Hatted 1T/2H‐Phase MoS2 on Ni3S2 Nanorods for Efficient Overall Water Splitting in Alkaline Media

A new hatted 1T/2H‐phase MoS2 on Ni3S2 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 Ni3S2, 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 Ni3S2 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. A hatted‐rod MoS2‐Ni3S2@NF heterostructure is a promising electrocatalyst for water splitting. The facile one‐pot hydrothermal synthesis strategy, high electrocatalytic activity, and robust stability for HER and OER are prominent features of this work. The phase transformation and electrocatalytic activity of the hatted nanorod materials can be adjusted by controlling the addition of aqueous ammonia (see scheme).