Matrix phase induced boosting photoactive performance of ZnO nanowire turf-coated Bi2O3 plate composites

Abstract

A new nanocomposite consisting of ZnO nanowire turf-coated Bi2O3 plates was synthesized using a method combining a chemical bath and hydrothermal crystal growth through sputtering ZnO seed layer-assisted growth. Structural analysis revealed that highly crystalline, high-density, one-dimensional (1D) ZnO crystals were uniformly coated on the organized two-dimensional (2D) Bi2O3 plates with a single beta phase or dual alpha/beta polymorphic phases. The Bi2O3-ZnO composites exhibited enhanced absorption properties in the ultraviolet and visible regions compared with pristine Bi2O3 and ZnO. Furthermore, the Bi2O3-ZnO composites exhibited higher photoactive performance than that of the pristine Bi2O3 and ZnO because of the low recombination rate of photoinduced electron-hole pairs caused by the vectorial transfer of electrons and holes between ZnO and Bi2O3 and the substantially increased surface area of the unique composite morphology. The ZnO nanowire turf-coated Bi2O3 plates with a alpha/beta-Bi2O3 matrix exhibited photoelectrochemical and photocatalytic properties superior to those of the composite with a single beta-Bi2O3 matrix. The coexistence of alpha/beta homojunction in the Bi2O3 matrix and the abundant heterojunctions between the ZnO nanowires and Bi2O3 plates substantially enhanced photoexcited charge separation efficiency. Growing high-density 1D ZnO on 2D Bi2O3 via a combination methodology and crystallographic phase control provided a promising material design route for nanocomposite systems with high photoactivity for photoexcited device applications.