Design of One-Dimensional Cadmium Sulfide/Polydopamine Heteronanotube Photocatalysts for Ultrafast Degradation of Antibiotics

Abstract

The removal of antibiotics in environmental water is of significant importance due to their severe threats to human health and the ecosystem balance but remains as a major challenge. Visible-light photocatalytic degradation provides a desirable way to dispose of antibiotics by natural solar energy. Herein, cadmium sulfide-doped polydopamine (CdS/PDA) heteronanotubes (HNTs) featuring superior photocatalytic capability for ultrafast antibiotic degradation under visible light (14.2 times higher than traditional CdS) was developed via an in situ coordination polymerization strategy. The exceptional catalytic ability was attributed to multiple-level synergistic effects between PDA and CdS. PDA nanotubes (NTs) served as a scaffold for in situ growth of CdS nanocrystals, and the resulting CdS/PDA heterostructures exhibited strong visible-light-harvesting capability and a high transfer rate of photogenerated electron–hole pairs. Furthermore, the photocatalytic mechanism of the CdS/PDA HNTs toward model molecule tetracycline is disclosed in detail, and it is shown that superoxide radical anions (•O2–) and photogenerated holes (h+) play the key roles in the decomposition of tetracycline. Our findings demonstrate that the incorporation of PDA NTs as the scaffold is a feasible strategy to enhance the visible-light sensitivity of photocatalysts used in aqueous antibiotic degradation. This work provides new insights into the development of new functional nanocomposite catalysts with important engineering and environmental applications.