Two-dimensional single-crystal periodic macroporous ZnO sheets for extraordinary photocatalytic performance for antibiotics

Abstract

Periodic macropores are extensively utilized in the design of photocatalytic materials owing to their capacity to enhance the availability of active sites, shorten carrier migration distances, and improve mass transfer efficiency. However, their three-dimensional periodic structure, primarily composed of stacked nanoparticles, may not be fully utilized due to pore channel blockage. Additionally, the numerous grain boundaries greatly increase the recombination probability of photogenerated electrons and holes. In comparison with typical three-dimensional periodic macroporous structures two-dimensional single-crystal periodic macropores (2DSPM) not only replicate the benefits associated with periodic macropore structures but also substantially diminish the influence of grain boundaries on migration of photogenerated carriers. In this research, we develop 2D single-crystal periodic macroporous (2DSPM) ZnO sheets aimed at accelerating carrier separation and migration while expanding the specific surface area to achieve high photo-oxidation activity towards antibiotics such as ciprofloxacin, norfloxacin, and tetracycline. The notable mechanisms underlying the notable improvement in the photo-oxidation performance are ascribed to the periodic macroporous sheets that shorten carrier transport distances and provide more surface-active sites, thereby enhancing the mass transfer rate and surface photochemical reaction efficiency. Furthermore, the single-crystal structure facilitates smooth migration of photogenerated carriers. This innovative construction strategy is of great significance for crafting 2D single-crystal periodic macroporous photocatalyst materials.