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Dive into the research topics where Amir Al-Ahmed is active.

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Featured researches published by Amir Al-Ahmed.


ACS Applied Materials & Interfaces | 2017

Tuning the Interplay between Selectivity and Permeability of ZIF-7 Mixed Matrix Membranes

Bassem A. Al-Maythalony; Ahmed M. Alloush; Muhammed Faizan; Hatim Dafallah; Mohammed A. A. Elgzoly; Adam A. A. Seliman; Amir Al-Ahmed; Zain H. Yamani; Mohamed A. M. Habib; Kyle E. Cordova; Omar M. Yaghi

Nanoparticles of zeolitic imidazolate framework-7 (nZIF-7) were blended with poly(ether imide) (PEI) to fabricate a new mixed-matrix membrane (nZIF-7/PEI). nZIF-7 was chosen in order to demonstrate the power of postsynthetic modification (PSM) by linker exchange of benzimidazolate to benzotriazolate for tuning the permeability and selectivity properties of a resulting membrane (PSM-nZIF-7/PEI). These two new membranes were subjected to constant volume, variable pressure gas permeation measurements (H2, N2, O2, CH4, CO2, C2H6, and C3H8), in which unique gas separation behavior was observed when compared to the pure PEI membrane. Specifically, the nZIF-7/PEI membrane exhibited the highest selectivities for CO2/CH4, CO2/C2H6, and CO2/C3H8 gas pairs. Furthermore, PSM-nZIF-7/PEI membrane displayed the highest permeabilities, which resulted in H2/CH4, N2/CH4, and H2/CO2 permselectivities that are remarkably well-positioned on the Robeson upper bound curves, thus, indicating its potential applicability for use in practical gas purifications.


ieee international energy conference | 2010

Hydrogen highway: An overview

Amir Al-Ahmed; Safdar Hossain; Bello Mukhtar; Sleem ur Rahman; H.I. Abualhamayel; Javaid S. M. Zaidi

This article presents the status of the technology to conceptualize hydrogen as a fuel and fuel cell car and hydrogen fueling station i.e. hydrogen infrastructure. Hydrogen is the lightest and most abundant element in the universe and it is an energy carrier. It can be produced from several sources using various methods and delivered to the fueling station or even it can be produced at the fueling station. Electrolysis of water or reforming of hydrocarbons such as natural gas can produce hydrogen in a big plant or even at the fueling station. But when it is produced using renewable energy such as wind, solar, geothermal, or hydroelectric, it has zero emissions in well to wheel. Hydrogen powdered vehicles either burns hydrogen in an internal combustion engine, or reacts with oxygen in a fuel cell. Developing a chain of hydrogen-equipped fueling stations and other infrastructure along the city road or highway, which will allow hydrogen powered cars to travel, is basically the concept of hydrogen highway. More substantial delivery infrastructure for hydrogen will require the use of high-pressure compressors for gaseous hydrogen and liquefaction system for cryogenic hydrogen. Hydrogen can be transport by road via cylinders, tube trailers, cryogenic tankers, and in pipelines or can be produced onsite. Each of these delivery and production modes requires a significantly different fueling station design. While hydrogen dispensers are basically the same regardless of the delivery or production mode, but the compressed and liquid hydrogen fueled vehicles are completely different. These combinations of hydrogen delivery or production at the station, compressed or liquid hydrogen dispensing, and various components and integration alternatives make up the array of hydrogen fueling station design and visualize total hydrogen infrastructure. Today, all the major automobile manufacturers have one or more prototype hydrogen fuel cell cars in their lineup. Again the advent of onsite hydrogen production system and/or home hydrogen fueling stations can help with the present infrastructure shortcoming. Companies such as Honda, ITM Power and Hydrogenics have at least prototype home hydrogen production and pumps, that may be available soon.


IEEE Journal of Photovoltaics | 2016

Enhancing Power Conversion Efficiency of Dye-Sensitized Solar Cell Using TiO 2 -MWCNT Composite Photoanodes

Umer Mehmood; Ibnelwaleed A. Hussein; Amir Al-Ahmed; Shakeel Ahmed

The aim of this work is to improve the power conversion efficiency (PCE) of dye-sensitized solar cells (DSSCs) using composite films consisting of titanium oxide (TiO2) nanoparticles and multiwalled carbon nanotubes (MWCNTs). A transmission electron microscope (TEM) was used to confirm the dispersion of carbon nanotubes (CNTs) in TiO2. Composite photoanode-based solar cells were characterized by UV-Visible absorption spectroscopy, photocurrent-voltage (I-V) characteristics, and electrochemical impedance spectroscopy. It was found that the PCE (ηc) of DSSCs strongly depends on the concentration of CNTs in the nanocomposite films. The solar cell assembled with photoanode containing 0.06% MWCNTs shows the highest efficiency of 5.25%, which is 46% greater than unmodified photoanode. The density functional theory (DFT) quantum modeling technique was used to compute the band gap of TiO2 and CNT-TiO2 clusters.


Journal of Materials Chemistry C | 2017

Surface-related properties of perovskite CH3NH3PbI3 thin films by aerosol-assisted chemical vapour deposition

Mohammad Afzaal; B. Salhi; Amir Al-Ahmed; Heather M. Yates; Abbas Saeed Hakeem

A modified three-step aerosol-assisted chemical vapour deposition process was used to grow dense and uniform CH3NH3PbI3 thin films directly on borosilicate glass. The resulting photoluminescence spectrum was blue shifted with respect to its bandgap. X-ray photoelectron spectroscopy studies confirmed non-stoichiometric lead : iodine ratios within the films, due to decomposition of the CH3NH3PbI3 layers over time into lead iodide and the release of ammonia and hydrogen iodide. The complex refractive index and dielectric function of the deposited thin films were determined by variable angle spectroscopic ellipsometry.


Materials Science Forum | 2013

Metal Doped TiO2 Photocatalysts for CO2 Photoreduction

Amir Al-Ahmed

Greenhouse gases such as CO2, CH4 and CFCs are the primary causes of global warming. Worldwide, people are exploring techniques to reduce, capture, store CO2 gas and even convert this gas in to some useful chemicals. CO2 can be transformed into hydrocarbons in a photocatalytic reaction. The advantage of photo reduction of CO2 is to use inexhaustible solar energy. Knowledge of elementary steps in photocatalytic CO2 reduction under UV irradiation is required in order to improve the photo efficiency of the photocatalyst. A semiconductor photocatalyst mediating CO2 reduction and water oxidation needs to absorb light energy, generate electron hole pairs, spatially separate them, transfer them to redox active species across the interface and minimize electron hole recombination. This requires the semiconductor to have its conduction band electrons at higher energy compared to the CO2 reduction potential while the holes in the valence band need to be able to oxidize water to O2. A single semiconductor does not usually satisfy these requirements. Some recent developments in this field have been moves towards rational photocatalyst design, the use of highly active isolated Ti-species in mesoporous and microporous materials, metal-doping of TiO2, development of catalysts active at longer wavelengths than can be achieved with commercially available titania etc. The use of transition-metal loaded titanium dioxide (TiO2) has been extensively studied as a photocatalyst in photoreactions. Unlike traditional catalysts drive chemical reactions by thermal energy, semiconducting photocatalysts can induce chemical reactions by inexhaustible sunlight and convert CO2 in to the useful hydrocarbons. In this review article we will cover different aspects of metal doped nano structured TiO2 photocatalysts, used to convert/reduce CO2 in to useful hydrocarbons.


Materials Science Forum | 2012

Application of titanium dioxide (TiO 2) based photocatalytic nanomaterials in solar and hydrogen energy: A short review

Amir Al-Ahmed; Bello Mukhtar; Safdar Hossain; S.M. Javaid Zaidi; Sleem ur Rahman

Tremendous amount of research work is going on Titanium dioxide (TiO2) based materials. These materials have many useful applications in our scientific and daily life and it ranges from photovoltaics to photocatalysis to photo-electrochromics, sensors etc.. All these applications can be divided into two broad categories such as environmental (photocatalysis and sensing) and energy (photovoltaics, water splitting, photo-/electrochromics, and hydrogen storage). Synthesis of TiO2 nanoparticles with specific size and structural phase is crucial, for solar sell application. Monodispersed spherical colloids with minimum size variation (5% or less) is essential for the fabrication of photonic crystals. When sensitized with organic dyes or inorganic narrow band gap semiconductors, TiO2 can absorb light into the visible light region and convert solar energy into electrical energy for solar cell applications. TiO2 nanomaterials also have been widely studied for water splitting and hydrogen production due to their suitable electronic band structure given the redox potential of water. Again nanostructured TiO2 has extensively been studied for hydrogen storage with good storage capacity and easy releasing procedure. All these issues and related finding will be discussed in this review.


Polymer Bulletin | 2017

Proton conducting blend membranes: physical, morphological and electronic properties

Amir Al-Ahmed; Mazen Khaled Nazal; Abdullah S. Sultan; Jimoh K. Adewole; Syed Javaid Zaidi

Blend membranes of sulfonated poly(ether ether ketone) (SPEEK) and sulfonated polyetherimide (SPEI) have been prepared and investigated as a potential polymer electrolyte membrane (PEM) for direct methanol fuel cell (DMFC). Polymers were dissolved in N-methyl-2-pyrrolidone (NMP) in different mixing ratios and membranes were casted using a semi-automatic casting machine on a pre-cleaned glass plate. The influence of SPEI percentage on ion exchange capacity (IEC), water uptake, methanol permeability and proton exchange capacity have been investigated. Blend membranes showed slightly better IEC, water uptake and methanol crossover properties as compare to pure SPEEK; but proton conductivity was slightly lower than that of pure SPEEK membrane. Membrane morphology was investigated by FESEM, TGA and AFM. Overall, a homogeneous surface was observed for most of the blend membranes, with minor phase separation at higher SPEI contents samples. AFM image of the membrane surface shows nanoscale surface roughness.


IEEE Journal of Photovoltaics | 2017

Transparent Conductive Oxide Films for High-Performance Dye-Sensitized Solar Cells

Umer Mehmood; Mohammad Afzaal; Amir Al-Ahmed; Heather M. Yates; Abbas Saeed Hakeem; Haider Ali; Fahad A. Al-Sulaiman

In this paper, atmospheric pressure chemical vapor deposition of fluorine-doped tin oxide (FTO) thin films of various thicknesses and dopant levels is reported. The deposited coatings are used to fabricate dye-sensitized solar cells, which exhibited reproducible power conversion efficiencies in excess of 10%. No surface texturing of FTOs or any additional treatment of dye-covered films is applied. In comparison, the use of commercial FTOs showed a lower cell efficiency of 7.11%. Detailed analysis showed that the cell efficiencies do not simply depend on the resistivity of FTOs but instead rely on a combination of carrier concentration, thickness, and surface roughness properties.


Advanced Materials Research | 2013

Biomedical Perspectives of Polyaniline Based Biosensors

Amir Al-Ahmed; Haitham M.S. Bahaidarah; Mohammad A. Jafar Mazumder

Electrically conducting polymers (ECPs) are finding applications in various fields of science owing to their fascinating characteristic properties such as binding molecules, tuning their properties, direct communication to produce a range of analytical signals and new analytical applications. Polyaniline (PANI) is one such ECP that has been extensively used and investigated over the last decade for direct electron transfer leading towards fabrication of mediator-less biosensors. In this review article, significant attention has been paid to the various polymerization techniques of polyaniline as a transducer material, and their use in enzymes/biomolecules immobilization methods to study their bio-catalytic properties as a biosensor for potential biomedical applications.


IEEE Journal of Photovoltaics | 2018

Enhancement of the Photovoltaic Performance of a Dye-Sensitized Solar Cell by Cosensitizing TiO

Umer Mehmood; Amir Al-Ahmed; Mohammad Afzaal; Abbas Saeed Hakeem; Samsuddeen Abdullahi Haladu; Fahad A. Al-Sulaiman

Spray coating of a lead xanthate precursor on titanium dioxide surfaces has been carried out to deposit uncapped lead sulfide (PbS) nanocrystals. Cosensitizing N719 dye with resulting PbS nanocrystals in dye-sensitized solar cells demonstrates marked efficiencies up to 7.9%, an improvement of 29% compared with the absence of a cosensitizer. In this case, most of the absorbed light is involved in the photocurrent generation, confirmed by an incident photon-to-current conversion efficiency analysis, which is also in line with the ultraviolet–visible absorption spectra of these photoanodes. An increased precursor concentration has the negative effect on the power conversion efficiencies, primarily due to the blocking of incident light reaching the photosensitizer.

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Umer Mehmood

King Fahd University of Petroleum and Minerals

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Fahad A. Al-Sulaiman

King Fahd University of Petroleum and Minerals

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Abdullah S. Sultan

King Fahd University of Petroleum and Minerals

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Abbas Saeed Hakeem

King Fahd University of Petroleum and Minerals

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Jimoh K. Adewole

King Fahd University of Petroleum and Minerals

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Anwar Ul Haq Khan

King Fahd University of Petroleum and Minerals

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Bello Mukhtar

King Fahd University of Petroleum and Minerals

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M. Irfan Malik

King Fahd University of Petroleum and Minerals

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Mazen Khaled Nazal

King Fahd University of Petroleum and Minerals

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