Peracetic acid catalytic activation using Co3O4 nanocluster decorated graphitic carbon nitride for cefapirin degradation in water

This study innovated cobalt-based catalytic nanocomposites (CCNs) for the heterogeneous activation of peracetic acid (PAA), a green and efficient advanced oxidation process for removing antibiotics from water. Commercial Co 3 O 4 catalysts exhibit limited activity due to stable electronic structures. To overcome this, CCNs were synthesized using a one-step condensation method, incorporating a size control strategy that anchors Co 3 O 4 nanoclusters within 4–5 nm onto six-fold cavity of g-C 3 N 4 , simultaneously modifying the coordination environment of Co. This alteration significantly enhances the adsorption energy of PAA and catalytic activity compared to commercial Co 3 O 4 . The improved performance of CCN2, in particular, is attributed to a shift in the cobalt d band center towards the Fermi level, facilitating electron delocalization and transfer, enhancing Co–O bonding, and accelerating PAA decomposition. CCN2’s superior activity, with a cefapirin (CFP) degradation kinetic rate constant ( k 1 = 0.760 min −1 ) ~11 times that of PAA direct oxidation ( k 1 = 0.070 min −1 ) and ~5 times that of commercial Co 3 O 4 /PAA system ( k 1 = 0.164 min −1 ), is due to its ability to generate dominant reactive species for antibiotic degradation, including alkoxy radicals (CH 3 C(=O)OO•), high valence metal (Co IV (=O) 2+ ), and singlet oxygen ( 1 O 2 ), with the latter two being crucial for the degradation process. The degradation of CFP involved three mechanisms, including direct oxidation by PAA, decarboxylation, and open-ring reactions at nitrogen sites. This research provides insights into developing high-activity catalysts for efficient PAA activation and antibiotic removal, leveraging the strategy of shifting the transition metal d band center.