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

Abstract

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.