Recognizing Ti-site coordination geometry in titanium-oxo clusters for enhanced photo-Fenton-like catalysis

Titanium-based materials have emerged as promising candidates for photo-Fenton-like catalysis, whereas their structural complexities impede precise understanding of the relevant structure–activity relationships. Owing to their well-defined and tunable structures, titanium-oxo clusters appear to be facile models for looking into the photophysical and photochemical processes in Ti-H₂O₂ systems. Using PTC-3 as a prototype, we interrogated the relationship between Ti-site coordination environments and photo-Fenton-like behaviors. Through integrated in-situ/ex-situ spectroscopic analyses and theoretical simulations, we elucidated light-driven H₂O₂ activation on hexa-coordinated and penta-coordinated Ti sites in PTC-3. The superiority of penta-coordinated Ti site was identified, where extended visible-light absorption and promoted electron transfer could synergistically boost the activation of H₂O₂ into superoxide radicals. This work brightens the role of Ti-site coordination geometry in photo-Fenton-like processes and paves the way for pursuing titanium-based advanced oxidation.