Studies on the preparation and optical properties of ZnO hollow nanosphere/ZnCo2S4 nanoparticle composite photocatalyst

A new binary composite photocatalyst consisting of ZnO hollow nanospheres and ZnCo2S4 nanoparticles was prepared by a two-step method. Carbon nanospheres as templates for the preparation of ZnO hollow nanospheres were synthesized by a hydrothermal method. Using X-ray photoelectron spectroscopy (XPS), ultravioletvisible diffuse reflectance spectroscopy (UVvis DRS) and MottSchottky curve measurements, the regulated band structure of the composite was determined, and then the type-II carrier transfer mechanism in the composite was identified. The effect of the mass ratio of ZnCo2S4 to ZnO on the photocatalytic performance of the composite was investigated. With the increase in the mass ratio of ZnCo2S4 to ZnO, the photocatalytic performance of the composite first increases and then decreases, and the composite sample with a mass ratio of 30% shows the best performance. Furthermore, the introduction of oxygen vacancy (VO) defects into ZnO hollow nanospheres not only improves the photocatalytic performance of the composite but also greatly improves photocorrosion resistance. Therefore, the newly discovered ZnCo2S4/ZnO composite photocatalyst has potential practical applications.