Janus Layers in the TiSe2–TiS2 System

Our experimental results indicate the formation of extended ordered S–Ti–Se layers (Janus layers) in the Ti­(Se1–x S x )2 system. The presence of these layers is observed as a folding of the typical Fermi surface of TiS2 and TiSe2. High-resolution transmission electron microscopy (HRTEM) allows us to observe these layers by a typical rotation of the moiré fringe images. Analysis of the dependence of the electromotive force of the electrochemical cell on the S:Se ratio, angle-resolved photoelectron spectroscopy, resonant photoelectron spectroscopy, Fermi surface mapping, and HRTEM data allows us to conclude that the structure of the solid solution consists of S–Ti–Se and TiCh2 (Ch = S or Se) Janus layers.