Enhancement of Dye Degradation in Piezo-Photocatalytic ZnO–MoS2 Heterostructures

Abstract

Photocatalysis is a novel approach to degrade hazardous compounds, frequently employed in environmental remediation such as eliminating methyl orange (MO) dye from wastewater. However, low efficient usage of visible light due to the large band gap of photocatalysts and its high rate of recombination limit the process. To address this issue, piezophototronics has been utilized to improve the efficacy of catalytic degradation. Specifically for this study, the piezo-photocatalytic efficiency of ZnO–MoS₂ heterostructures has been realized using solar and mechanical energy in degrading MO dye. One-dimensional heterostructures with an average length of 3.34 μm and an average diameter of 872.6 nm compactly aligned on glass substrates were synthesized through a two-step hydrothermal process. Under simulated solar illumination and ultrasonic vibration, the ZnO–MoS₂ effectively degraded MO, improving the degradation efficiency from 55% to 84% by introducing piezopotential in ZnO. Ultrasonication aided the photocatalysis through field-assisted separation of the photogenerated electrons and holes, reducing recombination. Coupled liquid chromatography and mass spectrometry confirmed the degradation of MO into its smaller metabolites. The catalyst films have achieved 61% degradation even after 3 times reuse.