“…In recent years, transition metal chalcogenides (TMCs) have emerged as promising candidates for the electrocatalytic hydrogen evolution reaction (HER) due to their unique electronic and structural properties such as higher abundance, easy synthesis routes, and low hydrogen binding energy. , Several monometallic TMCs such as MoS 2 , FeSe 2 , NiSe 2 , CoSe 2 , VS 2 , FeS 2 , WTe 2 , and MoTe 2 have been studied by researchers in detail for hydrogen evolution. − Among them, the two-dimensional (2D) MoS 2 with a layered structure exhibits unique surface effects, optimum hydrogen adsorption–desorption capability, and numerous structural engineering possibilities, which greatly improve their HER performance. , The properties of MoS 2 depend on its phases, namely, bulk 2H phase or layered 1T phase. Although the 2H-MoS 2 phase is known for its stability, the low electrical conductivity due to the inactive semiconducting basal plane hinders its development as a commercial electrocatalyst, whereas 1T-MoS 2 exhibits metallic conductivity, with both basal surface and edge atoms being catalytically active .…”