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

Joaquin Lorenzo V. Moreno
Elvis F. Arguelles

Abstract (English)

Efficient and reversible hydrogen storage remains a critical challenge in advancing hydrogen-based energy systems. Lightweight carbon nanostructures such as the C₁₂ carbyne ring offer a promising platform but often suffer from hydrogen adsorption energies outside the ideal range (−0.2 to −0.4 eV) for practical storage. Transition metal decoration has been proposed to enhance adsorption through stronger interactions with H₂ molecules.  This study investigates the hydrogen storage capabilities of Ni-, Co-, and Ti-decorated C₁₂ carbyne using Density Functional Theory (DFT). Three adsorption sites were explored: the ring center (hollow site), a C–C single bond, and a C≡C triple bond. For Co and Ti, the hollow site produced adsorption energies within the ideal range, while the single and triple bond sites were less favorable. Ni, by contrast, adsorbed at all three sites but showed adsorption energies outside the ideal range in all cases. The addition of H₂ molecules showed that Co and Ti could adsorb up to 6 and 5 H₂ molecules, respectively, at the hollow site without dissociation, indicating reversible adsorption behavior.  These results highlight the potential of transition metal-decorated carbyne rings, particularly with Co and Ti, as promising nanostructures for hydrogen storage applications.

Abstract Format

html

Abstract (Filipino)

Ang mabisa at naibabalik (reversible) na pag-iimbak ng hydrogen ay nananatiling isang kritikal na problema sa pagsulong ng mga sistemang pang-enerhiya na nakabase sa hydrogen. Ang mga magagaan na carbon nanostructure tulad ng C₁₂ carbyne ring ay nag-aalok ng magandang plataporma ngunit madalas ay may hydrogen adsorption energies na labas sa ideal na saklaw (−0.2 hanggang −0.4 eV) para sa praktikal na pag-iimbak.

Iminungkahi ang paglalagay ng transition metal upang mapabuti ang adsorption sa pamamagitan ng mas malakas na interaksyon sa mga H₂ molecule. Sinisiyasat ng pag-aaral na ito ang kakayahan sa pag-iimbak ng hydrogen ng C₁₂ carbyne na nilagyan ng Ni, Co, at Ti gamit ang Density Functional Theory (DFT).

Tatlong lugar ng adsorption ang sinuri: ang gitna ng ring (hollow site), ang C–C single bond, at ang C≡C triple bond. Para sa Co at Ti, ang hollow site ay nagresulta ng adsorption energies na pasok sa ideal na saklaw, habang ang mga single at triple bond site ay hindi gaanong angkop. Sa kabaligtaran, ang Ni ay kumapit (adsorbed) sa lahat ng tatlong site ngunit nagpakita ng adsorption energies na labas sa ideal na saklaw sa lahat ng kaso.

Ang pagdaragdag ng mga H₂ molecule ay nagpakita na ang Co at Ti ay kayang mag-adsorb ng hanggang 6 at 5 H₂ molecule, ayon sa pagkakasunod, sa hollow site nang hindi nagkakahiwalay (without dissociation), na nagpapahiwatig ng reversible adsorption behavior. Binibigyang-diin ng mga resultang ito ang potensyal ng mga transition metal-decorated carbyne ring, partikular ang may Co at Ti, bilang mga nanostructure na may pag-asa para sa mga aplikasyon ng pag-iimbak ng hydrogen.

Abstract Format

html

Language

English

Format

Electronic

Keywords

Titanium compounds; Nickel compounds; Cobalt compounds; Nanostructured materials

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Embargo Period

1-18-2026

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