Activation of peroxymonosulfate by CoP@Co2P heterostructures via radical and non-radical pathways for antibiotics degradation

In recent years, peroxymonosulfate (PMS)-based advanced oxidation process have been raised widely attention due to the efficient the degradation of antibiotics. However, the low efficiency in PMS activation is still a challenge for practical application. Designing the catalysts which can activate PMS towards hybrid of radical and non-radical pathways may be a promising approach. Herein, CoP@Co2P heterostructure catalyst has been constructed by a convenient calcination method. Characterizations and theoretical calculations confirm the electron transfer process between CoP and Co2P interface, which forms the electron-deficient Co2P and electron-rich CoP. Thus, Co2P oxidizes PMS to produce 1O2, and CoP reduces PMS to produce SO4 center dot-, which mediates both the radical and the non-radical reaction for tetracycline (TC) degradation. Besides, the TC degradation efficiency by CoP@Co2P-3/PMS system was 4.53 and 5.37 times than CoP/PMS and Co2P/PMS system, respectively, and the mineralization rate of TC reached 84.7% after 60 min. CoP@Co2P-3/PMS system still displayed outstanding catalytic performances with the coexistence of anions in natural water, indicating the excellent stability of the catalysts. Besides, three possible degradation pathways of TC were proposed and CoP@Co2P/PMS oxidation system was very efficient at detoxifying TC.