Sharif Digital Repository

Room temperature gas sensing behavior of arrayed one-dimensional (1D) nickel nanowires (Ni NWs) are investigated using impedance spectroscopy. Ni nanowires synthesized via electrochemical deposition method based on anodic aluminum oxide (AAO) templates. Their structural characterization verified by scanning electron microscopy (SEM), x-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR) analysis. Impedance spectroscopy as an essential technique utilized to understand the mechanism of gas interaction with the wires through the changes in their electronic behavior. Bode and Nyquist plots with the real and imaginary impedances are plotted versus frequency range of 500 Hz... 

Two main origins of failure for hard tissue replacements are structural loosening and prosthetic implant infections (PIIs). Bioinspired multifunctional TiO2 hierarchical micro/nanostructures of conical-shaped TiO2 (CTO), regular TiO2 nanotubes (RTO) and irregular TiO2 nanotubes (ITO) with tunable improved cell growth and inhibited bacteria adhesion were synthesized. CTO and ITO samples indicated superhydrophilicity with contact angles of less than 5°. The MTT assay demonstrated excellent biological performance for RTO and CTO sample with 98.1% and 103.1% of cell viability, respectively. The bridging force for osteoblast cell attachment onto the synthesized porous coatings was presented as a... 

This study aimed to prepare nanoporous anodic alumina on AA3003-H14 aluminum alloy using a mild anodization process with minimal working voltage and treatment time. The microstructural features, mechanical properties, and tribocorrosion behavior of the coatings were assessed to determine the optimum conditions for the fabrication of nanoporous anodic alumina on AA3003-H14 alloy. The microstructural analysis showed both uniform and nonuniform pore nucleations during anodization in H2SO4/C2H2O4, H2SO4/H2CrO4, and EG/H2O/NH4F electrolytes, where the optimal nanoporous structure with an average thickness, porosity, pore diameter, and interpore distance of 382 nm, 19%, 16 nm, and 35 nm,... 

Nanomedicine has seen a significant rise in the development of new research tools and clinically functional devices. In this regard, significant advances and new commercial applications are expected in the pharmaceutical and orthopedic industries. For advanced orthopedic implant technologies, appropriate nanoscale surface modifications are highly effective strategies and are widely studied in the literature for improving implant performance. It is well-established that implants with nanotubular surfaces show a drastic improvement in new bone creation and gene expression compared to implants without nanotopography. Nevertheless, the scientific and clinical understanding of mixed oxide... 

Urea is a major source of nitrogen pollution in domestic sewage and its denitrification is difficult since it is very likely to be converted into ammonia or nitrate instead of expected N2. Herein, we propose an exhaustive denitrification method for urea via the oxidation of amine/ammonia-N with chlorine oxide radical, which induced from a bi-functional RuO2//WO3 anode, and the highly selective reduction of nitrate-N on cathode in photoelectrochemical cell (PEC). Under illumination, the WO3 photoanode side promotes the quantities hydroxyl and reactive chlorine radical, and these radicals are immediately combined to stronger chlorine oxide radical by RuO2 side, which obviously enhances the... 

Titanium type lithium ion-sieve nanotubes synthesized by the hydrothermal method were extensively explored over recent years due to its promising properties. However, on account of nanotubes′ tangled structure impeding the lithium adsorption in the interior nanotube walls, unalterable dimensions of the synthesized nanotubes, and a long period of annealing, the anodizing technique was proposed. It is shown that lithium uptake and adsorption capacity is improved because of easier mass transfer during the ion exchange process. This work focuses on a novel anodizing method for nanotube ion-sieve synthesis. The optimum anodizing condition was discovered by altering anodizing voltage, time, and... 

The preparation and electrochemical performance of the carbon nanotube-paste electrode modified with salophen complexes of cobalt(III) perchlorate, with various substituents on the salophen ligand, as well as their electrocatalytic activity toward the oxidation of N-acetylcysteine (NAC) is investigated. Several Schiff base complexes containing various nucleophilic and electrophilic functional groups were prepared, and their electrochemical characteristics for the electro-oxidation of NAC were evaluated using cyclic and differential pulse voltammetry (CV and DPV). The results revealed, the modified electrodes show an efficient and selective electrocatalytic activity toward the anodic... 

Nickel and nickel-copper alloy modified glassy carbon electrodes (GC/Ni and GC/NiCu) prepared by galvanostatic deposition were examined for their redox process and electrocatalytic activities towards the oxidation of methanol in alkaline solutions. The methods of cyclic voltammetery (CV) and chronoamperometry (CA) were employed. The cyclic voltammogram of NiCu alloy demonstrates the formation of β/β crystallographic forms of the nickel oxyhydroxide under prolonged repetitive potential cycling in alkaline solution. In CV studies, in the presence of methanol NiCu alloy modified electrode shows a significantly higher response for methanol oxidation. The peak current of the oxidation of nickel... 

Nickel - copper alloy modified glassy carbon electrodes (GC/NiCu) prepared by galvanostatic deposition were used for the electrocatalytic oxidation of glucose in alkaline solutions. The electro-oxidation of glucose in a 1 M NaOH solution at different concentration of glucose was studied by the method of ac-impedance spectroscopy. The impedance behavior show different patterns, capacitive, and inductive loops and negative resistances, at different applied anodic potential. The influence of the electrode potential on the impedance pattern is studied and a quantitative explanation for the impedance behavior of glucose oxidation is put forward by a proposed mathematical model. At potentials... 

In this paper we report an efficient synthesis of hydrolyzed collagen-g-poly(sodium acrylate-co-2-hydroxyethyl aery late) hydrogel through chemical cross-linking by graft copolymerization of these two monomers onto the protein backbone in the presence of a cross-linker. Infrared spectroscopy and thermogravimetric analysis (TGA) were carried out to confirm the chemical structure of the hydrogel. Moreover, morphology of the samples was examined by scanning electron microscopy (SEM). To investigate the effect of monomer ratio on swelling behavior in various media three hydrogels with different acrylic acid/2-hydroxyethyl acrylate (AA/HEA) weight ratios were synthesized and swelling capacity was... 

In copper electrorefining process, some additives are added to the electrolyte to improve the morphology of cathode deposits as well as the quality of products. In the present investigation, the effects of thiourea, glue and chloride ions (as additives) on the passivation of industrial copper anodes under high current densities have been reported. Experiments were conducted at 65 °C; using a synthetic electrolyte containing 40 g/l Cu2+ and 160 g/l H2SO4. Results obtained from chronopotentiometry experiments showed that increasing the concentration of chloride ion leads to increase in passivation time. The results also indicated that from a certain level on, namely 2 ppm, the increase in... 

Anodic aluminium oxide films were fabricated by well known two-step anodizing process in oxalic acid electrolyte. The ordering characteristics (ordered pore domains, average pore diameter size and through-pore arrangement) of anodic aluminium oxide films, obtained in different growth sequences, were identified by microscopic analysis such as ex situ contact-mode atomic force microcopy and scanning electron microscopy. Flattened areas in which some pits are seen mostly cover the electropolished surface of aluminium. Single anodizing of aluminium produces a broad distribution of nanopore size, whereas induces a highly ordered hemispherical pattern, which plays the ordered nucleation sites for... 

Amorphous lithium metal alloys (LixM, with M=Si, Ge, Sn, …) are attractive anode materials for lithium-ion batteries owing to their high energy-storage capacity and safety characteristics. However, repeated insertion of lithium often leads to chemo-mechanical degradation of the alloy, which can severely reduce the battery capacity and cycle life. Better understanding of the chemo-mechanical response of lithium alloys is needed to guide the design of damage-resistant anode microstructures. In this work, we propose a constitutive theory that couples large, viscoplastic deformations to the insertion and extraction of lithium in amorphous electrode materials. The theory relies on the concept of... 

Accumulative roll bonded (ARBed) AA1050 and Al-2 vol% SiCp (AMC) samples were anodized in an H2SO4 electrolyte to improve corrosion resistance. The SEM images revealed that the anodic oxide's morphology is significantly dependent on the microstructure of the ARBed bare samples, owing to high internal energy that accelerates Al consumption during anodizing process. Potentiodynamic polarization measurements and EIS evaluation showed that anodic oxide improves the corrosion resistance of both ARBed AA and AMC samples; however, the electrochemical behavior of the processed samples changed due to the formation of a complex oxide structure comprising of twisted pore channels and attack routes. ©... 

In this study, the influence of the sample position (anode) on the incorporation of nano/micro alumina particles on the AZ31B magnesium alloy substrate was investigated by plasma electrolytic oxidation (PEO) coating. For characterized this effect, Scanning electron microscopy (SEM), potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), and pin-on-disk test were used to the evolution of the microstructure, corrosion resistance, and the wear behavior of the films. Based on the obtained results, the effect of the anode position from vertical to horizontal is dependent on particle size and it can be influenced only on the incorporation of nanoparticles. The... 

Here, cobalt oxide nanostructures synthesized on vertically aligned copper oxide nanowires (NWs) have been investigated as a possible anode material for Lithium-ion batteries (LIBs). Copper oxide NWs were formed by thermal oxidation of electrochemically deposited copper on the stainless steel mesh substrate. The process used allows the formation of highly dense copper oxide NWs with excellent adhesion to the conductive current collector substrate. A simple hydrothermal method was implemented for the deposition of cobalt oxide nanostructures on the copper oxide NWs. The as-prepared binder-free copper oxide@cobalt oxide NWs electrode exhibits a high initial specific capacity of 460 mAh g-1 at... 

A pseudocapacitive electrode based on mesoporous manganese dioxide (MnO2) was fabricated via the anodic pulse electrodeposition method. Pulse current (PC) has many parameters that affect the physicochemical and electrochemical properties of the material. PC parameters are generally divided into independent and dependent types. Independent pulse parameters consist of the time of applying current (ton), interval time with zero current (toff), and peak current density (Ip). Dependent pulse parameters include duty cycle (θ), frequency (f), and average current density (Ia). In this work, the changes of two independent parameters (ton and toff) at the constant Ip = 2 mA cm-2 on the anodic pulse... 

Solid oxide fuel cells (SOFCs) introduce a promising electrochemical conversion technology to generate electricity directly from fuel oxidization. A three-dimensional (3D) numerical model is proposed to evaluate the SOFC performance by employing computational fluid dynamics (CFD) approach based on the finite element method. This research includes simultaneously solving momentum, energy, and mass transport equations linked with the electrochemical reactions. First, the modeling results of a SOFC system with a rectangular channel in the absence of obstacles are compared with the experimental data, showing very good agreement. The effects of different shapes and numbers of obstacles on fuel...