Hatted 1T/2H-Phase MoS2 on Ni3 S2 Nanorods for Efficient Overall Water Splitting in Alkaline Media

Abstract

A new hatted 1T/2H-phase MoS₂ on Ni₃ S₂ nanorods, as a bifunctional electrocatalyst for overall water splitting in alkaline media, is prepared through a simple one-pot hydrothermal synthesis. The hat-rod structure is composed mainly of Ni₃ S₂ , with 1T/2H-MoS₂ adhered to the top of the growth. Aqueous ammonia plays an important role in forming the 1T-phase MoS₂ by twisting the 2H-phase transition and expanding the interlayer spacing through the intercalation of NH₃ /NH₄ ⁺ . Owing to the special "hat-like" structure, the electrons conduct easily from Ni foam along Ni₃ S₂ to MoS₂ , and the catalyst particles maintain sufficient contact with the electrolyte, with gaseous molecules produced by water splitting easily removed from the surface of the catalyst. Thus, the electrocatalytic performance is enhanced, with an overpotential of 73 mV, a Tafel slope of 79 mV dec^-1 , and excellent stability, and the OER demonstrates an overpotential of 190 mV and Tafel slope of 166 mV dec^-1 .

Keywords: bifunctional electrocatalysts; electrochemistry; hatted nanorods; hydrothermal synthesis; nanostructures; water splitting.