Engineering ultra-low density and fully exposed atomic cobalt sites for antibiotics removal

Single atom site catalysts (SSCs) have exhibited broad potential due to their ability to produce abundant active species for the eradication of contaminants in Fenton-like system. However, it is difficult to realize 100% metal atom utilization and reduce metal leaching to meet environmental safety standards in advanced oxidation processes. Herein, the catalysts with ultralow atomic Co site contents (∼0.17%) are obtained by strong polar force to increase metal atom utilization and reduce the risk of metal leaching during the elimination of antibiotics. As expected, the catalysts with limited Co sites accompanied by abundant defects and numerous open-framework pores distributed from macropores to mesopores and to micropores, achieve the rapid tetracycline degradation (0.07133 min⁻¹) and an excellent normalized rate constant (k_per-site, 2.4726 × 10⁵ min⁻¹ M⁻¹). Both the experimental and theoretical results perform that fully exposed Co sites with abundant C–N defects can increase the electronic density of Co active sites and decrease the peroxydisulfate (PDS) adsorption energy, thereby optimizing Co atom utilization for PDS activation. This study may provide valuable insights into the design of high performance and environmentally safe SSCs for water restoration.