Effectively enhanced piezocatalytic activity in flower-like 2H-MoS2 with tunable S vacancy towards organic pollutant degradation

Piezocatalysis technology is emerging as a promising strategy for removing organic pollutants from water by harvesting mechanical energy from the surrounding environment. Herein, 2H-MoS 2 flower-like nanosheets with tunable S vacancies was synthesized via a hydrothermal method by adjusting pH of the precursor solution, Mo and S molar ratio, reaction time and temperature. The results showed that the presence of S vacancy leads to significantly enhanced piezoelectric response in the MoS 2 nanosheets, as confirmed by both theoretical calculation using first-principle based density functional theory and probe force microscopy (PFM) measurements. As a result, the as-obtained MoS 2 nanoflower piezocatalyst exhibited excellent degradation efficiency for Orange Ⅱ solution (removal rate > 95 % in 1 h) under ultrasonic vibration (40 kHz and 110 W). Importantly, we demonstrated for the first time that the piezocatalytic performance was tightly related with the water level in ultrasonic cleaner. The present work not only reports a simple and effective strategy for improving the piezocatalytic degradation activity of MoS 2 by introducing vacancy, but also provides new insights and deeper understanding on the underlying mechanism.