Controllable selenium vacancy engineering in basal planes of mechanically exfoliated WSe2monolayer nanosheets for efficient electrocatalytic hydrogen evolution

Engineering intrinsic selenium vacancies (Se-vacancies) was achieved in mechanically exfoliated WSe₂ monolayer nanosheets (WSe₂ MLNSs) via an annealing treatment. Our theoretical and experimental results reveal that these Se-vacancies can efficiently activate and optimize the basal planes of the WSe₂ MLNSs. As expected, the optimized catalyst exhibits efficient electrocatalytic hydrogen evolution.