Fluid eddy induced piezo-promoted photodegradation of organic dye pollutants in wastewater on ZnO nanorod arrays/3D Ni foam

A novel nanocomposite with ZnO nanorod arrays vertically growing on the three-dimensional (3D) Ni foam has been synthesized under hydrothermal conditions, which displays both the piezoelectric and photocatalytic functions. When the solution is stirred by magnetic rotation, fluid eddies are produced within the unique macroporous structure in 3D network, causing deformation of ZnO nanorod to generate piezoelectric field. Meanwhile, UV light irradiation on ZnO semiconductor generates photoelectrons and holes, followed by starting photocatalytic degradation of organic dye pollutants in wastewater. The piezo-induced bias voltage promotes the separation of photoelectrons and holes and thus can inhibit their recombination, leading to the enhanced quantum efficiency (more than 5 times). The photocatalytic activity increased by increasing the stirring rate owing to the enhanced piezoelectric field.