A First-Principle Study of Phosphorene-based Gas Sensors
S. M.S.
Seyyedi
الکترونیک، دانشکده مهندسی برق و کامپیوتر، پردیس دانشکده های فنی، دانشگاه تهران، تهران
author
M.
Roshankar
الکترونیک، دانشکده مهندسی برق و کامپیوتر، پردیس دانشکده های فنی، دانشگاه تهران، تهران
author
M.
Pourfath
الکترونیک، دانشکده مهندسی برق و کامپیوتر، پردیس دانشکده های فنی، دانشگاه تهران، تهران
author
text
article
2019
per
Two-dimensional materials have been the focus of research activities over the past decade.Their interesting and unique properties render them as excellent candidates for future electronic,optoelectronic, sensing, and bio applications. For gas sensing it is essential to maximize the ratio of thesurface to volume of the sensor, which is the case for two-dimensional materials. This work presents acomprehensive study on adsorption properties of H2S, NH3, CO, and NO on phosphorene, by employing firstprinciple calculations. The optimized atomic sites, directions and the associated adsorption mechanisms are carefully analyzed. Transfer of charge between the gas molecule and the layer modifies the layer’s resistance. By evaluating the resistance variation, the concentration of gas molecules can be determined. The results indicate that nitrogen-based molecules especially NO, show the highest sensitivity among the studied gases. In addition, strain effects on sensor characteristics and adsorption behavior are investigated. The optimal locations for the absorption of the gases and the mechanism of absorption energy under various strain conditions are analyzed. The results indicate that sensitivity increases with strain and significantly improves the selectivity of the sensor. The results show that both strained and unstrained phosphorene are suitable candidates for sensitive gas sensing applications.
Nanoscale
انجمن نانوفناوری ایران
2423-5628
5
v.
4
no.
2019
295
303
https://nanomeghyas.ir/article_46519_068265583ee89d6cb28a8fb30490049f.pdf
Investigation of NO Adsorption on the Rh-Cu Nanoclusters Supported on Graphene Nano Sheet by Density Functional Theory
A.
Ghasemi
دانشکده شیمی، دانشگاه سمنان، سمنان
author
A.
Arab
دانشکده شیمی، دانشگاه سمنان، سمنان
author
text
article
2021
per
The stable structures and different adsorption modes of RhxCu4-xx0-4 nanoclusters on the graphene nano sheet were studied by DFT using B3PW91 functional. Then, the adsorption of NO on the most stable structure of Graphene-Cluster was investigated. The results showed that adsorption of bimetallic Rh-Cu clusters on the graphene nano sheet was energetically more favored compared to the pure Cu4 cluster. Among bimetallic clusters, adsorption of Rh3Cu on the graphene nano sheet was energetically more favored compared to the pure Rh4 cluster. For all the studied adsorption modes of NO on the clusters, it was observed that adsorption from the nitrogen end was more favored than adsorption from the oxygen end. Also. Adsorption of NO on Rh atoms was more favored than adsorption on Cu atoms. Adsorption energies of NO were obtained in the -1.62 eV to -2.63 eV range indicating the strong interaction between NO and cluster. With increasing the amount of Rh in the cluster, the adsorption energy of NO increased in a regular trend and the maximum adsorption energy
Nanoscale
انجمن نانوفناوری ایران
2423-5628
5
v.
4
no.
2021
305
318
https://nanomeghyas.ir/article_46521_e36ef74b9d4cbf03672d9952cca0aef8.pdf
Absorption Enhancement of Spherical Nano-Shells Using Graphene Substrate
H.
Nouri Mahtaj
گروه مهندسی برق- مخابرات، دانشکده فنّی و مهندسی، دانشگاه بین المللی امام خمینی )ره(، قزوین
author
S.
Jarchi
گروه مهندسی برق- مخابرات، دانشکده فنّی و مهندسی، دانشگاه بین المللی امام خمینی )ره(، قزوین
author
A.
Keshtkar
گروه مهندسی برق- مخابرات، دانشکده فنّی و مهندسی، دانشگاه بین المللی امام خمینی )ره(، قزوین
author
text
article
2019
per
In this article the effect of using graphene substrate on absorption of spherical metallic gold Au and silver Ag nano shells has been investigated. In this study, for each one of two mentioned metallic nano shells, three kind of different dielectrics: air, silicon si and alumina Al_2 O_3, have been considered. Investigation, simulation and comparison of these nano shells have been done in two sizes of structure overall radius equal to 25 nm and 50 nm. According to performed studies on results, it is observed that utilizing graphene substrate under metallic nano shells increases amplitude of absorption. In this case, some parameters such as, thickness of metallic nano shells, thickness of graphene substrate, material of used dielectric, overall radius of structure and also material of surrounding medium are very effective on improving and increasing amplitude of absorption cross section ACS. So, to have maximum absorption, a trade of should be exist among mentioned parameters.
Nanoscale
انجمن نانوفناوری ایران
2423-5628
5
v.
4
no.
2019
319
327
https://nanomeghyas.ir/article_46523_5918fafebb0076ad2ea4fea82f56d317.pdf
Transmission Coefficient of a Lengthy Ladder-Like Graphene Nanoribbin Connected to Some Additional Benzene Rings
F.
Nadri
گروه فیزیک، دانشکده علوم پایه، دانشگاه شهرکرد، شهرکرد
author
M.
Mardaani
گروه فیزیک، دانشکده علوم پایه، دانشگاه شهرکرد، شهرکرد
author
H.
Rabani
گروه فیزیک، دانشکده علوم پایه، دانشگاه شهرکرد، شهرکرد
author
text
article
2019
per
In this paper, we consider the electronic transport of a ladder-like nanoribbon which is connected to some benzene rings in its small part by using Green’s function method and tight-binding approach. For this purpose, we first rewrite the Hamiltonian of the system in a way the Hamiltonian of the ideal parts converts to the Hamiltonian of two simple chains. The results show that the existence of extra rings makes conductance decreasing and creation of anti-resonance deeps in the transmission coefficient spectra in some cases. The electronic conductance of different configurations which are constructed with position variation of extra rings is studied and compared. Particularly, the value of the transmission coefficient in the Fermi energy for different configurations is taken into the investigation.
Nanoscale
انجمن نانوفناوری ایران
2423-5628
5
v.
4
no.
2019
329
334
https://nanomeghyas.ir/article_46526_0339097e5fb97c69e30ca3d44fd1c2fe.pdf
Sol-Gel Preparation, Characterization and Electromagnetic Interference Shielding of MWCNTBaTiO3/Silica Nanocomposite
M.
Tohidifar
گروه مهندسی مواد و متالورژی، دانشکده مهندسی، دانشگاه زنجان، زنجان
author
R.
Malekfar
گروه فیزیک، دانشکده علوم پایه، دانشگاه تربیت مدرس، تهران
author
text
article
2019
per
This paper investigated the preparation of a multi-walled carbon nanotube MWCNT-barium titanate/silica nanocomposite using a sol-gel technique. The synthesis was conducted using different amounts of MWCNT 2, 4, 6 and 8 wt. Scanning electron microscopy SEM, X-ray diffraction XRD, Fourier transform infrared spectroscopy FTIR, Simultaneous thermal analysis STA, Dielectric behavior and Electromagnetic interference shielding effectiveness EMI SE were used to characterize the as-synthesized specimens. It was found that the sol-gel process provided the nanocomposite with higher EMI SE value compared to the same nanocomposite prepared by the other methods. This is resulted due to a good mixing and homogeneous distribution of MWCNTs and other composite constituents. Results also indicated that the grain size of 98 nm for the nanocomposite prepared with 8 wt MWCNT and sintered at 750°C was concluded.
Nanoscale
انجمن نانوفناوری ایران
2423-5628
5
v.
4
no.
2019
335
346
https://nanomeghyas.ir/article_46528_e3d895bf4b9e889c974a4649c896a097.pdf
Preparation of Clinoptilolite Nanostructure from this Zeolite ore and its Application in Copper Ions Removal from Water
M.
Sheidaei
دانشکده شیمی، دانشگاه خوارزمی، تهران
author
A.
Balanejad Gasemsoltanlu
دانشکده شیمی، دانشگاه خوارزمی، تهران
author
A.
Beiraghi
دانشکده شیمی، دانشگاه خوارزمی، تهران
author
text
article
2019
per
In this work, natural clinoptilolite nanaostructures were prepared from natural zeolite and used to remove Cu2 cation from polluted water. In the first section the natural clinoptilolite particles were converted to nanostructures using a ball mill. The natural clinoptilolite and prepared nanostructures samples were characterized by SEM, XRD, and BET. The SEM images approved the development of clinoptilolite nanostructures. The result obtained from BET analysis indicated the increase pore volume of clinoptilolite nanostructures related to the clinoptilolite microparticles. In the second part of this work, the nanostructures were used as adsorbent for removal of Cu2 cation from polluted water. Effect of initial pH of solution, adsorbent dosage and contact time on the Cu2 removal efficiency was investigated, where the 6, 1.2 g/L and 6 were determined as optimum conditions, respectively. Isotherm and kinetics of the adsorption process were analyzed. The equilibrium data were fitted well to the Langmuir isotherm model and pseudo-second-order kinetic model.
Nanoscale
انجمن نانوفناوری ایران
2423-5628
5
v.
4
no.
2019
347
353
https://nanomeghyas.ir/article_46566_de5ab687863c71d6c4c4048d518829cf.pdf
Effect of Growth Condition on Charactristic of ZnO nanorods
Neda
Shahi
گروه فیزیک، دانشکده علوم پایه، دانشگاه ولیعصر )عج(، رفسنجان، استان کرمان
author
A.
Rahmati
گروه فیزیک، دانشکده علوم پایه، دانشگاه ولیعصر (عج)، رفسنجان، استان کرمان
author
P.
Iranmanesh
گروه فیزیک، دانشکده علوم پایه، دانشگاه ولیعصر )عج(، رفسنجان، استان کرمان
author
text
article
2019
per
One- dimensional well-aligned ZnO nanostructures nanorods array have been synthesized by low temperature method less than 120oC using seed layer. The effect of bath concentration and temperature, seed layer annealing and thickness was studied on nanorods density, diameter, height and their optical absorption. Post annealing of the synthesized nanorods causes to increase in crystalline qualityand perfected growth in c normal direction. The structure, morphology, chemical and optical, properties of ZnO NRs array were studied by X-ray diffractometery XRD, field emission-scanning electron microscope/energy dispersive X-ray spectroscopy FE-SEM/EDX and UV-Vis-near IR optical absorption spectroscopy,respectively. The height, mean diameter and density of trongly well-aliged ZnO NRs array are 190nm, 31-52nm and 290-413 rods/µm2 on ZnO seed layer, respectively. The annealing of ZnO NRs results in bandgap energy reduction to 3.19 eV in comparision to 3.29 eV for as-grown ZnO NRs. The increase in chemical bath temperature 110oC cause to random orientation in ZnO NRs and bandgap energy shrinkage. The annealing of seed layer in 200- 600oC decreases the densityas well decreases bandgap energy. The seedlayer thickness lowering decreases the ZnO NRs diameter and increases their density.
Nanoscale
انجمن نانوفناوری ایران
2423-5628
5
v.
4
no.
2019
355
368
https://nanomeghyas.ir/article_46567_61e00e297cd9f91bde06a282f3fb1bc3.pdf
Influence of Temperature and Frequency on Electrical Properties Nanocomposite Chloroindium Phthalocyanine-Polypyrrole
M. E.
Azim Araghi
گروه فیزیک حالت جامد، دانشکده فیزیک، دانشگاه خوارزمی، تهران
author
S.
Mahmoudi
گروه فیزیک حالت جامد، دانشکده فیزیک، دانشگاه خوارزمی، تهران
author
text
article
2019
per
In this research work, the AC electrical properties of nanocomposite chloroindium phthalocyanine-polypyrrole were studied. Nanocomposites (ClInPc+%5 PPy) & (ClInPc+%15 PPy) & (ClInPc+%25 PPy) were synthesized and Subsequently sandwich devices (Al/ClInPc+PPy/Al) were prepared on pre-cleaned glass substrates, which were deposited in a high vacuum device of the electron-beam gun in the pressure of 10-5 mbar. Capacitance and Dissipation factor were measured in the range of 102-105 Hz frequency and 307-383 K temperatures. the capacitance and loss factor reduced by increasing the frequency and enhanced by increasing the temperatures. The AC electrical properties thin films of our materials are in good agreement with Goswami and Goswami model. The dependence of the electrical conductivity on the frequency is analyzed by the equation σ(ω) = AωS which is typical for charge transport. The dominance of each mechanism depends on the experimental conditions and the temperature and frequency intervals. In this present research, the conduction mechanism is specified with hopping models. furthermore, the activation energies of the device are achieved as a function of frequency. The surface morphology of the nanocomposite thin film was investigated by field emission scanning electron microscope (FESEM) images.
Nanoscale
انجمن نانوفناوری ایران
2423-5628
5
v.
4
no.
2019
369
376
https://nanomeghyas.ir/article_46568_2e4d7e5991eac09c1fbfdd584bcbe836.pdf
Plasmonic Nano-pixels for Security Applications
E.
Heidari
آزمایشگاه سنسورهای نانوفوتونیکی و اپتوفلویدیک، دانشکده فیزیک، دانشگاه خوارزمی، تهران، ایران
پژوهشکده علوم کاربردی،دانشگاه خوارزمی، تهران، ایران
author
text
article
2019
per
In this paper, we developed full-color nano-pixels with a nanoscale resolution based on plasmonic nano-slits. For this purpose, we combine electron beam lithography and dry etching nanotechnologies to nanofabricate plasmonic nano-slits behaving as polarization-dependent nano-pixels. Arrays of this nano-pixels with different lengths and periods are used for generation of different colors and consequently storing information. In addition, finite-difference time domain method is used to investigate the selection rule and the electric field distributions in these plasmonic nano-slits and compared them with the experimental results. It is revealed that the electric field distribution is perpendicular to the polarization of the excitation white light and the concentration is on the sharp edges close to the center of the nano-slits on the top and the bottom sides. These plasmonic surfaces are promising for anti-counterfeiting applications due to their nanoscale details, lack of the public access to the fabrication equipment and fabrication expertise. Therefore, these plasmonic surfaces have a great potential to be used for development of the next generation of credit cards, security labels and bank notes.
Nanoscale
انجمن نانوفناوری ایران
2423-5628
5
v.
4
no.
2019
377
381
https://nanomeghyas.ir/article_46569_b8fce51444fc943f2e56e0e3c440bd75.pdf