Electrochemically enhanced activation of Co₃O₄/TiO₂ nanotube array anode for persulfate toward high catalytic activity, low energy consumption, and long lifespan performance

Advanced oxidation processes (AOPs) can directly degrade and mineralize organic pollutants (OPs) in water by generating reactive oxygen species with strong oxidizing ability. The development of advanced electrode materials with high catalytic performance, low energy consumption, no secondary pollution, and long lifespan has become a challenge that must be addressed in this field. A heterojunction catalyst loaded with Co₃O₄ on TDNAs (Co₃O₄/RTDNAs) was designed and constructed by a simple and efficient pyrolysis (Co₃O₄/TDNAs) and electrochemical reduction. Co₃O₄ can be uniformly distributed on the inner wall and surface of the TiO₂ nanotubes, enhancing the specific surface area while forming a tight conductive interface with TiO₂. This facilitates rapid transmission of electrons, thereby assisting Co₃O₄ in quickly activating PS to form reactive oxygen species. The Ti³⁺ and Ov generated in Co₃O₄/RTDNAs can significantly improve the electrocatalytic degradation of OPs. Also, the interface formed by Co₃O₄ and RTDNAs will effectively suppress Co²⁺ leakage, thereby reducing the risk of secondary pollution. When the reaction conditions were 1 mM PMS (PDS) and a current density of 5 mA/cm² in the EA-PMS (PDS)/Co₃O₄/RTDNA system, 30 mg/L TC can achieve 83.24 % (81.89 %) removal in 120 min, with very low cobalt ion leaching, while the energy consumption was reduced significantly. Therefore, EA-PS/Co₃O₄/RTDNA system has strong stability and a high potential for treating the OPs in AOPs.