MoS2/NiFeS2 heterostructure as a highly efficient electrocatalyst for overall water splitting at high current densities.

Searching for efficient, stable and low-cost nonprecious catalysts for oxygen and hydrogen evolution reactions (OER and HER) is highly desired in overall water splitting (OWS). Herein, presented is a nickel foam (NF)-supported MoS 2 /NiFeS 2 heterostructure, as an efficient electrocatalyst for OER, HER and OWS. The MoS 2 /NiFeS 2 /NF catalyst achieves a 500 mA cm−2 current density at a small overpotential of 303 mV for OER, and 228 mV for HER. Assembled as an electrolyzer for OWS, such a MoS 2 /NiFeS 2 /NF heterostructure catalyst shows a quite low cell voltage (≈1.79 V) at 500 mA cm−2, which is among the best values of current non-noble metal electrocatalysts. Even at the extremely large current density of 1000 mA cm−2, the MoS 2 /NiFeS 2 /NF catalyst presents low overpotentials of 314 and 253 mV for OER and HER, respectively. Furthermore, MoS 2 /NiFeS 2 /NF shows a ceaseless durability over 25 h with almost no change in the cell voltage. The superior catalytic activity and stability at large current densities (>500 mA cm−2) far exceed the benchmark RuO 2 and Pt/C catalysts. This work sheds a new light on the development of highly active and stable nonprecious electrocatalysts for industrial water electrolysis. [Display omitted] • MoS 2 /NiFeS 2 /NF shows ultrahigh activity for OER and HER at large current density. • Ultralow overpotentials (η 1000, OER = 314 mV, η 1000, HER = 254 mV) are needed. • MoS 2 /NiFeS 2 /NF exhibits ultralow cell voltage of 1.79 V@500 mA/cm2 for OWS. • The catalyst shows high stability with no decay in the CP test for OWS over 25 h. [ABSTRACT FROM AUTHOR]