Performance of Magn'eli phase Ti4O7 and Ti3+self-doped TiO2 as oxygen vacancy-rich titanium oxide anodes: Comparison in terms of treatment efficiency, anodic degradative pathways, and long-term stability

This study compared hydrogen annealing and cathodic polarization (producing Magne & PRIME;li phases and Ti3+ self-doped TiO2, respectively) as strategies to fabricate electrically conducting titanium oxides through oxygen non-stoichiometry creation for anodic water treatment. Electrochemical characterization techniques suggested that Ti4O7 best-suited for redox electrocatalysis among the Magne & PRIME;li phases exhibited higher electrical conduc-tivity than the self-doped TiO2. This aligned with the superiority of Ti4O7 over the self-doped TiO2 in chlorine evolution and anodic organic oxidation. Hydroxyl radical primarily contributed to anodic oxidation by two conductive titanium oxides at sulfate-based electrolyte, based on the retarding effects of radical scavengers, multi-activity assessment, electron paramagnetic resonance spectral features, and product distribution. Repeti-tive batch experiments and long-term tests in continuous operation mode demonstrated that self-doped TiO2 underwent more drastic performance reduction than Ti4O7. This accorded with the self-doped TiO2 being more vulnerable to activity loss, chemical alteration, and structural damage during prolonged application.

Automated summary

This study compared hydrogen annealing and cathodic polarization as strategies to fabricate electrically conducting titanium oxides through oxygen non-stoichiometry creation for anodic water treatment. Ti4O7 exhibited higher electrical conductivity and superior performance in chlorine evolution and anodic organic oxidation. Hydroxyl radical primarily contributed to anodic oxidation, and self-doped TiO2 underwent more drastic performance reduction and vulnerability to activity loss and structural damage.