Synthesis of zinc oxide fibers from precursor bis(acetylacetonato)zinc. Tracking the mineralization process and micro- and nano-structural changes

Zinc oxide (ZnO) fiber was prepared from the precursor bis(acetylacetonato)zinc (Zn(acac)₂). Fine polycrystalline Zn(acac)₂ fiber was obtained by the sublimation of Zn(acac)₂ powder. When the Zn(acac)₂ fiber was decomposed with superheated steam, it was converted to ZnO fiber, while maintaining the original shape of the Zn(acac)₂ fiber. At this stage, polycrystalline ZnO, aggregated ZnO single crystal grains, which had diameters of a few nanometers, were present along with relatively large amounts of carbon (C) and hydrogen (H). The ZnO fiber sample produced after crystal grain growth by heat treatment contained almost no C and H, and nearly complete mineralization had been achieved. This ZnO fiber consisted of ZnO microrods, and these microrods consisted of ZnO nanorods. The surface of the ZnO nanorods was covered with scale-like nanosized-single-crystal grains, which had high crystallinity, clean surfaces, and diameters of a few tens of nanometers. The visible-light photocatalytic ability of the ZnO fiber may be strongly related to the nanosized-single-crystal grains located on the surface that have diameters of a few tens of nanometers.