Efficient degradation of ciprofloxacin by Co3O4/Si nanoarrays heterojunction activated peroxymonosulfate under simulated sunlight: Performance and mechanism

The development of stable and efficient photocatalysts to activate peroxo monosulfate (PMS) is of great significance in water treatment, but it is still a major challenge. In this paper, Co3O4/Si nanoarrays (Co3O4/SiNWs) heterojunction is successfully synthesized through simple and effective approaches, and the peroxymonosulfate (PMS) assisted photocatalytic degradation system based on the Co3O4/SiNWs heterojunction under simulated sunlight is constructed for ciprofloxacin (CIP) degradation. The Co3O4/SiNWs-30/PMS system exhibits a high CIP photocatalytic degradation rate of 93.51% and a kinetic constant of 0.0474 min−1 in 60 min accompanied with good degradation stability. The appropriate energy band structure of Co3O4/SiNWs heterojunction allow the formation of internal electric field, resulting in the establishment of a typical Z-scheme charge transfer system. On the one hand, the formed Co3O4/SiNWs Z-scheme heterojunction can synchronously inhibit the recombination of photo-generated electron-hole (e--h+), which promotes the transfer of photogenerated carriers and improve the photocatalytic activity. On the other hand, photogenerated e- contribute to produce active radicals by activating PMS, and photogenerated h+ can also be directly used as active radicals, thereby realizing high-efficiency photocatalytic degradation. This work gives a good insight into the photocatalytic degradation of antibiotics in water.