Effects of the aspect ratio on the piezocatalytic performance of self-assembled hierarchical MoS2 nanotubes for degradation of sulfamethazine

Abstract

In this manuscript, hierarchical MoS2 nanotubes (NTs) with different aspect ratio (length/diameter) were successfully synthesized via one-step solvothermal method for piezocatalytic applications. SEM indicated that the constructed MoS2 NTs-13 had perfect uniformity while TEM demonstrated the hollow interior. Such hierarchical tubular structures consisting of cross-linked MoS2 single-/few-layered nanosheets featured large specific surface area (85.83 m2g−1) and high porosity. The MoS2 NTs-13 with high aspect ratio exhibited the optimum piezocatalytic performance, achieving 93.26% degradation efficiency for sulfamethazine (SMZ, 20 mg/L) within 10 min, leading to a high first-order rate constant of 0.2486 min−1, which was 2.48 times higher than that of MoS2 NTs-10. Piezoelectrochemical measurements suggested that MoS2 NTs-13 displayed stronger piezoelectric current response and lower charge transfer resistance. The radical trapping experiments and electron spin resonance analysis confirmed that hydroxyl radicals (OH) and superoxide radicals (O2–) were the main reactive oxygen species (ROS) for SMZ degradation. Furthermore, six degradation intermediates of SMZ were identified and two possible degradation pathways were proposed. This work provides design strategies for optimizing structural stability of ultrathin two-dimensional nanomaterials, and offers a highly efficient method for typical antibiotics removal.