Ultrathin Bi2S3 Nanowires: Surface and Core Structure at the Cluster-Nanocrystal Transition

Herein, we present the structural characterization of the core and surface of colloidally stable ultrathin bismuth sulfide (Bi2S3) nanowires using X-ray Absorption Spectroscopy (EXAFS and XANES), X-ray Photoelectron Spectroscopy (XPS), and Nuclear Magnetic Resonance (NMR). These three techniques allowed the conclusive structural characterization of the inorganic core as well as the coordination chemistry of the surface ligands of these structures, despite the absence of significant translational periodicity dictated by their ultrathin diameter (1.6 nm) and their polycrystallinity. The atomic structure of the inorganic core is analogous to bulk bismuthinite, but Bi atoms display a remarkably higher coordination number than in the bulk. This can be only explained by a model in which each bismuth atom at the surface (or in close proximity to it) is bound to at least one ligand at any time.