Controlled facile synthesis, growth mechanism, and exothermic properties of large-area Co 3O 4 nanowalls and nanowires on silicon substrates

Co ₃O ₄ nanowalls and nanowires have been synthesized onto silicon substrates by low-temperature thermal oxidation of sputtered Co thin films in static air. The synthesis method is very simple and suitable for large-scale fabrication. The effects of the thermal oxidation temperature and duration on the size, amount, and length of the nanowires and nanowalls are systematically investigated both by scanning electron microscopy characterization and differential scanning calorimetry thermal analysis. It is found that the Co/CoO oxidation and Co ₃O ₄ decomposition are important factors contributing to the growth of the Co ₃O ₄ nanowalls and nanowires. The mechanical adhesion between the Co ₃O ₄ nanowalls/nanowires/film and the silicon substrate is observed to be very strong, which is beneficial for many practical applications. Based on the experimental observations, the detailed growth mechanisms of the nanowalls and nanowires are presented. Finally, the promising novel exothermic reaction properties of the Co ₃O ₄ nanowalls and nanowires with Al are investigated by thermal analysis. © 2012 American Institute of Physics.