Additional d electron of heterometal dopant enhances electronic perturbation in 2D MoS2 for efficient hydrogen evolution

Transition metal doping is a well-established strategy to modulate the electronic structure of 2D transition metal dichalcogenide (TMD) for efficient electrocatalysis. Conventionally, the oxidation state of the heterometal doped in 2D TMD is divalent, which limited its electronic perturbation strength towards active sites. Therefore, introducing low-valent heterometal into 2D TMD is proposed to be a feasible strategy to enhance the electronic perturbation through the presence of additional d electrons, leading to novel electrocatalytic activity. As a proof of concept, Co(0) is introduced into MoS₂ (Co(0)-MoS₂) through “intercalation-vulcanization” in this work. Comparing to Co(II) doped MoS₂ (Co(II)-MoS₂), the presence of additional d electrons at Co dopant in Co(0)-MoS₂ facilitated the electronic perturbation between “Co-S-Mo” atoms, which optimizes the electronic structure of the active sites at MoS₂. As results, the H₂O dissociation and H* desorption for electrocatalytic alkaline HER were simultaneously facilitated by Co(0)-MoS₂, leading to HER activity superior to most of MoS₂-based catalyst (overpotential: 28 mV at 10 mA/cm²; Tafel slope: 47 mV/dec).