Cu embedded Co oxides and its fenton-like activity for metronidazole degradation over a wide pH range: Active sites of Cu doped Co3O4 with {1 1 2} exposed facet

• Surface Cu + on {1 1 2}-enclosed Co 3 O 4 has been demonstrated as the main active species. • This Cu + with raised d-band center and accelerated redox process under Co-Cu interaction improved H 2 O 2 dissociation. • A degradation pathway of metronidazole was proposed. Cu-Co bimetallic catalysts show excellent performance for metronidazole (MNZ) degradation in a Fenton-like reaction, a near complete conversion was achieved. Cu doped Co 3 O 4 with {1 1 2} exposed facet has proved to promote the oxidation of Co 2+ to Co 3+ in Cu-CoO x . The surface Cu + on {1 1 2}-enclosed Co 3 O 4 was identified as the main active species for the reaction and its concentration counts a lot in performance. The Cu + with raised d-band center under Co-Cu synergistic interaction has boosted the dissociation of H 2 O 2 into •OH with stronger electron donation to H 2 O 2 and elongated O-O bond. Meanwhile, the accelerated redox process especially for Cu on the {1 1 2} facet of Co 3 O 4 with a faster electron transfer rate also contributed to the excellent performance. The optimization of operational parameters of Co 1 Cu 2 in MNZ removal with investigation of degradation pathway were also thoroughly performed.