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

Cerium dioxide (CeO2) 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, CeO2 nanomaterials with different morphologies were prepared via a facile hydrothermal and template method. Systematic material characterizations suggested that the synthetic CeO2 has different morphologies with CeO2 nanorods (NRs), nanocubes (NCs), nanosheets (NSs), hollow spheres (HSs), and mesoporous CeO2 (m-CeO2), respectively. The visible-light-induced degradation performance of CeO2 with different morphologies was investigated in aqueous solution using the antibiotic tetracycline (TC) as a model pollutant. The experimental results exhibited that the CeO2NRs 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 Ce3+ and OVs on the surface of CeO2 with different morphologies were discrepancy, and the improved photocatalytic performance of CeO2NRs was mainly due to the higher concentration of Ce3+ and OVs on the catalyst surface. These results confirmed that the regulation of the morphology of CeO2 could effectively enhance its photocatalytic activity. Furthermore, the results of active species trapping experiments proved that the super oxide anion (•O2-) radical and hole (h+) played dominant roles in the degradation of TC.