Fig. 10: Proposed HER and dissolution pathways.

Graphical representation of the hydrogen evolution mechanism for a-MoS_3-x (top) and c-MoS₂ (bottom) driven by the Mo³⁺ hydride formation as proposed by Tran et al. and Bau et al. (refs. ^32,39., green arrows), along with the proposed cathodic dissolution pathways for Mo and S (red arrows). For clarity purposes the electrochemical loss of apical sulphur in a-MoS_3-x is omitted (1-proton, 1-electron transfer process), which takes place in either a previous step or coupled to terminal sulphur loss (2-proton, 2-electron transfer process). Mo, S, O and H atoms are shown in blue, yellow, red and white, respectively.