MoS₂–Ni₃S₂ Heteronanorods as Efficient and Stable Bifunctional Electrocatalysts for Overall Water Splitting

Exploring noble-metal-free electrocatalysts with high efficiency for both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) holds promise for advancing the production of H₂ fuel through water splitting. Herein, one-pot synthesis was introduced for MoS₂–Ni₃S₂ heteronanorods supported by Ni foam (MoS₂–Ni₃S₂ HNRs/NF), in which the Ni₃S₂ nanorods were hierarchically integrated with MoS₂ nanosheets. The hierarchical MoS₂–Ni₃S₂ heteronanorods allow not only the good exposure of highly active heterointerfaces but also the facilitated charge transport along Ni₃S₂ nanorods anchored on conducting nickel foam, accomplishing the promoted kinetics and activity for HER, OER, and overall water splitting. The optimal MoS₂–Ni₃S₂ HNRs/NF presents low overpotentials (η₁₀) of 98 and 249 mV to reach a current density of 10 mA cm^–2 in 1.0 M KOH for HER and OER, respectively. Assembled as an electrolyzer for overall water splitting, such heteronanorods show a quite low cell voltage of 1.50 V at 10 mA cm^–2 and remarkable stability for more than 48 h, which are among the best values of current noble-metal-free electrocatalysts. This work elucidates a rational design of heterostructures as efficient electrocatalysts, shedding some light on the development of functional materials in energy chemistry.