Seed-Mediated Synthesis of Au Nanocages and Their Electrocatalytic Activity towards Glucose Oxidation

We report a modified seed-mediated approach for the synthesis of uniform Au nanocages (AuNCs). HAuCl4 was reduced in an aqueous mixture of hexamethylenetetramine (HMT), poly(N-vinyl-2-pyrrolidone) (PVP), and AgNO3. The nanocages were (54.6 +/- 13.3) nm in outer-edge length and about 12 nm in wall thickness. The structure of the AuNCs was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, and X-ray photoelectron spectroscopy (XPS). Morphological changes associated with the seed-mediated growth of Au nanoparticles (AuNPs) in the absence of HMT or PVP were examined. The results demonstrate that both PVP and HMT play important roles in the formation of the nanocage structure. The function of AgNO3 was also studied. A possible formation mechanism for the AuNCs was investigated by monitoring TEM images of the Au nanostructures formed at various reaction times. The electrocatalytic activity of the AuNCs towards the oxidation of glucose was explored, and a nonenzymatic glucose sensor with high sensitivity and good stability was further fabricated. To the best of our knowledge, this is the first report of the preparation of AuNCs by a seed-mediated strategy and of the application of AuNCs in the electrocatalytic oxidation of glucose. Our results should facilitate the creation of novel nanomaterials with various morphologies and the exploration of their applications in nanotechnological, optical, catalytic, and materials science fields.