Photocatalytic activity and mechanism of cerium dioxide with different morphologies for tetracycline degradation

Cerium dioxide (CeO 2 ) semiconductor has received wide attention in the field of energy and environment due to its excellent oxygen storage capacity and abundant oxygen vacancies (OVs). Previous research demonstrated that the morphology and structure of the crystal had great influence on the physicochemical properties of the material. Herein, CeO 2 nanomaterials with different morphologies were prepared via a facile hydrothermal and template method. Systematic material characterizations suggested that the synthetic CeO 2 has different morphologies with CeO 2 nanorods (NRs), nanocubes (NCs), nanosheets (NSs), hollow spheres (HSs), and mesoporous CeO 2 (m-CeO 2 ), respectively. The visible-light-induced degradation performance of CeO 2 with different morphologies was investigated in aqueous solution using the antibiotic tetracycline (TC) as a model pollutant. The experimental results exhibited that the CeO 2 NRs possessed the best adsorption capacity and photocatalytic activity and more than 89.35% TC could be removed within 90 min. Combined with the XPS characterization results implied that the concentrations of Ce 3+ and OVs on the surface of CeO 2 with different morphologies were discrepancy, and the improved photocatalytic performance of CeO 2 NRs was mainly due to the higher concentration of Ce 3+ and OVs on the catalyst surface. These results confirmed that the regulation of the morphology of CeO 2 could effectively enhance its photocatalytic activity. Furthermore, the results of active species trapping experiments proved that the super oxide anion (•O 2 - ) radical and hole (h + ) played dominant roles in the degradation of TC.