Sonocatalytic Activity of 1T/2H MoS 2 Nanoflower for Ultrafast Dye Removal: Influence of Visible Light

2D MoS 2, a wonder material, has emerged as a highly efficient catalyst owing to its unique morphology, band structure, and reduced size. Here, hierarchical MoS 2 nanoflowers with exposed petals and abundant edges are hydrothermally synthesized and evaluated for sonocatalytic dye removal. The polymorphic few-layer MoS 2 nanosheets comprising metallic 1T (45%) and semiconducting 2H (55%) phases exhibit dual functionality in adsorption and piezocatalysis toward ultrafast dye removal when subjected to mechanical strain. Under ultrasonic irradiation, the 1T/2H MoS 2 sonocatalyst removes 99.6% of RhB dye within 9 min, which is five times faster than the adsorption process. Other dyes, such as MB and RB, are also very rapidly removed within a few seconds by the MoS 2 sonocatalyst. On application of ultrasound vibration, a built-in piezoelectric field is developed across the few-layer 1T/2H MoS 2 nanosheet which drives the separation and migration of charge carriers promoting redox reactions for dye degradation. The low dimensionality, high fraction edge sites, wider bandgap (1.55 eV), and abundant sulfur vacancies of 1T/2H MoS 2 collectively enhance the piezocatalyst property of the material. The photo-sonocatalytic study of the material exhibits a slower removal reaction process when the material is subjected to simultaneous ultrasound and visible light irradiation. This photo-assisted retardation phenomenon can be attributed to the depletion of piezoelectric polarization by the photo-generated carriers. Hence, this work explores the remarkable catalytic properties of the few-layer 1T/2H MoS 2 nanosheet for efficient mechanical-energy-driven pollutant removal under ultrasound and visible light irradiation.