Lanthanide\nHydroxide as a New Platform for Efficient\nElectrocatalytic Alkaline Hydrogen Evolution

For the alkaline hydrogen evolution\nreaction (HER), the\nreplacement\nof conventional precious metal electrocatalysts with lanthanide metal\nhydroxides (Ln(OH)<sub>3</sub>) with superior water dissociation and\nthermodynamic stability is essential for large-scale applications\nin green energy conversion and chemical synthesis. However, Ln(OH)<sub>3</sub> has not yet been directly used as an HER electrocatalyst\ndue to its strong adsorption of H* and the blockage of the active\nsite caused by the highly oxygenophilic overbinding of OH<sup>–</sup> in alkaline conditions. Herein, we discover that engineering alkali\nmetal ion doping of Yb(OH)<sub>3</sub> loaded onto nickel foam (NF)\nallows for the optimal performance of K–Yb(OH)<sub>3</sub>@NF\ncatalyst with exceptional activity with a low overpotential of 275\nmV at 500 mA cm<sup>–2</sup>. Density functional theory (DFT)\ncalculation shows that the strong interaction between the p and d\norbitals of K and the d orbital of Yb better regulates the electronic\nstructure, thus promoting water dissociation and weakening *H adsorption.\nMoreover, the introduction of the K site enhances the binding energy\nof the surrounding local *OH, breaking through the *OH blockage, thus\naccelerating the HER process. K–Yb(OH)<sub>3</sub> operated\nstably as a cathode in an AEM electrolyzer for 1500 h at 1 A cm<sup>–2</sup> without dissolution and reconstruction in alkaline\nconditions, far exceeding most reported transition metal-based catalysts.\nIn addition, the application of K–Yb(OH)<sub>3</sub> in an\nAEM electrolyzer steadily can achieve an energy consumption of 46.3\nkWh kg<sup>–1</sup> H<sub>2</sub> and a projected cost of ∼US$\n0.926 kg<sup>–1</sup> H<sub>2</sub> (DOE’s target: $2\nkg<sup>–1</sup> of H<sub>2</sub> by 2026).