Topology conversion of 1T MoS2 to S-doped 2H-MoTe2 nanosheets with Te vacancies for enhanced electrocatalytic hydrogen evolution

Metastable 1T′ MoTe2 has attracted much attention as a cost-effective electrocatalyst for hydrogen evolution reaction (HER) in recent years. However, few studies were done over common stable 2H phase because it often exhibits inferior performance. Herein, stable 2H MoTe2 with S-doped Te vacancies has been synthesized by one-step telluride conversion of 1T MoS2 at 700°C under Ar/H2 atmosphere. It is demonstrated that the synergistic effect of S-doping and Te vacancies changes the electronic structures of the catalyst. Density functional theory (DFT) studies show that plentiful electrons accumulate on the surface S atoms in S-doped Te vacancies of 2H MoTe2 catalyst, which may be as active sites to promote HER. Moreover, the as-synthesized catalyst can be directly used as working electrode, and realizes current density of 100 mA cm−2 at overpotential of 217 mV with Tafel slope of 94 mV dec−1. This work stimulates intensive studies on the activation of inert phase of other nanocatalysts towards various reactions.