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Papers by Asratemedhin Habtemariam

Research paper thumbnail of Synthesis of WO3 Nanoparticles using Rhamnus Prinoides Leaf Extract and Evaluation of its Antibacterial Activities

Biointerface Research in Applied Chemistry, 2021

Tungsten trioxide (WO3) is a transition metal oxide exhibiting unique properties suitable for var... more Tungsten trioxide (WO3) is a transition metal oxide exhibiting unique properties suitable for various applications as in electrochromic devices, gas sensors, photocatalysis, and antimicrobial activities. Preparation of WO3 nanostructures with controlled crystal structure and morphology is, thus, receiving greater attention. In this study, a facile and eco-friendly method was employed to successfully synthesis tungsten trioxide nanoparticles with monoclinic structure from Rhamnus prinoides plant leaf extract and sodium tungstate precursor. The obtained powder was characterized by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Fourier Transform Infrared (FTIR) spectroscopy. Antibacterial activities of the synthesized WO3 nanoparticles were evaluated against Gram-positive and Gram-negative bacteria such as Staphylococcus aureus, Listeria monocytogenes, Escherichia coli, and Salmonella typhimurium.

Research paper thumbnail of Chromium (III) Oxide Nanostructures Synthesized from Vernonia Amygdalina Leaves Extract

Letters in Applied NanoBioScience, 2020

This contribution reports first time synthesis of Cr2O3 nanostructures from chromium (III) chlori... more This contribution reports first time synthesis of Cr2O3 nanostructures from chromium (III) chloride hexahydrate precursor using Vernonia amygdalina leaves extract as a reducing and stabilizing agent. Powder X-ray diffraction, Fourier-transform infrared spectroscopy, and scanning electron microscopy techniques were used to study the structural and morphological properties of the as-synthesized Cr2O3 nanostructures. Powder X-ray diffraction patterns spectral analysis showed that hexagonal Cr2O3 nanostructures with an average crystallite size of 23.4 nm were synthesized with the minor appearance of CrO2. SEM images showed that the synthesized nanomaterials are granules. Fourier-transform infrared spectra represent a sharp absorption band at 552 cm-1, which indicates Cr-O-Cr vibrational and stretching modes.

Research paper thumbnail of Facile Synthesis of Nickel Oxide Nanoparticles Using Rhamnus prinoides Leaf Extract and Evaluation of its Antibacterial Activities

Regenerative Engineering and Translational Medicine, 2022

Synthesis of multifunctional oxide nanomaterials using a cost-effective and eco-friendly route is... more Synthesis of multifunctional oxide nanomaterials using a cost-effective and eco-friendly route is being extensively carried out in recent times. NiO is one among the many metal oxides that has various technological applications such as gas sensing and catalysis. In the present study, NiO nanoparticles were successfully synthesized from an aqueous extract of Rhamnus prinoides leaf which acts as reducing and stabilizing agents. The formation of NiO nanoparticles was confirmed by different techniques such as powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). In addition, Rietveld refinement analysis was also used to confirm the formation of face-centered cubic NiO nanoparticles. XRD pattern analysis revealed that the synthesized NiO nanoparticles have face-centered cubic structure in the bunsenite phase with an average crystallite size of 25.72 nm. FTIR spectral analysis of NiO exhibited the presence of a functional group responsible for the synthesis of NiO nanoparticles. Antibacterial activities of the synthesized nanoparticles were evaluated against Gram-positive (Staphylococcus aureus, listeria Mnocytogenes), and Gram-negative bacteria (Escherichia coli, Salmonella typhimurium) and the synthesized NiO nanoparticles exhibited effective growth inhibition property of Gram-negative bacteria. In summary, nano-sized NiO nanoparticles were successfully synthesized through a cost-effective and environmentally friendly method, and its effectiveness for Gram-negative antibacterial growth inhibition was tested. The green synthesis of nanoparticles using plant leaf extract is a good alternative to conventional synthesis methods because of the simple synthesis procedure and eco-friendly property. Moreover, the synthesized nanoparticles are stable compared to those synthesized by conventional methods. In this work, NiO nanoparticles were successfully synthesized and their antibacterial activity was tested to be effective for Gram-negative bacteria (E. coli).

Research paper thumbnail of Doped vanadium dioxide by hydrothermal and green processes: synthesis and physical properties

Research paper thumbnail of One-step hydrothermal synthesis and characterization of Mg/Mo co-doped VO2 nanorods

SN Applied Sciences

This paper reports the successful syntheses of Mg/Mo co-doped thermochromic vanadium dioxide nano... more This paper reports the successful syntheses of Mg/Mo co-doped thermochromic vanadium dioxide nanorods by hydrothermal technique. In particular, the effect of magnesium and molybdenum co-doping on insulator-metal transition of vanadium dioxide was investigated. The synthesized Mg/Mo co-doped VO 2 nanorods exhibited high purity and crystallinity. X-ray diffraction, scanning electron microscopy, X-ray energy-dispersive spectrometer, transmission electron microscopy, and Fourier transform (FTIR) were used to study the structure and morphology of the as-synthesized rods. X-ray diffraction patterns of the samples show an increase in intensity and a slight shift in the peaks toward lower 2-theta with increasing dopant concentration. The co-doping reduces ΔT c and has been considered as an effective method for manipulating the phase change in VO 2. The results revealed that smart radiation devices based on Mg/Mo co-doping of VO 2 can be a promising material for thermal control of spacecraft.

Research paper thumbnail of Effect of process parameters on the phase transition property of molybdenum-doped vanadium dioxide nanorods

Research paper thumbnail of Synthesis of WO3 Nanoparticles using Rhamnus Prinoides Leaf Extract and Evaluation of its Antibacterial Activities

Biointerface Research in Applied Chemistry, 2021

Tungsten trioxide (WO3) is a transition metal oxide exhibiting unique properties suitable for var... more Tungsten trioxide (WO3) is a transition metal oxide exhibiting unique properties suitable for various applications as in electrochromic devices, gas sensors, photocatalysis, and antimicrobial activities. Preparation of WO3 nanostructures with controlled crystal structure and morphology is, thus, receiving greater attention. In this study, a facile and eco-friendly method was employed to successfully synthesis tungsten trioxide nanoparticles with monoclinic structure from Rhamnus prinoides plant leaf extract and sodium tungstate precursor. The obtained powder was characterized by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Fourier Transform Infrared (FTIR) spectroscopy. Antibacterial activities of the synthesized WO3 nanoparticles were evaluated against Gram-positive and Gram-negative bacteria such as Staphylococcus aureus, Listeria monocytogenes, Escherichia coli, and Salmonella typhimurium.

Research paper thumbnail of Chromium (III) Oxide Nanostructures Synthesized from Vernonia Amygdalina Leaves Extract

Letters in Applied NanoBioScience, 2020

This contribution reports first time synthesis of Cr2O3 nanostructures from chromium (III) chlori... more This contribution reports first time synthesis of Cr2O3 nanostructures from chromium (III) chloride hexahydrate precursor using Vernonia amygdalina leaves extract as a reducing and stabilizing agent. Powder X-ray diffraction, Fourier-transform infrared spectroscopy, and scanning electron microscopy techniques were used to study the structural and morphological properties of the as-synthesized Cr2O3 nanostructures. Powder X-ray diffraction patterns spectral analysis showed that hexagonal Cr2O3 nanostructures with an average crystallite size of 23.4 nm were synthesized with the minor appearance of CrO2. SEM images showed that the synthesized nanomaterials are granules. Fourier-transform infrared spectra represent a sharp absorption band at 552 cm-1, which indicates Cr-O-Cr vibrational and stretching modes.

Research paper thumbnail of Facile Synthesis of Nickel Oxide Nanoparticles Using Rhamnus prinoides Leaf Extract and Evaluation of its Antibacterial Activities

Regenerative Engineering and Translational Medicine, 2022

Synthesis of multifunctional oxide nanomaterials using a cost-effective and eco-friendly route is... more Synthesis of multifunctional oxide nanomaterials using a cost-effective and eco-friendly route is being extensively carried out in recent times. NiO is one among the many metal oxides that has various technological applications such as gas sensing and catalysis. In the present study, NiO nanoparticles were successfully synthesized from an aqueous extract of Rhamnus prinoides leaf which acts as reducing and stabilizing agents. The formation of NiO nanoparticles was confirmed by different techniques such as powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). In addition, Rietveld refinement analysis was also used to confirm the formation of face-centered cubic NiO nanoparticles. XRD pattern analysis revealed that the synthesized NiO nanoparticles have face-centered cubic structure in the bunsenite phase with an average crystallite size of 25.72 nm. FTIR spectral analysis of NiO exhibited the presence of a functional group responsible for the synthesis of NiO nanoparticles. Antibacterial activities of the synthesized nanoparticles were evaluated against Gram-positive (Staphylococcus aureus, listeria Mnocytogenes), and Gram-negative bacteria (Escherichia coli, Salmonella typhimurium) and the synthesized NiO nanoparticles exhibited effective growth inhibition property of Gram-negative bacteria. In summary, nano-sized NiO nanoparticles were successfully synthesized through a cost-effective and environmentally friendly method, and its effectiveness for Gram-negative antibacterial growth inhibition was tested. The green synthesis of nanoparticles using plant leaf extract is a good alternative to conventional synthesis methods because of the simple synthesis procedure and eco-friendly property. Moreover, the synthesized nanoparticles are stable compared to those synthesized by conventional methods. In this work, NiO nanoparticles were successfully synthesized and their antibacterial activity was tested to be effective for Gram-negative bacteria (E. coli).

Research paper thumbnail of Doped vanadium dioxide by hydrothermal and green processes: synthesis and physical properties

Research paper thumbnail of One-step hydrothermal synthesis and characterization of Mg/Mo co-doped VO2 nanorods

SN Applied Sciences

This paper reports the successful syntheses of Mg/Mo co-doped thermochromic vanadium dioxide nano... more This paper reports the successful syntheses of Mg/Mo co-doped thermochromic vanadium dioxide nanorods by hydrothermal technique. In particular, the effect of magnesium and molybdenum co-doping on insulator-metal transition of vanadium dioxide was investigated. The synthesized Mg/Mo co-doped VO 2 nanorods exhibited high purity and crystallinity. X-ray diffraction, scanning electron microscopy, X-ray energy-dispersive spectrometer, transmission electron microscopy, and Fourier transform (FTIR) were used to study the structure and morphology of the as-synthesized rods. X-ray diffraction patterns of the samples show an increase in intensity and a slight shift in the peaks toward lower 2-theta with increasing dopant concentration. The co-doping reduces ΔT c and has been considered as an effective method for manipulating the phase change in VO 2. The results revealed that smart radiation devices based on Mg/Mo co-doping of VO 2 can be a promising material for thermal control of spacecraft.

Research paper thumbnail of Effect of process parameters on the phase transition property of molybdenum-doped vanadium dioxide nanorods