Microwave-assisted synthesis of 3D Bi2MoO6 microspheres with oxygen vacancies for enhanced visible-light photocatalytic activity

Oxygen vacancies (OVs) defects in metal oxide-based photocatalysts play a crucial role in improving the charge carrier separation efficiencies to enhance the photocatalytic performances. In this work, OVs were introduced in 3D Bi2MoO6 microspheres through a facile and fast microwave-assisted method via the modulation of tetramethylethylenediamine (TMEDA). EPR, Raman and XPS results demonstrated that large amounts of oxygen vacancies were formed on the surface of BMO microspheres. The photocatalytic properties of the samples were studied by degradation of tetracycline (TC) under visible light. The optimal Bi2MoO6 with OVs exhibited optimum photocatalytic activity, and the degradation rate was 7.0 times higher than that of pristine Bi2MoO6. This enhancement can be attributed to the 3D structure furnishing more surface active sites and suitable OVs defects favoring the electron-hole separation. Moreover, the defective Bi2MoO6 microspheres exhibit high stability because the photocatalytic activity remains almost unchanged after 5 cycles, making them favorable for practical applications. Finally, a possible visible light photocatalysis mechanism for the degradation of TC was tentatively proposed.