Construction of S-scheme heterojunction WO3/Bi2O4 with significantly enhanced visible-light-driven activity for degradation of tetracycline

Recently, S-scheme heterojunctions have drawn much attention due to their unique interface charge transfer pathway and resultantly excellent photocatalytic performance. Herein, a novel 2D/1D S-scheme heterojunction photocatalyst was constructed by loading WO3 nanosheets on the surface of rod-shaped Bi2O4. The S-scheme charge transfer mechanism between WO3 and Bi2O4 was affirmed by the results of the Fermi level and in situ irradiated X-ray photoelectron spectroscopy (XPS). The construction of the S-scheme heterostructure significantly accelerated the separation and migration of the photoinduced electrons and holes in WO3/Bi2O4 and preserved the photogenerated holes and electrons with high redox capability in the valence band of WO3 and the conduction band of Bi2O4. Compared to the pristine WO3 and Bi2O4, the heterojunction WO3/Bi2O4 exhibits significantly boosted activity for the degradation of tetracycline (TC) under visible-light irradiation. The photodegradation efficiency of TC is up to 90 %. The degradation rate constant (0.0587 min−1) for WO3/Bi2O4 toward TC is 2.21 and 28.34 times those for Bi2O4 and WO3. The improved activity of WO3/Bi2O4 is attributed to S-scheme interfacial charges migration pathway, unique 2D/1D heterostructure and exceptional visible light absorption ability. Additionally, WO3/Bi2O4 shows good photochemical stability and acid-alkali suitability. The common inorganic ions and humus (fulvic acid) in natural water have little influence on the photodegradation of TC. This work brings a new idea for constructing heterojunction photocatalysts with high activity for boosted TC photodegradation.