Spatial Separation Co-catalysts for Efficient Charge Separation: Hollow Pt/CdS/N-ZnO/CoOx Graphene Microtubule with High Stability for Photocatalytic Reaction
Effective separation of charge and high cycle stability are key factors for photocatalysts application. In this paper, the spatially separated Pt/CdS/N-ZnO/CoOx graphene microtubule (PCNZCo-GM) is prepared by capillary action assisted hydrothermal method for enhancing charge separation efficiency and photocatalytic oxidation ability. In the spatial separation composite, Pt as electron collectors and CoOx as hole collectors were selectively decorated on the inner and outer surfaces of CdS/N-ZnO graphene microtubule, which prompts photogenerated electrons and holes near the surface to move in the opposite direction. N-ZnO possesses wider light absorption range, and the construction of Z-scheme heterojunction between CdS and N-ZnO can effectively promote the charge separation. The graphene microtubule structure with an oxidation-reduction co-catalyst supported on its inner and outer surfaces is conducive to charge separation, reusability and mass transfer in photocatalytic process. The PCNZCo-GM composite photocatalyst displays a remarkable photocatalytic oxidation efficiency for methyl orange (MO, 93% removal efficiency in 60 min), and excellent bacterial inactivation rate almost 100% under 60 min illumination. Based on the macroscopic appearance and preferable mechanical strength of 3D graphene microtubule, the PCNZCo-GM composite possesses high cycle stability in photocatalytic process and its excellent photocatalytic performance was well maintained after five applications.