Multi-hollow spherical CeO₂ activates persulfate for heterogeneous degradation of organics

In this work, a multi-hollow spherical CeO₂ material was prepared, which when combined with persulfate (PS) efficiently catalyzed the degradation of basic orange II (BOII) under visible light. In the CeO₂/PS/Vis system, the degradation rate reached 99.70% within 15 min, which suggested very strong photocatalytic activity. The effects of pH and dissolved oxygen were evaluated to provide a basis for subsequent verification of free radicals. Superoxide radicals (O₂^·−), hydroxyl radicals (·OH), and oxidative sulfate radicals (SO₄^·−) generated in the process are conducive to efficient degradation. Afore mentioned radicals were proved by radical scavenging experiments with detection by electron spin-resonance spectroscopy, and the possible degradation pathways are proposed. In addition, after three consecutive degradation cycles, the degradation efficiency of the material was not less than 99%, which proved that the prepared multi-hollow spherical cerium oxide had high stability and recoverability. Graphical abstract: [Figure not available: see fulltext.].