A deterministic approach to the thermal synthesis and growth of 1D metal oxide nanostructures

Abstract

The 1D metal oxide nanostructures, including nanowires, are researched for at least two decades. However, the theoretical models on their synthesis and growth mechanisms are still controversial, even for the simplest growth method, namely thermal oxidation of a metallic surface. In this paper, the relevance analysis of the growth conditions reported in the literature is conducted, followed by the developed theoretical model, which was verified by our experiment on copper oxide nanowires. The model quantitatively describes the two most applied hypotheses concerning the single- and bi-crystalline growth of copper oxide nanowires. The numerical simulations reveal the conditions for both obtained mechanisms. It is also established that for the growth of the relatively thick nanowires associated with the single crystals, the internal energy of oxygen molecules determines the mechanism of oxygen adsorption. The energy can be re-distributed at the oxygen attachment, and the molecule can desorb at the account of this energy. Furthermore, the obtained result are also useful for developing the theory on nanowire seed generation, identifying the key control factors and basic mechanisms behind the growth modes, making a step toward a deterministic, highly predictable synthesis of dense 1D copper oxide nanostructures.