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 (V_Os). However, controlling the self-assembly of organization into 3D hierarchical nanostructures while introducing V_Os in photocatalysts remains a challenge. Herein, we reported an ethylene glycol (EG) mediated approach to craft 3D hydrangea-structure Bi₂MoO₆ with V_Os 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 V_Os in Bi₂MoO₆. The V_Os 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 (·O²⁻ and ·OH) for the efficient tetracycline decomposition. 3D Bi₂MoO₆ hydrangea with V_Os 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 V_Os for highly efficient photocatalysis.