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Ternary transition metal phosphides (TTMPs) with two-dimensional heterointerface and adjustable electronic structures have been widely studied in hydrogen evolution reactions (HER). However, single-phase TMPs often have inappropriate H* adsorption energy and electronic transfer efficiency in HER. Herein, we utilized the heterogeneity in the crystal structure to design an efficient and stable catalyst from the NiCoP nanowire@NiCoP nanosheet on nickel foam (NW-NiCoP@NS-NiCoP/NF) for HER. Layered double hydroxides (LDHs) with a heterogeneous matrix on crystal surfaces were grown under different reaction conditions, and non-metallic P was introduced by anion exchange to adjust the electronic structure of the transition metals. The hierarchical structure of homologous NiCoP/NF from the LDH allows for a larger surface area, which results in more active sites and improved gas diffusion. The optimized NW-NiCoP@NS-NiCoP/NF electrode exhibits excellent HER activity, with an overpotential of 144 mV, a Tafel slope of 84.2 mV dec−1 at a current density of 100 mA cm−2 and remarkable stability for more than 500 h in 1.0 M KOH electrolyte. This work provides ideas for elucidating the rational design of structural heterogeneity as an efficient electrocatalyst and the in situ construction of hierarchical structures. [ABSTRACT FROM AUTHOR]

Ternary transition metal chalcogenide (TTMC) with multicomponent, different phases and unique electronic structures have been studied in electrocatalytic hydrogen evolution reaction (HER). However, the strong interaction between adsorbed H (H∗) and sulfur leads to the unfavorable hydrogen desorption properties of considerable TTMC. Herein, we constructed the hierarchical hollow NiCo 2 S 4 nanotube@NiCo 2 S 4 nanosheet arrays on Ni foam substrate (NT-NiCo 2 S 4 @NS-NiCo 2 S 4 /NF) by ion-exchange method. Homogeneous anion diffusion facilitates the formation of regular ultrathin nanosheets on hollow NiCo 2 S 4 nanotube arrays, which presents hierarchical architecture with more surface area and channels to active site exposure, electrolyte diffusion, and gas desorption for HER. As-synthesized optimal NT-NiCo 2 S 4 @NS-NiCo 2 S 4 /NF electrode demonstrates an excellent HER activity, especially an overpotential of 221 mV, a Tafel slope of 108 mV dec−1, and remarkable stability at current densities of 100 mA cm−2 in 1.0 M NaOH electrolyte. • Hierarchical hollow NT-NiCo 2 S 4 @NS-NiCo 2 S 4 arrays supported on nickel foam were synthesized by ion-exchange method. • Hierarchical structure assembled from TTMC can facilitate active sites accessibility and hydrogen desorption properties. • The optimized NT-NiCo 2 S 4 @NS-NiCo 2 S 4 /NF-1.0 exhibited an overpotential of 221 mV at 100 mA/cm2 and persistent stability. [ABSTRACT FROM AUTHOR]