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

Abstract

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.

First-Principles Study of the Degradation of Perfluorooctanesulfonate and Perfluorobutanesulfonate on a Magnéli Phase Ti4O7 Anode

“…One recent study indicated that Ce 3+ doping on a Ti 4 O 7 anode enhanced the electrooxidation of PFOS and attributed it to increased surficial oxygen vacancies. 30 Other possible dopants could be selected among elements such as Co, Pt, Mo, Ta, W, Y, and Zr by the computation strategies and criteria developed in this study. The destruction of PFASs in water, short chain PFAAs in particular, is challenging for the purpose of treatment.…”

“…29 In addition to having all of the properties required for an anode used for water treatment, TSO anodes are relatively facile to fabricate at low costs. 30 Ti 4 O 7 has the highest conductivity (1500 S cm −1 ) among all TSOs, comparable to graphite, and has been studied for EO applications. 31 Recent studies have demonstrated the great performance of Ti 4 O 7 -based EO in degrading a wide variety of organic contaminants, 32 including substituted phenols, 33 tetracycline, 34 trichloroethylene, 35,36 amoxicillin, 37 and chloroform, 36 as well as disinfecting pathogens and viruses.…”

“…Recent studies have indicated the great promise of an alternative anode material for EO applications in water treatment, Magnéli phase titanium suboxides (TSOs) with a general formula of Ti n O 2 n –1 (4 < n < 10) . In addition to having all of the properties required for an anode used for water treatment, TSO anodes are relatively facile to fabricate at low costs . Ti 4 O 7 has the highest conductivity (1500 S cm –1 ) among all TSOs, comparable to graphite, and has been studied for EO applications .…”

Electrochemical technologies for per‐ and polyfluoroalkyl substances mitigation in drinking water and water treatment residuals

“…A cost analysis demonstrated that Ti 4 O 7 electrodes were cheaper to synthesize relative to boron‐doped diamond, at ~$0.36 per m 2 versus ~$7125 per m 2 (Chaplin, 2019). Although Ti 4 O 7 are cheaper to produce than boron‐doped diamond, they are not without limitation; for example, Ti 4 O 7 electrodes are a nascent technology with shorter electrode lifespans than boron‐doped diamond (Huang et al, 2020; Lin et al, 2021; Stirling et al, 2020). Thus, more research on extending electrode lifespan and stability relative to boron‐doped diamond electrodes is essential to facilitate implementation in water treatment applications.…”

Green Synthesis of Mesoporous Sodalite and Graphene Oxide Hybrid Sodalite Using Lithium Silica Fume Waste

“…Reactive oxygen species (ROS, i.e., • OH, O 2 •– , and SO 4 •– ) with one or more unpaired electrons have attracted much attention in various fields, including oil rancidification, food spoilage, and organic degradation. , The high oxidation potential of ROS breaks Si–O–Si bonds (with energy barrier of 4 kcal/mol in aluminosilicate gel) and increases the crystallization rate for zeolite growth at low temperatures. Recently, Yu et al proposed that • OH could accelerate the crystallization process of zeolite by catalyzing the depolymerization of the aluminosilicate gel and reforming the Si, Al–O–Si, and Al bonds .…”