Browsing by Author "Dr. Farah Alvi"

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A Study of Structural properties of Porous ZeoliteImidazole Based 2-Dimensional Nanostructures For Electrochemical Applications
(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2021) Nadir Ali; CUI/SP20-RPH-055/LHR; Dr. Farah Alvi; LHR TP 7701
Recently, 2-D metal oxide frameworks (MOFs) have exhibited great potential for energy storage devices including supercapacitors and batteries. This is due to their superior and highly tunable porous, structural, and morphological features. Zeolite imidazolate frameworks (ZIFs) are highly chemically, and thermally stable class of MOFs which offer a wide variety of tunable porous structures and morphologies in comparison to widely used nano porous carbon which requires inert gas environment and high temperature treatment for large scale production and is therefore hazardous and expensive. In this work, facile and one-step environmentally friendly synthetic routes will be investigated and implemented for tuning of ZIF-67 derived porous nanostructures as electrode materials for renewable energy storage applications. The structural properties of the developed novel materials will be investigated using RAMAN spectroscopy measurements and analysis. The porosity of the materials will be estimated using Brunauer–Emmett–Teller (BET) surface area analyzer. The variation in morphology, pore size and structure will be studied by analyzing the shift in Raman vibrational modes of the samples.
Electronic Structure and Photo-catalysis Properties of Hetero Bilayered Materials
(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2022) Humaira Rafique; CIIT/FA20-RPH-013/LHR; Dr. Farah Alvi; LHR TP 7976
This thesis is dedicated to the synthesis of LiZnO and MgZnO based semiconductor materials for photocatalysis. As solar cell is an efficient device for clean energy production. To enhance the efficiency of such type of clean energy devices an efficient photocatalytic material is required for proper working. The efficiency of photocatalysis water-splitting reaction has been limited. However, to solve this issue we will develop a simple and novel reaction mechanism as well as an important need for stable and highly efficient catalytic materials. Therefore, in this research work LiZnO and MgZnO semiconductor materials was made by sol-gel method. To analyze the structural properties of the synthesized samples XRD has been carried out and find out one phases in LiZnO and MgZnO materials. By using RAMAN and UV spectroscopy, to detect vibrational, rotational, and other states in a molecular system and optical properties have been studied of materials respectively. From the graphs of electrochemical characterizations, we conclude that the best performance among two prepared samples is given by the sample MgZnO. The reason is that MgZnO behaves like a good photocatalyst as compared to that of LiZnO. Further DFT calculations was performed to study electronic structure, current density and optical properties of the material.
Fabrication of Nanocomposite Based Electrochemical Sensor for Environmental Application
(Library Information Services COMSATS University Islamabad Lahore Campus, 2021-02-23) Muhammad Mathar Bashir; FA19-R06-020; Dr. Farah Alvi; LHR TP 7315
With the advancement in industrial world, heavy metal ions are becoming great concern because industrial effluents contain large quantity of heavy metal ions. The increase in concentration of metal ions in water is creating many problems for aquatics life and human beings. Traditionally for detection of heavy metal ions atomic absorption, atomic emission, UV/Visible spectroscopy, inductively coupled plasma mass spectrometryetc are used but they are very sophisticated, expensive and require trained personals to operate. In contrast to that electrochemical techniques are inexpensive, portable and easy to use. The aim of this research was to modify our electrode to increase sensing ability of our electrode. We prepared nanocellulose and PANI based metal nanocomposites and fabricated our glassy carbon electrode by drop casting method. Cyclic voltammerty and electronic impedance spectroscopy were used for heavy metal ion sensing. Acid hydrolysis was used to prepare nanocellulose. Characterization techniques used to confirm our synthesis of composite were FTIR and XRD.
Investigation of Doped (III-V) Group Elements Emissive Layer for Visible LED Applications
(2019) Aqsa Hashmi; CIIT/FA17-RPH-043/LHR; Dr. Farah Alvi; LHR TP 5728
This study Sb2S3 was prepared by applying hydrothermal technique with different concentration of Ag as a doping impurity to improve its optical and electrical properties to be used in optoelectronics for LED applications. FTIR spectra was used to analyze the vibrations of chemical bonds present in the different groups in the sample. The intensity of the peaks is reduced with the increase in doping concentration, this is because the strength of chemical bonds decreases because of intermolecular transition of groups present in the sample. Optical properties were studied by UV-Vis and PL spectroscopy. UV-vis spectra was used to calculate bandgap that comes out between 2.5-1.9 eV. The bandgap was reduced with the increase in doping concentration of Ag which indicate its good compatibility for LED applications. IV measurements were used to analyze IV characteristics of the samples and to find out the turn on voltage of the device. SEM results were helpful in analyzing the surface morphology of the samples and measuring the particle size. The device was characterized by electroluminescence spectra which confirmed the red emission from LEDs having emissive layers of undoped and doped Sb2S3. So the materials have bright future for visibe LED applications.
Optical Investigation of N-acetyl-L Capped Core- Shell Sb2Se3/ZnS Nanowires for Visible LED Application
(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2019) Muhammad Ejaz Dildar; CIIT/FA16-RPH-025/LHR; Dr. Farah Alvi; LHR TP 5707
Light emitting diodes have always gained high interest to their potential for high efficiency lighting. Fabrication of Sb2Se3/ZnS core- shell nanowire LED is reported for first time. In this report Sb2Se3/ZnS core-shell nanowire synthesis by hydrothermal method and this composition was spin coated on FTO substrates to make thin films. UV visible spectroscopy, Photoluminescence spectroscopy and X-ray diffraction techniques were used to characterized thin films of Sb2Se3/ZnS core-shell composition. UV visible spectroscopy showed that the absorption spectrum of Sb2Se3/ZnS core-shell thin films was in UV region and photoluminescence spectroscopy showed that the emission spectrum is in visible and infra-red region. X-ray diffraction (XRD) was used to determine crystalline structure and phases within a solid. For device fabrication NiO and ZnO were used as hole transport layer and electron transport layer respectively. Sb2Se3/ZnS core-shell nanowires were sandwiched between hole transport layer and electron transport layer. Device was characterized by electroluminescence spectroscopy and IV measurements.
Optical Properties of Carbon Doped Metal Telluride Core-Shell Structures for Optoelectronic Applications
(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2021) Tamoor Ali; SP20-RPH-061; Dr. Farah Alvi; LHR TP 7702
Modern lighting technologies (LEDs and display devices) based on semiconductor Quantum dot (QD) luminescent materials employ semiconductor metal chalcogenides including ZnS, ZnSe, PbS, PbSe, CdS and CdSe. However, they suffer with non-radiative recombination due to surface and structural defects and most of the metal chalcogenides including Cd and Pb are toxic in nature. Moreover, zinc-based chalcogenides including ZnS and ZnSe are also investigated as luminescent materials but sulfides and selenides are toxic in nature. Therefore, there is a large space available to explore non-toxic novel materials and to investigate their luminescent properties based on also exhibit toxicity and their luminescent properties are tuned using complex architectures such as ZnSxSe(1- x) and CdSxSe(1-x). Whereas, Zinc telluride is a chalcogenide having optimum band gap of 2.25eV is less toxic and its optical properties are easily tunable due to optimum bandgap. Moreover, carbon-based materials (carbon derivatives, QDs) offer a huge variety of tunable energy states with non-toxic nature of the materials. and their photoluminescent properties investigated suitable for lighting devices including LEDs, display devices and photo-sensors. In this work, ZnTe/carbon allotropes (graphene derivatives/QDs) based nanocomposite/core-shell nanostructures synthesized by wet-chemical method. The structural, morphological, and optical properties of the prepared samples are studied using XRD, Raman spectroscopy, UV-Visible and PL spectroscopy techniques
Preparation and Evaluation of Molybdenum based Catalyst for SOFC Anode
(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2022) MUHAMMAD TALHA; CIIT/SP21-RPH-017/LHR; Dr. Farah Alvi; LHR TP 8163
The world's greatest single drain is the energy problem. To meet energy requirements, fossil fuels are considered a major energy source. They are not enough to meet energy requirements. Using them for energy purposes becomes the cause of the emission of poisonous gases. There is a need to adopt renewable energy resources to meet energy requirements and avoid poisonous gasses emissions. Solid oxide fuel cells (SOFCs) are considered one of the best solutions for energy generation due to their great efficiency, very low toxic emissions, and fuel flexibility. The performance of the fuel cell is based on the catalytic activity of the anode. While operating with methane as fuel, carbon is deposited on the fuel cell anode which becomes the cause of cell degradation, and low performance. High operating temperature is also a challenge for SOFC. Because of the fuel flexibility and cost-effective anode materials features. The structural and electrochemical properties of anode materials with the configuration of MOx-(La0.25Sr0.35Ni0.4O3-δ)1-x (where x=0, 0.02, 0.04, 0.06) have been examined in this research work to enhance electrocatalytic properties and to avoid carbon deposition on the anode. The proposed anode materials have been synthesized through the solid-state reaction method. The Fourier Transform Infrared Spectroscopy (FTIR) is performed to get information about an infrared spectrum of absorption or emission and molecular bonding. The crystalline nature of the materials, vibrational modes, and carbon deposition are confirmed using Raman spectroscopy. The optical band gap and absorption spectra are observed by UV–Visible spectroscopy. The conductivity of prepared anode materials is investigated through Electrochemical Impedance Spectroscopy (EIS). The detailed Raman spectroscopy and conductivity analysis shows that carbon deposition on the anode is decreased, and conductivity is enhanced by increasing the Mo ratio. The findings suggest that the developed materials are suitable catalysts of anode for Solid oxide fuel cell (SOFC).
Silicon Carbide Core and Lanthanum Strontium Cobalt Ferric Oxide as Shell Based Anode Material
(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2023) Anum Aslam; CIIT/FA21-RPH-002/LHR; Dr. Farah Alvi
Human life is derived by the energy. With an expanding world population, economic growth, and technological advancement, the need for energy is rapidly rising. It is anticipated that the rise in the world's energy demand will be dramatic in the next years. With the advancement of industrialization, the pace of fossil fuel use expanded quickly, providing cheap and consistent energy to power the rapid rise of Western economies, most notably [1]. However, some experts questioned if fossil fuels actually aided in the evolution of the world. There are undoubtedly some advantages to using fossil fuels, including affordable energy, energy security, opportunities for employment, foreign exchange, and geopolitical power. However, there are also some drawbacks [2]. The two major problems associated with fossil fuels in the twenty-first century have been resource shortage and environmental deterioration. Global climate change, environmental externalities, ozone non-attainment, air toxins, solid waste disposal, and other environmental issues are among the issues that need to be addressed [3]. Due to the finite nature of fossil fuels and their unequal distribution throughout the planet, the problem of resource scarcity develops [4]. Further difficulties are brought about by energy geopolitics, which has been more prevalent among the major nations in recent years. The global energy system is currently dependent on fossil fuels, but country-by-country levels of dependence range from 32.1% to 100%.
Up and Down Conversion Nanoparticles, Synthesis, Mechanism for Photovoltaics Application.
(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2022) Muhammad Shameer Haider; CIIT/SP20-RPH-005/LHR; Dr. Farah Alvi; LHR TP 7681
Fluorescent labelling is a usually utilized critical tool in biology in today's quickly advancing technology. Traditional down conversion fluorescent labels that employ UV or short wavelength light have issues such as fluorescence, low transmission ratio and indirect cell damage to live cells. When irradiated with near infrared light, upconversion nanoparticle release radiation of lower frequency in the near infrared or visible region, a process known as up conversion. They have the most amazing qualities, such as greater photo stability, as compared to existing up-converting materials. They have very low auto fluorescence, no photo harm to living cells, high detection sensitivity and a great depth of photon penetration, overcoming some of the shortcomings of standard down conversion labels, making it a suitable fluorescent label for bio imaging. They avoid some of the drawbacks of traditional down conversion labels by offering benefits such as very low fluorescence, no phototoxicity to live cells, excellent detection sensitivity and a great depth of photon penetration, category to them a suitable fluorescent for bio imaging. Upconversion nanoparticles are being changed in a variety of ways to make them more hydrophilic and biocompatible. Because of these advantages, upconversion nanoparticles could be used in immunoassays, bio imaging and PD. Because of their enormous size, lack of organic compounds for biological conjugation, and instability in aqueous solutions, upconversion nanoparticles can yet be improved. Co-doping between two distinct lanthanides ions, one behaving as an absorber and the other as an emitter, is commonly used to improve upconversion nanoparticles by utilizing the energy transfer mechanism. The spectrum features of the system NaYF4 doped with Er3+ and Yb3+ with an increased electromagnetic field will be studied in this work. As a spacer, silica will be utilized and characterization will be done using conventional optical techniques