The growth of pine-leaf-like hierarchical SnO2 nanostructures

Pine-leaf-like SnO2 hierarchical nanostructures (NSs) were grown by a two-step vapour transport deposition process with a combination of vapour–solid and vapour–liquid–solid mechanisms at the primary and secondary processes, respectively. This type of hierarchical structure consisted of SnO2 trunk with homo-branching nanowires (NWs). The branched NWs connected the trunk NWs at included angles of 56° and 90° for two different types of hierarchical NSs. Based on the thermodynamic calculation, the formation of branched NWs at those angles are all energetically favourable.