Yusuke Ide

He received his Ph.D. from Waseda University in 2007. After working as a research associate there, in 2010, he moved to Hiroshima University to work as an assistant professor. In 2012, he became a senior researcher at NIMS and was promoted to a principal researcher in 2020. Since 2023, he has been a group leader at NIMS as well as a professor at Yokohama National University. His current interests include the development of high- performance, cost-effective, and environmentally friendly materials alternative to existing commodities and industrial products. He also tries to synthesize key materials for realizing a hydrogen society.

Hamza El-Hosainy

He received his Ph.D. in Nanoscience from Kafrelsheikh University, Egypt, through a joint program with NIMS, Japan, in 2021. He has been a postdoctoral researcher at the National Institute for Materials Science (NIMS), Japan, since 2022, and is also a Lecturer at Kafrelsheikh University, Egypt. His current research focuses on the design of atomically dispersed and defect-engineered catalysts, layered nanomaterials, and iron-based functional materials for solar-to-chemical energy conversion, selective organic transformations, environmental remediation, and safer UV-shielding technologies.

Atomically dispersed Cu catalysts on TiO₂ represent a promising non-noble-metal platform for photocatalytic H₂ evolution, but their durability is often limited by structural instability, aggregation, and Cu leaching under irradiation. Here, we show that oxygen-vacancy modulation in TiO₂ can regulate the nuclearity of supported Cu species and promote the formation of Cu–O–Cu dual-atom sites as shwon in Fig. 1. Atomic‑resolution microscopy, X-ray absorption spectroscopy, and first-principles calculations collectively support the emergence of surface Cu–O–Cu motifs at high oxygen-vacancy densities, in which each Cu center is coordinated by approximately four oxygen atoms in a semi-equatorial arrangement. The resulting dual-atom catalyst achieves a near-unity apparent quantum yield at 340 nm and an apparent Cu-normalized turnover frequency of up to 335 h⁻¹, while maintaining robust photocatalytic stability with Cu leaching suppressed by at least fivefold relative to the single-atom counterpart. Calculations further reveal that these oxygen-vacancy-mediated Cu configurations introduce dispersive defect bands and an indirect bandgap, thereby favoring charge separation and efficient interfacial charge transfer. Together, these findings demonstrate that pairing atomically dispersed Cu into vacancy-stabilized Cu–O–Cu motifs creates a more robust catalytic architecture than predominantly isolated Cu sites, thereby establishing metal-nuclearity control as an effective strategy for durable, atom-efficient photocatalysts.