Ruthenium-Based High-Entropy\nAlloys Expediting Hydrogen\nEvolution through Catalytic Hydrolysis of Ammonia Borane

Currently, ammonia borane (AB, NH<sub>3</sub>BH<sub>3</sub>) hydrolysis\nis considered an available tactic for hydrogen evolution under ambient\nconditions, which includes many complex reaction steps, such as the\nactivation and adsorption of AB and water molecules on the catalyst.\nTherefore, exploiting the high-performance catalysts with multiple\nactive sites to match the multistep catalytic processes in AB hydrolysis\nis a critical and urgent task but a tough challenge. Herein, we propose\na synthesis scheme for a high-entropy alloy (HEA) catalyst for hydrogen\nliberation from AB hydrolysis. The FeCoNiMnRu HEA with face-centered\ncubic (fcc) phase was synthesized by the polymer fiber nanoreactor\nmethod using low-cost transition metals of Co, Fe, Mn, and Ni as basic\nelements combined with the precious metal Ru, which facilitates the\nelectron transfer and enhances the synergistic interaction between\nthese elements, hence enhancing the catalytic activity toward AB hydrolysis\nto release hydrogen. For instance, the as-synthesized Fe<sub>23</sub>Co<sub>27</sub>Ni<sub>27</sub>Mn<sub>12</sub>Ru<sub>11</sub> HEA\ncatalyst shows superior activity in catalyzing AB hydrolysis with\nan apparent activation energy (<i>E</i><sub>a</sub>) of\n42.3 kJ·mol<sup>–1</sup> and a turnover frequency (TOF)\nof 55.3 mol<sub>H2</sub>·mol<sub>Ru</sub><sup>–1</sup>·min<sup>–1</sup> at 298 K. This work affords a facile\napproach for the synthesis of low-cost and high-efficiency catalysts\nfor AB hydrolysis to produce hydrogen.