Polysulfide-Induced Synthesis of Coral-Like MoS₂/NiS₂ Nanostructures for Overall Water Splitting

The development of multifunctional electrocatalysts with rich resources, excellent performance, and stability is necessary for water splitting to achieve sustainable hydrogen and oxygen production. Herein, we report the preparation of a bifunctional coral-like nanostructured electrocatalyst (p-MoS 2 /NiS 2 ) by in situ vulcanization of polymeric sulfur with a MoO 3 /Ni as the precursor. It is exciting that the whole preparation process of the electrocatalyst can be completed in a few hours. The as-fabricated multimetallic sulfide not only exhibits well-defined heterointerfaces and the defect-rich two-dimensional (2D) nanoconfiguration with high conductivity to overcome the poor hydrogen evolution reaction (HER) activity, but also promotes the formation of the 1T phase. The obtained p-MoS 2 /NiS 2 nanostructures exhibit low overpotentials of −115 mV at −10 mA cm –2 and 337 mV at 100 mA cm –2 toward the HER and oxygen evolution reaction (OER), respectively, which surpass most of the previously reported bimetallic sulfide-based electrocatalysts. Benefiting from the stability of the hierarchical heterostructure and the coupling effect between the inner layer of NiS 2 and outer layers of MoS 2, the p-MoS 2 /NiS 2 catalyst is endowed with high activity for water splitting. It can be used as a bifunctional electrocatalyst for water splitting with a cell voltage of 1.51 V at a current density of 10 mA cm –2 . Overall, this work proposes a simple in situ vulcanization method to synthesize MoS 2, which expands the interlayer spacing and realizes the coexistence of a metastable structure and metal doping.