High-efficiency periodate activation by CeO₂ under solar light via coordination environment modulation: Synergy...

Cerium oxide (CeO₂) is a rare earth metal oxide that shows potential for wastewater treatment in sunlight-mediated periodate (PI) activation, although its application of CeO₂ is restricted by limited active sites and light absorption. In this work, facet engineering and heterometallic atom substitution were used to manipulate the coordination environment of CeO₂ to boost its catalytic activity. Cu species-modified CeO₂ with dominant exposed {100}, {110}, and {111} facets were prepared, respectively. The modification of facets by Cu species improved the degradation efficiency of CeO₂ for antibiotic wastewater, and the degradation efficiency was Cu-{110} (99.28 %) > Cu-{100} (95.80 %) > Cu-{111} (89.24 %). In the sunlight-mediated PI activation, Cu-{110} exhibits a wide pH adaptability range for pollutant degradation, excellent anti-inhibition to anions and water matrices, and long-term catalytic stability. The biological toxicity of TC wastewater treated with Cu-{110} was completely removed and deeply purified. Characterization and theoretical calculations revealed that the facet engineering and Cu species modification coupling strategy regulated the coordination environment of the CeO₂ surface, induced the adsorption and complexation of PI in the low-coordinated state ≡Ce(III) atoms adjacent to oxygen defects, and thus accelerated the generation of radicals ^•OH, IO₄^•- and non-radical ¹O₂, as well as the electron transfer process. Besides, the regulation of the coordination environment expanded the absorption range of CeO₂ for sunlight and elevated the separation of photogenerated carriers, achieving continuous regeneration of active sites. This work develops an efficient catalyst for sunlight-mediated PI activation and provides new insights into modulation of the coordination environment of metal oxide catalysts to boost their activity in wastewater purification.