Anisotropic monolayer of ReX_(2)on Au foils for exploring abnormal growth behavior and electronic properties

As an emerging class of semiconducting transition metal dichalcogenides(TMDCs),two-dimensional(2D)rhenium dichalcogenides(ReX_(2),X=S or Se)have recently aroused great research interest due to their unique anisotropic structure(1T′phase),and the related novel properties and applications.Recently,many efforts have been devoted to the controllable syntheses of high-quality monolayer or few-layer ReX_(2)flakes/films by chemical vapor deposition(CVD),wherein the metallic Au foil is found to be a unique substrate,due to the relatively strong interfacial coupling between monolayer ReX_(2)and Au.And the conductive nature of Au enables in situ characterizations of the as-grown ReX_(2)samples,which is essential for exploring the fundamental properties and internal growth mechanisms.Hereby,this review focuses on the recent progresses on the CVD syntheses and in situ characterizations of high-quality monolayer ReX_(2)flakes/films and their heterostructures with graphene on Au foils.The effects of Au foils on improving the crystal quality and inducing the growth of monolayer ReX_(2)single crystals are intensively addressed.The crystallinity,domain morphology,atomic and electronic structures,as well as the growth behaviors of monolayer ReX_(2)flakes/films and graphene/ReX_(2)heterostructures on Au revealed by in situ characterization techniques are also highlighted.As contrasts,the growth behaviors of monolayer or few-layer ReX_(2)on insulating substrates are also discussed.Besides,the potential applications of 2D ReX_(2)in new-generation electronic,optoelectronic devices,and energy-related fields are also introduced.Finally,future research directions are also prospected for propelling the practical applications of 2D ReX_(2)materials in more versatile fields.