فصلنامه نانو مقیاس
سال نهم شماره 1 (پیاپی 33، بهار 1401)

Luminescent solar concentrator (LSC) is a promising technology to reduce the cost of solar power conversion. Perovskite quantum dots are promising candidates as luminescent material in the LSC, due to their suitable absorption/emission spectra as well as high luminescent quantum efficiency. Absorption/emission spectra with the least overlap, luminescent quantum efficiency, concentration of quantum dots in LSC, and LSC surface area and length are the most important parameters affecting the optical efficiency of the LSC. Here, we investigated the effect of all the aforementioned parameters on the optical efficiency of the LSC by Monte Carlo simulation method. The simulation results show that Mn:MAPbCl3 quantum dots serves better than MAPbCl3 quantum dots in the LSC. This can be attributed to the lower overlap between the absorption and emission spectra for the Mn:MAPbCl3 compared to MAPbCl3 quantum dots. More suitable properties of Mn:MAPbCl3 quantum dots let us to make longer LSC with larger surface area.

A theoretical study of the electronic, thermoelectric and thermal properties of two-dimensional nanomaterial C18N6 is presented using density functional theory (DFT). Our calculations indicate that two-dimensional nanomaterials C18N6 have a direct band gap in the center of the Brilluin region of 2.2 eV. The predicted Seebeck coefficient is 2888 μV/K and decreases with increasing temperature. Electrical conductivity, thermoelectric conductivity and power factor are in maximum positive chemical potential values. It also has good thermoelectric properties in the temperature range of 500 to 700 K.

Recent astonishing progresses in crystal growth technology, i.e. molecular beam epitaxy, have provided the possibility of fabricating quantum well structures in which electrons confined to move in one or two dimensions. The motion of electrons in such semiconducting structures is confined and leads to size quantization effects. In this research, we investigated the limited mobility by ionized impurity scattering or from the uniform distribution of remote impurity for a one-dimensional semiconductor device such as n-type gallium arsenide and Indium Arsenide nanowire, which first calculated and then plotted. The effect of various relevant physical parameters such as temperature and radius and impurity density on mobility has been investigated. Numerical results show that limited mobility increases uniformly and slowly with increasing temperature due to background impurity scattering, while limited mobility increases rapidly with temperature due to scattering of remote impurities. It has also been shown that the mobility for both impurities decreases with increasing wire radius and with increasing density, mobility increases. The results obtained from this investigation are in agreement to recent experimental and theoretical data.

In this paper, a binary full adder circuit is designed with eight quantum rings where each ring is threaded by a magnetic flux phi0/2. The quantum rings are divided into two categories with four rings connected to each other in parallel. They are attached symmetrically to two semi-infinite one-dimensional metallic electrodes, and three gate voltages are applied as three inputs of the full adder. The Hamiltonian of the system is approximated by the tight-binding method, and the calculations are performed by using Green’s function formalism. The conductance-energy and current-voltage characteristics are obtained for different values of applied gate voltage. The results show this quantum circuit behaves as a binary full adder.

Twisted Bilayer Graphene (TBLG) is formed when two layers of graphene are twisted at a small angle. In this paper, the electrical structure, adsorption mechanism, density of states (DOS), partial density of states (PDOS), charge transfer process, band structure and TBLG recovery time with and without copper impurities have been investigated to identify oxygen. Changes in Fermi energy, adsorption energy, increase in the area under the DOS confirm the increase in sensory properties of Cu-doped TBLG . The results also showed that Cu-doped TBLG semiconductor acquires conductive properties by adsorbing oxygen. On the other hand, the calculated results for Cu-doped TBLG recovery time show that oxygen adsorption on this structure is more stable compared to TBLG. Accordingly, the Cu-doped TBLG compound for sensor applications at temperatures above room temperature and TBLG at temperatures below room temperature are introduced. The working temperature of the oxygen sensor was 60 K for TBLG with a working time of 28 S and 1600 K for the Cu-doped TBLG with a working time of 118 S.

In this work, the effects of static electric field (SEF) and ion field (hydrogen ions (nH+) on the interaction of cyanogen bromide (BrCN) with boron nitride nanocage (B12N12) using density function theory (DFT) and time-dependent density function theory (TD-DFT) have been investigated. Using optimized configurations the parameters of structural, electrical, quantum and thermodynamic, adsorption energy, quantum theory of atoms in molecules (QTAIM), reduced density gradient (RDG), nonlinear optical properties (NLO), ultraviolet-visible spectra ( UV-Vis) are calculated. The calculated results indicate that the amount of adsorption energy, enthalpy (∆H) and Gibbs free energy (∆G) are negative for all adsorption states and the adsorption process of cyanogen bromide on the surface of B12N12 nanocage is thermodynamically exothermic and spontaneous. With increasing electrical field strength from SEFz-0.005 a.u to SEFz-0.07 a.u and H+ ionic field, the adsorption energy increase and gap energy between the HOMO and LUMO orbitals significantly reduce, so the sensitivity of the nanocage to adsorb and detect of toxic cyanogen bromide increase.

In this paper, the electronic properties of AGNRs defected by quantum antidots is studied. The defected AGNRs are introduced by imposing linear, diagonal, triangle, hexagonal and symmetric and asymmetric rhomboid topologies of antidots in the middle of pristine nanoribbons which leads to antidot super-lattice of AGNRs. It can be realized that the quantum confinement of nanoribbons is quite changed by the presence of defects. This new quantum confinement leads to the new electronic properties. In addition, the electronic properties of nanoribbons are investigated by scaling dimensional parameters such as the distance between two adjacent antidots(d). Finally, one can extracted that the electronic properties of armchair graphene nanoribbons can be tuned by changing dimensional parameters. Numerical tight-binding model, coupled with the non-equilibrium Green’s function formalism are applied to extract the electronic properties of nanoribbons.

In this study, the DD3R zeolite powder and membrane were synthesized via a secondary growth method. The XRD and SEM analyses show the successful synthesis of the DD3R zeolite powder and membrane. The calcination of the membrane was carried out at 500 ◦C with a heating rate of 0.2 ◦C/ min. The N2 gas permeation test was carried out at different temperature steps simultaneously with increasing the temperature. The results show that after 425 ◦C, N2 permeation increases by about 100 times, which indicates thermal shock and creating non-zeolite pores with size in nanometric range in the membrane. The calcination of another membrane at 500 ◦C with a heating rate of 0.1 ◦C/ min also was resulted in defects of the membrane. Finally, the calcination of the DD3R membrane at 425 ◦C with a heating rate of 0.2 ◦C/min prevented thermal shock, and then the defects were minimized in the membrane. So that, the perm-selectivity of CO2/CH4 and N2/CH4 were measured 10-11 and 4-5, respectively.

In this study, graphene oxide immobilized on chitosan contains cobalt ferrite (CoFe2O4@CS@GO) as a new recyclable magnetic nabnocatalyst was used in the synthesis of bis(aminopyrimidine) derivatives by the reaction of aromatic aldehydes and 6-aminouracil in ethanol with good to excellent yields under reflux conditions. The CoFe2O4@CS@GO catalyst can be easily recovered by magnetic separation and used several times without significantly reducing its catalytic activity. The catalyst was characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermal gravimetric analysis (TGA), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDs) and vibrating sample magnetometer (VSM).The high efficiency of the products and easy separation of the nanocatalyst from the products with external permanent magnet are some advantages of this method. Products were identified by the comparison of their physical properties and spectra data, with those reported for authentic samples.

In this research, Co-BDC coordination polymer nanoparticles were grown on the surface of cellulose-based substrate (filter paper). First, filter paper is functionalized with chloroacetic acid in alkaline media and COO‒ groups are placed on its surface. The grafting process is facilitated by surface functionalization of the cellulose fibers, and terminal carboxylate groups act as appropriate sites to coordinate Co(II) ions. By adding benzene-1,4-dicarboxylic acid (H2-BDC) rapid nucleation on the porous support surface is began and coverage of coordination polymer on the surface of the filter paper is confirmed by scanning electron microscopy (SEM). The functionalized filter paper with coordination polymer nanoparticles is used as an adsorbent which demonstrated rapid and effective removal of methylene blue (MB) (82% after 60 min). This approach delineates an efficient pathway toward grafting the water stable Co-BDC on the filter paper with potential far-reaching applications such as dye removal from aqueous solutions.

In this research, two-dimensional graphene nanostructure as a coating and copper with 111 crystal orientation as a substrate were simulated. All simulations were performed by molecular dynamics using LAMMPS software. Simulation results on systems with different number of molecules Water droplets show that for nanoparticles consisting of 4000 molecules and above, the contact angle is independent of the nanoparticle size. Therefore, nanoparticles consisting of 4000 molecules were used. In order to investigate the role of the substrate on the occurrence and persistence of graphene wetting transparency, we changed the interaction power of copper atoms with water molecules and investigated the state of graphene wettability transparency in each case. The results showed the occurrence of graphene wetting transparency in all cases. In the final part, simulations were performed for graphene pair nanorods. The interaction strength of each of layers 1 and 2 with water molecules in different states was investigated in three states of equal interaction, strong on weak and weak on strong. . The sum of the results showed that the interaction strength of the upper coating has a more prominent role on the wettability of the system compared to the lower coating.

In this study, pyrite nanoparticles (FeS2) were prepared using a new method. The nanoparticles were characterized using Fourier transform infrared spectroscopy, X-ray diffraction spectroscopy and scanning electron microscopy. Electronic microscope images showed an approximate particle size of about 20 nm. The nanoparticles were coated on a glass-carbon electrode as substrate and the electrochemical capacitive behavior of the electrode was investigated by cyclic voltammetry at different scan rates and different electrolytes including KOH 6M, H2SO4 1M, NaOH 3M, Na2SO4 1M. Experimental results and surface calculations below the voltammetry curves showed that the electrode in H2SO4 1M electrolyte with a specific capacity of 17.18 farads per gram has the best supercapacitor performance.

In this study, the synthesis of gold nanoparticles and its anti-cancer properties were studied. In order to obtain gold nanoparticles with morphology, appropriate size and stability of microwave, sonochemical and green synthesis methods using HAuCl4, tri sodium citrate, PVP (polyvinylpyrrolidine), chitosan and beet extract were used. Morphology, uniform distribution and the size of nanoparticles synthesized by XRD, SEM, FT-IR, UV-Vis and TEM devices were studied. Nanoparticles are easily introduced in to cancer cells, which is why the nanoparticles synthesized by this method for experiments involving the interaction of gold nanoparticles with DNA of the calf thymus gland DNA (CT-DNA) using UV-Vis spectroscopy technique in trace buffer containing chloride Sodium (10 mM) and pH = 7 at 300 K were studied. The cytotoxicity studies of gold nanoparticles by MTT on the breast cancer cell line (MCF-7) showed Ic50 of gold nanoparticles of 24.1. Therefore, these nanoparticles are capable of inhibiting the activity, growth and proliferation of cancerous cells at low concentrations

In order to better understand and improve the treatment of cancer, the study of the structural properties and mechanical properties of healthy cell tissues is of great importance. Therefore, the process of Nano manipulation of cancerous and healthy tissues using atomic force microscopy leads to the recognition of this disease. In this study, the critical force and time of gastric cancer tissue in the manipulation process have been evaluated by considering frictional forces with different models. In the general process of manipulation, a critical force occurs when overcoming resistive forces such as friction, and the high force causes damage to cancerous tissues. Coulomb, LuGre and HK friction models have been used in this research. By analyzing the topographic images obtained by atomic force microscopy, the geometry of gastric cancer tissue is assumed to be spherical. The simulations are performed by different friction models. Graphs of all forces are plotted in 2D manipulation, and the resultant force diagram is used for comparison. After fixing the amount of force in different friction models, the amount of force and critical time are considered. The lowest force and critical time for gastric cancer tissue were also recorded for the LuGre friction model with 0.51 nN and 64 ms.

In this study, zinc oxide (ZnO) nanoparticles were synthesized using Wild Mentha pulegium extract without the use of chemicals and then embedded in chitosan biopolymer. The optical, structural and morphological properties of the prepared ZnO were investigated by various characterization methods including UV-vis, XRD, EDAX, FTIR and FESEM measurements. The average size of ZnO nanoparticles was estimated to be 45.4 nm using the Debye Scherrer equation. Also, X-ray diffraction result showed that the synthesized sample has a wurtzite crystal structure without any additional or oxide peaks and it is consistent with previous reports. According to the results obtained from the EDX-Map measurement, the presence of Zn in the structure that was synthesized using the extract was confirmed. Also, the prepared transparent and biocompatible polymer coating showed good antibacterial and UV filtering properties for packaging applications.

Among the various electron transport layers used in perovskite solar cells, titanium oxide (TiO2) is by far the most efficient electron transfer layer. But the high recombination of electrons and holes in the titanium oxide layer is a problem that researchers face. Researchers have tried to solve this problem by doping various additives in this layer. In this study, for modification this defect, polyaniline was added to the precursor of the titanium oxide mesoporous layer (mP-TiO2) to improve the performance of the perovskite methyl ammonium solar cell. Scanning electron microscopy images showed the morphology, crystallinity, and coverage of the perovskite film deposited on the mP-TiO2 substrate doped with polyaniline at volume ratios of 2%, 4%, and 8% compared with the perovskite film deposited on Pure mP-TiO2 substrate have improved. By adding polyaniline to the mP-TiO2 layer with different volume ratios, open circuit current density(J_SC) and charge factor (FF) were increased. The increase in these parameters is due to the reduction of recombination at the TiO2 / perovskite interface as well as reduction of charge traps, which improve cell performance. Cells made on the modified mP-TiO2 substrate with a volume ratio of 4% polyaniline show the best morphology, crystallinity and performance(7.31%).

In this research Double perovskite BiCr1-xCoxO3 (BCCO) with x=0, 0.15, 0.3, 0.5 (BCCO, BCO-15CO, BCO-30CO, BCCO) Thin films were prepared by Sol-Gel and spin coating method. The formation of crystal phase was investigated using X-ray diffraction. Ultraviolet-visible spectroscopy was used to determine the band gap of these materials. The results show that by increasing the percentage of cobalt in the samples, an indirect band gap is formed in them, which is much smaller than the direct gap and increases the adsorption. The experimental results obtained are consistent with theoretical research on the optical properties of this material.

In this study, the effect of elastomeric nanoparticles on the thermal and cure kinetic behavior of epoxy resin was investigated. The thermal behavior of epoxy resins and epoxy nanocomposites were investigated at three different temperatures of 65, 70, and 75 oC under isothermal conditions . For this purpose, scanning electron microscopy and differential scanning calorimeter tests were used. Morphological examination of epoxy nanocomposites showed that the appearance of elastomeric nanoparticles is spherical and shows good dispersion in the epoxy matrix at both 0.5% and 1%.Examination of the heat flow of epoxy resin and epoxy nanocomposite showed that it initially increases and decreases after reaching a maximum point and by adding elastomeric nanoparticles the degree of curing, the total enthalpy of the reaction and the peak heat flow time increased .Curing kinetics modeling showed that epoxy resin and epoxy nanocomposites follow the nth-order model and with increasing the presence of elastomeric nanoparticles, the activation energy decreased and this type of nanoparticles plays a catalytic role in reaction with epoxy resin and laboratory data are in good agreement with the results of curing kinetics modeling.

In recent years, the use of nanosensors for the development of research in nuclear technology has had a special place. Due to the high accuracy in absorbing, detecting and measuring gamma rays, these devices are noticed well. In this study, the development of composite gamma nanosensors of cadmium telluride quantum dots using gadolinium ion paramagnetic ions was considered. The nanocomposite was synthesized using a polyvinyl acetate matrix containing characterized cadmium telluride quantum dots doped with gadolinium. The nano-sensor was then fabricated using gold-plated copper electrodes. The characteristics of nanosensors against gamma ray were investigated and compared with other nanosensors without gadolinium ion. The results showed that nanosensors with gadolinium ion in the structure of quantum dots have better and more accurate performance as gamma ray probes.

Recent studies have demonstrated the ultrafast water flow through smooth carbon nanotubes. Several reasons have been suggested for this phenomena, one of the most important of which is the smoothening of the potential energy landscape felt by water molecules. In practice, carbon nanotubes may not have a perfectly simple smooth geometry. This feature can be cuased by any kind of defects during practical construction or deliberately created to provide nanochannels with specific applications. Molecular dynamics simulation method has been employed to study the effect of wall roughness and the rate of wettability of nanochannel’s wall on the transport of water in carbon nanotubes. We start with a (10,10) carbon nanotube (CNT) as our reference channel and generate nano-junctions by attaching other CNTs with larger radius but same length to it. This pattern is repeated alternately and as many as time desired. In adittion to the effect of wall roughness, another effective parameter is the wettability of nanochannel’s wall that can be adjusted by varying the interaction strength between tube wall and water molecules. Our results show that the fluid-wall friction coefficient increases compared to smooth nanotubes and also friction coefficient increases with increasing roughness in nanotubes (increasing the amplitude or decreasing the wavelength of roughness), while the slip legth decreases. In addition, we observed that by reducing the interaction parameters the friction coefficient decreases compared to the hydrophilic case. Finally, from the analysis of our simulations we obtain a useful insight into the equilibrium structure of water and the dependance of quantities such as friction coefficient, viscosity and slip length on wettability and roughness of carbon nanotubes. While the results of first stage, i.e the filling of nanotube with water, aid in improving our previous knowledge about the capillary effect in rough carbon nanotubes.