Synergetic piezo-photocatalytic effect in SbSI for highly efficient degradation of methyl orange

Abstract

SbSI nanowires (SbSI NWs) and SbSI microrods (SbSI MRs) were synthesized by simple sonochemical and hydrothermal methods, respectively. The SbSI NWs possess better catalytic performance due to the smaller size and larger specific surface area. Meanwhile, the piezoelectric effect and photocatalytic performance of SbSI were combined for the first time. The degradation rate of methyl orange (MO) solution (30 mg/L) by SbSI NWs reaches 97.1% within 2 min under the synergistic effect of visible light and ultrasonic vibration, which is 4.83 times of photocatalysis and 14.22 times of piezocatalysis. The reactive oxide species (ROS) such as hydroxyl radicals (•OH) and superoxide radicals (•O2−) were examined by radical trapping experiments to demonstrate their critical role in degrading MO molecule. Furthermore, a possible mechanism of the piezo-photocatalytic process was proposed and degradation pathway of MO dyes by SbSI NWs was suggested based on the HPLC-MS results. It shows that the degradation process of MO includes the breakage of azo double bond, the removal of sulfonic group, the breakage of carbon nitrogen bond, and finally the formation of NO3−, SO42−, CO2 and H2O. This work provides a promising case for the practical application in dye wastewater treatment of piezoelectric semiconductors.