Novel magnetic Fe₃O₄/g-C₃N₄/MoO₃ nanocomposites with highly enhanced photocatalytic activities: Visible-light-driven degradation of tetracycline from aqueous environment

by Tianpei He, Yaohui Wu, Chenyang Jiang, Zhifen Chen, Yonghong Wang, Gaoqiang Liu, Zhenggang Xu, Ge Ning, Xiaoyong Chen, Yunlin Zhao

In the present work, a series of magnetically separable Fe₃O₄/g-C₃N₄/MoO₃ nanocomposite catalysts were prepared. The as-prepared catalysts were characterized by XRD, EDX, TEM, FT-IR, UV-Vis DRS, TGA, PL, BET and VSM. The photocatalytic activity of photocatalytic materials was evaluated by catalytic degradation of tetracycline solution under visible light irradiation. Furthermore, the influences of weight percent of MoO₃ and scavengers of the reactive species on the degradation activity were investigated. The results showed that the Fe₃O₄/g-C₃N₄/MoO₃ (30%) nanocomposites exhibited highest removal ability for TC, 94% TC was removed during the treatment. Photocatalytic activity of Fe₃O₄/g-C₃N₄/MoO₃ (30%) was about 6.9, 5, and 19.9-fold higher than those of the MoO₃, g-C₃N₄, and Fe₃O₄/g-C₃N₄ samples, respectively. The excellent photocatalytic performance was mainly attributed to the Z-scheme structure formed between MoO₃ and g-C₃N₄, which enhanced the efficient separation of the electron-hole and sufficient utilization charge carriers for generating active radials. The highly improved activity was also partially beneficial from the increase in adsorption of the photocatalysts in visible range due to the combinaion of Fe₃O₄. Superoxide ions (·O₂⁻) was the primary reactive species for the photocatalytic degradation of TC, as degradation rate were decreased to 6% in solution containing benzoquinone (BQ). Data indicate that the novel Fe₃O₄/g-C₃N₄/MoO₃ was favorable for the degradation of high concentrations of tetracycline in water.