Date of Defense
4-6-2026 2:00 PM
Location
F3-134
Document Type
Dissertation Defense
Degree Name
Doctor of Philosophy in Physics
College
COS
Department
Physics
First Advisor
Prof. Nacir Tit
Keywords
2D materials, Density Functional Theory (DFT), Volatile Organic Compounds (VOCs), Cancer Biomarkers, Green Energy, Hydrogen Storage.
Abstract
This dissertation is motivated by two driving forces:
(i) the need for biosensors for early cancer diagnosis, and
(ii) the need for hydrogen storage materials to support a future energy hydrogen-based economy.
Throughout this thesis, both challenges were addressed using computational methods based upon density functional theory (DFT), as implemented in the Vienna Ab-initio Simulation Package (VASP), ab-initio molecular dynamics (AIMD), and thermodynamic analysis.
On the side of cancer biomarker detection, exhaled breath containing volatile organic compounds (VOCs) have been shown to offer the analysis of a promising non-invasive diagnostic strategy. This thesis explored the functionalization of two distinct 2D material platforms for the selective detection of VOCs associated with two cancer diseases (i) gastric cancer (GC) and (ii) colorectal cancer (CRC). For the gastric cancer detection, transition-metal (TM) single-atom catalysts (SAC) – specifically Co, Fe, Mn, Ni – were embedded in nitrogen-functionalized carbon nanoribbons (N-CNRs) composed of 4-5-6-8 membered rings. Seven VOC molecules representative of GC biomarkers were studied: 2-pentanone, butanone, isoprene, methylglyoxal, N-decanal, N-pentanal, and pyridine. All these seven VOCs were found to have adsorptionenergies higher on Fe-doped N-CNR (N-CNR:Fe), all surpassing those of interfering air molecules (N2, O2, H2O, CO2). Charge density analysis, work function calculations, and half-metallicity character of N-CNR:Fe confirmed its high potential for selective GC biomarker sensing.
For colorectal cancer (CRC) detection, four VOC molecules representative of CRC were studied: benzaldehyde, butanol, indole, and isopropanol. The detection platform was the Boron Monoxide (BO) monolayer functionalized with Light-Metal (LM) atoms (Li, Na, K, Ca) in a single-atom catalyst approach. Among the investigated systems, K@BO and Ca@BO demonstrated excellent selectivity toward CRC-related VOCs with adsorption energies significantly exceeding those of interfering air molecules. The 2K@BO case yielded adsorption energies of -1.928, -1.300, -1.665, and -1.354 eV for the respective four VOCs, with sensor responses exceeding 200%, and confirming the high selectivity potential of these systems. Thermodynamic stability of the detecting material was confirmed by ab-initio molecular dynamics (AIMD) simulations at 300 K.
On the side of hydrogen storage, this dissertation investigates a defect engineered beryllium dinitride (BeN2) monolayer decorated with alkali metal atoms (Li, Na, K) as a platform for promising high gravimetric capacity, reversible H2 storage. A primitive cell containing two intrinsic Be vacancy sites (BeN2: 2VBe) can accommodate four Li, Na, or K atoms without clustering, with average metal binding energies of -3.80, -2.94, and -3.18 eV, respectively, all exceeding the corresponding bulk cohesive energies. Ab-initio molecular dynamics (AIMD) simulations at 400 K confirm the thermodynamic stability of the metal decorated framework. The vacancy stabilized alkali metal centers generate localized charge polarization that facilitates adsorption of up to 20 H2 molecules per supercell, with average adsorption energies of -0.182 eV (Li), -0.191 eV (Na), and -0.177 eV (K) per H2 molecule, falling within the ideal reversible window of 0.15-0.6 eV recommended by the US department of Energy (US-DOE). The corresponding theoretical gravimetric hydrogen storage capacities reach 11.64 wt% (Li), 9.82 wt% (Na), and 8.49 wt% (K), all significantly exceeding the US-DOE ultimate target of 6.5 wt%. Thermodynamic analysis using the Langmuir adsorption model further confirms favorable adsorption-desorption behavior within practical operating windows (30 atm/25°C for adsorption; 3 atm/100°C desorption), with Li decorated monolayer maintaining an effective capacity of 7.69 wt%, above the DOE threshold, under realistic conditions.
Collectively, these findings demonstrate that LM- and TM- functionalized 2D materials represent a versatile and powerful strategy to prepare platform for both non-invasive cancer diagnostics and clean energy storage applications, with implications for the design of next-generation nano-biosensors and hydrogen fuel cell technologies.
Included in
AB-INITIO INVESTIGATION OF 2D MATERIALS FOR VOC-BASED CANCER BIOMARKER DETECTION AND HYDROGEN STORAGE APPLICATION
F3-134
This dissertation is motivated by two driving forces:
(i) the need for biosensors for early cancer diagnosis, and
(ii) the need for hydrogen storage materials to support a future energy hydrogen-based economy.
Throughout this thesis, both challenges were addressed using computational methods based upon density functional theory (DFT), as implemented in the Vienna Ab-initio Simulation Package (VASP), ab-initio molecular dynamics (AIMD), and thermodynamic analysis.
On the side of cancer biomarker detection, exhaled breath containing volatile organic compounds (VOCs) have been shown to offer the analysis of a promising non-invasive diagnostic strategy. This thesis explored the functionalization of two distinct 2D material platforms for the selective detection of VOCs associated with two cancer diseases (i) gastric cancer (GC) and (ii) colorectal cancer (CRC). For the gastric cancer detection, transition-metal (TM) single-atom catalysts (SAC) – specifically Co, Fe, Mn, Ni – were embedded in nitrogen-functionalized carbon nanoribbons (N-CNRs) composed of 4-5-6-8 membered rings. Seven VOC molecules representative of GC biomarkers were studied: 2-pentanone, butanone, isoprene, methylglyoxal, N-decanal, N-pentanal, and pyridine. All these seven VOCs were found to have adsorptionenergies higher on Fe-doped N-CNR (N-CNR:Fe), all surpassing those of interfering air molecules (N2, O2, H2O, CO2). Charge density analysis, work function calculations, and half-metallicity character of N-CNR:Fe confirmed its high potential for selective GC biomarker sensing.
For colorectal cancer (CRC) detection, four VOC molecules representative of CRC were studied: benzaldehyde, butanol, indole, and isopropanol. The detection platform was the Boron Monoxide (BO) monolayer functionalized with Light-Metal (LM) atoms (Li, Na, K, Ca) in a single-atom catalyst approach. Among the investigated systems, K@BO and Ca@BO demonstrated excellent selectivity toward CRC-related VOCs with adsorption energies significantly exceeding those of interfering air molecules. The 2K@BO case yielded adsorption energies of -1.928, -1.300, -1.665, and -1.354 eV for the respective four VOCs, with sensor responses exceeding 200%, and confirming the high selectivity potential of these systems. Thermodynamic stability of the detecting material was confirmed by ab-initio molecular dynamics (AIMD) simulations at 300 K.
On the side of hydrogen storage, this dissertation investigates a defect engineered beryllium dinitride (BeN2) monolayer decorated with alkali metal atoms (Li, Na, K) as a platform for promising high gravimetric capacity, reversible H2 storage. A primitive cell containing two intrinsic Be vacancy sites (BeN2: 2VBe) can accommodate four Li, Na, or K atoms without clustering, with average metal binding energies of -3.80, -2.94, and -3.18 eV, respectively, all exceeding the corresponding bulk cohesive energies. Ab-initio molecular dynamics (AIMD) simulations at 400 K confirm the thermodynamic stability of the metal decorated framework. The vacancy stabilized alkali metal centers generate localized charge polarization that facilitates adsorption of up to 20 H2 molecules per supercell, with average adsorption energies of -0.182 eV (Li), -0.191 eV (Na), and -0.177 eV (K) per H2 molecule, falling within the ideal reversible window of 0.15-0.6 eV recommended by the US department of Energy (US-DOE). The corresponding theoretical gravimetric hydrogen storage capacities reach 11.64 wt% (Li), 9.82 wt% (Na), and 8.49 wt% (K), all significantly exceeding the US-DOE ultimate target of 6.5 wt%. Thermodynamic analysis using the Langmuir adsorption model further confirms favorable adsorption-desorption behavior within practical operating windows (30 atm/25°C for adsorption; 3 atm/100°C desorption), with Li decorated monolayer maintaining an effective capacity of 7.69 wt%, above the DOE threshold, under realistic conditions.
Collectively, these findings demonstrate that LM- and TM- functionalized 2D materials represent a versatile and powerful strategy to prepare platform for both non-invasive cancer diagnostics and clean energy storage applications, with implications for the design of next-generation nano-biosensors and hydrogen fuel cell technologies.