Synthesis of Highly Crystalline Flakes of 3R‐MoS2 and 3R‐WS2 and Their Electrocatalytic and Photocatalytic Hydrogen Evolution Reactivity

In the present study, we are able to synthesize flakes of the 3R‐polytypes of MoS 2 and WS 2 from sodium molybdate and sodium tungstate in the presence of H 2 S gas by solid‐state reaction. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, X‐ray photoelectron spectroscopy (XPS), and X‐ray diffraction are utilized to characterize the morphology, structure, and chemical composition of the 3R‐MoS 2 and 3R‐WS 2 flakes. The electrocatalytic and photocatalytic activities of 3R‐MoS 2 and 3R‐WS 2 flakes have been measured in hydrogen evolution reactions.