Postsynthesis Growth of CoOOH Nanostructure on SrCo_0.6Ti_0.4O_3-δ Perovskite Surface for Enhanced Degradation of Aqueous Organic Contaminants

The deployment of an efficient catalyst is critical for successful application of peroxymonosulfate-based advanced oxidation processes to the rapid degradation of retardant organics in wastewater. Considering the rich properties of perovskite oxides and their drawbacks of low specific area and easy cation leaching, we reported a facile postsynthesis hydrothermal treatment method for preparing SrCo_0.6Ti_0.4O_3-δ@CoOOH (SCT@CoOOH) nanocomposite as an efficient catalyst for PMS activation here. Surprisingly, CoOOH nanosheets were grown in situ over the surface of SCT substrate, resulting in a significantly increased surface area (22.1 m² g^-1), enhanced charge transfer capability, more generated surface oxygen defects and a strongly synergistic effect created between the bulk SCT and CoOOH surface layer. Remarkably, SCT@CoOOH exhibited higher (1.7 times) catalytic activity (0.84 mg L^-1 min^-1) for phenol degradation than SCT. Additionally, suppressed cobalt leaching was demonstrated in the SCT@CoOOH/PMS system. Notably, singlet oxygen as additional oxidative species were formed to accelerate phenol degradation in the radical-based SCT@CoOOH/PMS system due to the surface oxygen defects. The beneficial effect of higher pH value and different influence of foreign anions on the reation rate were also investigated. As a universal method, it may be also useful for the development of innovative functional materials for other various applications.