Bismuth molybdate photocatalyst for the efficient photocatalytic degradation of tetracycline in water under visible-light irradiation

Based on a solvothermal method using Bi2MoO6 (BMO) as the raw material, a novel BiOCl BMO photocatalyst with a flower-like spherical structure was synthesized. The photocatalytic activity of this catalyst was evaluated using a Xe lamp (λ ≥ 420 nm) to simulate sunlight. The crystal structure, morphology, and photochemical characteristics of the BiOCl–BMO photocatalyst were characterized by X-ray diffractometry, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, UV-vis spectroscopy, Raman spectroscopy, photoluminescence measurements, and electrochemical impedance spectroscopy. Under visible-light irradiation, 50 mg BiOCl–BMO with a BiOCl/BMO mass rate of 0.06 degraded 97.23% of a tetracycline (TC) hydrochloride solution (50 mL, 10 mg/L) within 100 min, with a mineralization rate of 81.22%. Free-radical capture experiment revealed that the •OH, •O2−, h+, and e− species (and in particular •OH and •O2−) promoted TC degradation. Furthermore, the active free radicals and TC photodegradation intermediates were identified, and the mechanism and degradation pathways of TC photodegradation by the heterojunction structures were proposed. This study describes an efficient catalyst for the removal of TC from water and introduces a new approach that could be applied in the design of other Bi-based photocatalysts with excellent photocatalytic properties. At the same time, the developed system is of great significance for the efficient removal of TC from aqueous environments.