Fig. 1: Materials characterization of Mo-S-Mo/CTF catalysts.

a SEM image of Mo-S-Mo/CTF before H2 reduction treatment. b HR-TEM images of Mo-S-Mo/CTF before H2 reduction treatment. c AC-HAADF-STEM images of Mo-S-Mo/CTF before H2 reduction treatment. d AFM image of Mo-S-Mo/CTF before H2 reduction treatment. e The AFM corresponding height profiles. f HAADF-STEM images of Mo-S-Mo/CTF. g Element mapping images of Mo-S-Mo/CTF. The scale bar is 50 nm. h AC-HAADF-STEM images of Mo-S-Mo/CTF. i Intensity profiles of dual-atom sites in a red frame.