The development of hydrothermal synthesis has greatly promoted bottom-up nanoscience for the rational growth of diverse zinc oxide (ZnO) nanostructures. In comparison with normal ZnO nanowires, ZnO nanostructures with a larger surface area, for instance,
branched nanowires, are more attractive in the application fields of catalysis, sensing, dye-sensitized solar cells
etc. So far the ZnO
branched nanowires achieved by either one-step or multistep growth always present a
boundary-governed nonepitaxial
branch/stem interface. In this report, seeded growth of single-crystalline ZnO hexa
branched nanostructures was achieved by selecting polyethylene glycol (PEG) as capping agent based on a low-temperature, laterally epitaxial solution growth
strategy. We investigated the generality of this PEG-assisted growth process using different ZnO seed layers including continuous film, patterned dots,
and vertically aligned nanowire arrays. It was revealed that PEG is a distinctive
c-direction inhibitor responsible for the lateral growth
and subsequent
branching of ZnO due to its nonionic
and nonacidic feature
and weak reactivity in the solution system. All the obtained
branched nanostructures are of single crystallinity in nature, which is methodologically determined by the homoepitaxial growth mode. This PEG-assisted process is versatile for diameter tuning
and branch formation of ZnO nanowires by secondary growth. Our proof-of-concept experiments demonstrated that the ZnO hexa
branched nanostructures presented superior photocatalytic efficiency for dye degradation relative to the normal ZnO nanowires.
Keywords:
branching&qsSearchArea=searchText">branching; epitaxial growth; structure-directing agent; ZnO nanowires; photocatalytic degradation