Ruthenium-Based High-Entropy Alloys Expediting Hydrogen Evolution through Catalytic Hydrolysis of Ammonia Borane

Currently, ammonia borane (AB, NH3BH3) hydrolysis is considered an available tactic for hydrogen evolution under ambient conditions, which includes many complex reaction steps, such as the activation and adsorption of AB and water molecules on the catalyst. Therefore, exploiting the high-performance catalysts with multiple active sites to match the multistep catalytic processes in AB hydrolysis is a critical and urgent task but a tough challenge. Herein, we propose a synthesis scheme for a high-entropy alloy (HEA) catalyst for hydrogen liberation from AB hydrolysis. The FeCoNiMnRu HEA with face-centered cubic (fcc) phase was synthesized by the polymer fiber nanoreactor method using low-cost transition metals of Co, Fe, Mn, and Ni as basic elements combined with the precious metal Ru, which facilitates the electron transfer and enhances the synergistic interaction between these elements, hence enhancing the catalytic activity toward AB hydrolysis to release hydrogen. For instance, the as-synthesized Fe23Co27Ni27Mn12Ru11 HEA catalyst shows superior activity in catalyzing AB hydrolysis with an apparent activation energy (E a) of 42.3 kJ<middle dot>mol-1 and a turnover frequency (TOF) of 55.3 molH2<middle dot>molRu -1<middle dot>min-1 at 298 K. This work affords a facile approach for the synthesis of low-cost and high-efficiency catalysts for AB hydrolysis to produce hydrogen.