Low-Temperature Synthesis of Cuboid Silver Tetrathiotungstate (Ag₂WS₄) as Electrocatalyst for Hydrogen Evolution...

Ternary bimetallic sulfide silver tetrathiotungstate (Ag₂WS₄) was prepared by a simple low-temperature precipitation method. The structure of Ag₂WS₄ was determined using the data from powder X-ray diffraction, which is in space group I4̅2 m (I-phase) with a tetragonal unit cell of a = b = 5.950 71 Å and c = 9.562 65 Å, containing layers of edge-sharing AgS₄ and WS₄ tetrahedra. The Ag₂WS₄ was also used as an electrocatalyst for the hydrogen evolution reaction (HER) in acid electrolyte. The results demonstrated that, attributed to its unique composition, large electrochemical active surface area, and high electric conductivity, the Ag₂WS₄ exhibited superior electrocatalytic activity for HER, in comparison with the ternary counterparts of WS₂ and Ag₂S with a low onset potential and small Tafel slope. The Ag₂WS₄ also presented superior stability and maintained the electrocatalytic activity of HER for at least 24 h in 0.5 M H₂SO₄.