Fig. 1. Schematic of Mo and S vacancies in bilayer MoS₂ defined by (vacancy, layer, number of vacancies) (a) Mo vacancies in the upper layer; (Mo,1,4), (b) Mo vacancies in two layers; (Mo–Mo,1–2,4–4), (c) S vacancies in the upper layer; (S,1,8) and (d) S vacancies in two layers; (S–S,1–2,4–4).