Synthesis of Bismuth Niobate Nanoparticles Rich in Oxygen Vacancies and Efficient Degradation of Tetracycline Hydrochloride

With the increasing energy crisis and environmental pollution problems, the development of solar-powered photocatalytic technologies for green and efficient removal of emerging pollutants from aquatic ecosystems has become an urgent need. Bismuth niobate (Bi₃NbO₇), as a bismuth-based photocatalyst, has attracted much attention due to its unique electronic structure and optical properties. However, Bi₃NbO₇ synthesized by the traditional hydrothermal method suffers from the problems of large size, limited active sites, and harsh preparation conditions, which severely limit its photocatalytic performance. In this study, small-sized Bi₃NbO₇ nanoparticles (BNO-Ov-3) enriched with oxygen vacancies were successfully synthesized by a one-step solvothermal method using ethylene glycol as the solvent and structure-directing agent. Glycol not only inhibited the grain growth and reduced the size from micrometers to nanometers, but also promoted the formation of oxygen vacancies through its reducing property. Compared with Bi₃NbO₇ synthesized by the conventional hydrothermal method, BNO-Ov-3 enhanced the degradation rate of tetracycline hydrochloride (TC) from 49.8% to 92.1% under visible light irradiation. The mechanism of the performance enhancement was revealed by XPS, EPR, and PL characterization: the synergistic effect of nanosize and oxygen vacancies effectively inhibited the photogenerated carrier complexation and promoted charge separation and transfer. This study provides a strategy for the controlled synthesis of bismuth niobate and lays a theoretical foundation for its application in photocatalysis.