The kinetics and potential dependence of the hydrogen evolution reaction optimized for the basal-plane Te vacancy site of MoTe2

Electrocatalysis at the edge sites of transition-metal dichalcogenides has been well studied, particularly for the hydrogen evolution reaction (HER). Here, we explore instead the HER activity on the basal plane of MoTe2 by creating anion vacancies via computational predictions followed by experimental validation. Using the grand canonical potential kinetics method, we predict that overpotentials of 535 and 565 mV can achieve a current density of 10 mA cm−2 for 1T′-MoTe2 and 2H-MoTe2 containing 1.14×1014cm−2 and 3.45×1013cm−2 Te vacancies, respectively. This is in good agreement with experimental overpotentials of 561 and 634 mV for 1T′-MoTe2 and 2H-MoTe2 containing similar vacancies (1.28×1014cm−2 and 3.54×1013cm−2, respectively). Furthermore, we used Ar plasma treatment to increase the Te vacancy on the basal plane and found an optimal vacancy concentration of 3.18×1014cm−2 for 1T′-MoTe2 and 1.02×1014cm−2 for 2H-MoTe2. Increasing or decreasing the vacancy concentrations from this level further reduces HER performance.