Figure 2

Schematic presentations of (a) La₂O₂SO₄ and (b) La₂O₂S crystal structure. (c) Illustration of process of heat treatment of hydrothermal precursor to synthesis La₂O₂S and La₂O₂SO₄. XRD patterns of (d) La₂O₂SO₄ and (e) La₂O₂S calcined at different temperatures for 2 h in the atmosphere of air and CS₂/CO, respectively.