Articles
Physica Scripta (00318949)100(1)
In this study, a novel approach has been utilized to Please specify the corresponding author.explore the room temperature thermoelectric properties of zigzag phosphorene nanoribbon-based monolayer-bilayer-monolayer junctions. To achieve thermoelectric properties at room temperature, a quasi-flat energy band with limited width is required. It has been demonstrated, for the first time, that such bands can be observed by considering a junction of the monolayer and bilayer phosphorene nanoribbons. By adjusting the ribbon widths, quasi-flat bands are produced. This geometrical problem is solved using analytical calculations for a general system and applied to phosphorene. We show that the edge states of phosphorene resemble a one-dimensional tight-binding system, with a close agreement between their results. Using the introduced approach, we calculate the electronic energy band structure of the specified system. Initially, we demonstrate that the formation of zigzag monolayer-bilayer-monolayer junctions can lead to the emergence of quasi-flat impurity bands within the energy bandgap. Furthermore, we show that utilizing these structures at room temperature, across a wide range of lead temperature differences, results in significant output electrical power and improved thermoelectric efficiency. The electrical power and thermoelectric efficiency are examined as functions of applied bias voltage and average chemical potential. Additionally, we explore how the output electrical power, thermoelectric efficiency, and efficiency at maximum power vary with the temperature difference between the leads at the ends of the structure. © 2024 IOP Publishing Ltd. All rights, including for text and data mining, AI training, and similar technologies, are reserved.
Iranian Journal Of Materials Science And Engineering (17350808)22(1)pp. 37-50
Nanomaterials have significantly transformed multiple scientific and technological fields due to their exceptional properties resulting from their quantum confinement effects and high surface-to-volume ratios. Among these materials, zinc oxide (ZnO) and titanium dioxide (TiO 2) nanoparticles have attracted considerable interest because of their diverse applications. In this study, TiO2-ZnO nanocomposites were synthesized using varying calcination times of 1, 1.5, 2, 2.5, and 3 hours. Characterization of fabricated samples through X-ray diffraction (XRD) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), and energy-dispersive X-ray spectroscopy (EDXS) confirmed the successful fabrication of the nanocomposites. In this regard, XRD analysis revealed anatase TiO2 and hexagonal wurtzite ZnO phases. Raman spectroscopy also supported these findings, identifying characteristic peaks of both TiO2 and ZnO. The calcination time had a minimal effect on the crystal structures and the nanocomposites' morphology, which gave rise to its negligible impact on the samples' optical properties and biological activities. Optical properties assessed using UV-visible and photoluminescence (PL) spectroscopy showed consistent band gap absorption and emission profiles across all samples, among which the nanocomposite calcined for 1 hour exhibited the best optical properties. The sample prepared at 1 hour showed the most favorable optical properties and significant antibacterial, antifungal, and cytotoxic activities, making it suitable for various applications. In this regard, more than 99.9% reduction occurred in the number of Escherichia coli, Staphylococcus aureus bacteria, and Candida albicans fungus using TiO2-ZnO nanocomposite. Besides, adding 500 µg/ml of nanocomposite decreased the cell viability to 34.47%, which signifies its high cytotoxicity activity. © 2025, Iran University of Science and Technology. All rights reserved.
