M.Phil / MS
Permanent URI for this collectionhttps://repository.cuilahore.edu.pk/handle/123456789/60
This collection archives the complete set of theses produced by students of the COMSATS University Islamabad, Lahore Campus.
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Item The Coated Carbonates on Silicon Carbide Materials as an Electrolyte and it's Electrochemical Characterization(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2022) Muddasir Ammar; CIIT/FA20-RPH-040/LHR; Dr. Shahzada Qamar Hussain; LHR TP 7996In this work we synthesized Silicon Carbide and Coated Carbonate on Silicon Carbide composite as an effective electrolyte material in fuel cell. Fuel cell is considered an efficient device for its clean energy production. To enhance the efficiency of such type of clean energy devices an efficient electrolyte material is required for its proper working. Therefore, in this research work Si- C composite was made by hydrothermal method and Solid-state method. While coated the Sodium Carbonate (Na2CO3) and Potassium Carbonate (K2CO3) on Si-C by dip coating method. To analyze the structural and phase properties of the synthesized samples FTIR has been carried out. Through FTIR spectra various types of stretching and vibrational bonding were studied and find out that there were different kinds of bonding like Si-O-Si, Si-C and C=O present in the prepared samples. UV- Visible spectroscopy was carried out to study the optical bandgap of the prepared samples. Conductivity and electrical bandgap for all composite material was measured by using EIS and the maximum conductivity was found 0.082 Scm-1 at a temperature of 650oC for the sample Si-C (1:1). Furthermore, the three-layer fuel cell was fabricated in which prepared material use as electrolyte and LiNiCuZn as cathode and Anode. The maximum Voc of 0.89 V wi th highest power density of 16.5 (mWCm-2) was recorded by using hydrogen as a fuel.Item Development and Electrochemical Characterization of Nanocomposites for Biogas Based Fuel Cells(2018) Asia Rafique; CIIT/FA13-PPHY-003/LHR; Dr. Rizwan Raza; LHR TP LHR TP 5602There is an urgent need to explore affordable and renewable energy resources because of the decline in reserves of fossil fuels. Biomass is an abundantly available resource in nature and can be used to generate energy in a sustainable manner. Fuel cells deliver a combination of advantages and make use of renewable energy sources. Solid oxide fuel cells (SOFCs), specifically, overcome the petroleum scarcity issue by using biofuel. The aim of this thesis is the development of nanocomposite electrolytes and anode composite catalysts for low-temperature SOFCs fuelled with biogas for clean energy applications. In the present work, Sr/Sm-doped ceria (Sr-SDC) nanocomposite electrolytes with a core shell structure are synthesized with different compositions for low temperature SOFCs. A co-doping technique is successfully used to achieve a significant enhancement in the ionic conductivity of 0.50 S/cm at 600 ˚C for the nanocomposite electrolyte Sr0.1Sm0.1Ce0.8O2-δ-carbonate. The carbonate phase (shell layer) acts as a barrier and protects the SDC (core) from the partial reduction by the fuel. This carbonate shell introduces an interface between these two phases, which is the key to realizing the interfacial super-ionic conduction pathways. This work also describes the development of ceria electrolytes that are doped and co-doped with lanthanum (La) and zirconium (Zr) and show excellent thermal stability. The ionic conductivity of La0.2Ce0.8O2-δ (LDC), Zr0.2Ce0.8O2-δ (ZDC) and Zr0.2La0.2Ce0.6O2-δ (ZLDC) has been measured in the temperature ranges of 450 °C to 650 °C and LDC achieved a high ionic conductivity of 0.81 × 10-2 S/cm. Thermal expansion coefficients (TECs) of these electrolytes have also been found to have good concurrence and compatibility with commonly used electrolytes and electrodes. The main objective of this work is the development of stable and active anode catalysts that run over biogas as well as hydrogen for low temperature SOFCs. The anode composite Ni0.6Zn0.4- Gd0.2Ce0.8O2-δ (NiZn-GDC) has been developed that exhibits semiconductor conductive behaviour, and a maximum conductivity of 1.37 S/cm has been achieved at 600 ˚C. This composite anode is found to have excellent thermally stability as well as being carbon resistant to coking during testing with biogas. A maximum power density of xii 820 and 548 mW/cm2 has been reported with hydrogen and biogas fuels, respectively, at 600 ˚C. This thesis also describes Ni-based and Ni-free anode catalysts NiLiCu-oxide with LDC for SOFCs fuelled with biogas. The anode composite NLC622-LDC has reported a maximum DC conductivity of 3.47 S/cm with Pmax of 650 and 390 mW/cm2 for hydrogen and biogas, respectively, at 600 ˚C. A Ni free anode catalyst Zn0.2Li0.2Cu0.6O2-δ (ZnLiCu-oxide) is also developed as a potential candidate for biogas-based SOFCs that bypasses the difficulty of carbon deposition and has a maximum conductivity of 4.0 S/cm at 600 ˚C. An open circuit voltage (OCV) of 0.96 V is achieved with maximum power density of 600 mW/cm2 with biogas (50% methane) at 650 ˚C. In the present work, a theoretical model of FC system has been designed using MATLAB software, and it makes use of biomass (animal waste, redwood, rice husk and sugar cane). In the last part of the thesis, a partial research work has been conducted to cast the tapes of NiO-GDC (NiO-Gd0.1Ce0.9O1.95) as anode and GDC (Gd0.1Ce0.9O1.95) as electrolyte via aqueous tape casting method. The aqueous tape casting is an emerging and cost-effective technique for the commercialization of SOFCs but faces challenges with ceria tapes due to its poor mechanical strength and co-sintering of half-cells.Item Facile Synthesis of Nanostructured Bimetallic Mixed Oxides and their Electrochemical Characterization as Energy Storages Devices(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2019) Muhammad Mudassir Hassan; CIIT/FA17-RPH-007/LHR; Dr. Rizwan Raza; LHR TP 5711Global warming is the major issue of our modern world. Thus, scientists and researchers are in search of more efficient and more environmental friendly energy materials. With the increasing development in the field of nanoscience and nanotechnology the modern world has transformed the old energy devices into more efficient and more sustainable energy devices. Therefore, there is a lot of need to find out more high performance energy storage devices. In this regard supercapacitor has a lot of potential to overcome the modern world Challenges. In this research work supercapacitor electrodes are prepared with improved energy density and power density. The material used in this research work for supercapacitor is Fe2(MoO4)3 which is a bimetallic mixed oxide. Sample is prepared by a facile hydrothermal method. The structural properties of the prepared sample are analyzed by the X-ray diffraction XRD. The XRD of the prepared sample shows the monoclinic crystal structure with average crystallite size of 68nm. To study the bonding between the atoms FTIR analysis is done. The results of FTIR shows the strong bonding between Fe and MoO4 ions. For electrochemical measurements 3 electrode system is used and two characterizations are done. CV of the prepared sample is done in two electrolytes to find out the best results. The CV curve shows the clear redox reactions occurring. As the scan rate is increased the current increases which confirms the fast electron transfer of electrons in the sample. GCD measurements shows that the sample has fast charging and discharging rate with excellent cyclability. The energy density and power density of the prepared sample was calculated to be 99.91 Wh/Kg and 5533.78 W/Kg respectively.Item Electrochemical Characterization of Mixed Ionic- Electronic Ceria Doped LSM Conductors for Solid Oxide Fuel Cells(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2025) Sania Ashfaq; CIIT/FA23-RPH-037/LHR; Dr. M. Ashfaq Ahmad; LHR TP 9863In this study, composite cathode materials were fabricated for solid oxide fuel cells (SOFCs). Ceria based electrolyte (NDC, GDC, SDC, and CDC) doped in LSM and (LSM-NDC, LSM-GDC, LSM-SDC and LSM-CDC) cathode composites for solid oxide fuel cell were prepared successfully. All these Composites were prepared by Solid State reaction method. These materials give better results and produce more oxygen ions vacancies which enhance the oxidation reduction reaction. The synthesized material is characterized by using Raman Spectroscopy, UV-Vis spectroscopy, and Electrochemical Impedance Spectroscopy. Raman spectra show vibration modes and the structure of materials particles. Raman spectroscopy showed well defined CeO2 vibrational modes at 455 cm⁻ ¹ and 461 cm⁻ ¹, suggesting increased crystallinity and weak intense peak representing oxygen ion vacancies. It tells about which type of shifting occurring in prepared material. In all prepared materials, there is red shifting and wavelength is increasing which shows that particles size is increasing. In UV-Vis’s spectroscopy result demonstrated the band gap values which ranges from 2.5 eV to 3.5 eV. EIS tells about charge transfer and mass transfer in material. EIS tells about the ionic and electronic behavior of materials. in (La0.2Sr0.8 MnO3-δ)0.6 –(Nb0.2Ce0.8O2-δ)0.4 cathode showed the lowest resistances, 0.38 Ω series resistance, 0.68 Ω charge transfer resistance, and 0.30 Ω polarization resistance, in electrochemical impedance spectroscopy at 700°C. These findings were confirmed by fuel cell testing, which showed that (La0.2Sr0.8 MnO3- δ)0.6/(Nb0.2Ce0.8O2-δ)0.4cathode showed highest open circuit voltage of 1.07 V at 700 °C. The conductivity of materials can be calculated with the help of EIS, which is found to be 0.801 Scm -1 at 700 °C