Date of Publication
2025
Document Type
Master's Thesis
Degree Name
Master of Science in Physics
Subject Categories
Physics
College
College of Science
Department/Unit
Physics
Thesis Advisor
Al Rey C. Villagracia
Defense Panel Chair
Emmanuel T. Rodulfo
Defense Panel Member
Gil Nonato C. Santos
Elvis F. Arguelles
Abstract (English)
This study investigates the quantum capacitance enhancement of Ti₂C MXene through alkali metal (Li, Na, K) surface decoration using density functional theory calculations. Pristine Ti₂C was confirmed as a non-magnetic metal with a lattice constant of 3.05 Å and quantum capacitance ranging from ~125 to ~780 μF/cm² dominated by Ti 3d orbitals. Bader charge analysis revealed electron transfer of 1.17 e⁻ (Li), 0.61 e⁻ (Na), and 0.62 e⁻ (K) to the substrate, with donated electrons populating Ti 3d conduction states and enhancing the density of states near the Fermi level. Quantum capacitance calculations revealed pronounced peaks at negative potentials for all decorated systems: Li-Ti₂C (~760 μF/cm² at -0.5 V), Na-Ti₂C (~750 μF/cm² at -0.35 V), and K-Ti₂C achieving exceptional peak performance of ~1400 μF/cm² at -0.4 V. Surface charge density analysis confirmed anode character for all decorated systems, with K-Ti₂C exhibiting the highest absolute negative charge storage capacity (-480 μC/cm²). These results establish alkali metal decoration as an effective strategy for engineering Ti 3d orbital occupancy to enhance MXene quantum capacitance for asymmetric supercapacitor applications.
Abstract Format
html
Abstract (Filipino)
Inimbestigahan ng pag-aaral na ito ang pagpapahusay ng quantum capacitance ng Ti₂C MXene sa pamamagitan ng pagdekorasyon ng alkali metal (Li, Na, K) sa ibabaw nito gamit ang mga kalkulasyon ng density functional theory. Nakumpirma na ang pristine na Ti₂C ay isang non-magnetic metal na may lattice constant na 3.05 Å at quantum capacitance na nasa pagitan ng ~125 hanggang ~780 μF/cm² na pinangungunahan ng Ti 3d orbitals. Ipinakita ng Bader charge analysis ang paglipat ng elektron na 1.17 e⁻ (Li), 0.61 e⁻ (Na), at 0.62 e⁻ (K) patungo sa substrate, kung saan ang mga inilipat na elektron ay pumupuno sa Ti 3d conduction states at nagpapataas ng density of states malapit sa Fermi level. Nagpakita ang mga kalkulasyon ng quantum capacitance ng mga matitingkad na tugatog sa negatibong potensyal para sa lahat ng decorated na sistema: Li-Ti₂C (~760 μF/cm² sa −0.5 V), Na-Ti₂C (~750 μF/cm² sa −0.35 V), at K-Ti₂C na nakamit ang pambihirang peak performance na ~1400 μF/cm² sa −0.4 V. Kinumpirma ng surface charge density analysis ang katangiang anode para sa lahat ng decorated na sistema, kung saan ang K-Ti₂C ang nagpakita ng pinakamataas na absolute negative charge storage capacity (−480 μC/cm²). Pinatutunayan ng mga resultang ito na ang pagdekorasyon ng alkali metal ay isang epektibong estratehiya para sa pag-e-engineer ng Ti 3d orbital occupancy upang mapahusay ang quantum capacitance ng MXene para sa mga aplikasyon ng asymmetric supercapacitor.
Abstract Format
html
Language
English
Format
Electronic
Keywords
MXenes; Density functionals; Supercapacitors; Electronic structure; Charge transfer; Energy storage
Recommended Citation
Morillo, M. (2025). A first-principles study of quantum capacitance in Ti₂C MXene decorated with Li, Na and K. Retrieved from https://animorepository.dlsu.edu.ph/etdm_physics/25
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Embargo Period
12-11-2026
