Cu2+ Ion Doping-Induced Self-Assembled ZnO-CuxO Nanostructures for Electrochemical Sensing of Hydrogen Peroxide and p‑Nitrophenol.

The development of functional oxide nanostructures with a controlled size and morphology is crucial for fine-tuning of the properties and their applications in diverse areas. Herein, a simple and facile, template-free synthetic approach has been adopted for the fabrication of hybrid ZnO-Cu_xO nanostructures with a flower-like morphology through a hydrothermal pathway using a polyethylene glycol–water mixture as a reaction medium in a single step. The ZnO-Cu_xO nanoflowers thus obtained were characterized using a variety of spectroscopic and electron microscopic techniques. The formation of flower-like superstructures with diameters in the range of 8–10 μm could be confirmed from the electron microscopic studies. A detailed analysis indicates the critical role of metal counterions as well as the amount of water in the reaction medium during the shape-controlled evolution of the flower-like structures. The nanoflowers could be successfully utilized for the electrochemical detection of p-nitrophenol as well as H₂O₂. The limits of detection for p-nitrophenol and H₂O₂ were calculated to be 15.7 and 7.3 μM, respectively. The excellent detection ability can be attributed to the synergistic effect between ZnO and Cu_xO in the hybrid composite. The template-free synthesis of ZnO-Cu_xO nanostructures might provide a simple method for the development of other mixed oxide nanostructures with application potential in sensing of environmental hazards. [ABSTRACT FROM AUTHOR]