Hierarchical CuO nanoflowers: water-required synthesis and their application in a nonenzymatic glucose biosensor

For the first time, a facile, one-pot water/ethanol solution-phase transformation of Cu2(NO3)(OH)3 precursors into bicomponent CuO hierarchical nanoflowers is demonstrated by a sequential in situ dissolution–precipitation formation mechanism. The first stage produces a precursory crystal (monoclinic Cu2(NO3)(OH)3) that is transformed into monoclinic CuO nanoflowers during the following stage. Water is a required reactant, and the morphology-controlled growth of CuO nanostructures can be readily achieved by adjusting the volume ratio between water and ethanol. Such a bicomponent CuO hierarchical nanoflower serving as a promising electrode material for a nonenzymatic glucose biosensor shows higher sensitivity and excellent selectivity. The findings reveal that the different CuxMy(OH)z (M = acidic radical) precursors synthesized in a water/ethanol reaction environment can be utilized to obtain new forms of CuO nanomaterials, and this unique water-dependent precursor-transformation method may be used to effectively control the growth of other metal oxide nanostructures.