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Article First-Principles Investigation of Kaolinite/YSZ Heterostructure for Solar-Driven Photocatalytic Hydrogen Production(Pergamon-Elsevier Science Ltd, 2025) Park, Jongee; Yu, Eunmi; Fatima, Syeda AfrinishThis work employs density functional theory (DFT) to elucidate the structural, electronic, and photocatalytic properties of a kaolinite/yttria-stabilized zirconia (Kaol/YSZ) heterostructure tailored for solar-driven hydrogen generation. The lattice mismatch between Kaol(001) and YSZ(111) was determined to be 4.4 % along the a-axis and 2.2 % along the b-axis. Two interface terminations were modeled: an O-terminated Si-O surface and an OH-terminated Al-OH surface. The OH-terminated interface demonstrated a stronger interfacial binding energy (-9.32 eV per cell) and enhanced thermodynamic stability, indicating its suitability for photocatalytic water splitting. Electronic structure analysis reveals that the Kaol/YSZ heterostructure exhibits a narrowed band gap of 1.46 eV relative to the isolated components, which promotes enhanced visible-light absorption. A type-II band alignment is observed, facilitating photoinduced electron transfer from the conduction band of YSZ to the conduction band of Kaol and promoting efficient charge separation. Hirshfeld charge analysis confirms the existence of a built-in electric field at the interface that further drives charge migration. Calculated optical absorption spectra shows a red shift in the heterostructure's absorption edge, extending its photoresponse into the visible region. Under simulated solar irradiation, photogenerated electrons preferentially migrate to Kaol for proton reduction, while holes remain on the YSZ surface to oxidize water, enabling simultaneous H2 evolution and O2 evolution pathways. These findings highlight the promise of the Kaol/YSZ heterostructure as a robust visible-light photocatalyst for sustainable hydrogen production and environmental remediation.Article Citation - WoS: 6Citation - Scopus: 5Computational Analysis of Tic3 as a High-Efficiency Anode for Calcium-Ion Batteries(Elsevier, 2024) Park, Jongee; Fatima, Syeda AfrinishA comprehensive analysis of the structural, electronic, and thermal properties of TiC3 has been conducted. The calculated thermal expansion coefficient throughout a significant portion of the temperature range leads to a negative value underscoring the material's significance. The carbon-rich polytype of titanium carbide (TiC3) is being proposed for the first time as an anode material for calcium-ion batteries (CIB). The adsorption of Ca2+ ions has been determined to be favorable, with high accommodation of guest atoms and sufficiently rapid ionic mobility. The total volume expansion for a maximum Ca2+ adsorbed TiC3 configuration is calculated to be 8.2 %, which is lower compared to other anode materials for CIBs. Through the calciation of TiC3 up to the highest Ca2+ concentration (Ca7TiC3), an exceptionally high theoretical capacity of 2236 mAh/g has been achieved. Regarding battery rate capability, the lowest diffusion barrier calculated is 0.13 eV, with a remarkably high diffusion coefficient along the corresponding pathway equal to 10-3 cm2/s, indicating the ease of Ca ion movement within the host material. Furthermore, the equilibrium distance (2.5 & Aring;) between our host and guest atoms indicates a robust interaction between them. These findings lay the groundwork for the development of high-performance anode materials for CIBs.