v_s-NiS₂/NiS Heterostructures Achieving Ultralow Overpotential in Alkaline Hydrogen Evolution

Abstract

The hydrogen evolution reaction (HER) usually has slow kinetics in an alkaline environment because of the lack of binding protons. Herein, we use a simple strategy to prepare NiS 2 /NiS heterostructure (HS) electrocatalysts rich in sulfur vacancies (v s ). The v s -NiS 2 /NiS HSs demonstrate an ultralow overpotential of 44 mV at the current density of 10 mA cm −2 and corresponding Tafel slope of 42 mV dec −1 . The improved activity and accelerated reaction kinetics of v s -NiS 2 /NiS HSs are derived from the dual regulation of morphology engineering and defect engineering, which not only increases the number and exposure of active sites but also optimizes the adsorption of active sites and active species. This work provides a potential non-noble metal candidate for efficient hydrogen evolution in an alkaline environment and a feasible method for constructing a high-performance electrocatalyst.

CoS2-MoS2 Nanoflower Arrays for Efficient Hydrogen Evolution Reaction in the Universal pH Range

“…Transition-metal carbides, , sulfides, − selenides, nitrides, phosphides, − and oxides have been demonstrated as the alternative materials for Pt electrocatalysts. Among them, layered transition-metal chalcogenides, especially MoS 2 , are considered as promising compounds for water splitting due to their good stability, high edge-site activity, and unique layered structure. , However, the active sites of MoS 2 are mainly distributed at the edges and they occupy only a small part in the bulk of MoS 2 , thereby leading to inferior catalytic activity. − In addition, the poor bulk conductivity of MoS 2 also affects its catalytic efficiency. , To remedy these defects, researchers construct reasonable nanostructures and introduce conductive substrates to simultaneously enhance the exposure of edge sites and conductivity. , For example, under acidic conditions, the introduction of Fe 2+ , Co 2+ , or Ni 2+ into the bulk could effectively enhance the activity of unsaturated Mo and S sites in MoS 2 , as reported in previous studies .…”

Synthesis of NiMoO4/NiMo@NiS Nanorods for Efficient Hydrogen Evolution Reactions in Electrocatalysts

“…NiS is another material currently being considered for electrochemical hydrogen production [ 40 ]. NF was selected as the substrate for the study due to its high porosity and electrical conductivity; however, its bare framework structure may result in an uneven dispersion of active species [ 41 , 42 ].…”