Synthesis of Air‐stable 1T Phase of Molybdenum Disulfide for Efficient Electrocatalytic Hydrogen Evolution

Abstract Phase engineering of MoS 2 from the thermodynamically stable 2H phase to the metastable 1T phase has been demonstrated as an effective way to enhance the electrocatalytic activity for hydrogen evolution reaction (HER). However, the development of highly stable and efficient 1T‐MoS 2 ‐based electrocatalysts toward HER still remains a great challenge. Herein, a facile hydrothermal strategy was introduced for the preparation of stable 1T‐MoS 2 via a reduced graphene oxide (RGO)‐assisted process. The optimal catalyst of MoS 2 /RGO can keep highly stable in air over 90 days without significant activity fading due to Mo−O interactions, which effectively prevent the transformation of 1T phase back to 2H. The catalyst affords superior HER catalytic activity with a low overpotential of 213 mV versus reversible hydrogen electrode (RHE) at a current density of −10 mA cm −2 , a small Tafel slope of 43 mV dec −1 , a high exchange current density of 0.83 mA cm −2 , and excellent durability, which outperforms its corresponding 2H counterpart. The enhanced electrocatalytic activity of the optimal MoS 2 /RGO sample is associated with the RGO, which can not only facilitate charge transfer along MoS 2 nanosheets but also stabilize the 1T‐MoS 2 with a high exposure of active sites for HER. This work paves a new pathway for designing highly efficient MoS 2 ‐based electrocatalysts through phase engineering.