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The active-site density, intrinsic activity, and durability of Ni-based catalysts are critical to their application in industrial alkaline water electrolysis. This work develops a kind of promoters, the bixbyite-type lanthanide metal sesquioxides (Ln2O3), which can be implanted into metallic Ni by selective high-temperature reduction to achieve highly efficient Ni/Ln2O3 hybrid electrocatalysts toward hydrogen evolution reaction. The screened Ni/Yb2O3 catalyst shows the low overpotential (20.0 mV at 10 mA cm−2), low Tafel slope (44.6 mV dec−1), and excellent long-term durability (360 h at 500 mA cm−2), significantly outperforming the metallic Ni and benchmark Pt/C catalysts. The remarkable hydrogen evolution activity and stability of Ni/Yb2O3 are attributed to that the Yb2O3 promoter with high oxophilicity and thermodynamic stability can greatly enlarge the active-site density, reduce the energy barrier of water dissociation, optimize the free energy of hydrogen adsorption, and avoid the oxidation corrosion of Ni. While renewable H2 evolution will require inexpensive, abundant catalysts, non-noble metals typically show relatively low activities. Here, authors examine lanthanide metal sesquioxide doped metallic Ni and show efficient, stable performances for alkaline H2 evolution electrocatalysis. [ABSTRACT FROM AUTHOR]