Direct Synthesis of Stable 1T-MoS 2 Doped with Ni Single Atoms for Water Splitting in Alkaline Media.

Metallic MoS 2 (i.e., 1T-MoS 2 ) is considered as the most promising precious-metal-free electrocatalyst with outstanding hydrogen evolution reaction (HER) performance in acidic media comparable to Pt. However, sluggish kinematics of HER in alkaline media and its inability for the oxygen evolution reaction (OER), hamper its development as bifunctional catalysts. The instability of 1T-MoS 2 further impedes its applications for scaling up, calling an urgent need for simple synthesis to produce stable 1T-MoS 2 . In this work, the challenge of 1T-MoS 2 synthesis is first addressed using a direct one-step hydrothermal method by adopting ascorbic acid. 1T-MoS 2 with flower-like morphology is obtained, and transition metals (Ni, Co, Fe) are simultaneously doped into 1T-MoS 2 . Ni-1T-MoS 2 achieves an enhanced bifunctional catalytic activity for both HER and OER in alkaline media, where the key role of Ni doping as single atom is proved to be essential for boosting HER/OER activity. Finally, a Ni-1T-MoS 2 ||Ni-1T-MoS 2 electrolyzer is fabricated, reaching a current density of 10 mA cm -2 at an applied cell voltage of only 1.54 V for overall water splitting.