Defect Engineering on a Ti4O7 Electrode by Ce3+ Doping for the Efficient Electrooxidation of Perfluorooctanesulfonate

Defect engineering in an electrocatalyst, such as doping, has the potential to significantly enhance its catalytic activity and stability. Herein, we report the use of a defect engineering strategy to enhance the electrochemical reactivity of Ti 4 O 7 through Ce 3+ doping (1–3 at. %), resulting in the significantly accelerated interfacial charge transfer and yielding a 37–129% increase in the anodic production of the hydroxyl radical (OH • ). The Ce 3+ -doped Ti 4 O 7 electrodes, [(Ti 1– x Ce x ) 4 O 7 ], also exhibited a more stable electrocatalytic activity than the pristine Ti 4 O 7 electrode so as to facilitate the long-term operation. Furthermore, (Ti 1– x Ce x ) 4 O 7 electrodes were also shown to effectively mineralize perfluorooctanesulfonate (PFOS) in electrooxidation processes in both a trace-concentration river water sample and a simulated preconcentration waste stream sample. A 3 at. % dopant amount of Ce 3+ resulted in a PFOS oxidation rate 2.4× greater than that of the pristine Ti 4 O 7 electrode. X-ray photoelectron spectroscopy results suggest that Ce 3+ doping created surficial oxygen vacancies that may be responsible for the enhanced electrochemical reactivity and stability of the (Ti 1– x Ce x ) 4 O 7 electrodes. Results of this study provide insights into the defect engineering strategy for boosting the electrochemical performance of the Ti 4 O 7 electrode with a robust reactivity and stability.