Hoda Hafez
University of Sadat City, Nanotech.Dept., Faculty Member
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Plasmonic Pd–ZnO nano photocatalysts synthesized via a green chemistry approach represent an innovation of visible-light-induced photocatalysis that can be applied for photobiogas production from organic dye pollutants. Different... more
Plasmonic Pd–ZnO nano photocatalysts synthesized via a green chemistry approach represent an innovation of visible-light-induced photocatalysis that can be applied for photobiogas production from organic dye pollutants. Different plasmonic Pd–ZnO nanophotocatalysts have been synthesized via green microwave-assisted methods using orange peel extract as a capping agent by adding different proportions (3, 5, and 7 wt%) from Pd-metal plasmons. This fast and green innovative method anchored well distribution of Pd-metal plasmons (2-5 nm) on the surface of ZnO (17–27 nm). XRD has investigated the nanostructures' crystallographic, morphological, and optical characteristics,XPS, TEM, UV–Vis DRS, and as.BET surface area analysis. A higher surface area data have been achieved by incorporating Pd plasmons from 9.2 m2 g-1 inpure ZnO to 16.9 m2 g-1 in 7% Pd–ZnO. The analysis of XPS spectra shows anincrease of the lattice oxygen (OL) from 62.36% to 65.08%, suggesting anincrease in the number of oxygen vacancies on the surface of the Pd–ZnO plasmonic photocatalysts that leads to enhancing its photocatalytic performance. UV–Vis optical spectra of the different Pd–ZnO photocatalysts reveal the visible light absorption capability due to the localized surface plasmonic resonance effect (LSPR). The photocatalytic activity of the obtained Pd–ZnOnanomaterials has been tested on the photobiogas production during the photocatalytic destruction of Reactive Yellow 15 (R.Y.) in two prototype photobiogas reactors, cylindrical UV reactor and a pilot-scale CPC solar reactor,under nitrogen atmosphere. A higher yield of biogas (CH4) and hydrogen (H2)gases have been achieved by the effect of Pd plasmons on the ZnOphotocatalyst.
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White Nanophosphors based on praseodymium doped barium tungstate matrix (y mol Pr 3+ : BaWO 4 (PBWO) (y = 0.01, 0.03, 0.05, 0.07 mol) were synthesized by ultrasound assisted hydrothermal method in the presence of citric acid and... more
White Nanophosphors based on praseodymium doped barium tungstate matrix (y mol Pr 3+ : BaWO 4 (PBWO) (y = 0.01, 0.03, 0.05, 0.07 mol) were synthesized by ultrasound assisted hydrothermal method in the presence of citric acid and characterized as novel down-conversion materials for dye-sensitized solar cells (DSSCs) applications. The different prepared PBWO Nanophosphors show high crystalline tetragonal phase with nano-cubic morphology. The PBWO photoluminescence spectra give strong emission peaks at 486, 529, 615, 623 and 643 nm are corresponding to the 3
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Muchos problemas ambientales actuales están relacionados con los desechos industriales y municipales (lodos de depuradora, etc.), debidos al gran volumen que se genera, así como a los elementos peligrosos que incluyen en ellos (metales... more
Muchos problemas ambientales actuales están relacionados con los desechos industriales y municipales (lodos de depuradora, etc.), debidos al gran volumen que se genera, así como a los elementos peligrosos que incluyen en ellos (metales pesados). Su almacenamiento, tratamiento y transporte conlleva también costos económicos. En Egipto en el año 2002 se generaron de 12 a 15 kg/año por habitante de materia sólida procedente de los lodos de depuradora. En la actualidad, el destino principal de estos lodos es su vertido en el desierto.
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Pt electrode prepared by chemical method has been employed as counter electrode in dye-sensitized solar cell. TiO2 nanomaterial was deposited on fluorine-doped tin oxide substrate to be used as photoanode. Structure of the TiO2 and Pt... more
Pt electrode prepared by chemical method has been employed as counter electrode in dye-sensitized solar cell. TiO2 nanomaterial was deposited on fluorine-doped tin oxide substrate to be used as photoanode. Structure of the TiO2 and Pt films was investigated by atomic force microscope. The effect of illumination intensity on the photovoltaic parameters such as open circuit voltage, short circuit current density, output power, fill factor and efficiency of these cells was investigated in the range 2.5–130 mW/cm−2. The cell efficiency is stable above 70 mW/cm2. The fill factor is almost constant all over the studied range of illumination intensity. Impedance spectroscopy of the studied device as the summary measurements of the capacitance–voltage, conductance–voltage and series resistance–voltage characteristics were investigated in a wide range of frequencies (5 kHz–1 MHz). At low frequencies, the capacitance has positive values with peak around the origin due to the interfaces. At 200 and 300 kHz, the capacitance is inverted to negative with further increasing of the positive biasing voltage. Above 400 kHz, C–V profile shows complete negative behavior. Also, the impedance–voltage and phase–voltage characteristics were investigated. This cell shows a new promising device for photosensor applications due to high sensitivity in low and high illuminations.
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ABSTRACT Lanthanide doped inorganic nano-phosphor embedded into silica matrix have shown great potential in novel chemical and biological sensor development due to their pure, intense and stable photoluminescence (PL) properties. However,... more
ABSTRACT Lanthanide doped inorganic nano-phosphor embedded into silica matrix have shown great potential in novel chemical and biological sensor development due to their pure, intense and stable photoluminescence (PL) properties. However, their potential applications in forensic science, especially in latent fingerprint detection in particular, were still unexplored. In this study, we have succeeded in production of high PL, photo-stable and non-toxic x mol% Eu3+:Y2Ti2O7 embedded into silica matrix powder (x mol% Eu3+/Y2Ti2O7 where x = 1.0, 2.0, 4.0 6.0, 10, 15 and 30) using sol–gel method followed by heat treatment. The crystal, morphological, optical and PL properties of the nano-phosphor powders were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), energy dispersive spectroscopic (EDS), FT-IR and photoluminescence (PL) spectroscopy. Judd–Ofelt (J–O) theory was applied to a series of x mol% Eu3+:Y2Ti2O7 embedded into silica matrix based on their emission spectra. The results of in vivo toxicity test indicated that the prepared nano-phosphor embedded into silica matrix is non-toxic (LD50) for 15 mol% Eu3+ doped powder = 6.26 g/Kg). The prepared nano-phosphor was successfully developing in latent fingerprint from various forensic relevant materials, including non-porous and porous surfaces.
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The electrochemical anodization of a single crystalline silicon in hydrofluoric acid-based solution leads to the formation of porous silicon (PSi) with tunable pore sizes and morphology for a wide range of technological applications.
Research Interests: Materials Science and RSC
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City, six zone/n 328. Minufiya (Egipto) INTRODUCCIÓN. El control del medio ambiente es uno de los temas que cada vez preocupan más, no tan solo a la ciudadanía sino también a los órganos de dirección de los países y de los organismos... more
City, six zone/n 328. Minufiya (Egipto) INTRODUCCIÓN. El control del medio ambiente es uno de los temas que cada vez preocupan más, no tan solo a la ciudadanía sino también a los órganos de dirección de los países y de los organismos internacionales. Prueba de ello es la legislación desarrollada por la Unión Europea (UE) en los últimos años, cuya finalidad es la protección del medio ambiente por la importancia que tiene para la supervivencia de nuestra sociedad en un futuro no muy lejano. Uno de los puntos importantes es el control de las aguas residuales, de aquí la implantación de depuradoras de agua antes del vertido de las mismas. Todo proceso de depuración implica como resultado del mismo la obtención de unas aguas limpias reutilizables y unos lodos que concentren el material sólido y contaminante. El 6º Programa de Actuación Medioambiental (6EAP) recomienda tomar una serie de medidas coordinadas, tendentes a la reducción del impacto medioambiental, por el uso de recursos, de a...
The paper reports on the photocatalytic efficiency ofTiO2nanoparticles immobilized on polyvinyl pyrrolidone/acrylic acid (PVP/AAc) copolymer hydrogels, which are prepared by means ofγ-rays induced homo- and copolymerization. The... more
The paper reports on the photocatalytic efficiency ofTiO2nanoparticles immobilized on polyvinyl pyrrolidone/acrylic acid (PVP/AAc) copolymer hydrogels, which are prepared by means ofγ-rays induced homo- and copolymerization. The efficiency of immobilized photocatalyst is tested on a commercial textile dye namely Remazol Red RB-133. The results are compared with photocatalytic efficiencies of different types of non supportedTiO2photocatalysts such as aqueous slurries of colloidalTiO2prepared by sol-gel technique, and commercially available Degussa P25. Although less efficient than nonsupported ones, the hydrogel supportedTiO2photocatalyst has the practical advantages of easy separation and removal from the reactors. This makes it a viable technique for the safe disposal of textile wastewater into the water streams.
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We report on the design and structure principles of 5,5′-6,6′-tetrachloro-1,1′-dioctyl-3,3′-bis-(3-carboxypropyl)-benzimidacarbocyanine (Dye 1). Such metal-free amphiphilic cyanine dyes have many applications in dye-sensitized solar... more
We report on the design and structure principles of 5,5′-6,6′-tetrachloro-1,1′-dioctyl-3,3′-bis-(3-carboxypropyl)-benzimidacarbocyanine (Dye 1). Such metal-free amphiphilic cyanine dyes have many applications in dye-sensitized solar cells. AFM surface topographic investigation of amphiphilic molecules of Dye 1 adsorbed on TiO2anode reveals the ability of spontaneous self-organization into highly ordered aggregates of fiber-like structure. These aggregates are known to exhibit outstanding optical properties of J-aggregates, namely, efficient exciton coupling and fast exciton energy migration, which are essential for building up artificial light harvesting to the photovoltaic device. A light-to-electricity conversion efficiency of DSSC based on the metal free amphiphilic Dye 1 isη=3.75, which is about 50% of that based on metal-based N719 Ru-dye (Di-tetrabutylammoniumcis-bis(isothiocyanato)bis(2,2′-bipyridyl-4,4′-dicarboxylato)ruthenium(II)). DFT and TD-DFT studies show that large int...
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Pure andGd3+-doped titanate nanotubes (TNTs) materials were synthesized by a hydrothermal method. Their morphology, optical properties, thermal stability, and magnetic properties were characterized by X-ray diffraction (XRD), transmission... more
Pure andGd3+-doped titanate nanotubes (TNTs) materials were synthesized by a hydrothermal method. Their morphology, optical properties, thermal stability, and magnetic properties were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), UV-Vis spectroscopy, thermal analysis, and magnetic measurements. It was found that doping rendersGd3+-TNT visible light active and results in smaller crystallite size and larger surface area as well as higher thermal stability compared to pure titanate nanotubes. The estimated magnetic moments point to presence of weak antiferromagnetic interaction. Application of the preparedGd3+-TNT for modifying conventional photoanodes in polymer solar cells was attempted. Preliminary results show slightly improved photovoltaic energy conversion efficiency in the devices containing the newly designedGd3+-doped nanotubes.
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ABSTRACT Highly active ZnO rod-like nanostructures with pointed-shape ends have been synthesized via a simple hydrothermal method using acetic acid as an organic capping agent. The X-ray diffraction (XRD) pattern of the prepared sample... more
ABSTRACT Highly active ZnO rod-like nanostructures with pointed-shape ends have been synthesized via a simple hydrothermal method using acetic acid as an organic capping agent. The X-ray diffraction (XRD) pattern of the prepared sample reveals that the ZnO rod-like nanostructures are of pure hexagonal wurtzite structure. Morphology of the nanorods has been investigated by transmission electron microscope (TEM), which showed the formation of pointed nanorods of 30–50 nm in diameter and 400–650 nm in length. Optical properties have been investigated by UV–vis diffuse reflectance and photoluminescence spectroscopy. UV–vis absorption spectrum indicated that the ZnO nanorods have higher visible light harvesting as compared to the other morphologies in the literature. Intense room temperature green-red photoluminescence peaks at 486 nm and 564 nm has been observed for the prepared ZnO. This gives a good evidence of the presence of ionized oxygen vacancies which are favorable for photocatalytic reactions. The BET surface area and the average (BJH) adsorption pore size were 269.86 m2/g and 2.86 nm, respectively. The photocatalytic activity of the prepared sample was tested on the degradability of an industrial textile dye, Reactive Yellow 15 (Yellow GR), under sunlight irradiation. A 85.7% dye removal was achieved by applications of these rod-like nanostructures as a photocatalyst.The reusability of the synthesized ZnO nanomaterial has been investigated under the same experimental conditions for three time to evaluate the photoactivity of the photocatalyst.
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Abstract. The paper reports on the photocatalytic efficiency of TiO2 nanoparticles immobilized on polyvinyl pyrrolidone/acrylic acid (PVP/AAc) copolymer hydrogels, which are prepared by means of γ-rays induced homo-and copolymerization.... more
Abstract. The paper reports on the photocatalytic efficiency of TiO2 nanoparticles immobilized on polyvinyl pyrrolidone/acrylic acid (PVP/AAc) copolymer hydrogels, which are prepared by means of γ-rays induced homo-and copolymerization. The efficiency of ...
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The assessment of Chromium ion in the field of leather tanning industry; either in leathers or waste forms, using fluorescent sensor method, has not been thoroughly explored. Herein, a simple and sensitive fluorescent sensor based on x... more
The assessment of Chromium ion in the field of leather tanning industry; either in leathers or waste forms, using fluorescent sensor method, has not been thoroughly explored. Herein, a simple and sensitive fluorescent sensor based on x mol Eu 3þ :BaZrO 3 Nano-phosphor (EBZO) (x ¼ 0.00150, 0.0150, 0.0300, 0.0500 mol) has been prepared and characterized for Cr 3þ ion detection in tanning leathers or waste. Eu 3þ :BaZrO 3 Nano-sensor has strong and pure red emission with long lifetime upon UVC exci-tation; either in solid state or aqueous solutions. The sensing results reveal that EBZO Nano-sensor is quite selective and sensitive towards chromium ion over other metal ions. The assessment of chromium ion has been done using Stern-Volmer quenching method on the red fluorescence emitted from the sensor upon the addition of chromium in aqueous solution. Calibration plot has been achieved over the concentration 1.0e10 Â 10 À9 molL À1 with a correlation coefficient of 0.978 and a detection limit of 3.8 Â 10 À9 mol L À1. Optical fluorescence and lifetime measurements confirm that EBZO sensor is statically quenched via columbic interaction mechanism with chromium ions. Optimized EBZO Nano-sensor is successfully applied for Chromium detection in real tanning of leather or other waste samples with high recovery values.
In this research, PEDOT:PSS film is employed as a counter electrode in the dye-sensitized solar cell (DSSC) for low-cost photo-sensing applications. This DSSC is based on nanostructured TiO 2 as photoanode. The morphology of the counter... more
In this research, PEDOT:PSS film is employed as a counter electrode in the dye-sensitized solar cell (DSSC) for low-cost photo-sensing applications. This DSSC is based on nanostructured TiO 2 as photoanode. The morphology of the counter electrode was examined using atomic force microscope showing well distributed spherical clusters with average size 214.04 nm. This DSSC behaves like Schottky diode in the dark condition with rectification ratio 40 at 0.5 V. The photovoltaic behavior was studied in the light intensity range 10-130 mW cm −2. This solar cell has a stable fill factor (about 0.5) for most of the studied illumination intensity range. The photo-response of the current suggests that the new designed DSSC with the polymeric counter electrode is a promising device for low-cost photosensor. The cell shows capacitance inversion from positive to negative with increasing the applied frequency at about 100 kHz which recommends this cell for further applications. Also, the effect of frequency on the built-in potential and the series resistance has been investigated.
The assessment of Chromium ion in the field of leather tanning industry; either in leathers or waste forms, using fluorescent sensor method, has not been thoroughly explored. Herein, a simple and sensitive fluorescent sensor based on x... more
The assessment of Chromium ion in the field of leather tanning industry; either in leathers or waste forms, using fluorescent sensor method, has not been thoroughly explored. Herein, a simple and sensitive fluorescent sensor based on x mol Eu 3þ :BaZrO 3 Nano-phosphor (EBZO) (x ¼ 0.00150, 0.0150, 0.0300, 0.0500 mol) has been prepared and characterized for Cr 3þ ion detection in tanning leathers or waste. Eu 3þ :BaZrO 3 Nano-sensor has strong and pure red emission with long lifetime upon UVC exci-tation; either in solid state or aqueous solutions. The sensing results reveal that EBZO Nano-sensor is quite selective and sensitive towards chromium ion over other metal ions. The assessment of chromium ion has been done using Stern-Volmer quenching method on the red fluorescence emitted from the sensor upon the addition of chromium in aqueous solution. Calibration plot has been achieved over the concentration 1.0e10 Â 10 À9 molL À1 with a correlation coefficient of 0.978 and a detection limit of 3.8 Â 10 À9 mol L À1. Optical fluorescence and lifetime measurements confirm that EBZO sensor is statically quenched via columbic interaction mechanism with chromium ions. Optimized EBZO Nano-sensor is successfully applied for Chromium detection in real tanning of leather or other waste samples with high recovery values.