Co3O4 Nanocubes for Degradation of Oxytetracycline in Wastewater via Peroxymonosulfate Activation

Despite significant progress being made in the developmentof cobaltosicoxide or modified cobaltosic oxide nanomaterials in the degradationof organic pollutants, to our knowledge, there are only very few availablereports on the crystal facet effect of Co3O4 with different morphologies on peroxymonosulfate activation foroxytetracycline degradation. Herein, we first reported the synthesisof three kinds of Co3O4 nanocomposites withvarious morphologies, including nanocubes (Co3O4-c), octahedron (Co3O4-o), and truncated octahedron(Co3O4-t), for activating peroxymonosulfate(PMS) in the degradation of oxytetracycline at 30 & DEG;C. The detailedphysical characterizations illustrated that Co3O4-c, Co3O4-o, and Co3O4-t possessed a uniform morphology of nanocubes, octahedron, and truncatedoctahedron, with six {100} exposing facets, six {111} exposing facets,and a mixture of eight {111} and six {100} exposing facets, respectively.In particular, the optimal Co3O4 nanocubes (Co3O4-c) presented the highest catalytic reactivityin the activation of PMS for OTC degradation, with 82.8% degradationefficiency and 46.4% mineralization rate at 30 & DEG;C. The DFT resultsexhibited that the & UDelta;E (total) of PMSon Co3O4 {100} exposing facets (-23.7eV) was much lower than that of PMS on Co3O4 exposing {111} facets (-17.2 eV), indicating that PMS activationwas more likely to occur at the Co3O4 {100}exposing facets, which was in good accordance with the above experimentalconclusion. Overall, the explanation of the crystal facet effectson PMS activation proposes a research orientation for the synthesisof crystal engineering of heterogeneous catalysts on wastewater treatment.