Formation and Properties of Selenium Double-Helices inside Double-Wall Carbon Nanotubes: Experiment and Theory

TL;DR

This study demonstrates the synthesis and characterization of novel selenium double-helix structures inside double-wall carbon nanotubes, revealing unique properties and potential for new selenium chemistry.

Contribution

It presents the first experimental and theoretical evidence of covalently bonded selenium double-helices inside nanotubes, a new structural phase of selenium.

Findings

Selenium double-helices are formed inside nanotubes.

The structure differs from bulk selenium.

Electronic properties are significantly altered.

Abstract

We report the production of covalently bonded selenium double-helices within the narrow cavity inside double-wall carbon nanotubes. The double-helix structure, characterized by high-resolution transmission electron microscopy and X-ray diffraction, is completely different from the bulk atomic arrangement and may be considered a new structural phase of Se. Supporting ab initio calculations indicate that the observed encapsulated Se double-helices are radially compressed and have formed from free Se atoms or short chains contained inside carbon nanotubes. The calculated electronic structure of Se double-helices is very different from the bulk system, indicating the possibility to develop a new branch of Se chemistry.