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Exploring highly active and stable non-noble-metal-based electrocatalysts is of great significance for the wide application of hydrogen evolution reaction (HER) in alkaline media. Herein, we report that crystalline/amorphous Co2P/CoMoP x nanoparticles containing many active interfaces supported on nickel foam (NF) are highly efficient electrocatalysts for alkaline HER. The interface-engineered crystalline/amorphous Co2P/CoMoP x nanostructure is achieved by simple one-step electrodeposition method under a controllable constant current. The optimal electrocatalyst Co2P/CoMoP x -0.4/NF in this work exhibits superior activity for the alkaline HER with low overpotentials of −121 mV at −100 mA·cm–2 and prominent electrochemical stability for 50 h. Excellent HER performance can be attributed to a large amount of active interfaces formed between crystalline Co2P and amorphous CoMoP x , which provide effective exposure of highly active sites and promote electron transfer. This work may open up a new way for the design and preparation of earth-abundant, low-cost nanostructured materials as high-efficiency HER electrocatalysts for applications in the field of electrocatalysis.

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An enormous challenge in the development of renewable hydrogen sources for electricity-driven water-splitting systems has been the limitation of the earth-abundant and robust highly-active cathode electrocatalysts. In this work, we developed a simple sulfur-anion doping strategy to obtain the S-doped NiCo composite (S-NiCo@50) on Ni foam (NF) via a one-step electrochemical deposition. It was found that doped sulfur plays a crucial role in reducing the overpotential of hydrogen evolution by providing abundant active sites as identified by the XPS spectrum. The formed metallic Ni and Co effectively promoted electron transportation. The synergistic effects between the amorphous CoxNiyS(x+y) substance and crystalline Ni and Co metal seemed to result in enhanced HER activity. In particular, the S-NiCo@50 electrode, featuring a hierarchical morphology, showed an ultralow overpotential of 28 and 125 mV at 10 and 100 mA cm-2, respectively, in 1.0 M NaOH with a large exchange current density (j0) of 4.8 mA cm-2 as well as high conductivity and stability; its catalytic properties are superior to most of the reported alkaline electrocatalysts and are on par with commercial Pt/C. Assembled with the counter electrode (Ni-Fe/NF), the overall water splitting was proved with a low 1.55 V at 10 mA cm-2. Moreover, we built the Ni24Co6S6 cluster as the S-NiCo@50 model and revealed its intrinsic activity by density functional theory (DFT) calculations. This study shows that S-doping and component control can be an exquisite strategy for realizing high-efficiency electrochemical water reduction.