Dye wastewater treatment enabled by piezo-enhanced photocatalysis of single-component ZnO nanoparticles

Conventionally, composite materials are usually employed as a catalyst in piezo-photocatalytic dye wastewater treatment. Here, we report the synthesis of ZnO nanoparticles, as a single-component catalyst, by surfactant-assisted precipitation in which the size of ZnO nanoparticles (20-100 nm) can be simply controlled by the use of Tween80 as a surfactant. Although, ZnO nanoparticles exhibited appreciable photocatalytic activities for the degradation of methylene blue (MB) dye, upon the addition of a mechanical force, the photocatalytic dye degradation efficiency was substantially improved. Furthermore, we postulated that the surface properties of ZnO play an important role in charge transfer phenomena based on photoluminescence results together with functional groups on the surface of ZnO. In addition, application of single-component ZnO in piezo-promoted photocatalytic degradation of cationic and anionic dyes was accomplished. Our results regarding the behaviour of single-component ZnO nanoparticles under vibrational energy in addition to their conventional solar harvesting can provide a promising strategy for developing photocatalysts for practical wastewater treatment.