Encapsulate Co3O4 within ultrathin graphene sheets to enhance peroxymonosulfate activation by tuning surface electronic structures

Heterojunctions composed of cobalt-based materials and carbon materials have been recognized as the efficient catalysts for peroxymonosulfate (PMS) activation to generate reactive oxygen species for the removal of environmental contaminants . However, the role of carbon materials in promoting the heterojunction systems has not been fully understood. This study synthesized a heterojunction material of graphene sheets encapsulating Co 3 O 4 (GCO-500) through the pyrolysis of cobalt MOF and applied it to activate PMS for the removal of lomefloxacin . The results showed a high removal rate of 93.59 % with a degradation rate of k 1  = 0.0156 min −1 . Co 3 O 4 clusters was encapsulated within ultrathin graphene sheets (<2 nm). DFT calculations revealed that graphene layers improve the electron transfer ability of Co 3 O 4 and increased the d -band center of Co 3 O 4 (−1.61 eV) that promote the adsorption of PMS on GCO-500 (−1.32 eV). In the meanwhile, organic pollutant was enriched in graphene layers with high adsorption energy (−13.08 eV), which greatly enhanced the degradation efficiency of pharmaceuticals. This study provides an effective catalyst for PMS activation and sheds light on the fundamental electronic-level understanding of cobalt-based and carbon heterojunction catalysts in PMS activation.