Insights of Diffusion Doping in Formation of Dual-Layered Material and Doped Heterostructure SnS–Sn:Sb₂S₃ for Sodium Ion Storage

Abstract

Insights into the formation mechanism of a dual-layered and doped heterostructure material Sn^IIS-Sn^IV:Sb₂S₃ are reported. In the presence of mixed alkyl thiols, first nanotubes of Sb₂S₃ were formed, and upon introduction of Sn(IV), Sn^IIS was deposited onto the surface of these tubular structures. Upon further annealing at a constant temperature, sluggish transformation resulted in a Sn(II)S-Sn(IV) doped Sb₂S₃ heterostructure, which finally turned to flake-like layered doped Sb₂S₃ nanostructures. SnS and Sb₂S₃, both being layered materials, were explored for the study of Na-ion storage, and these heterostructures were observed to be superior in comparison to the individual materials as well as the final doped nanostructures. The mechanism of formation of the heterostructures, the epitaxy at the junction, the diffusion doping, and the dopant-induced axial exfoliations leading to the final doped structures were studied. The electrochemical conversions in the presence of Na ions were also investigated, and insights into the mechanisms of both are reported in this Letter.