Mixed-phase MoTe₂ with exposed edges and rich defects for catalyzing hydrogen evolution reaction with noble-metal-like performance

Exploring low-cost electrocatalysts for the hydrogen evolution reaction (HER) is important in the development of renewable energy storage and conversion technology. Transition metal dichalcogenides, such as MoX₂ (X = S, Se or Te), are a promising class of electrocatalysts for HER. However, MoX₂ shows poorer catalytic performance than the commercially used platinum catalyst. In this study, we prepared MoTe₂ with rich electroactive sites by morphology and defect engineering and investigated its electrocatalytic performance for the HER. The MoTe₂ was grown on the surface of a Mo mesh and comprises the 2H and 1T’ phases of MoTe₂ mixed evenly in the microscale. The morphology of MoTe₂ depends on the cooling rate after its formation on the Mo mesh. A fast cooling process results in volcano-shaped protrusions and a large amount of defects in MoTe₂, which facilitates the electrochemical reaction. The mixed-phase MoTe₂ delivers better performance than does the commercial 5% Pt/C catalyst in an acidic medium, especially at high current densities. Density functional theory calculations reveal that the Gibbs free energy change for H atom adsorption is close to thermoneutral for both, the 2H and 1T’ phases of MoTe₂. Their edges and Te vacancies can serve as active sites for catalyzing HER. This study provides a new strategy for developing inexpensive HER electrocatalysts that function optimally at high current densities.