Abstract
We have demonstrated a simple fabrication of hollow nanoparticles by halide-induced corrosion oxidation with the aid of surfactants. Cuprous oxide Cu 2 O nanoshells can be generated by simply mixing Cu nanoparticles with alkyltrimethylammonium halides at 55°C for 16 min. The hollowing mechanism proposed is that absorption of surfactants onto the Cu surface facilitates the formation of the void interior through an oxidative etching process. Upon extending the reaction up to 4 h. fragmentation, oxidation, and self-assembly were observed and the CuO ellipsoidal structures were formed. The headgroup lengths of the surfactants influenced the degree of CuO ellipsoidal formation, whereby longer surfactants favored the generation of ellipsoids. Optical absorption measured by UV-visible spectroscopy was used to monitor both oxidation courses of Cu→Cu 2 O and Cu 2 O→CuO and to determine the band-gap energies as 2.4 eV for Cu 2 O nanoshells and 1.89 eV for CuO ellipsoids. For the contact-angle measurements, the wettability changed from hydrophilicity (18°) to hydrophobicity (140°) as the Cu 2 O nanoshells shifted to CuO ellipsoids. © 2006 Wiley-VCH Verlag GmbH & Co. KGaA.