Formation of crystalline iron-mono-selenide in the restricted one-dimensional space of single-walled carbon nanotubes promoted with H2 annealing

Abstract The large spin–orbit interaction for transition metal elements and their composites with chalcogen atoms is of great interest in materials science, and painstaking efforts are being made to realize two-dimensional (2D) transition metal dichalcogenide (TMDC) layered materials. The discovery of the unique electronic properties of atomically thin 2D TMDC confirmed the foundation of 2D condensed matter physics and chemistry, and these properties have been explored in their 1D counterparts. The difficulty in the synthesis of isolated 1D transition metal chalcogenide (TMC) is due to the van der Waals (vdW) interaction, which leads to the material being 2D or 3D. Isolation of 1D vdW nanomaterial thus remains challenging. In this paper, we report a simple and reliable way to form transition metal mono-chalcogenide (TMMC) FeSe nanomaterials using single-walled carbon nanotubes (SWCNTs) as a template. Transmission electron microscopy reveals well-crystallized 1D FeSe nanomaterials in SWCNTs. X-ray photoelectron spectroscopy and Raman scattering spectroscopy clarify the interaction between FeSe nanomaterial and SWCNTs, explainable by electron charge transfer from inside FeSe nanomaterial to outside SWCNTs. Insights obtained in this study might reveal unprecedented features for low-dimensional materials, which could inspire the interface design between TMC nanomaterials and carbon nanotubes in high-end applications.