Fabrication and Characterization of the Porous Ti₄O₇ Reactive Electrochemical Membrane

Preparation of the Magnéli Ti₄O₇ reactive electrochemical membrane (REM) with high purity is of great significance for its application in electrochemical advanced oxidation processes (EAOPs) for wastewater treatment. In this study, the Ti₄O₇ REM with high purity was synthesized by mechanical pressing of TiO₂ powders followed by thermal reduction to Ti₄O₇ using the Ti powder as the reducing reagent, where the TiO₂ monolith and Ti powder were separated from each other with the distance of about 5 cm in the vacuum furnace. When the temperature was elevated to 1333 K, the Magnéli phase Ti₄O₇ REM with the Ti₄O₇ content of 98.5% was obtained after thermal reduction for 4 h. Noticeably, the surface and interior of the obtained REM bulk sample has a homogeneous Ti₄O₇ content. Doping carbon black (0wt%-15wt%) could increase the porosity of the Ti₄O₇ REM (38-59%). Accordingly, the internal resistance of the electrode and electrolyte and the charge-transfer impedance increased slightly with the increasing carbon black content. The optimum electroactive surface area (1.1 m²) was obtained at a carbon black content of 5wt%, which increased by 1.3-fold in comparison with that without carbon black. The as-prepared Ti₄O₇ REMs show high oxygen evolution potential, approximately 2.7 V/SHE, indicating their appreciable electrocatalytic activity toward the production of •OH.