Department of Chemistry

Permanent URI for this communityhttps://repository.cuilahore.edu.pk/handle/123456789/14

Browse

Author: search.filters.author.Dr. Mazhar Amjad Gilani

Search Results

Now showing 1 - 10 of 21
  • No Thumbnail Available
    Item
    Hydrogen Splitting using Single Metal Atom Doped Zinc Oxide Nanocage as a Catalyst: A DFT Study
    (Library Information Services, COMSATS University Islamabad, Lahore Campus, 2023) Ali Hussain; FA21-R06-016; LHR TP 8447; Dr. Mazhar Amjad Gilani
    Hydrogen dissociation reaction is a key step in sustainable, non-toxic and renewable energy production and single atom catalysts have shown promising catalytic activity in facilitating this reaction. The world is currently facing major challenges related to the environment, including climate change and the depletion of non-renewable energy sources. As a potential solution to these challenges, the use of clean and renewable energy sources, such as hydrogen, has gained increasing attention. Herein we employed DFT calculation on single atom catalyst-based study to investigate the adsorption and dissociation of H2 molecule over TM@ Zn12O12 catalysts. The analysis of the interaction energy reveals the stability of all transition metal doped complexes (Sc-Mn), with the highest interaction energy (-4.27 eV) observed in the Cr@Zn12O12 complex. Furthermore, electronic properties (FMOs, NBO analysis) confirm the electropositive nature of transition metal atoms. QTAIM and IRI analysis are employed to interpret shared or partially covalent interactions in TM@ Zn12O12 complexes. The mechanism of hydrogen dissociation reaction is studied for all the complexes (Sc-Mn), and it is found that Sc@Zn12O12 is the most efficient catalytic agent for the hydrogen dissociation reaction, with the lowest activation barrier (0.09 eV). EDD isosurface and NBO analysis confirm the charge transfer from metal to antibonding orbital of hydrogen which facilitates the hydrogen splitting. The pivotal insights gained from this study enhance our understanding about the stability, electronic properties, and hydrogen dissociation reaction of various transition metal doped Zn12O12complexes.
  • No Thumbnail Available
    Item
    Effect of Electric Field Variation on Electronic and Nonlinear Optical (NLO) Properties of Ionic Liquids: A DFT Study
    (Library Information Services COMSATS University Islamabad Lahore Campus, 2023-02-27) Dua Fatima; SP22-R06-018; Dr. Mazhar Amjad Gilani; LHR TP 8657
    The growing use of nonlinear optical (NLO) materials in various fields has generated interest in designing innovative smart NLO materials. This study focuses on three specific ionic liquids, where the same cation, 1-ethyl-3-methyl imidazolium, is combined with three different anions (Br-, C-, F-). The study explores the effects of External Electric Field (EEFs) on these three ILs using Density Functional Theory (DFT) calculations. The interaction energies calculated confirm the stability of the newly designed ILs. Applying external electric field (EEFs) ranging from 0.001 a.u to 0.006 a.u leads to a significant reduction in the E(H–L) gap, and the lowest energy gap of 4.43 eV is observed in EMIBr at field strength of 0.006 a.u. Natural Bond Orbital (NBO) analysis validates substantial charge transfer from cations to anions, with the highest transfer observed in EMIBr. External Electric field enhances the first hyperpolarizability, and EMIBr exhibits the highest value i.e 1828 a.u at 0.006 a.u. TD-DFT calculations are executed to derive electronic states influenced by an external electric field (EEF), and the highest λmax (nm) i.e. 227 nm, is observed in the case of EMIBr at 0.006 a.u. The study also determines frequency-dependent Second Harmonic Generation (SHG) and Electric-Optical Pockels Effect (EOPE), with noteworthy values observed i.e 2.0×103 and 9.8×103 respectively in case of EMIBr. In conclusion, the study provides guidelines for computationally designing efficient and thermodynamically stable complexes for optical and optoelectronic technologies. The proposed ILs could find potential applications in new electronic devices, contributing to the development of advanced NLO materials.
  • No Thumbnail Available
    Item
    Theoretical Assessment of Corannulene-Based Aggregates as High-Performance Nonlinear Optical Materials
    (Library Information Services COMSATS University Islamabad Lahore Campus, 2023-02-27) Sobia Waheed; SP22-R06-024; Dr. Mazhar Amjad Gilani; LHR TP 8662
    The growing use of nonlinear optical (NLO) materials in various fields has generated interest in designing innovative smart NLO materials. This study focuses on enhancing the nonlinear optical response through doping of alkali metals on the corannulene (C20H10) dimer through Density Functional Theory (DFT) calculations. The interaction energies calculated computationally confirm the stability of the newly designed alkali metal-doped cncx dimers. Alkali metal doping, particularly with Li, Na, and K, leads to a significant reduction in the E(H–L) gap, and the lowest energy gap of 3.17 eV is observed in K-doped cncx dimer. The TD-DFT study shows that these alkali metal doped complexes have λmax in the visible regions(568-576nm). Total density of states (TDOS) spectra support the involvement of dimer in forming new Highest Occupied Molecular Orbital (HOMO). Natural Bond Orbital (NBO) analysis validates substantial charge transfer from alkali metals to dimer, with the highest charge transfer (0.938 |e|) observed in the K@cncx complex. Doping with alkali metals enhances the first hyperpolarizability, and Li@cncx exhibits the highest value (9.3×104 au). The study also determines frequency-dependent Second Harmonic Generation (SHG), Electric-Optical Pockels Effect (EOPE), electro-optic dc-Kerr effect (EOKE). The value of 3.4×104 au is observed for SHG, while for EOPE the value is 4.6×105 au. A significantly enhanced EOKE value (1.0 × 1010 au) is shown by Na@cncx. Additionally, these structures exhibit a high nonlinear quadratic refractive index (a maximum value of 9.9×10-18cm2 W-1). In conclusion, the study provides guidelines for computationally designing efficient and thermodynamically stable complexes for optical and optoelectronic technologies.
  • No Thumbnail Available
    Item
    Exploration of Diradical Graphene Nanoflakes (GNFs) as NLO based Sensors for NOx
    (Library Information Services COMSATS University Islamabad Lahore Campus, 2023-02-27) Mawra Nasir; SP22-R06-009; Dr. Mazhar Amjad Gilani; LHR TP 8648
    Approximately 78% of the air is composed of nitrogen, which, in its elemental form, is not harmful. However, nitrogen oxides (NO, NO2, N2O) present in the air can have adverse effects on both human health and the environment. In the realm of environmental monitoring, the crucial task of adsorbing or detecting small (toxic) gas molecules relies on appropriate semiconductors. Although graphene nanoflakes (GNFs) find extensive applications in energy storage and optoelectronics, their potential as sensors is not extensively explored. This study investigates the adsorption of nitrogen-containing gaseous molecules i.e NO, NO2, and N2O on trigonal, rhombic, and bowtie GNFs sheets through Density Functional Theory (DFT) simulations. The analysis encompasses optimized geometries, adsorption energies, as well as Natural Bond Orbital (NBO) and Electron Density Differences (EDD) analyses to interpret the interaction between GNFs sheets and NOx gases. The theoretical findings reveal strong binding between GNFs sheets and NO2 molecule, with adsorption energies of -30.2, - 17.1, and -29.8 kcalmol-1 for NO2@t-GNFs, NO2@r-GNFs, and NO2@b-GNFs, respectively. Furthermore, Frontier Molecular Orbital (FMO), and Density of State (DOS) analyses underscore the significant impact of gas adsorption on GNF sheets. Interaction Region Indicator (IRI) and Quantum Theory of Atoms in Molecules (QTAIM) analyses indicate the covalent interactions between GNFs sheets and NO, NO2 gases, while van der Waals interactions are confirmed with N2O gases. UV-Vis and IR analyses demonstrate the selectivity of b-GNFs towards NO2 and NO, respectively. Based on Nonlinear Optical (NLO) response, b-GNFs exhibit the highest sensitivity towards NOx. In conclusion, GNFs sheets exhibit promising sensitivity to gaseous molecules, positioning them as potential multimode sensors, including UV, IR, and NLO-based applications. This theoretical insight aids experimentalists in developing novel GNFs-based sensors for the detection of toxic gases.
  • No Thumbnail Available
    Item
    Hydrogen Adsorption and Dissociation Using Single Metal Atom Doped Mg12O12 Nanocage as a Catalyst: A DFT Study
    (Library Information Services, COMSATS University Islamabad, Lahore Campus, 2025) Irsa Nageen; FA22-R06-008; Dr. Mazhar Amjad Gilani; LHR TP 9309
    Energy is the keystone of life on Earth, powering everything from microscopic levels to large scale chemical reactions. The expanding population and increasing industrial activities have reinforced the energy demands, traditionally sourced from fossil fuels. However, the finite nature of these resources and their detrimental environmental impacts necessitate a transition to sustainable energy solutions. Currently, hydrogen emerges as the outstanding substitute for fossil fuels, making it a more valuable energy source due to its high energy density, renewability, and clean burning nature, producing only water as a by-product. Hence, efficient hydrogen utilization requires its dissociation because molecular hydrogen is not an effective energy source as the atomic form. In this regard, hydrogen dissociation reaction on single-atom catalysts (SAC) is an essential step in sustainable and non-toxic energy production. Our study employed DFT calculations to investigate the adsorption and dissociation of molecular hydrogen on 3d transition metal atoms doped onto Mg12O12 nanocages. Each TM@Mg12O12 complex is evaluated to identify the most stable spin state for the catalytic reaction. The energetic analysis reveals that the Sc@Mg12O12 and Ti@Mg12O12 complexes exhibit high and identical interaction energy (-2.13eV) among the studied complexes. Further evaluation using NBO, FMO, IRI, and QTAIM analysis revealed the charge transfer carried from nanocage to metal and confirmed the partial covalent interactions between the TM-doped complexes. The adsorption of molecular hydrogen on the TM-doped nanocage exhibits negative adsorption energy which confirms the exothermic nature of H2 adsorption. Notably, the homolytic dissociation of H2 on the Ti@Mg12O12 complex displayed the lowest activation barrier (0.23eV), highlighting its potential as an efficient catalyst for hydrogen dissociation reactions. QTAIM of H2TM@Mg12O12 studies the interaction between the hydrogen and catalyst and confirms the covalency. NBO and EDD analysis confirm the transfer of charge from metal bonding to hydrogen antibonding orbital which leads to the dissociation of the H-H bond and facilitates the adsorption of hydrogen atoms on the catalyst. Our investigation sheds light on the factors that govern the electronic properties and catalytic ability of TM-doped Mg12O12 nanocage complexes in hydrogen dissociation reactions and paving the way for the development of improved hydrogen energy technology.
  • No Thumbnail Available
    Item
    Detection of Histamine and Serotonin as Chronic Stress Biomarkers Using Graphyne-based Sensor: A DFT Study
    (Library Information Services, COMSATS University Islamabad, Lahore Campus, 2025) Amina Haq; FA22-R06-027; Dr. Mazhar Amjad Gilani; LHR TP 9317
    Chronic stress is a leading cause of mental illnesses that is interceded by neuroinflammation and poses one of the most critical public health challenges globally therefore, a theragnostic strategy is needed for effective diagnosis of stress. Neuroinflammation induces an increase in histamine and a decrease in serotonin levels in blood during chronic stress. The sensitivity of pristine and alkali metal (IA = Li, Na, and K) doped C24H12 toward histamine and serotonin are probed herein at DFT/ωB97XD/6 31+G (d, p) level of theory in the water phase. The -NH2 group of histamine and -OH group of serotonin are coordinated with pristine and metal-doped C24H12 nanosheets. The adsorption of histamine and serotonin is an exothermic process and physi-chemisorbed as their adsorption energies range from -40 to -60 kJ/mole per atom for all complexes except His@C24H12, His@KC24H12, and Ser@C24H12. Considerable, charge transfer from biomarkers to the C24H12 except for Ser@C24H12 is revealed via NBO analysis and confirmed by.MEP, UV-visible, and IR spectroscopic analyses. Upon the adsorption of the biomarkers, the λmax of pristine C24H12 remains unchanged but, in metal-doped C24H12, a bathochromic effect is observed. The significant shift in vibrational frequencies of -NH and -OH stretch occurred due to charge transfer toward C24H12. Furthermore, the band gap of the pristine C24H12 is 6.86 eV which remains constant even after histamine and serotonin adsorption. However, the doping of alkali metals leads toward a significant decrease of the band gap of about 4.60 eV revealing that doping facilitated the charge transfer from biomarkers to graphyne for effective sensing. The QTAIM and IRI studies show the presence of non-covalent interactions among the biomarkers and C24H12. Finally, a shorter recovery time (fast desorption) is found in vacuum ultraviolet light, indicating the pristine and metal-doped C24H12 nanosheets as a reusable or non-disposable sensor. Therefore, it concludes that metal-doped C24H12 nanosheets are more sensitive toward histamine and serotonin adsorption than pristine C24H12.
  • No Thumbnail Available
    Item
    Therapeutic Potential of Alkali Metal Doped g- C3N4 as Drug Carrier for 5-Fluorouracil in Cancer Treatment
    (Library Information Services COMSATS University Islamabad Lahore Campus, 2023-02-27) Bibi Anbreen; SP21/R06/004; Dr. Mazhar Amjad Gilani; LHR TP 8638
    Owing to the mortalities caused by cancer and a high number of cases reported globally there are continuous studies on improving the cancer treatment methods. This study focuses on enhancing the therapeutic potential of g-C3N4 through surface modification by doping this carrier sheet with alkali metals like Li, Na, and K using DFT for the efficient delivery of 5-Fluorouracil. The interaction energies of the optimized geometry are calculated by the computational method B3LYP-D3, and the results indicate an obvious improvement in the interaction between the drug and the carrier sheet. The Ead values in the case of Li@g-C3N4-5FU complex in the gas phase and the aqueous phase are -10.21eV, and -3.23eV respectively and these values make this complex the most stable one as compared to g-C3N4-5FU, Na@g-C3N4-5FU and K@g-C3N4-5FU complexes. The frontier molecular orbital analysis indicates a significant decrease in the band gap after the doping of alkali metals from the HOMO-LUMO gap value of 3.7eV to 0.81eV in the case of g-C3N4-5FU and Li@g-C3N4-5FU respectively. This reduced band gap supports the idea of doping the carrier sheet with Li. The IRI and QTAIM analyses show the weak forces of interaction between the doped carrier sheets and the drug molecule and the presence of Van der Walls forces of attraction. To check the behavior of these complexes inside the body and to estimate the ease of unloading the drug upon reaching the targeted sites the complexes are also studied in the environment of low pH by the protonation of these complexes. It is observed that when the complexes are in the acidic medium the values of interaction energies decrease significantly. For instance, in the case of Li@g-C3N4-5FU complex the the Ead value decreases from -10.21eV to -4.9eV when the acidic medium is provided. This decrease in energy value shows that the carrier can easily release the drug when it reaches the cancer cells. In conclusion, the modification of the surface of the Graphitic Carbon Nitride greatly increases the therapeutic potential of g-C3N4 as a carrier for the delivery of 5-Fluorouracil in cancer treatment and this theoretical model can help the
  • No Thumbnail Available
    Item
    Theoretical Studies of Superalkalis Doping on Calix[4]arene; A Unique Approach for the Improvement of Nonlinear Optical Response
    (Library Information Services COMSATS University Islamabad Lahore Campus, 2023-02-27) Khalida Khalil; FA21-R06-024; Dr. Mazhar Amjad Gilani; LHR TP 8454
    Many scientists are interested in developing high-performance nonlinear materials because of their potential uses in areas such as optics, optoelectronics, optical computing, and others. Density Functional theory (DFT) is used to predict NLO response of the selected systems. The study revealed that the doping of superalkalis on calix[4]arene is an efficient strategy to design high performance NLO materials. The interaction energy (Eint) calculations are used to analyze the thermal stability of the complexes under consideration. Superalkali doping generates diffuse surplus electrons, which produce the alkalide properties in the corresponding systems. Through static and dynamic hyperpolarizability investigations, these alkalides are further studied for their nonlinear optical (NLO) responses. The large values of second (5.9×105) and third-order (1.9×108) NLO responses at 1200 nm, along with a high refractive index, demonstrate that the NLO response of the corresponding complexes increases at large wavelength. The nature of charge transfer was confirmed by the NBO analysis. The weak electrostatic interactions between calix[4]arene and superalkali was revealed through QTAIM and interaction region indicator analysis (IRI). The TD-DFT calculations confirmed the transparency of these superalkali (Li3O, Na3O and K3O) doped complexes in UV-VISIBLE regions. Overall, the study highlights the M3O@calix[4]arene as potential candidate for designing high performance NLO materials.
  • No Thumbnail Available
    Item
    Hydrogen Splitting using Single Metal Atom Doped Zinc Oxide Nanocage as a Catalyst: A DFT Study
    (Library Information Services COMSATS University Islamabad Lahore Campus, 2023-02-26) Ali Hussain; FA21-R06-016; Dr. Mazhar Amjad Gilani; LHR TP 8447
    Hydrogen dissociation reaction is a key step in sustainable, non-toxic and renewable energy production and single atom catalysts have shown promising catalytic activity in facilitating this reaction. The world is currently facing major challenges related to the environment, including climate change and the depletion of non-renewable energy sources. As a potential solution to these challenges, the use of clean and renewable energy sources, such as hydrogen, has gained increasing attention. Herein we employed DFT calculation on single atom catalyst-based study to investigate the adsorption and dissociation of H2 molecule over TM@ Zn12O12 catalysts. The analysis of the interaction energy reveals the stability of all transition metal doped complexes (Sc-Mn), with the highest interaction energy (-4.27 eV) observed in the Cr@Zn12O12 complex. Furthermore, electronic properties (FMOs, NBO analysis) confirm the electropositive nature of transition metal atoms. QTAIM and IRI analysis are employed to interpret shared or partially covalent interactions in TM@ Zn12O12 complexes. The mechanism of hydrogen dissociation reaction is studied for all the complexes (Sc-Mn), and it is found that Sc@Zn12O12 is the most efficient catalytic agent for the hydrogen dissociation reaction, with the lowest activation barrier (0.09 eV). EDD isosurface and NBO analysis confirm the charge transfer from metal to antibonding orbital of hydrogen which facilitates the hydrogen splitting. The pivotal insights gained from this study enhance our understanding about the stability, electronic properties, and hydrogen dissociation reaction of various transition metal doped Zn12O12complexes.
  • No Thumbnail Available
    Item
    Hydrogen Splitting Using Single Metal Atom Doped C3N Nanosheet as a Catalyst: A DFT Study
    (Library Information Services COMSATS University Islamabad Lahore Campus, 2022-02-26) Zulqarnain Haider; FA20-R06-010; Dr. Mazhar Amjad Gilani; LHR TP 7881
    Atomic hydrogen is the most intriguing free radical for high-energy applications. The ability of atomic hydrogen to protect DNA and mitochondria from oxidative damage may be advantageous in the treatment of chronic illnesses including cancer. When dissociation energy is supplied, a molecule of hydrogen dissociates into two atoms (H2 → 2H). In contrast to other radicals, hydrogen recombination requires no activation energy. The highest efficiency and stability for heterogeneous catalysis of hydrogen splitting are provided by single-atom catalysts adsorbed on the active surface. For support of single-atom catalyst (SAC), carbon nanotubes, graphene, metal hydrides, metal-organic frameworks, graphene, graphdiyne, carbon nitride, and silanes surfaces have been employed recently. The presence of nitrogen in carbon nitride surfaces is shown to be much more effective for hydrogen dissociation and considered as the most suitable substrate for SAC. Because of their varying oxidation states, transition metals have several spin states that can be tested, and the most stable spin states based on thermodynamic energy data may be determined. The optimized C3N nanosheet is doped with 3d transition metals. The lowest energy spin state of each doped metal is considered for further calculations. The stabilities of complexes have been measured by calculating the interaction energies of optimized geometries. Adsorption energies of H2 on metal doped carbon nitride surface are computed to investigate the adsorption mechanism and characterize the energetic heterogeneity of solid surfaces. The energy barrier (activation energy) and reaction energies are required to determine the splitting of hydrogen. This study shows that SAC can be used as the most efficient doping technique for hydrogen splitting.