Title: 2D Monolayer Molybdenum (IV) Telluride TMD: An Efficient Electrocatalyst for Hydrogen Evolution Reaction

Abstract: 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.