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Sunlight Assisted Photocatalytic Degradation of Ciprofloxacin in Water Using Fe Doped ZnO Nanoparticles for Potential Public Health Applications
摘要： Antibiotic residues in the aquatic environment have the potential to induce resistance in environmental bacteria, which ultimately might get transferred to pathogens making treatment of diseases difficult and poses a serious threat to public health. If antibiotic residues in the environment could be eliminated or reduced, it could contribute to minimizing antibiotic resistance. Towards this objective, water containing ciprofloxacin was treated by sunlight-assisted photocatalysis using Fe-doped ZnO nanoparticles for assessing the degradation potential of this system. Parameters like pH, temperature, catalytic dosage were assessed for the optimum performance of the system. To evaluate degradation of ciprofloxacin, both spectrophotometric as well as microbiological (loss of antibiotic activity) methods were employed. 100 mg/L Fe-doped ZnO nanoparticle catalyst and sunlight intensity of 120,000–135,000 lux system gave optimum performance at pH 9 at 30 °C and 40 °C. Under these conditions spectrophotometric analysis showed complete degradation of ciprofloxacin (10 mg/L) at 210 min. Microbiological studies showed loss of antibacterial activity of the photocatalytically treated ciprofloxacin-containing water against Staphylococcus aureus (108 CFU) in 60 min and for Escherichia coli (108 CFU) in 75 min. The developed system, thus possess a potential for treatment of antibiotic contaminated waters for eliminating/reducing antibiotic residues from environment.
关键词： antibiotic residues,ciprofloxacin,Fe-doped ZnO nanoparticles,aquatic environment,sunlight,photocatalysis
更新于2025-09-10 09:29:36
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Identification of the shallow donor state in Sb doped ZnO by photoluminescence excitation spectroscopy
摘要： Photoluminescence excitation (PLE) spectroscopy was used to investigate the optical properties of the recently discovered 3364.3 meV antimony-related donor bound exciton (D0X) in zinc oxide. By suitable control of the growth conditions, we achieved samples in which the Sb-related donor emission was the dominant near-bandgap luminescence feature. Resonant excitation using a tunable UV source enabled the observation of the two electron transitions of the donor bound exciton, enabling the direct determination of the binding energy of the Sb donor at 42:2 + 0:5 meV, the lowest value yet reported for a donor in this material. The two electron transitions exhibit an unusual blue shift with increasing temperature, which is explained in terms of thermalization of excited states of the D0X initial state. The D0X excited states were probed by PLE and follow the trends of conventional shallow group III donors such as Al, Ga, and In.
关键词： binding energy,two electron transitions,shallow donor state,Photoluminescence excitation spectroscopy,Sb doped ZnO
更新于2025-09-09 09:28:46
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Effects of Au nanoparticles and ZnO morphology on the photocatalytic performance of Au doped ZnO/TiO<sub>2</sub> films
摘要： Au doped ZnO nanocomposite films on TiO2 seeding layer (AuZ/T) were fabricated by hydrothermal processing and their photocatalytic performance was investigated. It could be found that the AuZ/T with micrometer(μm)-sized, lying ZnO bulks revealed optimal photocatalytic performance toward methyl orange (MO) under simulated sunlight, whose apparent degradation rate constant Kapp of 1.31 was about 20% higher compared to that of ZnO/TiO2 and 3 times higher compared to that of ZnO. The Au nanoparticles, TiO2 seeding layer and hydrothermal processing time imposed vital influence on the morphology of ZnO nanostructures, which played key roles in the formation of ZnO/TiO2 heterojunction and charge transfer(CT) inside it, as demonstrated by kinetics of transient photoluminescence (PL) decaying. The incorporation of Au nanoparticles not only induced the variations of ZnO crystallinity and reduction of ZnO band gap (Eg), but also generated the Schottky heterojunction of metal-semiconductor, which would be beneficial to the CT inside nanocomposite films and separation of photo-generated electron-hole pairs, as verified by the remarkable PL suppression. The mechanism responsible for photocatalysis enhancement, which was resulted from the hybrid effects of Au nanoparticles and the ZnO morphology was discussed in details.
关键词： photocatalytic performance,Au doped ZnO,heterojunction,TiO2
更新于2025-09-09 09:28:46
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Structural, Optical, and Magnetic Properties of Hydrothermally Grown Fe-Doped ZnO Nanorod Arrays on Glass Substrate
摘要： In this paper, undoped and Fe-doped ZnO nanorod arrays were grown on glass substrate by a facile hydrothermal method. Structural, optical, and magnetic properties of the prepared nanorods were investigated. Structural investigation clearly showed that the prepared nanorods had single phase wurtzite structure without any secondary phases and the prepared undoped and Fe-doped nanorods were grown vertically. The optical characterization revealed that the optical band gap of ZnO nanorods was decreased by increasing the value of Fe concentration. Furthermore, the formation of diluted magnetic semiconductor nanorod arrays was verified. The origin of room temperature ferromagnetism is explained by the bound magnetic polaron concept.
关键词： Diluted magnetic semiconductors,Bound magnetic polaron,Nanorod arrays,Fe-doped ZnO
更新于2025-09-09 09:28:46
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Experimental study on microcapsules of Ag doped ZnO nanomaterials enhanced Oleic-Myristic acid eutectic PCM for thermal energy storage
摘要： Novel microcapsules of Ag doped ZnO nanomaterials enhanced Oleic-Myristic acid eutectic phase change materials (PCMs) were synthesized by in-situ polymerization process. X-ray diffraction analysis reveals that Ag doped ZnO nanomaterials has a hexagonal wurtzite structure. Nano enhanced composite PCMs are prepared by mixing different weight percentage of nanomaterials with Oleic-Myristic acid eutectic mixture act as core material. Microscopic analysis reveals the formation of uniform spherical structure of Melamine-Formaldehyde shell over the core material with a perfect core-shell structure. Differential scanning calorimetric analysis showed that microencapsulated PCMs (MEPCMs) melts and freezes in the range of 4.37-5.81 °C and 10.84-11.86 °C with the latent heat of 75.39-79.35 J/g and 74.9-77.95 J/g. MEPCMs have better thermal conductivity, stability and reliability determined by thermal conductivity, thermogravimetric and thermal cycling analysis. Based on the results, MEPCMs with Ag doped ZnO nanomaterials could be suggested as the potential core material for low temperature thermal energy storage applications.
关键词： Thermal stability,Ag doped ZnO nanomaterials,Thermal energy storage,Eutectic mixture,Microcapsules
更新于2025-09-09 09:28:46
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Diffusion-Driven Al-Doping of ZnO Nanorods and Stretchable Gas Sensors Made of Doped ZnO Nanorods/Ag Nanowires Bilayers
摘要： A crystal-damage-free nano-doping method, which utilized the vacuum drive-in diffusion of Al into ZnO nanorods, was developed. In this method, vertical ZnO nanorod arrays that were grown by chemical bath deposition beforehand were deposited with Al thin film and subsequently heat-treated under a high vacuum. At an optimum condition, the surface Al atoms were completely diffused into ZnO nanorods, resulting in Al-doped ZnO nanorods. Stretchable gas sensors were fabricated by sequentially drop-casting Al-doped ZnO nanorods and silver nanowires on PDMS substrate. The resistance and response of the sensor could be optimized through the elaborate control of relative densities of Al-doped ZnO nanorods and silver nanowires. The sensor showed a high response of 32.3% to 10 ppm of NO2 gas at room temperature, even under a large strain of 30%. The NO2-sensing mechanism of Al-doped ZnO nanorods/silver nanowires bilayer sensors is discussed on the basis of synergistic interplay of Al-doped ZnO nanorods and silver nanowires.
关键词： Al-doped ZnO nanorods,Stretchable gas sensors,bilayers,drive-in diffusion,silver nanowires
更新于2025-09-09 09:28:46
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Cr(III)-Doped ZnO Nanoflowers: Synthesis, Mechanism and Enhanced Photocatalytic Activity
摘要： ZnO is one of the most widely used photocatalyst, however, because of the wide band gap, its utilization for visible light is unsatisfactory. Therefore, current efforts are directed toward reducing the band gap of ZnO. Transition metal doping has emerged as a promising method, being capable of not only effectively reducing the band gap of ZnO, but inhibiting the recombination of electron–hole pairs. Cr(III)-doped ZnO nano?owers with different Cr/Zn molar ratios were synthesized by a mild, facile and eco-friendly solvothermal process. Subsequently, through various characterizations, it was con?rmed that the dopant Cr(III) entered the lattices of ZnO, substituting the Zn. Owing to the synergy of ?ower-like morphology and Cr(III) dopant, the photocatalytic activity of the products was signi?cantly improved. The optimal Cr/Zn molar ratio was 4%, and the photocatalytic activity of 4% Cr(III)-doped ZnO nano?owers was 1.3 and 3.4 times higher than that of pure ZnO under UV and visible light irradiation, respectively. In addition, the photocatalytic degradation kinetics of methyl orange were also discussed. Furthermore, the mechanism for the improvement in photocatalytic performance of Cr(III)-doped ZnO nano?owers was also investigated based on a series of characterization results such as the UV-vis diffuse re?ectance spectra, photoluminescence, photocurrent and the ?rst-principles calculation.
关键词： Photocatalytic Activity,Mechanism,Nano?owers,Cr-Doped ZnO
更新于2025-09-04 15:30:14
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Studies of Surface Electrical Properties of Al doped ZnO Nanorods by STM
摘要： Pure and aluminum (Al) doped ZnO (Al:ZnO) nanorods (NRs) were deposited on silicon substrates by the hydrothermal method. The Al composition was kept at 2 % and 5 % for the Al:ZnO NR samples. The surface morphology and structural properties of the pure and Al:ZnO NRs were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. The XRD study revealed the hexagonal phase of the ZnO with (101), (002) and (100) peaks and it also revealed that the major orientation of ZnO NRs was along the (002) planes. The SEM micrographs showed perfectly grown ZnO NRs with hexagonal shaped tips. The electrical characterization of the pure and Al:ZnO NR thin film surface was done by scanning tunneling microscopy (STM). Local electron spectroscopy was conducted to measure the tunneling current with respect to the applied bias. The n-type behavior and bandgap of the pure and Al:ZnO NRs were confirmed from the dI/dV – V characteristics. These studies are of fundamental importance for the fabrication of pure and Al:ZnO NR based nanodevices.
关键词： X-ray diffraction,Al doped ZnO,scanning tunnelling microscopy,nanorods,hydrothermal
更新于2025-09-04 15:30:14
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Ab-initio study on electronic and magnetic properties of (Ga,Co) co-doped ZnO
摘要： Using first-principles calculations based on density functional theory within GGA formalism, we have studied the electronic structure and magnetic properties of (Ga,Co) co-doped ZnO system. The effect of impurity distances on ferromagnetic and antiferromagnetic ground state in Co0.056Zn0.944O has been studied. For the closest Co-Co distance, a ferromagnetic ground state with total magnetic moment of ~3.00μμ’ per Co atom has been found. The electronic structure also displays a nearly halfmetallic order. Conversely, for the farthest Co-Co distance an antiferromagnetic ground state was found for Co0.056Zn0.944O. When Zn2+ ions are replaced by Ga ions in Co0.056Zn0.944O, the new (Ga,Co) co-doped ZnO system is more energetically stable. It has also been found that Ga-doping reduces the Co0.056Zn0.944O band gap due to the sp-d exchange interactions, which is in good agreement with the experimental data. Moreover, the Ga-doping changes the nearly halmetallic order of Co0.056Zn0.944O to metallic. Results also show that Ga0.029Co0.056Zn0.915O is still ferromagnetic with a total magnetic moment of ~3.00μμ’ per Co atom. It was also found that the ferromagnetic ground state in (Ga,Co) co-doped ZnO vanishes as Ga concentration increases.
关键词： GGA formalism,(Ga,ab-initio,density functional theory,electronic structure,Co) co-doped ZnO,magnetic properties
更新于2025-09-04 15:30:14
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Hydrogen Sensing Properties of Co-Doped ZnO Nanoparticles
摘要： In this study, the gas sensing properties of Co-doped ZnO nanoparticles (Co-ZnO NPs) synthesized via a simple sol-gel method are reported. The microstructure and morphology of the synthesized Co-ZnO NPs were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM), respectively. Co-ZnO NPs were then used for developing a conductometric gas sensor for the detection, at mild temperature, of low concentration of hydrogen (H2) in air. To evaluate the selectivity of the sensor, the sensing behavior toward some VOCs such as ethanol and acetone, which represent the most important interferents for breath hydrogen analysis, was also investigated in detail. Results reported demonstrated better selectivity toward hydrogen of the Co-ZnO NPs sensor when compared to pure ZnO. The main factors contributing to this behavior, i.e., the transition from n-type behavior of pristine ZnO to p-type behavior upon Co-doping, the modification of oxygen vacancies and acid-base characteristics have been considered. Hence, this study highlights the importance of Co doping of ZnO to realize a high performance breath hydrogen sensor.
关键词： Co-doped ZnO,gas sensor,sol-gel,nanoparticle,sensing mechanism,hydrogen,ethanol
更新于2025-09-04 15:30:14