Phase-Guided Assembly of RuO2 Epitaxial Films on TiO2 Nanofibers: Interfacial Coherence Outperforming Defect-Driven Mismatch for Active Site Generation in Li–O2 Batteries

초록

Controlling the catalyst-support interface is essential for achieving high efficiency with reduced noble metal usage. In this work, a phase-tunable TiO2 nanofiber scaffold is developed via electrospinning and thermal annealing to regulate the interfacial growth of rationally loaded RuO2. The phase of TiO2 (anatase versus rutile) strongly influences lattice matching, oxygen vacancy formation, and RuO2 nucleation. Structural and chemical analyses (scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and electrochemical surface area measurement) confirm distinct RuO2 morphologies and catalytic site accessibility depending on the TiO2 crystal phase. Notably, rutile-based composites form conformal RuO2 domains with enhanced contact and defect-assisted conductivity. Electrochemical testing reveals that rutile-RuO2 cathodes achieve lower overpotentials (≤0.94 V) and higher cycling stability compared to the anatase counterparts. Furthermore, post-cycling transmission electron microscopy analysis indicates that the phase-engineered interfaces facilitate more reversible Li2O2 decomposition. These findings highlight the strong interplay between the oxide phase, interfacial bonding, and catalytic behavior. This work provides a scalable and efficient strategy to extract maximum performance from minimal RuO2 loading in Li-O2 batteries. © 2025 Wiley-VCH GmbH.

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