Bixbyite-type Ln2O3 as promoters of metallic Ni for alkaline electrocatalytic hydrogen evolution

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 (Ln(2)O(3)), which can be implanted into metallic Ni by selective high-temperature reduction to achieve highly efficient Ni/Ln(2)O(3) 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 H-2 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 H-2 evolution electrocatalysis.

Automated summary

This study develops efficient and stable Ni/Ln(2)O(3) hybrid electrocatalysts for industrial alkaline water electrolysis. The introduced Ln(2)O(3) promoter greatly enhances the active-site density, reduces the energy barrier of water dissociation, optimizes the free energy of hydrogen adsorption, and prevents the oxidation corrosion of Ni. The Ni/Yb2O3 catalyst outperforms metallic Ni and Pt/C catalysts in terms of low overpotential, low Tafel slope, and excellent long-term durability.