Construction of a novel hierarchical 2D/2D La₂Ce₂O₇/BiOCl heterojunction system for the photocatalytic degradation of sulfanilamide

Sulfonamides are commonly used antibiotics, but their residues in water bodies pose a potential threat to public health. In this study, we fabricated a 2D/2D composite heterojunction by integrating petal-like flake La₂Ce₂O₇ with stacked slice BiOCl through an in-situ self-assembly method using hydrothermal synthesis. The physicochemical properties of the synthesized materials were systematically characterized. The photocatalytic performance of the composite photocatalyst was found to be superior to that of pure La₂Ce₂O₇ and BiOCl, which can be attributed to the synergistic effect of both high carrier separation and mobility, which ultimately leads to the formation of a 2D/2D heterojunction interface contact between La₂Ce₂O₇ and BiOCl. Notably, the construction of type II heterojunction helps electrons and holes to react on different semiconductors and facilitates the separation of electron–hole pairs. And the hydroxyl radicals and superoxide radicals were captured by electron spin resonance and the strong oxidizing nature of the radicals can effectively break the C–X bond, which is more favorable for the conversion degradation of sulfonamides. A possible photodegradation mechanism based on the catalyst of La₂Ce₂O₇/BiOCl was hypothesized, providing a theoretical basis for preparing 2D/2D heterojunctions with a prominent photocatalytic activity.