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Papers by marwa nabil

IOP conference series, Oct 1, 2017

A new method has been developed to improve the photoluminescence intensity of porous silicon (PS)... more A new method has been developed to improve the photoluminescence intensity of porous silicon (PS). Self-organized (PS) can be used in various fields. The deposition of metal nanoparticles (Ni) allows utilizing the obtained nano-composite for numerous applications such as sensor technology, biomedicine, and many more. (Ni/PS) nano-composite powders are prepared using Ni deposition on the PS powder surface. The (Ni/PS) powders became hydrophilic by the deposited Ni nanoparticles. At the different percentages of (Ni: PS), at a higher percentage than (3:1) the values of the crystallite size of Ni and PS are nearly equivalent which suggests the saturation case of PS surface by Ni particles. It also depends on the deposition time value. In this study, that is the commercialization of nanostructured materials, it is important that the manufacturing costs are appropriate and inexpensive for large scale production, in addition, the enhancement of the photoluminescence intensity of (PS).

International Journal of Materials Technology and Innovation, 2021

Евразийский союз ученых, May 23, 2019

Using prepared dendritic porous silicon powder as a promise adsorbed material for heavy elements ... more Using prepared dendritic porous silicon powder as a promise adsorbed material for heavy elements (i.e. Cu) from wastewater. The maximum removal percent of Cu (II) reached 1383.9 mg/g and 92.5%, respectively, at an initial Cu (II) concentration of 200 mg/L, adsorption time of 10 min. АННОТАЦИЯ. Использование приготовленного дендритного пористого порошка кремния в качестве перспективного адсорбированного материала для тяжелых элементов (т.е. Cu) из сточных вод. Максимальный процент удаления Cu (II) достиг 1383,9 мг / г и 92,5% соответственно при начальной концентрации Cu (II) 200 мг / л, время адсорбции 10 мин. ABSTRACT. New and inexpensive dendritic Porous Silicon powder (dendritic PS) powder is prepared by alkali chemical etching using ball milling technique and is subsequently investigated as an adsorbent in batch systems for the adsorption Cu (II) ions in an aqueous solution. The optimum conditions for the Cu (II) ion adsorption capacity of the dendritic PS powder are studied in detail by varying parameters such as the initial Cu (II) concentration, the solution pH value, the adsorption temperature and contact time. The results indicated that the maximum adsorption capacity and the maximum removal percent of Cu (II) reached 1383.9 mg/g and 92.5%, respectively, at an initial Cu (II) concentration of 200 mg/L, adsorption time of 10 min and no effect of the solution pH and adsorption temperature.

Scientific Reports, Sep 29, 2022

Sodium ion batteries are favored in stationary and large scale power storage due to their low cos... more Sodium ion batteries are favored in stationary and large scale power storage due to their low cost and nontoxicity. As the lithium is replaced with sodium due to the cost motive, a cheap processing method is needed to maintain the cell price as low as possible. We report an ultra-fast synthesis method that utilizes the high microwave absorbance of silicon carbide content in rice straw ash. Amorphous/ maricite mixtures of sodium iron phosphates-carbon composites (NaFePO 4-C) are synthesized, crystallized, and carbon coated using one-step microwave heating. The sodium ion electroactive composites are prepared using different microwave heating durations ranging from 30 to 100 s. High purity inert gases are not needed during synthesis, processing, and even at cell assembly. The materials are characterized by elemental analysis techniques, X-ray diffraction (XRD), scanning/ transmission electron microscope (SEM/TEM), and Raman spectroscopy. The electrochemical performance of the synthesized nanocomposites is examined as sodium ion battery cathode and as symmetric supercapacitors. The optimum synthesis time is 60 s for the application as sodium ion batteries and as a supercapacitor. The maximum specific capacity is 108.4 mA h g −1 at 0.2 C in the case of using it as a battery cathode. While the capacitance is 86 F g −1 at 0.5 A g −1 as a supercapacitor. The capacity retention is 92.85% after 40 cycles at 0.2 C as sodium ion battery electrode. For supercapacitor, the capacity retention is 81.7% after 1000 cycles. Mobile applications such as electric vehicles (EVs), laptops and cell phones have been invaded by lithium ion technologies due to the high specific gravimetric capacities of Li cells 1. The lithium depletion fears came early to put the basics of their replacement with sodium ion technologies, especially in stationary and large scale common applications 2,3. Sodium has many characteristics that are very close to those of lithium, especially their electronegativity and ionic radius. On the other hand, sodium is environmentally friendly and its abundance in the earth's crust is about 1350 times more than that of lithium 4. Many nanomaterials have been revealed as cathodes and anodes for sodium ion batteries (SIBs) and have been published elsewhere 5-8. Sodium vanadium phosphates (NVP) Na 3 V 2 (PO 4) 3 and Na 3 VCr(PO 4) 3 with NASICON structures were among the most successful active cathode materials owing to their high and flat discharge potential at 3.4 V vs Na/Na + , which maximizes energy density. They also have the high rate capability advantage due to their sodium ion superconducting open framework structure. However, only two of the three Na + ions are available at this high potential, resulting in a relatively low theoretical capacity of 118 mA h g −1. In addition, their cost is relatively high 9,10. As a raw material, iron oxide is one tenth the cost of vanadium oxide, which lowers the cost advantage of using NVP when compared with LiFePO 4 11. The sodium iron phosphate with its different forms provides a cheap material as sodium ion battery cathodes, in addition to their environmental safety 5. Maricite, Olivine, and amorphous forms of NaFePO 4 , all with a theoretical capacity of 152 mA h g −1 , have been explored as active, low cost cathode materials for SIBs 12-16. Olivine NaFePO 4 can be prepared only from LiFePO 4 by electrochemical delithiation and subsequent sodiation. It possesses low ionic conductivity due to its one direction Na/Li diffusion tunnels 12,17. The conversion of maricite

Journal of Materials Science and Chemical Engineering, 2019

The purpose of the present research is the different morphologies production of crystalline and a... more The purpose of the present research is the different morphologies production of crystalline and amorphous-silica powder. It's a basic material for many pharmaceutical and environmental applications as well. And, it's produced using the combination of the alkali chemical etching process and the ultra-sonication technique. The critical preparation conditions are KOH concentration (weight %) and the sonication time (hour). The paper presents the chemical mechanism of the silica particle formation as well as the different morphology. The results show the formation of crystalline and amorphous-porous-silica particles in the micrometer range with the porous order network that has pore sizes range in micrometer too. This synthetic uses commercial silicon, which could be useful for large-scale production. Also, the nano-sphere and nano-cubic shapes of silica powder are formed starting by commercial silicon powder.

Scientific Reports, 2021

Microbial contamination is one of the major dreadful problems that raises hospitalization, morbid... more Microbial contamination is one of the major dreadful problems that raises hospitalization, morbidity and mortality rates globally, which subsequently obstructs socio-economic progress. The continuous misuse and overutilization of antibiotics participate mainly in the emergence of microbial resistance. To circumvent such a multidrug-resistance phenomenon, well-defined nanocomposite structures have recently been employed. In the current study, a facile, novel and cost-effective approach was applied to synthesize Ag@Ag2O core–shell nanocomposites (NCs) via chemical method. Several techniques were used to determine the structural, morphological, and optical characteristics of the as-prepared NCs. XRD, Raman, FTIR, XPS and SAED analysis revealed a crystalline hybrid structure of Ag core and Ag2O shell. Besides, SEM and HRTEM micrographs depicted spherical nanoparticles with size range of 19–60 nm. Additionally, zeta potential and fluorescence spectra illustrated aggregated nature of Ag@A...

Advances in Nanoparticles, 2016

A direct synthesis method is introduced to prepare nano-porous silicon-nickel nanocomposite (nPS/... more A direct synthesis method is introduced to prepare nano-porous silicon-nickel nanocomposite (nPS/Ni) powder for thermal isolation applications. In this paper, we study the thermal stability of nanocomposites consisting of nanoparticles metal incorporated into the pores of a porous silicon by a very simple method. The nickel element is chemically deposited whereas the nanoparticles are precipitated on the pore surfaces. The (nPS) and (nPS/Ni) nano-materials are thermally measured under nitrogen at temperatures of 40˚C-1000˚C, noticeable, demonstrating better thermal stability of (nPS/Ni) until 900˚C than in the case of (nPS) at 600˚C. Then, the improving of the thermal stability of the nPS powder is facilitated using it in many applications of the thermal insulation process.

Proceedings of the 2016 International Conference on Mechanics, Materials and Structural Engineering, 2016

The surface chemistry of anisotropic etching of p-type Si-wafer (400) is reviewed and the anisotr... more The surface chemistry of anisotropic etching of p-type Si-wafer (400) is reviewed and the anisotropic chemical etching of silicon in alkaline solution using wetting agent were discussed. The main factors which affect the production of silicon dioxide layer on crystalline silicon as a result of wet alkali anisotropic chemical etching are the concentration of etching solution (KOH) and wetting agent (n-propanol), temperature (80°C) and time of the etching (4 hr) process. Silicon dioxide layer has found applications in many advanced areas. The synthesized silica layer was systematically characterized by XRD, SEM and FTIR spectroscopy. The XRD results revealed the amorphous nature of silica layer. FTIR spectroscopy confirmed the presence of Si-O in produced samples. SEM confirmed the addition of n-propanol to the KOH solution resulted in an improvement in the etching anisotropy in a smooth etched Si (400) surface.

Alexandria Engineering Journal, 2014

Sensors and Actuators B: Chemical, 2015

Abstract The combination of nano-porous silicon (nPS) with Congo red (CR) represents a nano-porou... more Abstract The combination of nano-porous silicon (nPS) with Congo red (CR) represents a nano-porous matrix which offer broad avenue of new and interesting properties depending on the involved materials as well as their morphology. Chemical route was utilized as the host material to achieve pores filling. They were impregnated with Congo red, which gave good results for the porous silicon as a promising pH sensor. The behavior of (nPS/CR) pH sensor, transformation of color (red-blue), is reversible after exposure to NH3 vapors, (red-blue-red). The ON/OFF behavior of the composite material depends upon the chemical processes occurring inside the pores. The fabrication of (nPS/CR) pH sensor depends on several factors {CR concentration, solvent type, and the chemical mechanism of CR adsorption on PS}.

Applied Mechanics and Materials, 2015

Silica (SiO2) nanoparticles have found applications in many advanced areas. This research work is... more Silica (SiO2) nanoparticles have found applications in many advanced areas. This research work is concerned with the preparation of silica nanoparticles by wet alkali chemical etching technique of commercial silicon powder using (KOH, n-propanol and water). The synthesized nanoparticles were systematically characterized by XRD, FTIR and PL spectroscopy. The XRD results revealed the amorphous nature of silica nanoparticles. FTIR spectroscopy confirmed the presence of Si-O in all the samples. PL spectra have shown emission band at around 516 nm. Then, nanosilica is promise material for the realization of light-emitting silica-based optoelectronic devices.

Materials Sciences and Applications, 2013

New and inexpensive nanoporous silicon (NPS) powder was prepared by alkali chemical etching using... more New and inexpensive nanoporous silicon (NPS) powder was prepared by alkali chemical etching using sonication technique and was subsequently investigated as an adsorbent in batch systems for the adsorption Ni(II) ions in an aqueous solution. The optimum conditions for the Ni(II) ion adsorption capacity of the NPS powder were studied in detail by varying parameters such as the initial Ni(II) concentration, the solution pH value, the adsorption temperature and contact time. The results indicated that the maximum adsorption capacity and the maximum removal percent of Ni(II) reached 2665.33 mg/g and 82.6%, respectively, at an initial Ni(II) concentration of 100 mg/L, adsorption time of 30 min and no effect of the solution pH and adsorption temperature.

Materials

Nano-porous silicon (NPS) powder synthesis is performed by means of a combination of the ultra-so... more Nano-porous silicon (NPS) powder synthesis is performed by means of a combination of the ultra-sonication technique and the alkali chemical etching process, starting with a commercial silicon powder. Various characterization techniques {X-ray powder diffraction, transmission electron microscopy, Fourier Transform Infrared spectrum, and positron annihilation lifetime spectroscopy} are used for the description of the product’s properties. The NPS product is a new environmentally friendly material used as an adsorbent agent for the acidic azo-dye, Congo red dye. The structural and free volume changes in NPS powder are probed using positron annihilation lifetime (PALS) and positron annihilation Doppler broadening (PADB) techniques. In addition, the mean free volume (VF), as well as fractional free volume (Fv), are also studied via the PALS results. Additionally, the PADB provides a clear relationship between the core and valence electrons changes, and, in addition, the number of defect ...

Scientific Reports, 2021

Microbial contamination is one of the major dreadful problems that raises hospitalization, morbid... more Microbial contamination is one of the major dreadful problems that raises hospitalization, morbidity and mortality rates globally, which subsequently obstructs socioeconomic progress. The continuous misuse and overutilization of antibiotics participate mainly in the emergence of microbial resistance. To circumvent such a multidrug-resistance phenomenon, well-defined nanocomposite structures have recently been employed. In the current study, a facile, novel and cost-effective approach was applied to synthesize Ag@Ag 2 O core-shell nanocomposites (NCs) via chemical method. Several techniques were used to determine the structural, morphological, and optical characteristics of the as-prepared NCs. XRD, Raman, FTIR, XPS and SAED analysis revealed a crystalline hybrid structure of Ag core and Ag 2 O shell. Besides, SEM and HRTEM micrographs depicted spherical nanoparticles with size range of 19-60 nm. Additionally, zeta potential and fluorescence spectra illustrated aggregated nature of A...

Materials Science Forum

Silica is one of the most important materials used in many industries. The basic factor on which ... more Silica is one of the most important materials used in many industries. The basic factor on which the selection process depends is the structural form, which is dependent on the various physical and chemical properties. One of the common methods in preparing pure silica is that it needs more than one stage to ensure the preparation process completion. The goal of this research is studying the nucleation technique (Bottom-top) for micro-wires and micro-ribbons silica synthesis. The silica nanoand microstructures are prepared using a duality (one step); a combination of alkali chemical etching process {potassium hydroxide (3 wt %) and n-propanol (30 Vol %)} and the ultra-sonication technique. In addition, the used materials in the preparation process are environmentally friendly materials that produce no harmful residues. The powder product is characterized using XRD, FTIR, Raman spectrum and SEM for determining the shape of architectures. The most significant factor of the nucleation ...

Egyptian Journal of Chemistry

N EWLY, porous silicon (PS) powder has been developed to meet the requirements of various fields ... more N EWLY, porous silicon (PS) powder has been developed to meet the requirements of various fields due to its unique physical and chemical properties. In this research, the PS powder is produced using a combination of both (alkali chemical etching and ultra-sonication techniques) from commercial polycrystalline silicon powder. It shows the dependence of the crystal structure and the morphology on the value of wetting agent concentration, which is controlled on the rate of each chemical reaction in the formation process. For the first time, the PS pines shape is a product at using the preparation conditions (7 wt %KOH, 3 hours, and 15 Vol% NPA). On the other hand, the (PS) micro-rod clusters are produced with different values of both the diameter and the pore size at wetting agent concentrations variation (20, and 25 Vol% NPA). The most stable crystal structure of silicon surface is Si (111), it has a rhombohedral unit cell. By changing the wetting agent concentration value, then the crystal structure of the product powder is changed too, from rhombohedral plane Si (111) to the hexagonal plane Si (211). So, this increases the chances of using the PS product in many fields whether medical or engineering.

Egyptian Journal of Chemistry

I N this research, using powder technology manufacturing is as a pioneering, low cost, a simple a... more I N this research, using powder technology manufacturing is as a pioneering, low cost, a simple and safe method for the fabrication of nano-porous silicon (NPSpowder). It's attractive carriers for targeted in several research fields. It's prepared using a combination of alkali chemical etching process and ultra-sonication technique; through the utilization of commercial silicon powder; with high yield efficiency (81.43%). Several 3D-NPS-shapes (nanorods array, nanosheets, and nanoclusters) are fabricated. It's a mixture of microporous and mesoporous silicon powder {pore size (28-140 nm)}. The main factors which affect the production of NPS-powder are (KOHconc.), sonication time, separation process and drying velocity.

Materials Chemistry and Physics

Journal of Physics and Chemistry of Solids

IOP conference series, Oct 1, 2017

A new method has been developed to improve the photoluminescence intensity of porous silicon (PS)... more A new method has been developed to improve the photoluminescence intensity of porous silicon (PS). Self-organized (PS) can be used in various fields. The deposition of metal nanoparticles (Ni) allows utilizing the obtained nano-composite for numerous applications such as sensor technology, biomedicine, and many more. (Ni/PS) nano-composite powders are prepared using Ni deposition on the PS powder surface. The (Ni/PS) powders became hydrophilic by the deposited Ni nanoparticles. At the different percentages of (Ni: PS), at a higher percentage than (3:1) the values of the crystallite size of Ni and PS are nearly equivalent which suggests the saturation case of PS surface by Ni particles. It also depends on the deposition time value. In this study, that is the commercialization of nanostructured materials, it is important that the manufacturing costs are appropriate and inexpensive for large scale production, in addition, the enhancement of the photoluminescence intensity of (PS).

International Journal of Materials Technology and Innovation, 2021

Евразийский союз ученых, May 23, 2019

Using prepared dendritic porous silicon powder as a promise adsorbed material for heavy elements ... more Using prepared dendritic porous silicon powder as a promise adsorbed material for heavy elements (i.e. Cu) from wastewater. The maximum removal percent of Cu (II) reached 1383.9 mg/g and 92.5%, respectively, at an initial Cu (II) concentration of 200 mg/L, adsorption time of 10 min. АННОТАЦИЯ. Использование приготовленного дендритного пористого порошка кремния в качестве перспективного адсорбированного материала для тяжелых элементов (т.е. Cu) из сточных вод. Максимальный процент удаления Cu (II) достиг 1383,9 мг / г и 92,5% соответственно при начальной концентрации Cu (II) 200 мг / л, время адсорбции 10 мин. ABSTRACT. New and inexpensive dendritic Porous Silicon powder (dendritic PS) powder is prepared by alkali chemical etching using ball milling technique and is subsequently investigated as an adsorbent in batch systems for the adsorption Cu (II) ions in an aqueous solution. The optimum conditions for the Cu (II) ion adsorption capacity of the dendritic PS powder are studied in detail by varying parameters such as the initial Cu (II) concentration, the solution pH value, the adsorption temperature and contact time. The results indicated that the maximum adsorption capacity and the maximum removal percent of Cu (II) reached 1383.9 mg/g and 92.5%, respectively, at an initial Cu (II) concentration of 200 mg/L, adsorption time of 10 min and no effect of the solution pH and adsorption temperature.

Scientific Reports, Sep 29, 2022

Sodium ion batteries are favored in stationary and large scale power storage due to their low cos... more Sodium ion batteries are favored in stationary and large scale power storage due to their low cost and nontoxicity. As the lithium is replaced with sodium due to the cost motive, a cheap processing method is needed to maintain the cell price as low as possible. We report an ultra-fast synthesis method that utilizes the high microwave absorbance of silicon carbide content in rice straw ash. Amorphous/ maricite mixtures of sodium iron phosphates-carbon composites (NaFePO 4-C) are synthesized, crystallized, and carbon coated using one-step microwave heating. The sodium ion electroactive composites are prepared using different microwave heating durations ranging from 30 to 100 s. High purity inert gases are not needed during synthesis, processing, and even at cell assembly. The materials are characterized by elemental analysis techniques, X-ray diffraction (XRD), scanning/ transmission electron microscope (SEM/TEM), and Raman spectroscopy. The electrochemical performance of the synthesized nanocomposites is examined as sodium ion battery cathode and as symmetric supercapacitors. The optimum synthesis time is 60 s for the application as sodium ion batteries and as a supercapacitor. The maximum specific capacity is 108.4 mA h g −1 at 0.2 C in the case of using it as a battery cathode. While the capacitance is 86 F g −1 at 0.5 A g −1 as a supercapacitor. The capacity retention is 92.85% after 40 cycles at 0.2 C as sodium ion battery electrode. For supercapacitor, the capacity retention is 81.7% after 1000 cycles. Mobile applications such as electric vehicles (EVs), laptops and cell phones have been invaded by lithium ion technologies due to the high specific gravimetric capacities of Li cells 1. The lithium depletion fears came early to put the basics of their replacement with sodium ion technologies, especially in stationary and large scale common applications 2,3. Sodium has many characteristics that are very close to those of lithium, especially their electronegativity and ionic radius. On the other hand, sodium is environmentally friendly and its abundance in the earth's crust is about 1350 times more than that of lithium 4. Many nanomaterials have been revealed as cathodes and anodes for sodium ion batteries (SIBs) and have been published elsewhere 5-8. Sodium vanadium phosphates (NVP) Na 3 V 2 (PO 4) 3 and Na 3 VCr(PO 4) 3 with NASICON structures were among the most successful active cathode materials owing to their high and flat discharge potential at 3.4 V vs Na/Na + , which maximizes energy density. They also have the high rate capability advantage due to their sodium ion superconducting open framework structure. However, only two of the three Na + ions are available at this high potential, resulting in a relatively low theoretical capacity of 118 mA h g −1. In addition, their cost is relatively high 9,10. As a raw material, iron oxide is one tenth the cost of vanadium oxide, which lowers the cost advantage of using NVP when compared with LiFePO 4 11. The sodium iron phosphate with its different forms provides a cheap material as sodium ion battery cathodes, in addition to their environmental safety 5. Maricite, Olivine, and amorphous forms of NaFePO 4 , all with a theoretical capacity of 152 mA h g −1 , have been explored as active, low cost cathode materials for SIBs 12-16. Olivine NaFePO 4 can be prepared only from LiFePO 4 by electrochemical delithiation and subsequent sodiation. It possesses low ionic conductivity due to its one direction Na/Li diffusion tunnels 12,17. The conversion of maricite

Journal of Materials Science and Chemical Engineering, 2019

The purpose of the present research is the different morphologies production of crystalline and a... more The purpose of the present research is the different morphologies production of crystalline and amorphous-silica powder. It's a basic material for many pharmaceutical and environmental applications as well. And, it's produced using the combination of the alkali chemical etching process and the ultra-sonication technique. The critical preparation conditions are KOH concentration (weight %) and the sonication time (hour). The paper presents the chemical mechanism of the silica particle formation as well as the different morphology. The results show the formation of crystalline and amorphous-porous-silica particles in the micrometer range with the porous order network that has pore sizes range in micrometer too. This synthetic uses commercial silicon, which could be useful for large-scale production. Also, the nano-sphere and nano-cubic shapes of silica powder are formed starting by commercial silicon powder.

Scientific Reports, 2021

Microbial contamination is one of the major dreadful problems that raises hospitalization, morbid... more Microbial contamination is one of the major dreadful problems that raises hospitalization, morbidity and mortality rates globally, which subsequently obstructs socio-economic progress. The continuous misuse and overutilization of antibiotics participate mainly in the emergence of microbial resistance. To circumvent such a multidrug-resistance phenomenon, well-defined nanocomposite structures have recently been employed. In the current study, a facile, novel and cost-effective approach was applied to synthesize Ag@Ag2O core–shell nanocomposites (NCs) via chemical method. Several techniques were used to determine the structural, morphological, and optical characteristics of the as-prepared NCs. XRD, Raman, FTIR, XPS and SAED analysis revealed a crystalline hybrid structure of Ag core and Ag2O shell. Besides, SEM and HRTEM micrographs depicted spherical nanoparticles with size range of 19–60 nm. Additionally, zeta potential and fluorescence spectra illustrated aggregated nature of Ag@A...

Advances in Nanoparticles, 2016

A direct synthesis method is introduced to prepare nano-porous silicon-nickel nanocomposite (nPS/... more A direct synthesis method is introduced to prepare nano-porous silicon-nickel nanocomposite (nPS/Ni) powder for thermal isolation applications. In this paper, we study the thermal stability of nanocomposites consisting of nanoparticles metal incorporated into the pores of a porous silicon by a very simple method. The nickel element is chemically deposited whereas the nanoparticles are precipitated on the pore surfaces. The (nPS) and (nPS/Ni) nano-materials are thermally measured under nitrogen at temperatures of 40˚C-1000˚C, noticeable, demonstrating better thermal stability of (nPS/Ni) until 900˚C than in the case of (nPS) at 600˚C. Then, the improving of the thermal stability of the nPS powder is facilitated using it in many applications of the thermal insulation process.

Proceedings of the 2016 International Conference on Mechanics, Materials and Structural Engineering, 2016

The surface chemistry of anisotropic etching of p-type Si-wafer (400) is reviewed and the anisotr... more The surface chemistry of anisotropic etching of p-type Si-wafer (400) is reviewed and the anisotropic chemical etching of silicon in alkaline solution using wetting agent were discussed. The main factors which affect the production of silicon dioxide layer on crystalline silicon as a result of wet alkali anisotropic chemical etching are the concentration of etching solution (KOH) and wetting agent (n-propanol), temperature (80°C) and time of the etching (4 hr) process. Silicon dioxide layer has found applications in many advanced areas. The synthesized silica layer was systematically characterized by XRD, SEM and FTIR spectroscopy. The XRD results revealed the amorphous nature of silica layer. FTIR spectroscopy confirmed the presence of Si-O in produced samples. SEM confirmed the addition of n-propanol to the KOH solution resulted in an improvement in the etching anisotropy in a smooth etched Si (400) surface.

Alexandria Engineering Journal, 2014

Sensors and Actuators B: Chemical, 2015

Abstract The combination of nano-porous silicon (nPS) with Congo red (CR) represents a nano-porou... more Abstract The combination of nano-porous silicon (nPS) with Congo red (CR) represents a nano-porous matrix which offer broad avenue of new and interesting properties depending on the involved materials as well as their morphology. Chemical route was utilized as the host material to achieve pores filling. They were impregnated with Congo red, which gave good results for the porous silicon as a promising pH sensor. The behavior of (nPS/CR) pH sensor, transformation of color (red-blue), is reversible after exposure to NH3 vapors, (red-blue-red). The ON/OFF behavior of the composite material depends upon the chemical processes occurring inside the pores. The fabrication of (nPS/CR) pH sensor depends on several factors {CR concentration, solvent type, and the chemical mechanism of CR adsorption on PS}.

Applied Mechanics and Materials, 2015

Silica (SiO2) nanoparticles have found applications in many advanced areas. This research work is... more Silica (SiO2) nanoparticles have found applications in many advanced areas. This research work is concerned with the preparation of silica nanoparticles by wet alkali chemical etching technique of commercial silicon powder using (KOH, n-propanol and water). The synthesized nanoparticles were systematically characterized by XRD, FTIR and PL spectroscopy. The XRD results revealed the amorphous nature of silica nanoparticles. FTIR spectroscopy confirmed the presence of Si-O in all the samples. PL spectra have shown emission band at around 516 nm. Then, nanosilica is promise material for the realization of light-emitting silica-based optoelectronic devices.

Materials Sciences and Applications, 2013

New and inexpensive nanoporous silicon (NPS) powder was prepared by alkali chemical etching using... more New and inexpensive nanoporous silicon (NPS) powder was prepared by alkali chemical etching using sonication technique and was subsequently investigated as an adsorbent in batch systems for the adsorption Ni(II) ions in an aqueous solution. The optimum conditions for the Ni(II) ion adsorption capacity of the NPS powder were studied in detail by varying parameters such as the initial Ni(II) concentration, the solution pH value, the adsorption temperature and contact time. The results indicated that the maximum adsorption capacity and the maximum removal percent of Ni(II) reached 2665.33 mg/g and 82.6%, respectively, at an initial Ni(II) concentration of 100 mg/L, adsorption time of 30 min and no effect of the solution pH and adsorption temperature.

Materials

Nano-porous silicon (NPS) powder synthesis is performed by means of a combination of the ultra-so... more Nano-porous silicon (NPS) powder synthesis is performed by means of a combination of the ultra-sonication technique and the alkali chemical etching process, starting with a commercial silicon powder. Various characterization techniques {X-ray powder diffraction, transmission electron microscopy, Fourier Transform Infrared spectrum, and positron annihilation lifetime spectroscopy} are used for the description of the product’s properties. The NPS product is a new environmentally friendly material used as an adsorbent agent for the acidic azo-dye, Congo red dye. The structural and free volume changes in NPS powder are probed using positron annihilation lifetime (PALS) and positron annihilation Doppler broadening (PADB) techniques. In addition, the mean free volume (VF), as well as fractional free volume (Fv), are also studied via the PALS results. Additionally, the PADB provides a clear relationship between the core and valence electrons changes, and, in addition, the number of defect ...

Scientific Reports, 2021

Microbial contamination is one of the major dreadful problems that raises hospitalization, morbid... more Microbial contamination is one of the major dreadful problems that raises hospitalization, morbidity and mortality rates globally, which subsequently obstructs socioeconomic progress. The continuous misuse and overutilization of antibiotics participate mainly in the emergence of microbial resistance. To circumvent such a multidrug-resistance phenomenon, well-defined nanocomposite structures have recently been employed. In the current study, a facile, novel and cost-effective approach was applied to synthesize Ag@Ag 2 O core-shell nanocomposites (NCs) via chemical method. Several techniques were used to determine the structural, morphological, and optical characteristics of the as-prepared NCs. XRD, Raman, FTIR, XPS and SAED analysis revealed a crystalline hybrid structure of Ag core and Ag 2 O shell. Besides, SEM and HRTEM micrographs depicted spherical nanoparticles with size range of 19-60 nm. Additionally, zeta potential and fluorescence spectra illustrated aggregated nature of A...

Materials Science Forum

Silica is one of the most important materials used in many industries. The basic factor on which ... more Silica is one of the most important materials used in many industries. The basic factor on which the selection process depends is the structural form, which is dependent on the various physical and chemical properties. One of the common methods in preparing pure silica is that it needs more than one stage to ensure the preparation process completion. The goal of this research is studying the nucleation technique (Bottom-top) for micro-wires and micro-ribbons silica synthesis. The silica nanoand microstructures are prepared using a duality (one step); a combination of alkali chemical etching process {potassium hydroxide (3 wt %) and n-propanol (30 Vol %)} and the ultra-sonication technique. In addition, the used materials in the preparation process are environmentally friendly materials that produce no harmful residues. The powder product is characterized using XRD, FTIR, Raman spectrum and SEM for determining the shape of architectures. The most significant factor of the nucleation ...

Egyptian Journal of Chemistry

N EWLY, porous silicon (PS) powder has been developed to meet the requirements of various fields ... more N EWLY, porous silicon (PS) powder has been developed to meet the requirements of various fields due to its unique physical and chemical properties. In this research, the PS powder is produced using a combination of both (alkali chemical etching and ultra-sonication techniques) from commercial polycrystalline silicon powder. It shows the dependence of the crystal structure and the morphology on the value of wetting agent concentration, which is controlled on the rate of each chemical reaction in the formation process. For the first time, the PS pines shape is a product at using the preparation conditions (7 wt %KOH, 3 hours, and 15 Vol% NPA). On the other hand, the (PS) micro-rod clusters are produced with different values of both the diameter and the pore size at wetting agent concentrations variation (20, and 25 Vol% NPA). The most stable crystal structure of silicon surface is Si (111), it has a rhombohedral unit cell. By changing the wetting agent concentration value, then the crystal structure of the product powder is changed too, from rhombohedral plane Si (111) to the hexagonal plane Si (211). So, this increases the chances of using the PS product in many fields whether medical or engineering.

Egyptian Journal of Chemistry

I N this research, using powder technology manufacturing is as a pioneering, low cost, a simple a... more I N this research, using powder technology manufacturing is as a pioneering, low cost, a simple and safe method for the fabrication of nano-porous silicon (NPSpowder). It's attractive carriers for targeted in several research fields. It's prepared using a combination of alkali chemical etching process and ultra-sonication technique; through the utilization of commercial silicon powder; with high yield efficiency (81.43%). Several 3D-NPS-shapes (nanorods array, nanosheets, and nanoclusters) are fabricated. It's a mixture of microporous and mesoporous silicon powder {pore size (28-140 nm)}. The main factors which affect the production of NPS-powder are (KOHconc.), sonication time, separation process and drying velocity.

Materials Chemistry and Physics

Journal of Physics and Chemistry of Solids