Peroxymonosulfate activation for the efficient removal of organic pollutant by ZIF-67-derived low-crystalline CuCoOx with abundant oxygen vacancies

In this study, low-crystalline CuCoO_x with abundant oxygen vacancies (O_v) were prepared by hydrothermal-calcination method using ZIF-67 as the precursor. Abundant O_v in the catalyst enhanced the activation of PMS for bisphenol A (BPA) degradation. The optimum catalyst Cu₁Co₁O_x-2 completely removed BPA with a high rate constant of 0.544 min⁻¹, and it remained high activity in a wide pH range of 3–11. EPR analysis, electrochemical tests and quenching experiments revealed that the Cu₁Co₁O_x-2/PMS system degraded BPA via radical (SO₄^•−, •OH, O₂^•−), and non-radical (¹O₂, electron trasfer) pathways, with O₂^•− playing a predominant role. The synergistic effect between O_v and the bimetal synergy in the catalysts is the key for enhancing PMS activation. DFT analysis confirmed that the surface O_v of Cu₁Co₁O_x-2 enhanced the chemisorption of PMS on neighboring cobalt ions and facilitated the cleavage of the O-O bond of PMS. In addition, O_v enhanced the interfacial charge transfer to PMS, hence boosting PMS activation with a lower energy barrier. This method is useful for eliminating refractory organic pollutants in water.