  An electrocatalyst is needed to efficiently lower the reaction barriers to
produce hydrogen through the H2 evolution reaction (HER). Recently,
two-dimensional transition metal dichalcogenides (2D TMDs), such as the pure 2D
monolayer MoTe2 TMD, have become attractive materials for HER. Using the first
principle-based hybrid DFT-D method, we have computationally designed a pure 2D
monolayer MoTe2 TMD and examined its structural and electronic properties and
electrocatalytic efficacy towards HER. A non-periodic finite molecular cluster
model Mo10Te21 system was employed to explore the feasibility of both the
Volmer-Heyrovsky and Volmer-Tafel reaction mechanisms for the HER. The
solvent-phase calculations of the HER on the 2D monolayer MoTe2 TMD demonstrate
that this material can effectively undergo either Volmer-Heyrovsky or
Volmer-Tafel reaction pathways. This conclusion is supported by our
determination of low reaction barriers for the H*-migration, Heyrovsky, and
Tafel transition states (TSs), which were found to be approximately 9.80,
12.55, and 5.29 kcal.mol-1, respectively. These results highlight the potential
utility of MoTe2 TMD as a promising electrocatalyst for HER. The unusual
electrocatalytic activity of the pure 2D monolayer MoTe2 TMD is evidenced by
its ability to significantly reduce reaction barriers, achieving impressive
turnover frequency during the Heyrovsky and Tafel reaction steps, respectively.
Additionally, it demonstrates a remarkably low Tafel slope of 29.58 mV.dec-1.
Further exploration of its potential applications in electrocatalysis is
warranted. The present work provides valuable insights into the atomic
modulation of active sites for enhanced electrocatalytic performance towards
HER, paving a way for designing advanced non-noble metal free electrocatalysts.
