Department of Chemistry
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Item Designing of Modified Cerium Oxide-Based Enzyme Mimic Nanomaterials as Optical Sensors for the Sensitive and Selective Detection of Hydrogen Peroxide(Library Information Services COMSATS University Islamabad Lahore Campus, 2021-02-24) Aaiza Ramzan; FA19-R06-024; Dr. Muhammad Nasir; LHR TP 7338Imbalance in the amount of biological substances like hydrogen peroxide is the key reason behind different ailments and cell damage. Different approaches have been developed for the detection of hydrogen peroxide. However, they have many drawbacks, such as high cost of the substrates, expensive instruments which require trained personnel to handle and low sensitivity and selectivity. Therefore, to overcome mentioned limitations we devised a sensor-based system which is facile, easy to handle and less expensive. Nanorods comprising of cerium oxide doped iron and cobalt with variable concentrations were synthesized using hydrothermal method. To study its properties various characterization techniques were used such as FTIR analysis for the confirmation of different functional groups in the composite (Fe3+-Co2+-CeO2), XRD studies to study the crystallite size and growth of iron and cobalt inside the cerium oxide lattice of the prepared composites. SEM analysis was performed to check the surface morphology and the grain size of the synthesized samples. As a proof of the concept studies these prepared nanocomposites were used for the detection of hydrogen peroxide. Before using these nanocomposites for the detection, concentrations of different parameters were optimized, such as buffer amount and pH, incubation time, temperature and TMB (3, 3', 5, 5'-Tetramethyl-benzidine) amount etc. which have lot of impact on the sensor properties and its activity. TMB was used as a chromogenic substrate for colorimetric analysis of the prepared sample. The nanocomposite (Fe3+-Co2+-CeO2) helped in decomposition of hydrogen peroxide in its radicals and these radicals oxidized TMB in the reaction mixture which led to color change as a result. This change in color is the indication of amount of hydrogen peroxide present in the system, the more the color change the more the amount of hydrogen peroxide and vice versa. UV-Vis spectroscopy was used for measuring the absorbance of different percentages. The limit of detection (LOD) estimated using the data obtained under optimal conditions and within a linear range of 0.1 μm-20mM (R2=0.9402) was found to be as low as 0.057 μm. The selectivity of the platform was confirmed by the study of certain interfering species. The results confirmed the sensitivity of this colorimetric sensor for the detection of hydrogen peroxide.Item Carbon-based Nanomaterials for Electrocatalytic Oxidation of Methanol and Ethanol(Library Information Services COMSATS University Islamabad Lahore Campus, 2020-02-19) Salman Munawar; FA18-R06-022; Dr. Muhammad Javid Iqbal; LHR TP 6500Fuel cells attract validation every day due to the important characteristics of Pt, Pd, Ru and Rh as the traditional catalysts, including no mobile portion and energy generation, but also because they are uncommon and costly, they also produce toxic, intermediate, and slow-cinematic reactions. In this study, CoSe/CNT material was prepared which is responsible for methanol oxidation reaction in methanol fuel cell. The CoSe/CNT material has been synthesized through using of selenium (Se) along with cobalt chloride hexahydrate. For this preparation, single step hydrothermal is applied. XRD confirmed the successful composite synthesis along with SEM. x Laterally, the synthesized material has showed remarkable use in electrochemical reaction such as oxidation reaction of methanol studies. The trustable technique such as cyclic voltammetry has been applied which confirmed that the methanol oxidation is a diffusion-controlled process and forward peak current and peak potential increase with the scan rate when varying between 25, 50, 100, 150 and 200 mV/s. This technique was performed in acidic medium on modified glassy carbon electrode (GCE) via three electrode electrochemical system. The oxidation reaction of methanol is catalyzed by CoSe@CNTs catalyst and remarkable current density with peak value of 6.4 mA/cm2 by using 0.6 potential with scan rate of 50mV/s. The lower charge transfer resistance Rct has been confirmed by using electrochemical impedance spectroscopy and catalyst was highly stable.