Polar solvent induced in-situ self-assembly and oxygen vacancies on Bi2MoO6 for enhanced photocatalytic degradation of tetracycline

It has been proved to be an effective route to efficiently ameliorate photocatalytic performance of catalysts via designing three-dimensional (3D) hierarchical nanostructures and constructing oxygen vacancies (VOs). However, controlling the self-assembly of organization into 3D hierarchical nanostructures while introducing VOs in photocatalysts remains a challenge. Herein, we reported an ethylene glycol (EG) mediated approach to craft 3D hydrangea-structure Bi2MoO6 with VOs for efficient photocatalytic degradation of tetracycline. Through manipulating the EG concentration during the fabrication process, the influence of EG concentration on the Bi2MoO6 structure was systematically investigated. EG could promote the self-assembly of Bi2MoO6 nanosheets to form a 3D hierarchical structure. Compared with 2D nanoplates, 3D hierarchical architecture enhanced the surface area and the amount of active sites of Bi2MoO6. In addition, the reduction effect of EG on metallic oxide enabled the generation of VOs in Bi2MoO6. The VOs adjusted the electronic structure of Bi2MoO6, which not only enhanced the light harvesting, but also facilitated the simultaneous utilization of photo-induced electrons and holes to form reactive oxygen species (O-center dot(2-) and (OH)-O-center dot) for the efficient tetracycline decomposition. 3D Bi2MoO6 hydrangea with VOs achieved a 79.4% removal efficiency of tetracycline after 75 min. This work provides a simple yet robust EG-mediated strategy, which not only promotes the self-assembly of nano-catalysts into 3D hierarchical architectures, but also crafts tunable VOs for highly efficient photocatalysis.