https://scholar.dgist.ac.kr/handle/20.500.11750/249 Fri, 24 Apr 2026 15:29:49 GMT 2026-04-24T15:29:49Z https://scholar.dgist.ac.kr/handle/20.500.11750/60230 Title: Next-Generation Quantum Dot Engineering for Photoelectrochemical Hydrogen Production: Insights From Artificial Intelligence-Assisted Approaches Author(s): Lee, Hyo Cheol; In, Su-Il Abstract: The transition to sustainable energy requires efficient technologies for solar-driven hydrogen production. Quantum dots (QDs), with size-tunable bandgaps and favorable interfacial properties, significantly enhance photoelectrochemical (PEC) water splitting by enabling broad-spectrum light harvesting, optimized band alignment, and improved charge separation. However, QD design strategies for PEC systems remain less developed compared to those for light-emitting diodes and solar cells, constrained by incomplete understanding of interfacial photophysics, limited exploration of low-dimensional nanocrystals (1D/2D), and the absence of AI-assisted optimization. This review provides a comprehensive overview of material design strategies for QDs in PEC hydrogen production, encompassing fundamental principles, established approaches, and recent advances in both heavy-metal-based and nontoxic systems. Particular attention is given to emerging paradigms such as dimensional control and AI-driven optimization, which enable predictive modeling, accelerated synthesis, and performance tuning beyond conventional trial-and-error methods. Finally, we address critical challenges—including stability, toxicity, and scalability—and outline future directions for achieving efficient, sustainable QD-based PEC systems suitable for practical and economically viable commercialization. Wed, 31 Dec 2025 15:00:00 GMT https://scholar.dgist.ac.kr/handle/20.500.11750/60230 2025-12-31T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/59989 Title: Hydrogen Evolution via Oxygen Tolerant [NiFe]-Hydrogenase Immobilized on TiO2 Nanotubes Author(s): Kim, Hwapyong; Kim, Ki Nam; Lee, Sang-Hyeon; Nam, Chang-Hoon; Lee, Young-Sam; In, Su-Il Abstract: [FeFe]-hydrogenase has been of great interest due to its high enzymatic activity for hydrogen evolution reactions (HERs). However, the big challenge of [FeFe]-hydrogenase is a significant performance degradation in aerobic conditions. On the other hand, [NiFe]-hydrogenase of E. coli has an oxygen tolerant property. Therefore, using [NiFe]-hydrogenase is an effective solution to avoid performance degradation in aerobic conditions. Herein, we extracted [NiFe]-hydrogenases from E. coli and immobilized them on the TiO2 nanotube (TNT) electrode prepared by pyrrole-based electropolymerization for application in aerobic conditions. As a result, we can confirm that [NiFe]-hydrogenases coated TNT electrode demonstrates the increased HER activity underaerobic condition than control samples in in-vitro activity test using methylene viologen and linear sweep voltammetry. Wed, 31 Dec 2025 15:00:00 GMT https://scholar.dgist.ac.kr/handle/20.500.11750/59989 2025-12-31T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/59988 Title: Defect-Driven Dynamics in Gas-Phase Photocatalytic CO2 Conversion to Solar Fuels Using Ti3+/Ti4+ Containing TiO2 and Nonstoichiometric Ag2S Nanowires Author(s): Powar, Niket S.; Kwon, Soonho; Hiragond, Chaitanya B.; Lee, Junho; Gong, Eunhee; Kim, Hong Soo; Kim, Dongyun; Goddard, William A.; In, Su-Il Abstract: We studied CO2 photoreduction on nonstoichiometric surface photocatalysts using a comprehensive approach combining materials design, advanced spectroscopy, and Quantum Mechanics (QM) calculations. We developed a direct Z-scheme heterostructure, A-TiO2/Ag2S NWs, composed of amorphous TiO2 and nonstoichiometric Ag2S nanowires. This structure promotes defect-rich characteristics and a strong internal electric field (IEF), enhancing charge separation and minimizing electron-hole recombination. Employing in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and QM-simulated IR spectra revealed the CO2-to-CH4 conversion mechanism which involves H2COH* intermediate. Ti3+/Ti4+ and Ag+ defect environments were precisely characterized through X-ray photoelectron spectroscopy (XPS) and in situ extended X-ray absorption fine structure (EXAFS). Under concentrated solar illumination, this heterostructure achieved a CH4 production rate of 30.31 mu mol/g, a 5-fold enhancement over conventional 1-sun conditions. These findings provide valuable insights into solar-driven fuel synthesis through targeted defect engineering and strategic heterostructure design. Fri, 31 Oct 2025 15:00:00 GMT https://scholar.dgist.ac.kr/handle/20.500.11750/59988 2025-10-31T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/59985 Title: Photoelectrochemical Hydrogen Production Using TiO2/Mn-CdS Photoanode with ZnS Passivation and CoPi as Hole Transfer Relay Author(s): Kim, Hwapyong; Hiragond, Chaitanya B.; Koo, Sung Wook; Lee, Orim; In, Su-Il Abstract: To improve photoelectrochemical water splitting efficiency, it is crucial to simultaneously enhance light absorption, surface stability, and interfacial charge transfer. This work reports the rational design and fabrication of a multi-functional TiO2/Mn-CdS/ZnS/CoPi photoanode that integrates these critical aspects. TiO2 acts as a robust and conductive mesoporous film that absorbs UV light, while Mn-doped CdS broadens the absorption spectrum into the visible region owing to its narrower bandgap and suitable band alignment. To address the photocorrosion typically associated with CdS, a ZnS passivation is applied, offering chemical stability without impeding charge flow. Finally, cobalt phosphate is introduced as a surface catalyst to accelerate the oxygen evolution reaction, enhancing interfacial hole transfer and reducing the overpotential. This hierarchical architecture promotes synergistic interaction between each component, enabling efficient charge separation and transport. As a result, the TiO2/Mn-CdS/ZnS/CoPi photoanode achieves an enhanced photocurrent density under illumination. These results highlight the effectiveness of integrating light-harvesting, protective, and catalytic components to achieve high-performance and stable operation in PEC water splitting. https://scholar.dgist.ac.kr/handle/20.500.11750/59985