Sharif Digital Repository

A low-cost carbon cloth is applied in perovskite solar cells (PSC) as a collector composite and degradation inhibitor. This study incorporates carbon fibers as a back contact in perovskite solar cells, which results in enhancement in all photovoltaic parameters. This material is suitable for large-scale fabrication of PSCs as it has shown an improved long-term stability when compared to the gold counterpart under elevated temperatures  

A composition of multiwalled carbon nanotube (MWCNT), Nafion and cobalt(II)-5-nitrosalophen (CoNSal) is applied for the modification of carbon-paste electrode (CPE). The pretreated MWCNT is well dispersed in the alcoholic solution of Nafion under the ultrasonic agitation, and the resulted suspension is used as modifier (with 10% w/w) in the matrix of the paste electrode. The prepared electrode further modified by addition of 3 wt% of CoNSal. The resulted modified electrode is used as a sensitive voltammetric sensor for simultaneous determination of uric acid (UA) and ascorbic acid (AA). The electrode showed efficient electrocatalytic activity in lowering the anodic overpotentials and... 

This article describes the hydrogen storage capacity in different carbon nanotubes. The hydrogen storage capacities in the armchair, zigzag, and chiral nanotubes are investigated. The hydrogen storing capacities as a function of the carbon nanotube (CNT) diameter are investigated for the single-walled (SWNT), multi-walled (MWNT), and CNT bundles and results are compared. Hydrogen storage capacity in SWNTs is increased by increasing the nanotube diameter. For diameter d=0.3887 nm of (5,0) CNT the hydrogen capacity is 0.99%, while for the (17,17) SWNT with a diameter d=2.289 nm the capacity is increased to 5.06%. In comparison of different MWNTs for a common external diameter d=1.6064 nm the... 

A mini-column was made by packing α-diphenylglyoxime (DPG), a known ligand for complexation with nickel ions, loaded on activated charcoal (AC). Water samples were buffered at the pH range 8-9 and then passed through the column. After the preconcentration step, the column was eluted with 0.2 M nitric acid into the atomic absorption spectrometer (AAS). Mixed-level orthogonal array design (OAD) was used as a chemometric approach to study the effect of various factors on recovery of extraction. Factors such as pH, amount of sorbent, flow rate of sample, concentration and volume of the sample were investigated. Effects of interference ions, i.e., Co, Cu, Bi, Fe(I1), Pt and Pd was also studied.... 

Corrosion of mild steel in aqueous solutions containing carbon dioxide was modelled under condition that protective iron carbonate films formed on the steel surface. In this model, the film form on the steel surface due to precipitation of iron carbonate from saturated solution. The precipitation of iron carbonate produces a porous layer on the steel surface, reducing the diffusion of species toward the steel surface. If the precipitation rate is high, the porosity decreases and the mass transport becomes slower. Therefore, formation of protective layers on the steel surface reduces the corrosion rate. In this case, the corrosion processes are controlled with diffusion of species. The model... 

Low structure carbon black (CBN330), conductive high structure carbon black (CBXE2B) and carboxylated multiwalled carbon nanotube (MWCNT) were loaded into the blend of natural rubber (NR) and styrene butadiene rubber (SBR) at different contents up to 10 phr. Kraus plots showed that all the reinforcements interact with NR/SBR blend appropriately. However, the CBXE2B whose interfacial area is the highest showed greatest value of Kraus interaction parameter. Flory-Rhener model and effective torque value revealed that all of the reinforcements enhanced the crosslink density, among them CBXE2B showed the highest impact and MWCNT placed in the second rank. It was also shown that the cure kinetic... 

Carbonated water injection (CWI) is known as an efficient technique for both CO2 storage and enhanced oil recovery (EOR). During CWI process, CO2 moves from the water phase into the oil phase and results in oil swelling. This mechanism is considered as a reason for EOR. Viscous fingering leading to early breakthrough and leaving a large proportion of reservoir un-swept is known as an unfavorable phenomenon during flooding trials. Generally, instability at the interface due to disturbances in porous medium promotes viscous fingering phenomenon. Connate water makes viscous fingers longer and more irregular consisting of large number of tributaries leading to the ultimate oil recovery... 

In this paper, we describe a carbon dioxide mineralization process and its associated solid products. These solid products include amorphous silica, iron hydroxides and magnesium carbonates. These products were subjected to various characterization tests, and the results are published here. It was found that the iron hydroxides from this process can have different crystalline properties, and their formation depended very much on the pH of the reaction conditions. Different forms of magnesium carbonate were also obtained, and the type of carbonate precipitated was found to be dependent on the carbonation temperature. Hydromagnesite was obtained mainly at low temperatures, while dypingite was... 

In this paper, the classical and nonlocal elasticity are applied to investigate the deflection and instability of electrostatically actuated carbon nanotubes. The results are presented for different geometries and boundary conditions. They reveal that increasing radius and gap and decreasing length confine to increasing pull-in voltages of the carbon nanotubes. The results prove that application of the nonlocal elasticity theorem leads to stiffer structures with higher pull-in voltages. Thus, in order to obtain more accurate results about the mechanical and electromechanical behaviors of the carbon nanotubes, one should apply the nonclassical elasticity theories such as that applied in this... 

A glassy carbon electrode was coated with a thin layer of multi-walled carbon nanotubes and subsequently was electro-polymerized with polypyrrole. The prepared electrode was used for the voltammetric determination of olanzapine (OLZ). The peak current of OLZ increases remarkably on the surface of the modified electrode. This is due to the large increase in the microscopic area of the electrode surface along with the strong adsorption of OLZ on the surface of the electrode. The film modifier was characterized by scanning electron microscopy, atomic force microscopy and cyclic voltammetry techniques. Experimental variables, such as deposited amount of nanotube suspension, pH of the supporting... 

The paper deals with studying the deflection and pull-in voltages of the carbon nanotubes under electrostatic actuation with various dimensions and boundary conditions. The size-dependent behaviors of the carbon nanotubes (CNTs) are considered via application of the strain gradient theory. The results obtained from the strain gradient theory are compared to those estimated using the classical elasticity. The outcomes reveal that the classical elasticity theory underestimates the pull-in voltages of the carbon nanotubes and strain gradient theorem results in stiffer nano-structures with higher pull-in voltages. Increasing of the deflection due to the higher voltages increases the differences... 

The photocatalytic activity of mesoporous TiO2 modified by the addition of carbon nanotubes (CNTs) and Cu is reported. Nanocomposites of carbon nanotubes (CNTs) containing varying amounts of Cu were formed by treatment with Cu2+ then reduced to Cu0 using NaBH4 as the reducing agent. The mesoporous TiO2, synthesized by a sol-gel method from titanium isopropoxide, was combined with the CNT/Cu nanocomposites to form the photocatalysts which were characterized by XRD, SEM, TEM, FTIR, XPS and BET surface area analysis. The photocatalytic properties of the mesoporous TiO2 composites were studied by measuring the degradation of methyl orange (MO) which was optimal in the sample containing 20wt% of... 

A novel electrochemical sensor based on nanocellulose-carbon nanoparticles (NC-CNPs) nanocomposite film modified glassy carbon electrode (GCE) is developed for the analysis of metoclopramide (MCP). Atomic force microscopy, scanning electron microscopy and electrochemical impedance spectroscopy were used to characterize the roughness, surface morphology and performance of the deposited modifier film on GCE. SEM image demonstrated that modifier nanoparticles are uniformly deposited on GCE, with an average size of less than 50nm. The electrochemical behavior of MCP and its oxidation product is studied using linear sweep and cyclic voltammetry over a wide pH range on NC-CNPs modified glassy... 

The paper investigates the effects of application of nonlocal elasticity theory on electromechanical behaviors of single-walled carbon nanotubes under electrostatic actuation. The influences of different dimensions and boundary conditions on the vibration and dynamic instability of the carbon nanotubes are studied, in detail, using this theory. The results reveal that application of the non-local elasticity theory leads to the higher pull-in voltages for the nonlocal model applied for carbon nanotubes. Thus, in order to have more accurate results, one should apply nonclassical theorems such as the nonlocal elasticity theory to scrutinize the mechanical and electromechanical behaviors of the... 

The electrochemical behaviour of temozolomide on a glassy carbon electrode has been investigated. The reduction of temozolomide is an irreversible process, pH dependent, and the mechanism involves the addition of one electron and one proton to C5 to form an anion radical, causing the irreversible breakdown of the tetrazinone ring. The oxidation mechanism of temozolomide is an irreversible, adsorption-controlled process, pH dependent up to value close to the pKa and occurs in two consecutive charge transfer reactions, with the formation of the hydroxylated product. The electroanalytical determination of TMZ led to a detection limit of 1.1 μM  

Interface shear strength between soil and structural materials is dependent on the confining pressure. To increase the confining pressure, different methods of reinforcement and materials, such as carbon-fiber-reinforced polymer (CFRP) can be used. The shear strength of CFRP-improved soil is dependent on the interface properties of the soil and CFRP. The objective of this study is to investigate the interface properties (friction angle and adhesion) of sand and FRP experimentally using the direct shear test apparatus. To increase the surface roughness to improve the interface properties, a layer of sand was placed on saturated carbon fiber during the curing period [spark plasma sintering... 

Combined experimental and theoretical studies on the reactivity of iodosylbenzene (PhIO) show that PhIO is capable of activating weak C-H bonds of hydrocarbons via a hydrogen abstraction mechanism. © 2009 The Royal Society of Chemistry  

We present a general study on a high performance supercapacitor based on intercalated reduced graphene oxide with carbon black nanoparticles. Graphene oxide sheets were synthesized by oxidation and exfoliation of natural graphite and were reduced using hydroiodic acid in the presence of carbon black nanoparticles. Graphene paper was fabricated by one-step procedure via simultaneous reducing and drying the aqueous solution of mixed carbon black nanoparticles and graphene oxide on a conductive substrate. Transmission electron microscopy confirmed the intercalation of carbon black nanoparticles into reduced graphene oxide sheets, preventing them from restacking during the fabrication of paper.... 

Porous nitrogen-doped carbons derived from biomass wastes are considered as promising materials for energy storage devices. Herein, a novel and scalable synthesis route for preparation of these materials from sugarcane bagasse waste is demonstrated. The synthesis process includes a hydrogel intermediate in which delignified bagasse and polyacrylamide networks are interlaced in molecular scale and calcium acetate serves as a hard template within the polymeric chains. After pre-carbonization and chemical activation of the hydrogel, porous nitrogen-doped carbon with high surface area of 1834.3 m2 g−1 and considerable pore volume of 1.03 cm3 g−1 was obtained with nitrogen and oxygen contents of...