Ammonia sensor and antibacterial activities of green zinc oxide nanoparticles (original) (raw)
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Synthesis of ZnO/NiO nanocomposites for the rapid detection of ammonia at room temperature
Materials Science in Semiconductor Processing, 2019
This paper presents the facile synthesis of pure ZnO nanoparticles (NPs) and ZnO/NiO nanocomposites (NCs) and their ammonia sensing properties. The synthesis of ZnO/NiO NCs was done via a simple two-step process (co-precipitation followed by sol-gel method). Structural analysis of the prepared samples revealed the existence of hexagonal wurtzite structured ZnO and face center cubic structured NiO in ZnO/NiO sample. Surface morphological studies of the fabricated sensors show the porous nature, which further helps in enhanced sensing response. X-ray photoelectron spectroscope (XPS) results of ZnO/NiO NCs revealed the valence states of Ni (+2) and Zn (+2). Superior gas sensing response of the ZnO/NiO sensor towards ammonia at room temperature was observed from the gas sensing studies. The response of ZnO/NiO (~1208) was nearly 80 times higher than pristine ZnO (~15) towards 100 ppm ammonia at room temperature. Low detection limit was obtained for ZnO/ NiO sensor (8.27-1 ppm ammonia). The response and recovery times of ZnO/NiO were 5 s and 8 s respectively. The p-n junction formed between p-NiO and n-ZnO, and chemical sensitization and catalytic activity of the NiO contributed to the enhanced sensing performance of NiO/ZnO sensor.
ZnO: SnO 2 nanocomposite efficacy for gas sensing and microbial applications
The unique characteristics of 2-dimensional hetero structure offers efficient gas sensing with high selectivity to identify gases from the interference gases which is quite difficult. In the present work, ZnO: SnO 2 Nano composite clusters (NCC) is prepared. A resistive metal oxide volatile organic compound (VOC) gas sensor is fabricated with nullifying the effect of humidity by increasing temperature optimally. A single-step SOL-GEL (SG) synthesis is used to prepare ZnO: SnO 2 NCC with maximum Zn/Sn molar concentration ratio of 3. The morphological studies through Scanning Electron Microscopy (SEM), electrical properties due to oxygen vacancies and energy band variations of Nanocomposite are measured. The enhancement of gas sensor sensitivity due to highly mesoporous nature of the composite is observed. From the findings, the abundant mesopores in the range of 2 nm-14 nm and specific surface area of 54.2 m 2 g −1 with the average crystal size of 14.236 nm, and polar surface area of the composite 25.9651Åis achieved. When compared to bare ZnO and SnO 2 gas sensors, the present gas sensor offers the higher selectivity with enhanced performance due to the mesoporous structure. Fast repeatability rate of 2200 sec at 350C to ethanol is attained and the overall selectivity of the sensor increased twice as 2.085. The NCC compound is tested firstly with micro organisms such as B. subtilis (B. S), Bacillus cereus (B. C), B. coagulans (B. C), Pseudonymous auriginosa (P. A) are considered for antimicrobial activity. From the findings, zinc stannate compound showed good efficacy towards B. cereus Gram positive and P.A gram-negative. A bacterial growth is arrested highly with B. cereus.
Synthesis, Characterization and Ammonia Sensing Properties of Mn Doped Zinc Oxide Nano-Composite
International Journal of Science and Research (IJSR)
This paper reports the synthesis, characterization and ammonia sensing properties of nano-sized Zinc oxide (ZnO) and its nano composite Mn doped ZnO. A simple chemical co-precipitation method is used for the synthesis of ZnO nano-sized powder and its nano-composite. Zinc Acetate (Zn(C 2 H 3 O 2) 2) , Manganese acetate (Mn(CH 3 COO) 2 •2H 2 O) and the sodium hydroxide (NaOH) were used as a starting materials and double distilled water as a carrier. The resulting nano-sized powder was characterized by x-ray diffraction (XRD) measurements, transmission electron microscopy (TEM) and energy dispersive x-ray (EDAX). The NH 3 sensing properties of the synthesized nano-sized ZnO were investigated at different operating temperatures and NH 3 concentrations. The effects of operating temperature on the sensitivity, selectivity, response and recovery of the sensor in the presence of NH 3 and other gases were studied and discussed.
Effect of Particle Size on Ammonia SensingResponse of Zinc Oxide
2015
Efficient gas sensor was made with zinc oxide nanoparticles synthesized by mechanical alloying using high energy planetary ball mill. As received and milled zinc oxide nanoparticles were characterized with X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and UV-Vis Spectroscopy techniques. Morphological study was carried out by using Transmission Electron Microscopy (TEM). The particle size of ZnO nanoparticles was reduced from micron to nano meter range after milling for 45h. The Ammonia gas sensing response of as received and milled ZnO nanoparticles was studied from I-V characteristics plots obtained for different concentration of ammonia (50 to 600 ppm). The sensitivity of zinc oxide was observed to increase with decrease in particle size from micron to nanometer.
Antibacterial efficacy of zinc oxide nanoparticles synthesized by green and chemical methods
2024
Background: Zinc oxide (ZnO) as an antimicrobial and non-toxic agent has been widely explored in comparison with other materials. The green manufacturing of mineral nanoparticles using plant extracts has outperformed other manufacturing methods due to many advantages. Methods: ZnO nanoparticles (ZnO NPs) were synthesized using two distinct methods: chemical synthesis and a green method involving lemon leaf extract. The synthesized ZnO was characterized using UV-Vis, X-ray diffraction (XRD), scanning electron microscope (SEM) , and Fourier transform infrared spectroscopy (FTIR) analyses. The antibacterial activity of the resulting ZnO NPs was evaluated against two gram-negative bacterial strains, Escherichia coli and Pseudomonas aeruginosa, and one gram-positive strain, Staphylococcus aureus, using the etching diffusion method. Results: In this study, ZnO NPs were synthesized using a green method from an inexpensive and readily available source, lemon leaf extract, and compared with those synthesized by a chemical method. The results showed that ZnO NPs obtained via the green synthesis method had a semi-spherical shape with an average size of 14.25 nm, which is smaller than the average size of chemically synthesized ZnO NPs at 34 nm. The effectiveness of the ZnO NPs varied depending on the bacterial strain tested. Grampositive bacteria were more sensitive than gram-negative bacteria. Conclusion: ZnO NPs produced from lemon leaf extract were most effective against S. aureus. Chemically synthesized ZnO NPs were more effective against gram-negative bacteria.
Fabrication and antibacterial properties of ZnO–alginate nanocomposites
Carbohydrate Polymers, 2012
Alginate was used as a controlled environment for the growth of ZnO nanoparticles. The formation of nanostructured particles was confirmed by a blue shift in the onset of the optical absorption with respect to bulk ZnO. From the XRD measurements it was found that the obtained ZnO nanoparticles have a hexagonal crystal structure. The emission spectrum of the nanocomposite is dominated by a strong bandto-band recombination, while the emission from the ZnO defect states depended on the preparation conditions. Besides showing the presence of Zn 2p, O 1s, Na 1s and C 1s core levels, the XPS analysis also showed that the O 1s spectra can be resolved into two lines that are attributed to the presence of OH groups on the surface of the particles and ZnO, respectively. Antimicrobial tests revealed that the ZnO-alginate nanocomposite exhibits a strong activity against the common pathogens Staphylococcus aureus and Escherichia coli.
2020
In this paper, we report the green synthesis of ZnO nanoparticles by using the medicinal plant, Aloe Vera. Characterization of the prepared nanoparticles was carried out by various techniques such as field emission scanning electron microscopy (FESEM), elemental analysis (EDS), X-ray diffraction (XRD), ultraviolet-visible (UV-Vis), and Fourier-transform infrared (FTIR). The synthesized nanoparticles have the hexagonal wurtzite structure of an average grain size of 17 nm confirmed from X-ray diffraction analysis. Studies of antibacterial activity show that the synthesized ZnO nanoparticles have potential applications in this field. For antibacterial studies, we used Bacillus Subtilis and Staphylococcus Aureus as the gram-positive and Escherichia Coli and Salmonella Typhi as the gram-negative bacteria.
Ammonia sensors based on metal oxide nanostructures
Ammonia sensing characteristics of nanoparticles as well as nanorods of ZnO, In 2 O 3 and SnO 2 have been investigated over a wide range of concentrations (1-800 ppm) and temperatures (100-300 • C). The best values of sensitivity are found with ZnO nanoparticles and SnO 2 nanostructures. Considering all the characteristics, the SnO 2 nanostructures appear to be good candidates for sensing ammonia, with sensitivities of 222 and 19 at 300 • C and 100 • C respectively for 800 ppm of NH 3 . The recovery and response times are respectively in the ranges 12-68 s and 22-120 s. The effect of humidity on the performance of the sensors is not marked up to 60% at 300 • C. With the oxide sensors reported here no interference for NH 3 is found from H 2 , CO, nitrogen oxides, H 2 S and SO 2 .
Synthesis, Characterization of ZnO Nanoparticles and their Application in Antibacterial Activity
International Journal of Advanced Science and Engineering, 2022
The most cutting-edge field of the twenty-first century is nanotechnology. In comparison to their bulk counterparts, nanoparticles have grown significantly in importance due to their special features. Zinc oxide nanoparticles are among the most significant metal nanoparticles because they are used in optical, physical, and antibacterial characteristics, gas sensors, biosensors, cosmetics, medication delivery systems, and other products. ZnO NPs can be created via a variety of chemical processes, including the hydrothermal process, vapor transfer method, and precipitation method. Due to its great biocompatibility, affordability, and low toxicity, ZnO NPs have grown to become one of the most widely used metal oxide nanoparticles in biological applications over the past 20 years. By adjusting the growth temperature and precursor concentration, the hydrothermal technique was used to create stable, OH free zinc oxide (ZnO) nanoparticles. Fourier Transform Infrared Spectroscopy (FT-IR) and X-ray diffraction (XRD) results supported the formation of ZnO nanoparticles. It has been determined that the typical particle size is between 60 and 80 nm by particle size measurement using zeta sizer. By creating an agar-agar culture plate, ZnO nanoparticles as adsorbent materials were evaluated for the antimicrobial test by taking different microbial species. The zone of inhibition study was proved that ZnO nanoparticles were successful in limiting the bacterial growth in the petriplate culture media. According to experimental findings, among the chosen materials, ZnO NPs have demonstrated the best antifungal activity.
Sensing Performance of a ZnO-based Ammonia Sensor
Journal of Physical Science
Monitoring and remediation of toxic and flammable gases have become a critical task for the development of a clean society. Among various types of metal oxide semiconductors (MOS), zinc oxide (ZnO) is considered a potential material for gas sensing application because of its high sensitivity, easy synthesis, and high thermal stability behaviours. This research aimed to gain an in-depth understanding of the sensing task of a very stable and porous thin film of spin coated ZnO for detecting toxic ammonia vapour at room temperature. As-prepared ZnO films were characterised by x-ray diffraction (XRD), scanning electron microscopy (SEM), and ultraviolet-visible (UV-vis) analyses. XRD and SEM results revealed the polycrystalline wurtzite ZnO phase with grainy surface morphology. Optical calculations quantify the direct band gap of ZnO as 3.2 eV. The sensitivity measurements showed a good response ratio of 38.5 ± 0.6 with an exposure of 400 ppm of ammonia vapour. The results on sensitivity...