Engineering hierarchical NiFe-layered double hydroxides derived phosphosulfide for high-efficiency hydrogen evolving electrocatalysis

Exploring robust, highly efficient, and cost-effective non-noble metal electrocatalysts for replacing Pt in hydrogen evolution reaction (HER) is of great significance. In this study, we skillfully synthesized binary transition-metal (i.e., nickel and iron) phosphosulfides on nickel foam (NiFeSP/NF) via a sulfuration/phosphorization treatment of bimetallic layered double hydroxides (LDH). Taking the advantage of the presence of active heterointerfaces among Ni2P, Ni3S2, and FeS2, the NiFeSP/NF catalyst, which was advantageous of the highly exposed active sites, exhibited an extraordinary catalytic activity in HER—an overpotential of 70 mV at a current density of 10 mA cm−2 and a Tafel slope of 69 mV dec−1, outperforming most of the existing counterparts. Moreover, NiFeSP/NF catalysts demonstrated favorable long-term catalytic stability for 10 h. We contributed this superior catalytic activity to the characteristic attributes of NiFeSP/NF, which could be stemmed from its exquisite catalyst design: (i) the co-occurrence of highly HER-favored crystalline Ni2P, Ni3S2, and FeS2 in bimetallic phosphosulfides and (ii) the existence of multi-functional phase interfaces among Ni2P, Ni3S2, and FeS2 in the NiFeSP/NF hierarchical structure. The present study exemplified an effective strategy for designing HER-favored bimetallic phosphosulfides and provided the scientific base for the insight into the catalytic nature of multi-metallic phosphosulfides.