Facile synthesis of strontium molybdate coupled g-C3N4 composite for effective tetracycline and dyes degradation under visible light

This work was designed to synthesize SrMoO₄/g-C₃N₄ heterojunction for efficient degradation of tetracycline (TC) hydrochloride via photocatalysis. SrMoO₄/g-C₃N₄ samples were prepared through a grinding and roasting process. The prepared nanocomposite exhibited excellent visible-light-driven photocatalytic activity. The reaction rate of TC photodegradation reaches 0.0171 min^?1, which is 5.9 times higher than that of neat g-C₃N₄. The origin of the high photoactivity of SrMoO₄/g-C₃N₄ was investigated using a variety of characterization techniques including XRD, FT-IR, TG, SEM, TEM, XPS, DRS, Mott-Schottky, PL, PC, and EIS. Result showed that the added SrMoO₄ was closely loaded on the g-C₃N₄ surface, which is conducive to the electron transfer between SrMoO₄ and g-C₃N₄. Mott-Schottky analysis indicated that SrMoO₄ has a lower conduction band (CB) position than g-C₃N₄. As a result, photogenerated electrons in g-C₃N₄ can move to the CB of SrMoO₄ to hinder the recombination of charge carriers, thereby increasing the photocatalytic activity under visible light. The cycling test further suggested that the SrMoO₄/g-C₃N₄ heterojunction has good stability in the photocatalytic degradation of TC. Super oxygen radicals and holes are the main reactive species.