The in-situ construction of NiFe sulfide with nanoarray structure on nickel foam as efficient bifunctional electrocatalysts for overall water splitting

Abstract Developing high-efficiency, stable and cost-effective non-noble metal-based bifunctional electrocatalysts is crucial for the overall water splitting to produce clean hydrogen energy. Nanoarray structures electrocatalysts have attracted increasing research interests due to its structural advantages. Herein, Ni3S2/Fe9S10 with two dimensions (2D) nanosheet arrays in-situ growth on three dimensions (3D) nickel foam (Ni3S2/Fe9S10@NF) was prepared by step-wise hydrothermal method. Ni3S2/Fe9S10@NF was derived from NiFe layered double hydroxides, and the as-prepared Ni3S2/Fe9S10@NF electrode was directly served as a bifunctional catalyst for electrolysis of water. Benefiting from the directly contact with conductive Ni foam substrate, the positive synergy effect between Ni and Fe in the Ni3S2/Fe9S10@NF catalyst and its open 3D porous structure, the binder-free and integrated Ni3S2/Fe9S10@NF electrode displayed excellent catalytic activities towards hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), the overpotential for HER and OER are only 56 and 147 mV at 10 mA cm−2, respectively. Particularly, when the prepared Ni3S2/Fe9S10@NF further employed as both the cathode and anode electrocatalysts a symmetric cell Ni3S2/Fe9S10@NF|| Ni3S2/Fe9S10@NF, a low cell voltage of 1.43 V was achieved at 10 mA cm−2, with good stability. This work not only illustrated that non-noble metal-based electrocatalysts have tremendous potential applications for electrocatalytic electrolysis of water but also provided a feasible strategy to prepare high-efficiency and stable non- precious metal catalysts.