Facile fabrication of BiOI/Bi2WO6 Z-scheme heterojunction composites with a three-dimensional structure for efficient degradation of pollutants

Three-dimensional BiOI/Bi2WO6 Z-scheme photocatalysts were synthesized by one-step hydrothermal method. Detailed characterization via SEM and TEM revealed that these photocatalysts exhibit a unique three-dimensional flower-like structure, composed of two-dimensional sheets. The results of photocatalysis mechanism analysis demonstrated that the BiOI/Bi2WO6 heterojunctions have formed a Z-scheme charge transfer mechanism. Specifically, electrons transfer from the Bi2WO6 conduction band to the BiOI valence band, facilitating both enhanced separation of photogenerated charges and the preservation of the strong reducibility of BiOI conduction band electrons and the strong oxidation of Bi2WO6 valence band holes. This dual effect leads to increased generation of free radicals and a consequent improvement in photocatalytic property. Remarkably, when the molar ratio of BiOI/Bi2WO6 is set at 40%, the first-order reaction rate constant reaches 0.089 min-1, which is nearly 5.9 times that of pure Bi2WO6.