Synergistic enhanced activation of peroxymonosulfate by heterojunction Co3O4–CuO@CN for removal of oxytetracycline: Performance, mechanism, and stability.

Metal-organic frameworks (MOFs) as precursors for catalysts has drawn growing attentions. In this study, heterojunction Co 3 O 4 –CuO doped carbon materials (noted as Co 3 O 4 –CuO@CN) were prepared by direct carbonization of CuCo-MOF in air. It was found that the Co 3 O 4 –CuO@CN-2 exhibited excellent catalytic activity with the highest Oxytetracycline (OTC) degradation rate of 0.0902 min−1 at 50 mg/L of Co 3 O 4 –CuO@CN-2 dosage, 2.0 mM of PMS and 20 mg/L of OTC, which was 4.25 and 4.96 times that of CuO@CN and Co 3 O 4 @CN, respectively. Furthermore, Co 3 O 4 –CuO@CN-2 was efficient over a wide pH range (pH 1.9–8.4), and possessed good stability and reusability without OTC degradation decrease after five consecutive uses at pH 7.0. In a comprehensive analysis, the rapid regeneration of Cu(II) and Co(II) is responsible for their excellent catalytic performance, and the p-p heterojunction structure formed between Co 3 O 4 and CuO acts as an intermediary of electron transfer to accelerate PMS decomposition. Moreover, it was interesting to find that Cu rather than Co species played a vital role in the PMS activation. The quenching experiments and electron paramagnetic resonance demonstrated that . OH, SO 4 •−, and 1O 2 were the reactive species responsible for oxidation of OTC and the non-radical pathway triggered by 1O 2 was dominant. [Display omitted] • The k obs of Co 3 O 4 –CuO@CN-2 was 4.25 and 4.96 times that of CuO@CN and Co 3 O 4 @CN. • 1O 2 was the dominant species responsible for elimination of OTC. • The heterojunction and fast regeneration of Cu(II) and Co(II) accelerated catalytic activity. • Cu rather than Co species played a vital role in the PMS activation. • The Co 3 O 4 –CuO@CN-2 showed excellent stability and reusability for degradation of OTC. [ABSTRACT FROM AUTHOR]