Gas sensing mechanism of sulfur chain-encapsulated single-walled carbon nanotubes

Abstract

Atomic encapsulation inside single-walled carbon nanotubes (SWNT) has drawn notable attention recently due to the unique strength of an extremely confined, stable 1-dimensional structure. However, the charge transport characteristics of these SWNT species, particularly upon specific gas exposure, have not yet been elucidated. Herein, sulfur atoms are encapsulated inside the SWNT, and the electronic properties of sulfur chain-encapsulated SWNT (S@SWNT) are investigated. In addition, the current responses of both pristine and S@SWNT species upon exposure to gas molecules with distinctly opposite natures, oxygen and ammonia, are demonstrated under high vacuum conditions. While the same trends are observed with ammonia purging, oxygen purging induces opposite trends for the two species. Based on the comparison of gas responses between pristine SWNT and S@SWNT, the gas sensing mechanism of S@SWNT is proposed.