Synthesis of Birnessite Structure Layers at the Solution–Air Interface and the Formation of Microtubules from Them

Abstract

H_<i>x</i>MnO₂·<i>n</i>H₂O layers have been successfully produced through a facile low-temperature process at the solution–air interface without using any templates. The crystalline structures of layers can be tuned by the compositions and the pH of the growth solutions. The analysis of birnessite-like layers indicates that they are formed by nanosheets approximately 4–6 nm thick that are oriented for the most part normally to the interface. Our results demonstrated that 1–3-μm-thick layers can roll up into microtubules 20 to 100 μm in diameter and up to 10 mm long. The hypothesis explaining the formation of the microtubular structures is assumed