Design of cobalt-based catalysts with the uniformly distributed core-shell structure for ultra-efficient activation of peroxymonosulfate for tetracycline degradation

Catalysts that can rapidly degrade tetracycline (TC) in water without introducing secondary ion pollution have always been challenging. Herein, a cobalt-based catalyst (CoOx@P-C) is prepared so that CoOx quantum particles (5–10 nm) are uniformly distributed on a linear substrate, and the outer layer is covered with a shell (P-C). The quantum particles of CoOx provide many active sites for the reaction, which ensures the efficient degradation effect of the catalyst, and 30 mg/L TC can be completely degraded in only 5 min. The shell of the quantum particles' outer layer can effectively reduce ions' extravasation. The combination of the shell-like structure and the linear substrate greatly enhances the catalysis's stability and ensures that the catalyst is prepared into a film for practical application. The high catalytic activity of CoOx@P-C is mainly due to the following factors: (1) Uniformly distributed ultra-small nanoparticles can provide many active sites. (2) The microenvironment formed by the core-shell structure enhances not only catalytic stability but also provides the driving force to improve the reaction rate. (3) The composite of CoOx and P-C core-shell structure can accelerate electron transfer and generate many reactive oxygen species in a short time, which makes TC degrade extremely rapidly.