Acoustic Shock Wave-Induced Structural and Surface Modifications in MoS2 for Enhanced Visible-Light Photocatalytic Degradation of Methylene Blue Dye

Abstract Molybdenum disulfide (MoS2), a two-dimensional transition metal dichalcogenide, is a promising photocatalyst for environmental remediation under visible light irradiation. However, it is important to develop simple and chemical-free approaches to tune this material’s photocatalytic performance. In this work, we propose acoustic shock-wave treatment as a post-synthesis strategy for tuning the structural, optical and photocatalytic properties of MoS2. MoS2 samples were subjected to controlled acoustic shock-wave treatment as 100, 200, 300 and 400 shock pulses using a semi-automatic Reddy tube and followed by structural, optical and photocatalytic characterization for shock-untreated and shock-treated MoS2. The photocatalytic activity was estimated by degradation of methylene blue (MB) under visible-light irradiation. The degradation efficiency was enhanced from 85% for the untreated MoS2 to a maximum of 95% after 200 shock pulses, together with an increase in the reaction rate constant. XPS, EIS and BET analyses confirmed additional changes in surface chemical characteristics, charge-transfer behavior and accessible surface area after shock-wave treatment. A slight decrease in photocatalytic efficiency was observed at higher shock loading, suggesting that the degree of shock treatment affects the photocatalytic response. Overall, the results suggest that acoustic shock wave treatment is a good post-synthesis approach for the chemical-free modification of MoS2 and tuning of its photocatalytic activity.