Sharif Digital Repository

Ability to differentiate induced pluripotent stem cells to cardiomycocytes has attracted attentions,considering crucial role of the heart in the human body and great potential applications of these cells like disease modeling, new treatment methods and basic research. We are able to analyze the performance of beating cells through recording extracellular field potentials of cardiomyocytes using multi-electrode array (MEA) technology. This analysis is an essential step to use cardiac cells in any future development and experiment. Currently, the electrophysiology experts analyze recorded extracellular field potentials of induced cardiomyocytes by observing all the episodes of each record.... 

Part 1: In the first work, the electrochemical behavior of Ceftriaxone was thoroughly investigated at the surface of a glassy carbon electrode modified with nano-diamond graphite (NDG). The surface morphology and electrochemical properties of thin film modifier are characterized by Scanning electron microscopy (SEM) and cyclic voltammetry (CV) techniques. The prepared electrode showed a considerable improvement in the peak current of Ceftriaxone compared to either glassy carbon electrode or nanodiamond (NDs) modified glassy carbon electrode. Under the optimum conditions, the modified electrode showed a wide linear dynamic range of 0.04-10 μM with the detection limit of 10 nM for voltammetric... 

In the first work, a novel voltammetric biosensor basedon TiO2-nafion-carbon nanoparticles modified glassy carbon electrode (TiO2/N/CNP/GCE) was developed for the determination of DBA. The electrochemical performance of the modified electrode was investigated by means of cyclic voltammetry (CV), different pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) techniques. Characterization of the surface morphology and properties of TiO2/N/CNP was carried out by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Effective experimental variables, such as scan rate, pH of the supporting electrolyte, drop size of the cast modifier suspension and accumulation... 

In this thesis, in the first part, a promising electrochemical sensor was developed based on a layer by layer process by electropolymerization of pyrrole in the presence of new coccine (NC) as dopant anion on the surface of the CNTs pre-coated glassy carbon electrode (GCE). The modified electrode was used as a new and sensitive electrochemical sensor for voltammetric determination of sumatriptan (SUM). The results showed a remarkable increase in the anodic peak current of SUM in comparison to the bare GCE. In the second part, the electropolymerization of pyrrole was performed in the presence of Nitrazine Yellow (NY) as a dopant anion on the surface of the electrode precoated with CNTs. The... 

In several electro-optic and optoelectronic devices, we require the structures with simultaneous high electrical conductivity and optical transparency so as to transmit the incident light. Transparent Conductive Electrodes (TCEs) that are both highly conductive and transparent were introduced to be an answer to the mentioned challenge. Periodic arrays of metallic holes are amongst the most important structures that are used as transparent electrodes. Using the metals with low electrical resistivity, such as Au and Ag, provides these structures with high electrical conductance. On the other hand, since these micro/nano structures support the propagation of guided electromagnetic waves, light... 

In this study, transition metal phosphide, with a high accessible surface and abundant electroactive centers, was used as an electrocatalyst to fabrication an electrochemical sensor of Gloucose. The direct growth of thin film of nanocomposite can be considered as an efficient method to modify the electrode surface, and the application of these modified electrodes as electrochemical sensors. nanocomposite of transition metal phosphide (CuCoP) were directly grown on Cu(OH)2 nanotubes (as-prepared on GCE) in order to design hierarchical core-shell nanostructure with using efficient, inexpensive and fast method. Here, Cu(OH)2 nanotubes not only served as substrate, but also steer the CuCoP to... 

Dye-sensitized solar cells (DSSCs) are emerging as low-cost alternatives to conventional, solid-state, silicon solar cells. A porous network of a nanosize semiconductor material with a wide band-gaps usually TiO2, serves as charge transport medium. A monolayer of dye is chemically adsorbed on this material. Photoexcitation of dye causes injection of electrons into the conduction band of TiO2 from where they diffuse towards a transparent conducting oxide (TCO) substrate. The dye is regenerated through receiving electrons from a redox couple dissolved in the electrolyte. After passing through a desired load, the electrons enter the cell through a counter electrode to reduce the redox ions and... 

Graphene، a molecular single layer of graphite، has tremendous applications in materials science for the development of nanocomposites، tissue engineering and supercapacitors. Graphene application and its developing applications depend on its essential properties such as excellent mechanical and thermal properties. Accordingly، investigation on graphene has drawn significant attention to itself. Hence، exploitation of these important properties including the induction of graphene sheets in polymer matrix seems to be essential. In the present survey، salep، a biodegradable polysaccharide، has been used for either the reduction of graphene oxide or functionalization of graphene. Then، reduced... 

In the first part of thesis, the electropolymerization of pyrrole was performed in the presence of new coccine (NC) as a dopant anion on the surface of the electrode precoated with SWCNT. The modified electrode was used to study the voltammetric response of salbutamol (SAL). The results showed a remarkable increase in the anodic peak current of SAL in comparison to the bare GCE. The surface morphology PPY/CNT/GCE was thoroughly characterized by scanning electron microscopy (SEM) and cyclic voltammetry (CV) techniques. Under the optimized analysis conditions, the modified electrode showed two linear dynamic ranges of 0.02 – 0.1 μM and 0.1-10 μM with a detection limit of 6 nM for the... 

Titanium anodes activated by noble metal oxides under the trade name of dimensionally stable anodes (DSAs) are widely used in the electrolytic industry, particularly in chlor – alkali electrolysis. Over 20 years of use, the fundamental aspects of their long – lasting performance are not fully understand and the corrosion mechanisms are still the subject of many investigations. RuO2 – TiO2 coatings on titanium substrate, due to proper electrochemical characteristics and good corrosion resistance, is most applicable as an anode in chlor – alkali systems. In the present investigation, the first layer of Pt – Ir coating is applied via electrodeposition method on the pretreated titanium substrate... 

In this study a systematic effort was made to investigate the poisoning effect of sulfur-containing materials on the electro- oxidation of methanol and ethanol on Ni and Cu electrodes in alkaline solutions by the methods of cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy. Activation energy of methanol electro-oxidation in the absence of Na2S was obtained 30.7 kJ/mol by cyclic voltammetric at different temperatures, and its values increased by increase in Na2S concentrations to 97kJ/mol. Na2S adsorption isotherms corresponded with Langmuire isotherm, equilibrium constants of adsorption – desorption and adsorption enthalpy (ΔHads= -62kJ/mol) were calculated for... 

In the last half century, the recording of the electrophysiological activities of the neurons has been one of the most effective methods for neuroscience development. One of the techniques used to record the activity of the nerve cells is the use of multi-electrode arrays (MEAs). Current MEAs still face limitations such as low signal-to-noise ratio (SNR) and low spatial resolution. There is a need to develop arrays that are smaller in size and have less impedance to achieve better spatial resolution and lower noise levels. The main focus of this research is on the designing and fabrication of multi-electrode arrays and improvement of their properties using nanostructures and conductive... 

Today the water crisis affects billions around the world.According to existance of large amount of salty water on the earth, it seems one of the best soloution is desalination of salty water.There are methods for removing ions from water such as thermal methods, membrane methods , chemical methods and capacitive deionization.Capacitive deionization is based on the deviation of ions in the electric field.CDI system contains of two conductive porous electrodes that an elecric field is applied between them.While the brine pass through the space between the elecrodes the ions are absorbed by elecrodes. After a while the electrodes get saturated so a reverse potential is needed to regenerate the... 

The Transparent electrode (transparent conductive layer) is an essential component of electro-optical devices, especially screens, solar cells and touch screens. Today, most semiconductor oxides such as ITO are used for this purpose, which have problems such as inflexibility, high cost, environmental degradation and ion penetration in organic displays. In this research, the design, simulation and fabrication of a transparent electrode with a network of metal nanowires with low resistance between cross fibers and high aspect ratio during the production stages of polymer mold, metal coating and characterization has been done. Using the reducing atmosphere in the sputtering chamber, the... 

Photoelectrochemical (PEC) water splitting is exceedingly promising for converting solar energy into molecular hydrogen as a clean and sustainable fuel. However, the overall rate of water splitting reaction is severely limited by the sluggish kinetics of the anodic half-reaction, namely, the oxygen evolution reaction (OER). Bismuth vanadate (BiVO4) is a popular photoanode for PEC water splitting due to its high stability, low cost, narrow band gap (2.4 eV), high visible-light absorption, and environmental compatibility. However, BiVO4 suffers from poor charge transfer, fast recombination of electron-hole pairs, and inferior catalytic activity toward OER. An effective strategy to overcome... 

In the present study, TiO2-reduced graphene oxide (T-RGO) nanocomposites were synthesized via various in-situ and ex-situ methods, then their photovoltaic performance was examined as photoanode and mesoporous layers in dye-sensitized Solar Cells (DSSCs) and perovskite Solar Cells (PSCs), respectively. Graphene oxide (GO) was prepared using Hummer’s method with some modifications. Both thermal and hydrothermal processes were used to reduce GO. Structural and optical characterization was analytically demonstrated by subjecting of the obtained materials by several techniques, including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman, thermogravimetric analysis (TGA),... 

In the first work, a stable composite film of silver nanoparticles decorated on reduced graphene oxide is easily prepared. The surface morphology of the modified electrode is characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM) techniques. The electrochemical behavior of TNZ on the surface of the modified electrode is investigated by using linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS). The prepared modified electrode acts as a highly sensitive platform for the voltammetric determination of tinidazole (TNZ). Voltammetric investigations demonstrated that, in comparison to the glassy carbon electrode individually coated with... 

Supercapacitors are safe and environmentally friendly energy storage devices that have been considered for their diverse applications. One of the most important factors that control supercapacitors' capacity is the electrode material's structure and properties. Adding heteroatoms or composite materials synthesis is one way to improve electrode performance. In this study, a facile, fast, and economical hydrothermal method was used to synthesize N doped, P doped or N/P co-doped 3D reduced graphene oxide (rGO) for high-performance supercapacitor application. Nitrogen and phosphorus elements were replaced by carbon atoms simultaneously during the graphene oxide hydrothermal reduction procedure.... 

In the first part, 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). The electrochemical behavior of MCP was investigated on the surface of the modified electrode using cyclic voltammetry (CV). Characterization of the surface morphology and properties of NC/CNPs was carried out by scanning electron microscopy (SEM), atomic force microscopy (AFM) and electrochemical impedance spectroscopy (EIS). Effective experimental variables, such as scan rate, pH of the supporting electrolyte, drop size of the casted modifier suspension and accumulation... 

Miniaturization of electronic devices with portable, flexible and wearable characteristics created a great demand for high-performance microscale energy storage devices with lightweight and flexible properties. Among the energy storage devices, wire-shaped micro-supercapacitors have recently received tremendous attention due to their small size, lightweght, and high flexibility. In the first part, the porous dendritic Ni-Cu film was prepared on Cu wire substrate (CW) for fabrication of high- performance wire-type micro-supercapacitors (micro-SCs). The porous structure with dendritic morphology provides a high surface area, short ion diffusion pathway and low contact resistance between...