Single-crystalline heterostructure of ZnO nanowire arrays on large Ag microplates and its photocatalytic activity

This paper presents experimentally a photocatalytic heterogeneous structure of high-density ZnO nanowire (NW) arrays grown on large Ag microplates. First, the dense single-crystalline ZnO NW fabricated using an economical hydrothermal method possess a great reactive surface area because of their high surface-to-volume ratio. In addition, the large Ag microplates synthesized using a simple and competitive growth method serve as an electron reservoir. The heterojunction between ZnO NW and Ag microplates forms a Schottky contact to separate the electrons from the photogenerated excitons in ZnO NW, prolonging the lifetime of excitons and enhancing their photocatalytic capability. The photodegradation experiment employs the methylene blue aqueous solution to reveal a kinetic rate constant of up to 6.60 × 10−3 min−1 at a low concentration of the ZnO/Ag heterogeneous structure on the ppm scale, and indicates an outstanding figure of merit of 1.02 × 10−2 compared with previously reported ZnO/Ag heterogeneous structures.