Structure of Restacked and Pillared WS2: An X-ray Absorption Study

Abstract

Exfoliated and restacked tungsten disulfide were characterized by X-ray absorption at the sulfur K edge and tungsten L3 edge. The local organization around W atoms was probed by EXAFS, by applying a nonGaussian distance distribution model in order to take into account the high disorder in the structure. On the basis of previous structural determinations performed by electron microdiffraction and pair-distribution functions deduced from neutron diffraction, a structural model was tested by comparing the theoretical expected EXAFS signal deduced from this model to the experimental signal. All results converge to prove that upon exfoliation and restacking the WS2 structure evolves toward a clusterization that gives zigzag chains. Moreover, the local shift of the W atoms is in tandem with a periodic shift of the S atoms along the stacking axis, which causes the layer to deviate from full planarity. Further pillaring with various metal clusters does not affect this structural evolution.