Wang Y.,Fudan University |
Tang J.,Fudan University |
Peng Z.,Fudan University |
Jia D.,Fudan University |
And 5 more authors.
Nano Letters | Year: 2014
We report the development of a multifunctional, solar-powered photoelectrochemical (PEC)-pseudocapacitive-sensing material system for simultaneous solar energy conversion, electrochemical energy storage, and chemical detection. The TiO2 nanowire/NiO nanoflakes and the Si nanowire/Pt nanoparticle composites are used as photoanodes and photocathodes, respectively. A stable open-circuit voltage of ∼0.45 V and a high pseudocapacitance of up to ∼455 F g-1 are obtained, which also exhibit a repeating charging-discharging capability. The PEC-pseudocapacitive device is fully solar powered, without the need of any external power supply. Moreover, this TiO2 nanowire/NiO nanoflake composite photoanode exhibits excellent glucose sensitivity and selectivity. Under the sun light illumination, the PEC photocurrent shows a sensitive increase upon different glucose additions. Meanwhile in the dark, the open-circuit voltage of the charged pseudocapacitor also exhibits a corresponding signal over glucose analyte, thus serving as a full solar-powered energy conversion-storage- utilization system. © 2014 American Chemical Society.
Amin R.S.,National Research Center of Egypt |
Hameed R.M.A.,Cairo University |
El-Khatib K.M.,National Research Center of Egypt |
Youssef M.E.,Informatics Research Institute |
Elzatahry A.A.,Advanced Technology and New Materials Research Institute
Electrochimica Acta | Year: 2012
Pt catalyst was supported on Vulcan XC-72R containing 5 wt.% NiO using NaBH 4 as a reducing agent. The prepared catalyst was heat-treated at 400°C. XRD, TEM and EDX analyses were applied to characterize Pt-NiO/C electrocatalyst. The introduction of NiO reduces the particle size of Pt crystallites. The electrocatalytic activity of Pt-NiO/C electrocatalysts was examined towards methanol oxidation reaction in 0.5 M H 2SO 4 solution using cyclic voltammetry and chronoamperometry techniques. A three fold increment in the oxidation current density was gained at Pt-NiO/C electrocatalyst compared to Pt/C one. The corresponding chronoamperograms showed high steady state current density values suggesting better stability of Pt-NiO/C electrocatalyst towards the carbonaceous poisoning species. The enhanced electrocatalytic performance and the long-term cycle durability of Pt-NiO/C electrocatalyst are attributed to the strong interaction between Pt and NiO and the formation of small Pt crystals. © 2011 Elsevier Ltd. All Rights Reserved.
Zoweil H.,Advanced Technology and New Materials Research Institute
Journal of Modern Optics | Year: 2015
A novel all-optical flip-flop based on a chirped nonlinear distributed feedback laser structure is proposed. The flip-flop does not require a holding beam. The optical gain is provided by a current injection into an active layer. The nonlinear wave-guiding layer consists of a chirped phase shifted grating accompanied with a negative nonlinear refractive index coefficient that increases in magnitude along the wave-guide. In the OFF state, the chirped grating does not provide the required optical feedback to start lasing. An optical pulse switches the device ON by reducing the chirp due to the negative nonlinear refractive index coefficient. The reduced chirp grating provides enough feedback to sustain a laser mode. The device is switched OFF by cross gain modulation. GPGPU computing allows for long simulation time of multiple SET-RESET operations. The ON/OFF transitions delays are in nanoseconds time scale. © 2015 Taylor & Francis.
Kashyout A.B.,Advanced Technology and New Materials Research Institute |
Soliman M.,Alexandria University |
Fathy M.,Advanced Technology and New Materials Research Institute
Renewable Energy | Year: 2010
Nano-sized TiO2 powders have been prepared by sol-gel method. Influences of the different preparation parameters on the TiO2 nano-powder properties were investigated. Thermal gravimetric analysis (TGA) was used to examine the thermal properties of the produced TiO2 nanoparticles. Yield efficiency of the resulted nanoparticles was calculated and the reaction efficiency was estimated. Maximum efficiency of 98.9% was achieved at autoclaving temperature of 245 °C for time duration of 12 h. X-ray diffraction analyses show the presence of anatase structure at low and high autoclaving temperatures. Fraction of rutile phase is detected with increasing the calcination temperature and reach 40% at 850 °C. High resolution transmission electron microscopy (HRTEM) showed spherical nanoparticles of 8-9 nm at autoclaving temperature of 130 °C, while elongated nanoparticles of 14-18 nm in length and 9 nm in width were measured at autoclaving temperature of 245 °C. The solar cell performance was measured for various TiO2 dye sensitized solar cells. Samples of high autoclaving temperature gave an improvement in the efficiency to be 8.5% while those of lower autoclaving temperature had an efficiency of 7.29%. An enhancement in both open circuit voltage (Voc) and fill factor (FF) is obviously detected, where elongated nanoparticles are measured by HRTEM, which improved the electronic conductivity and consequently FF and Voc. © 2010 Elsevier Ltd.
Zoweil H.,Advanced Technology and New Materials Research Institute
Applied Optics | Year: 2010
A new, improved design of an all-optical flip flop is proposed. The waveguiding layer of the device consists of a phase-shifted nonlinear grating. The grating layers of a high refractive index have a negative nonlinear coefficient. A phase-shift section exists at the middle of the waveguiding layer. The optical gain is provided by current injection into an active layer. Nonlinearity in the waveguiding layer is achieved by direct absorption at the edge of the absorption band (Urbach tail). In the "OFF" state, the waveguiding layer forms a weak grating with an optical feedback below the laser threshold. In the "ON" state, the device functions as a distributed feedback (DFB) laser due to an induced strong grating in the nonlinear waveguiding layer. The improvements of the device performance by reducing the set pulse energy and accelerating the switch-off process are discussed. Field simulations in the time domain were performed. © 2010 Optical Society of America.
Nady N.,Advanced Technology and New Materials Research Institute
Membranes | Year: 2016
A major limitation in using membrane-based separation processes is the loss of performance due to membrane fouling. This drawback can be addressed thanks to surface modification treatments. A new and promising surface modification using green chemistry has been recently investigated. This modification is carried out at room temperature and in aqueous medium using green catalyst (enzyme) and nontoxic modifier, which can be safely labelled “green surface modification”. This modification can be considered as a nucleus of new generation of antifouling membranes and surfaces. In the current research, ferulic acid modifier and laccase bio-catalyst were used to make poly(ethersulfone) (PES) membrane less vulnerable to protein adsorption. The blank and modified PES membranes are evaluated based on e.g., their flux and protein repellence. Both the blank and the modified PES membranes (or laminated PES on silicon dioxide surface) are characterized using many techniques e.g., SEM, EDX, XPS and SPM, etc. The pure water flux of the most modified membranes was reduced by 10% on average relative to the blank membrane, and around a 94% reduction in protein adsorption was determined. In the conclusions section, a comparison between three modifiers—ferulic acid, and two other previously used modifiers (4-hydroxybenzoic acid and gallic acid)—is presented. © 2016 by the author; licensee MDPI, Basel, Switzerland.
Elkady M.F.,Advanced Technology and New Materials Research Institute |
Ibrahim A.M.,National Research Center of Egypt |
El-Latif M.M.A.,Advanced Technology and New Materials Research Institute
Desalination | Year: 2011
Immobilized eggshell with a polymer mixture of alginate and polyvinyl alcohol was applied as a biocomposite adsorbent (ESC) for the adsorption of C.I. Remazol Reactive Red 198 from aqueous solution. ESC was characterized using XRD, TGA, FTIR and SEM. The Red dye adsorption onto the ESC was investigated in a batch system with respect to initial dye concentration, pH, contact time, agitation speed, solution temperature and biocomposite dosage. The prepared biocomposite exhibits high efficiency for red dye adsorption and the equilibrium states could be achieved in 3. h for the different studied initial dye concentrations. The equilibrium isotherm study indicated that sorption data were analyzed and fitted well by both Langmuir and Temkin models compared to Freundlich model. The maximum monolayer dye adsorption capacity (at the optimum pH 1.0) was estimated to be 46.9. mg/g at 22 °C. The kinetic study revealed that pseudo-second order model fitted well the kinetic data, while both the intraparticle diffusion and Boyd kinetic model indicated that intraparticle diffusion was the main rate determining step in the biosorption process. The negative values of both the enthalpy (ΔH°) and Gibbs free energy (ΔG°) changes indicate exothermic as well as feasible and spontaneous nature of the biosorption process respectively. © 2011 Elsevier B.V.
Elzatahry A.,King Saud University |
Elzatahry A.,Advanced Technology and New Materials Research Institute
International Journal of Electrochemical Science | Year: 2014
The present work explores a facile route to synthesize NiO nanofibers using a hybrid method based on a combination of electrospinning and calcination techniques. Poly acrylonitrile was used as a template matrix to maintain the nanostructrure of produced NiO. The as-prepared nanostructured material was characterized with X-ray diffraction (XRD), energy dispersive X-Ray (EDX), and scanning electron microscopy (SEM), respectively. The electrochemical properties towards methanol oxidation have been studied using cyclic voltametry and Cchronoamperometry technique. Electrocatalytic oxidation of methanol on prepared NiO nanostructure in a potential range of 0-800 mV (versus SCE) is studied by cyclic voltammetry in alkaline medium (1.0 M KOH). Prepared NiO nanostructure showed an interesting activity towards methanol oxidation. The effect of scan rate has been studied and the process has approved to be diffuse rather than surface controlled. © 2014 by ESG.
El-Fawal G.,Advanced Technology and New Materials Research Institute
Journal of Food Science and Technology | Year: 2014
Carrageenan films have been formulated as a packaging material. Films plasticized with glycerol were loaded with citric acid (1, 0.75, 0.5, 0.25 and 0.1 %) for enhanced antimicrobial effects. Blank and citric acid loaded films were characterized by mechanical properties, scanning electron microscopy and contact angle. In addition, swelling and antibacterial studies were conducted to further characterize the films. Both blank and citric acid loaded films showed different morphology, high elasticity and acceptable tensile (mechanical) properties. These citric acid loaded films produced higher zones of inhibition against Staphylococcus aureus, Proteus mirabilis, Pseudomonas aeruginosa, Escherichia coli and Dickeya chrysanthemi strains compared to blank film. © 2014, Association of Food Scientists & Technologists (India).
Ibrahim A.M.,National Research Center of Egypt |
El-Latif M.M.A.,Advanced Technology and New Materials Research Institute |
Mahmoud M.M.,Advanced Technology and New Materials Research Institute
Journal of Alloys and Compounds | Year: 2010
Nano-sized single-phase cobalt ferrite samples were prepared via polyol method using ethylene glycol as a high boiling point solvent as well as a reducing agent. These samples were prepared by two different heating techniques; conventional heating technique and microwave assisting technique using a 2.45 GHz multimode microwave synthesis unit. The crystallite size of the obtained samples was found to be in the range from 10 nm to 12 nm. The obtained samples were characterized using transmission electron microscope (TEM) and X-ray diffraction (XRD). Quantum design SQUID magnetometer was used to study the magnetic measurement. © 2010 Elsevier B.V. All rights reserved.