Mohamed Harb - Academia.edu (original) (raw)

Papers by Mohamed Harb

Journal of Low Temperature Physics

The magnetocaloric effect-(MCE) of MgB2 is simulated, considering the effect of sintering tempera... more The magnetocaloric effect-(MCE) of MgB2 is simulated, considering the effect of sintering temperature on MCE. The results show that MCE of MgB2 samples is an inverse type in a temperature range of diamagnetic-paramagnetic transition. Moreover, the MCE for MgB2 is improved with high sintering temperature. The comparison between MCE of MgB2 samples and other some reported magnetic materials has been done, showing that MCE parameters of MgB2 samples are larger than some MCE parameters of La1-xCdxMnO3, La1.25Sr0.75MnCoO6, Gd1−xCaxBaCo2O5.5, Ni58Fe26Ga28, Ni2+xMn1−xGe, Ge0.95Mn0.05 film, and (001)-oriented MnAs film. It suggested that MgB2 samples could be a promising sharing candidate for MR in cryogenic temperatures.

Electromagnetic Sensor Using Plasmonic Different Nano Structure Array Models

2019 36th National Radio Science Conference (NRSC)

This article is based on The Plasmonic resonance technique which used to improve optical properti... more This article is based on The Plasmonic resonance technique which used to improve optical properties of nano sensors. In this work, two models of nano sensors are introduced. A novel fractal nano structures and Quantum dot (QD) arrays of gold Nano particles (NP) are introduced in this paper to enhance Strong absorbed radiation by nanoparticles then converted efficiently to heat by absorbed photon energy. The optimum absorption of the fractal design (first iteration) nano carpet element is equal to −50 db with enhancement of 76% compared to QD.

Simulation of magnetocaloric properties in La1-xBaxCoO3

Journal of Magnetism and Magnetic Materials

Proparation and Investigation of Introduced Gold Nanoparticles for Biomedical Sensing Applications

2018 International Japan-Africa Conference on Electronics, Communications and Computations (JAC-ECC), 2018

Photons absorption into nanoparticles dimensions leads to a large increase in its electromagnetic... more Photons absorption into nanoparticles dimensions leads to a large increase in its electromagnetic intensity and the nanoparticle's radiated properties. The strongly absorbed light by the nanoparticles is followed by converted efficiently into thermal energy to kill harmed cells without affecting the surrounding healthy cells. In this paper, gold nanoparticles (NPs) are prepared and investigated by x-ray diffraction (XRD), energy dispersive x-ray (EDX), UV-visible spectroscopy (UV-vis), and transmission electron microscopy (TEM). Experimental results are analyzed to obtain four different sensors designs. The reflection coefficient S11 and absorption of each design are introduced as a measure for the back scattering of the different structures. The High Frequency Structure Simulator (HFSS) is used to compare between results. Results show that design 2 has the minimum reflection coefficient (S11= −45.1 dB) at resonance frequency= 820THz which in IR region.

Environmentally Friendly Energy Harvesting Using Magnetocaloric Solid-State Nanoparticles as Magnetic Refrigerator

Journal of Low Temperature Physics, 2021

Metal organic framework/layer double hydroxide/graphene oxide nanocomposite supercapacitor electrode

Applied Physics Letters, 2021

Layered Double Hydroxide (LDH) based on Metal Organic Framework (MOF) structures has attracted a ... more Layered Double Hydroxide (LDH) based on Metal Organic Framework (MOF) structures has attracted a great deal of attention due to their high surface area, tailoring structure of the MOF, and high pseudocapacitance of LDH. Herein, an Ni-ZIF-67/Mn-LDH supercapacitor electrode was prepared via the solvothermal method at room temperature. A supercapacitor electrode based on Ni-ZIF-67/GO-LDH by replacing active metal Mn with graphene oxide (GO) was also synthesized to enhance the capacitance retention and stability from 78% to 97% after 1000 cycles. The morphology of these electrodes was characterized by scanning electron microscopy (SEM). It was found that the specific surface areas of Ni-ZIF-67/GO-LDH and Ni-ZIF-67/Mn-LDH are 82 and 20 m2 g−1. The electrochemical performance of the two nanocomposite supercapacitor electrodes was observed by cyclic voltammetry, charge–discharge, and electrochemical impedance spectroscopy measurements. The Ni-ZIF-67/GO-LDH electrode produced a specific capacitance (Cs) of 1036 F/g at 1 A/g, while the Ni-ZIF-67/Mn-LDH electrode results in a superior Cs value of 1420 F/g at 1 A g−1 with an energy density of 44 Wh/kg and a power density of 3.5 kW/kg.

Electrochimica Acta, 2021

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Strong tailoring magnetocaloric effect in highly (001)-oriented La0.7Sr0.3MnO3 thin films

Journal of Materials Research and Technology, 2021

Abstract In this work, we simulated the dependence of magnetization versus temperature for highly... more Abstract In this work, we simulated the dependence of magnetization versus temperature for highly (001)-oriented La0.7Sr0.3MnO3 (LSM) thin film prepared under several oxygen growth pressures to predict magnetocaloric effect (MCE). The results reveal that MCE of highly (001)-oriented LSM thin films is strongly tunable with oxygen growth pressure during preparation. Furthermore, the MCE of these films is enhanced with increasing oxygen growth pressure during preparation. The comparison of MCE parameters for (001)-oriented LSM thin films and some published works, showing that these films are considerably larger and comparable with some MCE parameters of these published works. It is suggested that (001)-oriented LSM thin films can be used as a function material of MR that cools at cryogenic and room temperatures.

Journal of Electronic Materials, 2018

An electrochemical method was used to prepare polyaniline (PANI) with hydrochloric acid as a dopa... more An electrochemical method was used to prepare polyaniline (PANI) with hydrochloric acid as a dopant. This electroactive material was fabricated using electrically modified carbon coated Teflon electrodes with an area of 0.64 cm 2 in 1 M HCl. PANI was electrochemically synthesized using cyclic voltammetry (CV) with a variable number of cycles, scan rates, and step sizes at potentials ranging from À 0.2 V to 0.8 V. Fabricated samples were tested using different electrochemical techniques including CV, differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). The DPV and EIS measurements indicate a linear relationship between both the current peak and the charge transfer resistance (R ct) and pH. These measurements showed that the prepared electrochemical device can be used as a sensor for pH. Optimum preparation parameters were 30 cycles, 50 mV/s scan rate and 2 mV step size. A linear relationship between oxidation current and pH of the solution with a correlation coefficient of 0.97 in the range of 1-5 makes PANI a candidate to be used as a pH sensor.

JOM, 2019

Nanofibers were prepared from a poly(acrylonitrile-co-vinyl acetate) [P(AN-co-VAC)]/polyvinyliden... more Nanofibers were prepared from a poly(acrylonitrile-co-vinyl acetate) [P(AN-co-VAC)]/polyvinylidene fluoride (PVDF) blend and used as a quasi-solid (QS) electrolyte for dye-sensitized solar cells (DSSCs). The effects of preparation parameters such as the flow rate and the weight percentage of PVDF on the fiber diameter, crystallinity, and ionic conductivity were investigated. Fourier-transform infrared (FTIR) spectroscopy, x-ray diffraction (XRD) analysis, and scanning electron microscopy (SEM) were used to characterize the prepared blend nanofibers. Current-voltage and electrochemical impedance spectroscopy (EIS) measurements were carried out on the fabricated DSSCs. It was found that the optimum weight ratio of P(AN-co-VAC) to PVDF in N,Ndimethylformamide (DMF) to produce uniform fibers with average diameter of 180 nm was 7:3 with ionic conductivity (r i) of 2.9 9 10 À3 S/cm. Moreover, the efficiency of DSSCs based on P(AN-co-VAC) as QS electrolyte was enhanced by 8.5 times by addition of PVDF. Finally, a model is proposed based on the EIS analysis.

The International Conference on Electrical Engineering, 2016

Supercapacitors represent an attractive alternative for portable electronics and automotive appli... more Supercapacitors represent an attractive alternative for portable electronics and automotive applications due to their high capacitance, specific power and extended life. In fact, the growing demand of portable systems and hybrid electric vehicles, memory protection in CMOS, logic circuit, VCRs, CD players, PCs, UPS in security alarm systems, remote sensing, smoke detectors, etc. require high power in short-term pulses. So, in the last 20 years, supercapacitors have been required for the development of large and small devices driven by electrical power. In this paper, asymmetric supercapacitors with high energy density were successfully fabricated using graphene as negative electrode and polyaniline as positive electrode. The weight of active material was 5.6 mg. The surface topography was characterized by scanning electron microscopy (SEM). The electrochemical properties of the composite were evaluated by cyclic voltammetry (CV), charge-discharge measurements and electrical impedance spectroscopy (EIS). The separator was a filter paper soaked in aqueous potassium hydroxide (6M).This enhances both the specific capacitance to 620.76 F/g at scan rate of 1 mV/s and the energy density to 86.22Wh/kg. Another low leakage supercapacitor was fabricated using polyvinyl alcohol (PVA) separator and 6 mole potassium hydroxide salt with specific capacitance of 220.35 F/g at scan rate of 1 mV/s.

The International Conference on Electrical Engineering, 2016

Supercapacitors have attracted increasing attention due to their widespread applications, such as... more Supercapacitors have attracted increasing attention due to their widespread applications, such as hybrid electric vehicles, power tools, portable electronic equipment and other devices. Using larger surface area of graphene electrodes and thinner dielectrics to achieve larger capacitances is a new trend for increasing capacitance of supercapacitors. This allows for energy densities greater than those of conventional capacitors and power densities greater than those of batteries.. In this paper, graphene oxide was synthesized by improved Hummers method. polyaniline PANI/grapheneoxide (GO) nanocomposite electrode materials were prepared from aniline (ANI), GO and ammoniumpersulfate (APS) by insitu chemical polymerization in ice bath. GO in composite was reduced for 5h and 20h. The crystal structure and the surface topography of all materials were characterized by Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy. The electrochemical properties were evaluated by cyclic voltammetry (CV), charge-discharge measurements, electrical impedance spectroscopy (EIS) and a four-point probe, respectively. The results show that with increasing reduction time, the oxygen content on the surface of GO was decreased, leading to increased ID/IG ratio in the Raman spectra of GO and increased conductivity of composite. Consequently, the capacitance properties of RGO/PANI composites could be significantly improved by the reduction of GO for 20h. The GO /PANI composite reduced for 20h had a specific capacitance as high as 1405.68 F/g at scan rate of 1 mV/s compared with 291.73 F/g for pristine graphene film.

Microsystem Technologies, 2018

Electrochemical biosensor has been developed for detection of danazol (Dz) based on electrochemic... more Electrochemical biosensor has been developed for detection of danazol (Dz) based on electrochemical polyaniline (PANI) electrode. Electrochemical PANI films were prepared by electrochemical polymerization technique. The Fourier transform infrared spectroscopy and X-ray diffraction were performed to identify the characteristic peaks and the degree of crystallinity of the prepared films. Cyclic voltammetry (CV) studies have been investigated for the electrochemical polyaniline films onto carbon electrode to determine the appropriate electro-active films to be used as electrochemical biosensor. CV of electrochemical polymerization of polyaniline films at different doping concentrations of 1, 1.2 and 1.5 M. CV results shown, the maximum peak current was 44.67 mA/cm 2 at 0.2 V/SCE for 1 M HCl. The prepared electrodes were used for detecting Dz using differential pulse voltammetry (DPV) technique and electrochemical impedance spectroscopy (EIS). The current peak of DPV produced inside solution containing Dz of concentration 2 nM is about 1.671 mA. Also, EIS showed that the charge transfer resistance (R ct) was increased with different Dz concentration.

Journal of Electronic Materials, 2017

In this work, an organic field-effect transistor (OFET) was fabricated and characterized based on... more In this work, an organic field-effect transistor (OFET) was fabricated and characterized based on the bottom contact of a polyaniline (PANI) or PANI/ TiO 2 nanocomposite as an active layer and SiO 2 as an insulating layer to be used for ammonia gas sensing applications. The OFET sensors exhibited a change in the drain current when exposed to NH 3. Titanium dioxide (TiO 2) nanoparticles with different weight percentages (0-50 wt.%) were added to dope PANI and enhance charge carrier transport, although the response of both the PANI OFET sensor and PANI/TiO 2 OFET sensor has reached saturation value at almost the same period. The response of PANI/TiO 2 transistor is (2.5), which is much higher than that of PANI (0.17). The results showed that the sensor response of the OFET device fabricated with PANI/TiO 2 is 15 times greater than that with an OFET device fabricated using pristine PANI.

Sprayed polyaniline layer onto chemically reduced graphene oxide as electrode for high performance supercapacitor

Synthetic Metals, 2016

Abstract In this work supercapacitors were fabricated from reduced graphene oxide (RGO), polyanil... more Abstract In this work supercapacitors were fabricated from reduced graphene oxide (RGO), polyaniline (PANI) and graphene/PANI (G/PANI) electrodes. The fabricated electrodes were characterized using scanning electron microscope (SEM) and UV–vis spectroscopy. The electrochemical activities of supercapacitors were assessed using cyclic voltammetry (CV), electrical impedance spectroscopy (EIS), and charge-discharge measurements. Graphene electrodes were prepared by exposure the graphene oxide (GO) sheets to hydrazine to reduce and restore the conducting carbon network. A maximum specific capacitance of 292 F/g with energy density of 40.5 Wh/kg in an aqueous electrolyte solution had been obtained for this graphene supercapacitor. Supercapacitor of sprayed PANI electrodes produced specific capacitance of 595 F/g and energy density of 82.63 Wh/kg. Finally, a hybrid supercapacitor had been developed by spraying PANI layer onto the reduced graphene oxide sheet (G/PANI). It was found that G/PANI supercapacitor displayed a specific capacitance of 916 F/g and energy density of 127.19 Wh/kg, which is much higher than that of pristine graphene and PANI electrodes supercapacitor.

An Introduced Hybrid Graphene/Polyaniline Composites for Improvement of Supercapacitor

Journal of Electronic Materials, 2015

Supercapacitors represent an attractive alternative for portable electronics and automotive appli... more Supercapacitors represent an attractive alternative for portable electronics and automotive applications due to their high capacitance, specific power and extended life. In fact, the growing demand of portable systems and hybrid electric vehicles, memory protection in complementary metal-oxide-semiconductor (CMOS), logic circuit, videocassette recorders (VCRs), compact disc (CD) players, personal computers (PCs), uninterruptible power supply (UPS) in security alarm systems, remote sensing, smoke detectors, etc. require high power in short-term pulses. Therefore, in the last 20 years, supercapacitors have been required for the development of large and small devices driven by electrical power. In this paper, graphene oxide (GO) was synthesized by improved Hummers method. Two polyaniline (PANI)/graphene oxide nanocomposites electrode materials were prepared from aniline, GO and ammoniumpersulfate (APS) by in situ chemical polymerization with the mass ratios (mGO:mAniline) 10:90 and 30: 70 in ice bath. The crystal structure and the surface topography of all materials were characterized by means of x-ray diffraction (XRD), Fourier transform infrared spectrum (FTIR), Raman spectroscopy and scanning electron microscopy (SEM). The electrochemical properties of the composites were evaluated by cyclic voltammetry (CV), charge–discharge measurements and electrical impedance spectroscopy (EIS), respectively. The results show that the composites have similar and enhanced cyclic voltammetry performance compared with pure PANI based electrode material. The graphene/PANI composite synthesized with the mass ratio (mANI:mGO) 90:10 possessed good capacitive behavior with a specific capacitance as high as 1509.35 F/g at scan rate of 1 mV/s in scanning potential window from −0.8 V to 0.8 V.

International Journal of Advanced Research in Electrical, Electronics and Instrumentation Engineering, 2015

In this paper, a proposed supercapacitorwas fabricated using an electrode of graphene layer cover... more In this paper, a proposed supercapacitorwas fabricated using an electrode of graphene layer covered with polyaniline layer. Uniform polyaniline layer was deposited using spraying technique. Characterizations were performed using scanning electron microscope (SEM) and UV-visible spectroscopy. The electrochemical measurements were assessed using cyclic voltammetry (CV), electrical impedance spectroscopy (EIS), and charge-discharge measurements. The results indicated that graphene/PANI double layers exhibited high porosity and large surface area. Polyaniline/graphenesupercapacitor had a specific capacitance as high as 915.78 F/g at scan rate of 5 mV/s in the scanning potential window from-0.8 to 0.8 V with 4 mg active material. The fabricated supercapacitor prototype has provided an energy density of 127.19 Wh/kg at potential difference of 1V using aqueous electrolyte of 6M potassium hydroxide. The effect of temperature on supercapacitor performance was investigated and it was found that the influence of temperature on specific capacitance was insignificant. It was observed that an improvement in the specific capacitance with about 1% in temperature range between 25 ˚C and 70 ˚C.

Journal of Taibah University for Science, 2016

In this paper, polyaniline is deposited using a spraying technique onto a flexible current collec... more In this paper, polyaniline is deposited using a spraying technique onto a flexible current collector for pseudocapacitor applications. The polyaniline is characterized using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and optical absorption studies. The energy density of a pseudocapacitor is higher than that of double-layer supercapacitors due to Faradaic reactions. A high specific capacitance of 594.92 F/g is obtained at a scan rate of 5 mV/s with a scanning potential window of (−0.8 to 0.8 V). The results show an increase in the energy density of 82.63 W h/kg at a potential difference of 1 V using a 4 M potassium hydroxide aqueous electrolyte.

Journal of Low Temperature Physics

The magnetocaloric effect-(MCE) of MgB2 is simulated, considering the effect of sintering tempera... more The magnetocaloric effect-(MCE) of MgB2 is simulated, considering the effect of sintering temperature on MCE. The results show that MCE of MgB2 samples is an inverse type in a temperature range of diamagnetic-paramagnetic transition. Moreover, the MCE for MgB2 is improved with high sintering temperature. The comparison between MCE of MgB2 samples and other some reported magnetic materials has been done, showing that MCE parameters of MgB2 samples are larger than some MCE parameters of La1-xCdxMnO3, La1.25Sr0.75MnCoO6, Gd1−xCaxBaCo2O5.5, Ni58Fe26Ga28, Ni2+xMn1−xGe, Ge0.95Mn0.05 film, and (001)-oriented MnAs film. It suggested that MgB2 samples could be a promising sharing candidate for MR in cryogenic temperatures.

Electromagnetic Sensor Using Plasmonic Different Nano Structure Array Models

2019 36th National Radio Science Conference (NRSC)

This article is based on The Plasmonic resonance technique which used to improve optical properti... more This article is based on The Plasmonic resonance technique which used to improve optical properties of nano sensors. In this work, two models of nano sensors are introduced. A novel fractal nano structures and Quantum dot (QD) arrays of gold Nano particles (NP) are introduced in this paper to enhance Strong absorbed radiation by nanoparticles then converted efficiently to heat by absorbed photon energy. The optimum absorption of the fractal design (first iteration) nano carpet element is equal to −50 db with enhancement of 76% compared to QD.

Simulation of magnetocaloric properties in La1-xBaxCoO3

Journal of Magnetism and Magnetic Materials

Proparation and Investigation of Introduced Gold Nanoparticles for Biomedical Sensing Applications

2018 International Japan-Africa Conference on Electronics, Communications and Computations (JAC-ECC), 2018

Photons absorption into nanoparticles dimensions leads to a large increase in its electromagnetic... more Photons absorption into nanoparticles dimensions leads to a large increase in its electromagnetic intensity and the nanoparticle's radiated properties. The strongly absorbed light by the nanoparticles is followed by converted efficiently into thermal energy to kill harmed cells without affecting the surrounding healthy cells. In this paper, gold nanoparticles (NPs) are prepared and investigated by x-ray diffraction (XRD), energy dispersive x-ray (EDX), UV-visible spectroscopy (UV-vis), and transmission electron microscopy (TEM). Experimental results are analyzed to obtain four different sensors designs. The reflection coefficient S11 and absorption of each design are introduced as a measure for the back scattering of the different structures. The High Frequency Structure Simulator (HFSS) is used to compare between results. Results show that design 2 has the minimum reflection coefficient (S11= −45.1 dB) at resonance frequency= 820THz which in IR region.

Environmentally Friendly Energy Harvesting Using Magnetocaloric Solid-State Nanoparticles as Magnetic Refrigerator

Journal of Low Temperature Physics, 2021

Metal organic framework/layer double hydroxide/graphene oxide nanocomposite supercapacitor electrode

Applied Physics Letters, 2021

Layered Double Hydroxide (LDH) based on Metal Organic Framework (MOF) structures has attracted a ... more Layered Double Hydroxide (LDH) based on Metal Organic Framework (MOF) structures has attracted a great deal of attention due to their high surface area, tailoring structure of the MOF, and high pseudocapacitance of LDH. Herein, an Ni-ZIF-67/Mn-LDH supercapacitor electrode was prepared via the solvothermal method at room temperature. A supercapacitor electrode based on Ni-ZIF-67/GO-LDH by replacing active metal Mn with graphene oxide (GO) was also synthesized to enhance the capacitance retention and stability from 78% to 97% after 1000 cycles. The morphology of these electrodes was characterized by scanning electron microscopy (SEM). It was found that the specific surface areas of Ni-ZIF-67/GO-LDH and Ni-ZIF-67/Mn-LDH are 82 and 20 m2 g−1. The electrochemical performance of the two nanocomposite supercapacitor electrodes was observed by cyclic voltammetry, charge–discharge, and electrochemical impedance spectroscopy measurements. The Ni-ZIF-67/GO-LDH electrode produced a specific capacitance (Cs) of 1036 F/g at 1 A/g, while the Ni-ZIF-67/Mn-LDH electrode results in a superior Cs value of 1420 F/g at 1 A g−1 with an energy density of 44 Wh/kg and a power density of 3.5 kW/kg.

Electrochimica Acta, 2021

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Strong tailoring magnetocaloric effect in highly (001)-oriented La0.7Sr0.3MnO3 thin films

Journal of Materials Research and Technology, 2021

Abstract In this work, we simulated the dependence of magnetization versus temperature for highly... more Abstract In this work, we simulated the dependence of magnetization versus temperature for highly (001)-oriented La0.7Sr0.3MnO3 (LSM) thin film prepared under several oxygen growth pressures to predict magnetocaloric effect (MCE). The results reveal that MCE of highly (001)-oriented LSM thin films is strongly tunable with oxygen growth pressure during preparation. Furthermore, the MCE of these films is enhanced with increasing oxygen growth pressure during preparation. The comparison of MCE parameters for (001)-oriented LSM thin films and some published works, showing that these films are considerably larger and comparable with some MCE parameters of these published works. It is suggested that (001)-oriented LSM thin films can be used as a function material of MR that cools at cryogenic and room temperatures.

Journal of Electronic Materials, 2018

An electrochemical method was used to prepare polyaniline (PANI) with hydrochloric acid as a dopa... more An electrochemical method was used to prepare polyaniline (PANI) with hydrochloric acid as a dopant. This electroactive material was fabricated using electrically modified carbon coated Teflon electrodes with an area of 0.64 cm 2 in 1 M HCl. PANI was electrochemically synthesized using cyclic voltammetry (CV) with a variable number of cycles, scan rates, and step sizes at potentials ranging from À 0.2 V to 0.8 V. Fabricated samples were tested using different electrochemical techniques including CV, differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). The DPV and EIS measurements indicate a linear relationship between both the current peak and the charge transfer resistance (R ct) and pH. These measurements showed that the prepared electrochemical device can be used as a sensor for pH. Optimum preparation parameters were 30 cycles, 50 mV/s scan rate and 2 mV step size. A linear relationship between oxidation current and pH of the solution with a correlation coefficient of 0.97 in the range of 1-5 makes PANI a candidate to be used as a pH sensor.

JOM, 2019

Nanofibers were prepared from a poly(acrylonitrile-co-vinyl acetate) [P(AN-co-VAC)]/polyvinyliden... more Nanofibers were prepared from a poly(acrylonitrile-co-vinyl acetate) [P(AN-co-VAC)]/polyvinylidene fluoride (PVDF) blend and used as a quasi-solid (QS) electrolyte for dye-sensitized solar cells (DSSCs). The effects of preparation parameters such as the flow rate and the weight percentage of PVDF on the fiber diameter, crystallinity, and ionic conductivity were investigated. Fourier-transform infrared (FTIR) spectroscopy, x-ray diffraction (XRD) analysis, and scanning electron microscopy (SEM) were used to characterize the prepared blend nanofibers. Current-voltage and electrochemical impedance spectroscopy (EIS) measurements were carried out on the fabricated DSSCs. It was found that the optimum weight ratio of P(AN-co-VAC) to PVDF in N,Ndimethylformamide (DMF) to produce uniform fibers with average diameter of 180 nm was 7:3 with ionic conductivity (r i) of 2.9 9 10 À3 S/cm. Moreover, the efficiency of DSSCs based on P(AN-co-VAC) as QS electrolyte was enhanced by 8.5 times by addition of PVDF. Finally, a model is proposed based on the EIS analysis.

The International Conference on Electrical Engineering, 2016

Supercapacitors represent an attractive alternative for portable electronics and automotive appli... more Supercapacitors represent an attractive alternative for portable electronics and automotive applications due to their high capacitance, specific power and extended life. In fact, the growing demand of portable systems and hybrid electric vehicles, memory protection in CMOS, logic circuit, VCRs, CD players, PCs, UPS in security alarm systems, remote sensing, smoke detectors, etc. require high power in short-term pulses. So, in the last 20 years, supercapacitors have been required for the development of large and small devices driven by electrical power. In this paper, asymmetric supercapacitors with high energy density were successfully fabricated using graphene as negative electrode and polyaniline as positive electrode. The weight of active material was 5.6 mg. The surface topography was characterized by scanning electron microscopy (SEM). The electrochemical properties of the composite were evaluated by cyclic voltammetry (CV), charge-discharge measurements and electrical impedance spectroscopy (EIS). The separator was a filter paper soaked in aqueous potassium hydroxide (6M).This enhances both the specific capacitance to 620.76 F/g at scan rate of 1 mV/s and the energy density to 86.22Wh/kg. Another low leakage supercapacitor was fabricated using polyvinyl alcohol (PVA) separator and 6 mole potassium hydroxide salt with specific capacitance of 220.35 F/g at scan rate of 1 mV/s.

The International Conference on Electrical Engineering, 2016

Supercapacitors have attracted increasing attention due to their widespread applications, such as... more Supercapacitors have attracted increasing attention due to their widespread applications, such as hybrid electric vehicles, power tools, portable electronic equipment and other devices. Using larger surface area of graphene electrodes and thinner dielectrics to achieve larger capacitances is a new trend for increasing capacitance of supercapacitors. This allows for energy densities greater than those of conventional capacitors and power densities greater than those of batteries.. In this paper, graphene oxide was synthesized by improved Hummers method. polyaniline PANI/grapheneoxide (GO) nanocomposite electrode materials were prepared from aniline (ANI), GO and ammoniumpersulfate (APS) by insitu chemical polymerization in ice bath. GO in composite was reduced for 5h and 20h. The crystal structure and the surface topography of all materials were characterized by Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy. The electrochemical properties were evaluated by cyclic voltammetry (CV), charge-discharge measurements, electrical impedance spectroscopy (EIS) and a four-point probe, respectively. The results show that with increasing reduction time, the oxygen content on the surface of GO was decreased, leading to increased ID/IG ratio in the Raman spectra of GO and increased conductivity of composite. Consequently, the capacitance properties of RGO/PANI composites could be significantly improved by the reduction of GO for 20h. The GO /PANI composite reduced for 20h had a specific capacitance as high as 1405.68 F/g at scan rate of 1 mV/s compared with 291.73 F/g for pristine graphene film.

Microsystem Technologies, 2018

Electrochemical biosensor has been developed for detection of danazol (Dz) based on electrochemic... more Electrochemical biosensor has been developed for detection of danazol (Dz) based on electrochemical polyaniline (PANI) electrode. Electrochemical PANI films were prepared by electrochemical polymerization technique. The Fourier transform infrared spectroscopy and X-ray diffraction were performed to identify the characteristic peaks and the degree of crystallinity of the prepared films. Cyclic voltammetry (CV) studies have been investigated for the electrochemical polyaniline films onto carbon electrode to determine the appropriate electro-active films to be used as electrochemical biosensor. CV of electrochemical polymerization of polyaniline films at different doping concentrations of 1, 1.2 and 1.5 M. CV results shown, the maximum peak current was 44.67 mA/cm 2 at 0.2 V/SCE for 1 M HCl. The prepared electrodes were used for detecting Dz using differential pulse voltammetry (DPV) technique and electrochemical impedance spectroscopy (EIS). The current peak of DPV produced inside solution containing Dz of concentration 2 nM is about 1.671 mA. Also, EIS showed that the charge transfer resistance (R ct) was increased with different Dz concentration.

Journal of Electronic Materials, 2017

In this work, an organic field-effect transistor (OFET) was fabricated and characterized based on... more In this work, an organic field-effect transistor (OFET) was fabricated and characterized based on the bottom contact of a polyaniline (PANI) or PANI/ TiO 2 nanocomposite as an active layer and SiO 2 as an insulating layer to be used for ammonia gas sensing applications. The OFET sensors exhibited a change in the drain current when exposed to NH 3. Titanium dioxide (TiO 2) nanoparticles with different weight percentages (0-50 wt.%) were added to dope PANI and enhance charge carrier transport, although the response of both the PANI OFET sensor and PANI/TiO 2 OFET sensor has reached saturation value at almost the same period. The response of PANI/TiO 2 transistor is (2.5), which is much higher than that of PANI (0.17). The results showed that the sensor response of the OFET device fabricated with PANI/TiO 2 is 15 times greater than that with an OFET device fabricated using pristine PANI.

Sprayed polyaniline layer onto chemically reduced graphene oxide as electrode for high performance supercapacitor

Synthetic Metals, 2016

Abstract In this work supercapacitors were fabricated from reduced graphene oxide (RGO), polyanil... more Abstract In this work supercapacitors were fabricated from reduced graphene oxide (RGO), polyaniline (PANI) and graphene/PANI (G/PANI) electrodes. The fabricated electrodes were characterized using scanning electron microscope (SEM) and UV–vis spectroscopy. The electrochemical activities of supercapacitors were assessed using cyclic voltammetry (CV), electrical impedance spectroscopy (EIS), and charge-discharge measurements. Graphene electrodes were prepared by exposure the graphene oxide (GO) sheets to hydrazine to reduce and restore the conducting carbon network. A maximum specific capacitance of 292 F/g with energy density of 40.5 Wh/kg in an aqueous electrolyte solution had been obtained for this graphene supercapacitor. Supercapacitor of sprayed PANI electrodes produced specific capacitance of 595 F/g and energy density of 82.63 Wh/kg. Finally, a hybrid supercapacitor had been developed by spraying PANI layer onto the reduced graphene oxide sheet (G/PANI). It was found that G/PANI supercapacitor displayed a specific capacitance of 916 F/g and energy density of 127.19 Wh/kg, which is much higher than that of pristine graphene and PANI electrodes supercapacitor.

An Introduced Hybrid Graphene/Polyaniline Composites for Improvement of Supercapacitor

Journal of Electronic Materials, 2015

Supercapacitors represent an attractive alternative for portable electronics and automotive appli... more Supercapacitors represent an attractive alternative for portable electronics and automotive applications due to their high capacitance, specific power and extended life. In fact, the growing demand of portable systems and hybrid electric vehicles, memory protection in complementary metal-oxide-semiconductor (CMOS), logic circuit, videocassette recorders (VCRs), compact disc (CD) players, personal computers (PCs), uninterruptible power supply (UPS) in security alarm systems, remote sensing, smoke detectors, etc. require high power in short-term pulses. Therefore, in the last 20 years, supercapacitors have been required for the development of large and small devices driven by electrical power. In this paper, graphene oxide (GO) was synthesized by improved Hummers method. Two polyaniline (PANI)/graphene oxide nanocomposites electrode materials were prepared from aniline, GO and ammoniumpersulfate (APS) by in situ chemical polymerization with the mass ratios (mGO:mAniline) 10:90 and 30: 70 in ice bath. The crystal structure and the surface topography of all materials were characterized by means of x-ray diffraction (XRD), Fourier transform infrared spectrum (FTIR), Raman spectroscopy and scanning electron microscopy (SEM). The electrochemical properties of the composites were evaluated by cyclic voltammetry (CV), charge–discharge measurements and electrical impedance spectroscopy (EIS), respectively. The results show that the composites have similar and enhanced cyclic voltammetry performance compared with pure PANI based electrode material. The graphene/PANI composite synthesized with the mass ratio (mANI:mGO) 90:10 possessed good capacitive behavior with a specific capacitance as high as 1509.35 F/g at scan rate of 1 mV/s in scanning potential window from −0.8 V to 0.8 V.

International Journal of Advanced Research in Electrical, Electronics and Instrumentation Engineering, 2015

In this paper, a proposed supercapacitorwas fabricated using an electrode of graphene layer cover... more In this paper, a proposed supercapacitorwas fabricated using an electrode of graphene layer covered with polyaniline layer. Uniform polyaniline layer was deposited using spraying technique. Characterizations were performed using scanning electron microscope (SEM) and UV-visible spectroscopy. The electrochemical measurements were assessed using cyclic voltammetry (CV), electrical impedance spectroscopy (EIS), and charge-discharge measurements. The results indicated that graphene/PANI double layers exhibited high porosity and large surface area. Polyaniline/graphenesupercapacitor had a specific capacitance as high as 915.78 F/g at scan rate of 5 mV/s in the scanning potential window from-0.8 to 0.8 V with 4 mg active material. The fabricated supercapacitor prototype has provided an energy density of 127.19 Wh/kg at potential difference of 1V using aqueous electrolyte of 6M potassium hydroxide. The effect of temperature on supercapacitor performance was investigated and it was found that the influence of temperature on specific capacitance was insignificant. It was observed that an improvement in the specific capacitance with about 1% in temperature range between 25 ˚C and 70 ˚C.

Journal of Taibah University for Science, 2016

In this paper, polyaniline is deposited using a spraying technique onto a flexible current collec... more In this paper, polyaniline is deposited using a spraying technique onto a flexible current collector for pseudocapacitor applications. The polyaniline is characterized using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and optical absorption studies. The energy density of a pseudocapacitor is higher than that of double-layer supercapacitors due to Faradaic reactions. A high specific capacitance of 594.92 F/g is obtained at a scan rate of 5 mV/s with a scanning potential window of (−0.8 to 0.8 V). The results show an increase in the energy density of 82.63 W h/kg at a potential difference of 1 V using a 4 M potassium hydroxide aqueous electrolyte.