Tubular nanostructures of Cr₂Te₄O₁₁ and Mn₂TeO₆ through room temperature chemical transformations of tellurium nanowires

Abstract

Tubular ternary nanostructures of tellurium were made through chemical transformations of tellurium nanowires (Te NWs). These transformations occur through reactions with CrO₃ and KMnO₄, two of the strongest oxidizing agents. In the case of CrO₃, the 1D structure of the NWs remained intact and the morphology changed to hollow wires of Cr₂Te₄O₁₁, but reaction with KMnO4 resulted in the loss of 1D structure, forming a carbon onion-like object composed of Mn₂TeO₆. As the reaction proceeded, the crystallinity of the NWs decreased, and the final products were amorphous. The reaction products were characterized using different spectroscopic and microscopic techniques. Time-dependent transmission electron microscopic (TEM) analysis of both of the reaction products showed that first a shell is formed around the NWs. Further reaction results in the formation of hollow structures. During the reaction with CrO₃, TEM in the intermediate stages showed that the periphery of the material was amorphous, whereas the inside, where unreacted parts of Te NWs remained, was crystalline with a clear lattice structure. X-ray photoelectron spectroscopy (XPS) as well as Raman spectroscopy showed a redox reaction in both cases. Studies suggest that both redox reactions and nanoscale Kirkendall effect might be involved in the formation mechanism.