 450°C annealing temperature, the intensity decreased by 94.822%, while at 650°C annealing temperature, the intensity decrease was 85.489%. This shows that increasing the annealing temperature can reduce the decrease in intensity after irradiation with alpha particles. The (002) plane shifted by 0.057˚ at 450°C annealing temperature and by 0.042˚ at 650°C after irradiation. In addition, the crystal lattice parameters increased after irradiation, which led to a change in the FWHM value and an increase in the crystal grain size.

Abstract: Cassava shell starch and crab shell chitosan can be used as basic for bioplastics with glycerol and additives such as zinc oxide (ZnO) to improve their mechanical properties. This study used the variables of ZnO percentage and crab shell chitosan mass, which has never been done before. This research process was carried out in several stages, the first was bioplastic synthesis using cassava shell starch, glycerol, and crab shell chitosan with variations of 1 g and 1.5 g with zinc oxide (ZnO) of 3% and 5% of the total mass of starch. The limitations of the research are that the thickness of the tensile test samples is only 0.1-1 mm and the method for making bioplastics is the solution casting method. The second stage is characterization using FTIR to analyze the functional groups of cassava peel starch. Next, observe the morphology on the sample surface using an optical microscope, then a tensile test is carried out to calculate the tensile strength value using the ASTM D882 standard. The results of this research show that the highest tensile strength value for the 1.5 g chitosan and 5% ZnO variation was 10,353 MPa, while the lowest was for the 1 g chitosan and 3% ZnO variation at 4,526 MPa. The elongation value obtained was the highest in the variation of 1.5 g of chitosan and 3% zinc oxide at 10.508%. Meanwhile, the lowest ductility value was found in specimens with variations of 1 g of chitosan and 5% zinc oxide, amounting to 6.716%. The level of water resistance from the swelling test was found to be the highest with the 1.5 g chitosan and 5% zinc oxide variation with water absorption of 23.14%, however, the highest water absorption of 39.36% was obtained with the 1 gr chitosan and zinc oxide variation 3%. Optical microscope testing on the surface of samples of variations of 1.5 g chitosan and 5% zinc oxide showed the best physical properties. Therefore, the addition of reinforcement in the form of chitosan and zinc oxide affects the tensile strength value of the bioplastic film, where the higher the amount of reinforcement used, the higher the strength value produced.

Abstract: Gamma-aminobutyric acid (GABA) is a crucial inhibitory neurotransmitter that decreases nervous system activity by inhibiting signal transmission across synapses. Imbalances in GABA levels are linked to neurological diseases. This study developed an electrochemical sensor for detecting GABA using a ZnO/GO composite as the sensing material. Graphene oxide (GO) was synthesized via a modified Hummer’s method, while nanoparticulate zinc oxide (ZnO) was prepared using a solution combustion method. X-ray diffraction and morphological analysis showed crumpled graphene oxide sheets stacked into multilayers and a single phase of wurtzite-structured ZnO with a crystallite size of 69.37 nm; however, the particles tended to cluster together into larger agglomerates, leading to a reduction in specific surface area. The ZnO/GO composite demonstrated synergistic electrocatalytic activity. Cyclic voltammetry in GABA solutions (0.1 to 1000 µM) revealed distinctive oxidation and reduction peaks with sensitivity ranged from 0.0184 to 0.6629 µA mM^-1 mm^-2. Despite moderate electrocatalytic performance, the ZnO/graphene oxide composite shows potential as a GABA sensing material.

Abstract: Vulcanization of rubber compounds is a crucial step in the process of developing natural rubber end products. Selected components are then used to formulate a rubber compound, which is further treated to create vulcanized rubber. In this study, a palm oil-based zinc stearate compound (ZS) developed by the National Research and Innovation Agency (BRIN) was used as a replacement for ZnO and stearic acid, which were previously used as activator and co-activator in the process of vulcanization. The goal of this study was to create a compound made of rubber formulation for use in the hand grip. The zinc stearate applied in this study ranged from 4 to 6 phr. To examine the effect of applying zinc stearate to vulcanized rubber, three primary parameters - tensile strength, hardness, and elongation at break of the vulcanized rubber - were evaluated. The results of the tests revealed that adding zinc stearate at a loading rate of 4 phr gave the hardness value of 27 Shore A, the tensile strength of 19 MPa, and the elongation at break by 590%. With this mechanical characteristic, the formula was identified as the optimal choice for achieving a robust and deformation-resistant hand grip while ensuring user comfort.