Fig. 5.

a Schematic illustration of the synthesis of Cu_2-xS-MoX₂ (X = S or Se) epitaxial heterostructure. b TEM image of a Cu_2-xS-MoSe₂ heterostructure. The circles indicate the Cu_1.94S (component i) and Cu₂S (component ii). The red arrows indicate the MoSe₂ (component iii). Inset: HRTEM image of Cu_2-xS-MoSe₂ taken in the square in (b). c HAADF-STEM and d annular bright-field STEM images of a Cu_2-xS-MoSe₂ heterostructure taken at the same area. e Schematic illustration of the crystal structure of Cu_2-xS-MoSe₂ heterostructure. Reproduced with permission from Ref. [117]. Copyright 2017, American Chemical Society