Electrochemical Growth of ZnO Nanobelt-Like Structures at 0 °C: Synthesis, Characterization, and in-Situ Glucose Oxidase Embedment

Single-crystalline ZnO nanobelt-like structures (NBS) of length, width, and thickness in the ranges of 5–10 μm, 50–400 nm, and 20–100 nm, respectively, are synthesized by a one-step, template-free electrochemical deposition technique at 0 °C. Scanning electron microscopy and transmission electron microscopy (TEM) reveal a unique morphology of the as-synthesized NBS, with an oval-shaped cross section. High-resolution TEM and selected area electron diffraction studies further confirm that individual NBS are single-crystalline, with a growth direction of [101̅0], while the X-ray diffraction data indicate its characteristic wurtzite structure. The successful formation of ZnO NBS at 0 °C using this simple, aqueous-solution-based, bottom-up approach is further exploited to fabricate a bionanocomposite. In particular, incorporation of a biomolecule, i.e., glucose oxidase (GOx) into the ZnO NBS in situ during electrodeposition is found to be highly effective in enhancing the activity and stability. The resulting GOx-embedded ZnO NBS are found to exhibit not only a higher enzymatic activity but also remarkable stability when compared to GOx surface-immobilized ZnO NBS. The present direct biomolecular embedment approach promises a new strategy for incorporating other compatible biomolecules in situ at low temperature while preserving their bioactivity.