Low-cost synthesis of a nanocomposite of MoS2 and alkali-activated halloysite nanotubes for photocatalytic RhB degradation

Abstract

In this work, a novel nanocomposite of highly-dispersed MoS₂ nanosheets supported on alkali-activated halloysite nanotubes (a-HNTs) was fabricated via a simple hydrothermal method. The alkali (5 M NaOH herein) could attack the inert outer surface of HNTs and thus abundant surface defects were created, while the crystal structure and tube morphology of HNTs were still preserved. Electron microscopy also evidenced that few MoS₂ sheets could grow on the outer surface of raw HNTs while they were uniformly assembled on both the outer surface and inner lumen of the a-HNTs. The above phenomenon suggested that both the defects at the outer surface and Al–OH at the lumen could serve as nucleation sites for the growth of MoS₂ nanosheets. Furthermore, the as-prepared MoS₂/a-HNT nanocomposite exhibited significantly improved photocatalytic performance for rhodamine B (RhB) degradation, compared with the MoS₂/HNTs and pristine MoS₂ microspheres, and photogenerated holes (h⁺) played a more important role than hydroxyl radicals (˙OH) and superoxide radicals (˙O²⁻) during the photocatalysis, which was confirmed by radical trapping experiments. This work provides a low-cost fabrication of high-performance 2D materials by using modified natural minerals as carriers.