Hollow sphere manganese–ceria solid solution enhances photocatalytic activity in tetracycline degradation

Abstract

As a typical representative of antibiotics, tetracycline is widely used in medicine and aquaculture due to its low cost and strong antibacterial ability. However, it is difficult for humans or animals to metabolize completely, resulting in the aggravation of water pollution in aquatic environments. Therefore, it is urgent to explore advanced photocatalysts for the degradation of antibiotics. In this work, we prepared a spherical manganese dioxide-ceria (MnCeO_x) solid solution by a simple one-step hydrothermal method and evaluated its photocatalytic degradation activity towards tetracycline using a Xe lamp. The study of the structure and optical properties showed that doping of Mn cations into a ceria lattice can introduce defect energy levels to narrow the band gap, which can then increase the number of surface oxygen vacancies, so as to improve the adsorption of tetracycline and promote the separation and transfer of photogenerated electrons and holes. MnCeO_x-10 with the highest oxygen defect showed the best photocatalytic performance (the promising degradation efficiency was 65% in 90 minutes), which was about 2.3 times and 1.3 times higher than those of the original CeO₂ and MnO_x/CeO₂ catalysts, respectively. In addition, the capture experiment verified that ˙O₂⁻ and h⁺ should be the reasons for enhancing the degradation process. This study provides guidance and a practical basis for the development of an efficient rare-earth photocatalyst system.