Lanthanide Hydroxide as a New Platform for Efficient Electrocatalytic Alkaline Hydrogen Evolution

For the alkaline hydrogen evolution reaction (HER), the replacement of conventional precious metal electrocatalysts with lanthanide metal hydroxides (Ln(OH)3) with superior water dissociation and thermodynamic stability is essential for large-scale applications in green energy conversion and chemical synthesis. However, Ln(OH)3 has not yet been directly used as an HER electrocatalyst due to its strong adsorption of H* and the blockage of the active site caused by the highly oxygenophilic overbinding of OH- in alkaline conditions. Herein, we discover that engineering alkali metal ion doping of Yb(OH)3 loaded onto nickel foam (NF) allows for the optimal performance of K-Yb(OH)3@NF catalyst with exceptional activity with a low overpotential of 275 mV at 500 mA cm-2. Density functional theory (DFT) calculation shows that the strong interaction between the p and d orbitals of K and the d orbital of Yb better regulates the electronic structure, thus promoting water dissociation and weakening *H adsorption. Moreover, the introduction of the K site enhances the binding energy of the surrounding local *OH, breaking through the *OH blockage, thus accelerating the HER process. K-Yb(OH)3 operated stably as a cathode in an AEM electrolyzer for 1500 h at 1 A cm-2 without dissolution and reconstruction in alkaline conditions, far exceeding most reported transition metal-based catalysts. In addition, the application of K-Yb(OH)3 in an AEM electrolyzer steadily can achieve an energy consumption of 46.3 kWh kg-1 H2 and a projected cost of similar to US$ 0.926 kg-1 H2 (DOE's target: $2 kg-1 of H2 by 2026).