https://scholar.dgist.ac.kr/handle/20.500.11750/249 2026-10-27T14:19:40Z 2026-10-27T14:19:40Z Kim, Kiwook Kim, Hwapyong Ha, Seung Beom Chung, Wookjin Lee, Hyo Cheol Park, Soo Ik Kim, Minseo Li, Shi Lee, Kyunghoon Lee, Gyudong Lee, Orim Ji, Seunghyun Ma, Hyeonjong Lim, Sung Jun Choi, Hongsoo Ko, Seo-Jin Kim, In Young Kim, Jae-Yup In, Su-Il Yang, Jiwoong https://scholar.dgist.ac.kr/handle/20.500.11750/60988 2026-10-20T03:10:13Z 2026-08-31T15:00:00Z

Title: Composition-driven anion vacancy control in I–III–VI CuIn(S1−xSex)2 quantum dots for efficient photoelectrochemical hydrogen production Author(s): Kim, Kiwook; Kim, Hwapyong; Ha, Seung Beom; Chung, Wookjin; Lee, Hyo Cheol; Park, Soo Ik; Kim, Minseo; Li, Shi; Lee, Kyunghoon; Lee, Gyudong; Lee, Orim; Ji, Seunghyun; Ma, Hyeonjong; Lim, Sung Jun; Choi, Hongsoo; Ko, Seo-Jin; Kim, In Young; Kim, Jae-Yup; In, Su-Il; Yang, Jiwoong Abstract: Heavy-metal-free I–III–VI quantum dots (QDs) are promising candidates for solar energy conversion owing to their strong light absorption, broadly tunable bandgap spanning the full solar spectrum, and environmentally benign composition. However, precise control over their composition and defect states remains challenging due to their complex multinary synthesis chemistry, which critically governs their optoelectronic properties. Here, we demonstrate composition-driven control of anion vacancies in p -type CuIn(S1− x Se x )2 QDs and elucidate their impact on photoelectrochemical (PEC) hydrogen production. Systematic variation of the chalcogenide S/Se ratio enables modulation of anion vacancy concentrations without altering QD size or Cu/In stoichiometry. Notably, CuIn(S0.5Se0.5)2 QDs exhibit the lowest density of anion vacancies, attributed to enhanced anion coordination and reduced lattice distortion. These structural improvements result in increased hole concentration and extended carrier lifetimes. As a result, when integrated into TiO2-based photoanodes, these QDs deliver a high photocurrent density of 15.1 mA cm−2 at 0.6 VRHE for PEC hydrogen generation, exceeding the performance of most previously reported heavy-metal-free QD-based systems. This work provides fundamental mechanistic insights into the role of anion vacancies in I–III–VI QDs and offers a promising strategy for advancing their PEC performance. © 2025 The Authors.

2026-08-31T15:00:00Z Hwang, Yunju Choi, Hansaem Lee, Seungeun In, Su-Il https://scholar.dgist.ac.kr/handle/20.500.11750/60958 2026-10-23T07:40:12Z 2026-07-31T15:00:00Z

Title: Titanium Architectures for Durable Water Electrolysis: From MXenes and Magnéli Phases to Single-Atom Catalysts Author(s): Hwang, Yunju; Choi, Hansaem; Lee, Seungeun; In, Su-Il Abstract: The urgent transition toward a carbon-neutral energy economy positions water electrolysis as a cornerstone for sustainable “green hydrogen” production. While noble-metal catalysts define current benchmarks, their prohibitive costs and scarcity necessitate the development of robust, Earth-abundant alternatives. This review provides a comprehensive analysis of advanced titanium (Ti)-based architectures—specifically 2D MXenes, Magnéli phase suboxides (TinO2n−1), and single-atom catalysts (SACs)—as transformative platforms for hydrogen and oxygen evolution reactions (HER/OER). We examine the synergistic effects of MXenes, where metallic conductivity and tunable surface terminations (Tx) optimize hydrogen adsorption energetics. Simultaneously, we highlight exceptional electrochemical stability and strong metal–support interactions (SMSI) of Magnéli phases, which effectively circumvent the “universal scaling relationship” bottlenecks in OER. Furthermore, we emphasize the integration of SACs on these Ti-based supports, where engineering the local coordination environment maximizes atom utilization and intrinsically boosts catalytic activity. A strategic emphasis is placed on direct seawater electrolysis, highlighting the “chlorophobic” and self-healing properties of Ti-interfaces that ensure long term durability against chloride corrosion and mineral scaling. By integrating AI-driven discovery and field-scale engineering perspectives, this review provides a strategic roadmap for designing high-performance, non-noble metal-based systems for industrial-scale energy conversion, offering a viable solution to the long-standing stability-activity trade-off in extreme environments.

2026-07-31T15:00:00Z Ali, Shahzad Kim, Dongyun Khalid, Muhammad Zeeshan Gong, Eunhee Lee, Junho Slabon, Adam Yuan, Jiayin Huttula, Marko In, Su-Il https://scholar.dgist.ac.kr/handle/20.500.11750/60619 2026-08-19T02:40:12Z 2026-06-30T15:00:00Z

Title: Activation to Deactivation Dynamics of Cu-Embedded TiO2 for Solar CH4 Generation Author(s): Ali, Shahzad; Kim, Dongyun; Khalid, Muhammad Zeeshan; Gong, Eunhee; Lee, Junho; Slabon, Adam; Yuan, Jiayin; Huttula, Marko; In, Su-Il Abstract: Photocatalytic CO2 reduction is known to accelerate on surfaces with defects such as oxygen vacancies (Vo), undercoordinatedmetal atoms, and hydroxyl groups (OH − ). This is further boosted while these defects, Vo-coupled undercoordinated metal atoms,and proximal OH − , act synergistically. However, it is challenging to make atomic-level patterns of such structural arrangementsand monitor their activation anddeactivation pathways. Herein, we report single-atom hydroxylated-Cu in the vicinity of Ti atomthat triggers Vo generation owing to specific structural arrangements. It finally activates CO 2 by coordinative activation andeventually transforms CO2 to CH 4 through Cu–*CHO intermediate. Alongside the activation, deactivation of photocatalyst alsoproceeds, accompanied by the change in the binding environment of the Cu, generation of the oxidizing hydroxyl radicals, andphotocatalytically inactive carbonaceous species. This work outlines the efficacious role of Cu in CO2 reduction to CH 4 andprovides valuable insights into the activation and deactivation mechanisms.

2026-06-30T15:00:00Z Gong, Eunhee Kim, Hwapyong Hiragond, Chaitanya B. Lee, Jeonghyeon Goddard III, William A. In, Su-Il https://scholar.dgist.ac.kr/handle/20.500.11750/60613 2026-08-14T07:10:12Z 2026-08-31T15:00:00Z

Title: Experimental and Machine Learning-Assisted Discovery of 2D Materials for Hydrogen Evolution: From Fundamentals to Industrial Applications Author(s): Gong, Eunhee; Kim, Hwapyong; Hiragond, Chaitanya B.; Lee, Jeonghyeon; Goddard III, William A.; In, Su-Il Abstract: Water splitting to produce hydrogen is recognized as a green technology with significant potential to replace traditional non-renewable energy sources. Substantial progress has been made in the hydrogen evolution reaction (HER), with two-dimensional (2D) materials for both photocatalytic and electrocatalytic HER due to their unique structural features and favourable properties. Along with experimental materials design, the properties of the 2D materials have been complemented by computational methods such as density functional theory (DFT) over the past decade. However, these computational approaches face limitations in terms of time and cost efficiency. Consequently, data-driven approaches, particularly machine learning (ML), are emerging as powerful tools in materials science for identifying structure-activity relationships by learning from existing experimental and DFT calculation data. This review discusses the progress of 2D materials for hydrogen evolution, encompassing experimental advances, theoretical insights, and ML-assisted discovery. First, the fundamental principles of HER are examined, combining insights from photocatalysis and electrocatalysis. Next, an overview of 2D materials for HER is presented, including key challenges related to kinetics, stability, and scalability. Subsequently, ML strategies for 2D material discovery and screening are explored. Case studies on ML applications for various 2D photocatalysts and electrocatalysts, including graphene, g-C3N4, transition metal chalcogenides, MXenes, etc., are discussed. Finally, factors influencing large-scale applications and challenges associated with integrating materials science and ML approaches for HER are addressed.

2026-08-31T15:00:00Z