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

Metastable 1T′ MoTe 2 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 MoTe 2 with S-doped Te vacancies has been synthesized by one-step telluride conversion of 1T MoS 2 at 700°C under Ar/H 2 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 MoTe 2 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.