Ni x B/Mo 0.8 B 3 Nanorods Encapsulated by a Boron‐Rich Amorphous Layer for Universal pH Water Splitting at the Ampere Level

Heterostructured interfaces are crucial to electrocatalysts for water splitting. Herein, coral‐like multiheterostructured Ni x B/Mo 0.8 B 3 (NMB) nanorods encapsulated by a boron‐rich amorphous layer are prepared for water splitting. Density‐functional theory (DFT) calculations indicate that the NMB interface adjusts the d ‐band center and electronic structure of the molybdenum sites. Owing to the strong electronic coupling between Ni, Mo, and B at the heterojunction, large number of exposed catalytic active sites, as well as the special hydrophilic characteristics endowed by the surrounding amorphous layer, the NMB catalyst exhibits remarkable universal‐pH hydrogen evolution reaction (HER) activity with low overpotentials ( η ) of 15, 26, and 83 mV to deliver 10 mA cm −2 in basic, acid, and neutral media, respectively, and outstanding oxygen evolution reaction (OER) characteristics in the basic medium with η 10 and η 500 of 170 and 420 mV, respectively. The unique self‐supporting 3D hierarchical interconnected structure facilitates mass transport thus leading to high mechanical stability for 450 and 200 h in HER and OER at ≈1000 mA cm −2 . More importantly, the NMB exhibits excellent performance toward overall‐water electrolysis as a bifunctional catalyst with ultralow cell voltages of 1.45/1.56/1.85 V @ 10/100/1000 mA cm −2 , demonstrating the large potential in industrial water splitting applications.