Bixbyite-type Ln2O3 as promoters of metallic Ni for alkaline electrocatalytic hydrogen evolution
Hongming Sun, Zhenhua Yan, Cai‐Ying Tian, Cha Li, Xinliang Feng, Rong Huang, Yinghui Lan, Jing Chen, Cheng‐Peng Li, Zhihong Zhang, Miao Du, Zhihong Zhang, Miao Du
Abstract
Abstract 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/Yb 2 O 3 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/Yb 2 O 3 are attributed to that the Yb 2 O 3 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.