When breaking heterojunctions unlocks a reactive compromise in photomechanocatalytic phenol degradation over P25-TiO2

Abstract

Mechanical activation and photochemical excitation are investigated for the environmental remediation of phenol using P25 TiO₂. Operating under a controlled low liquid-assisted grinding (LAG) regime with sequential H₂O₂ addition, this study demonstrates that mechanical energy effectively drives oxidative degradation in the absence of light. Multiscale characterization reveals that while the bulk crystalline integrity of the anatase and rutile phases is preserved, vibratory milling induces significant structural modifications and optical band gap narrowing. The physical disruption of anatase-rutile heterojunctions generates a defective surface layer that enables dark reactivity, which is further enhanced by simultaneous UV irradiation as the material remains distinctly photoactive. Operating in this state of reactive compromise, the system couples mechanical defect generation with the conservation of photocatalytic efficiency. Finally, green chemistry metrics highlight the significant environmental benefits of this nearly solvent-free photomechanocatalytic approach.