Defect dynamics in isoelectronically doped MoS₂ for hydrogen production

Molybdenum disulfide (MoS₂) has been widely investigated as prospective electrocatalysts for hydrogen production. MoS₂ edges have almost the same catalytic efficiency as platinum. However, the basal plane is inert. Manipulation with phases, vacancies, edges, and grain boundaries path the way to activate the basal plane. The isoelectronic doping during the chemical vapor deposition (CVD) of MoS₂ may effectively control these parameters desirably. This abstract describes the isoelectronic (W and Se) doping effect on the MoS₂ monolayer catalytic activity.

The addition of W and Se during the CVD synthesis causes the substitution of Mo and S. The Tafel slopes significantly decrease at low concentrations of W and Se defects (up to 30%), which indicates increasing efficiency of H₂ formation. High concentration of metallic and chalcogen substitution defects differently affects the catalytic efficiency. It is caused by the doping-triggered vacancies formation and phase transition. At lower doping rates, single-atom defects trigger the formation of S vacancies and the transition of the 2H phase into the metastable 1T. At high doping rates, the 1T phase transition is suppressed in W-doped samples, which is not the case for Se-doping. The DFT simulations support the defect-associated TMD’s structure changes and favorable hydrogen reaction on the doped MoS₂. Considering the interactions of cooperative effects path the way to understand the most effective TMD electrocatalyst design.