Novel nanoporous amorphous/nanocrystalline composite structured RuNiFeCo multicomponent alloys with exceptional catalytic activity for ammonia borane hydrolytic dehydrogenation

The pursuit of high-efficient and cost-effective catalysts for hydrogen generation is imperative to address the energy crisis. Herein, nanoporous RuNiFeCo alloys (np-RuNiFeCo) with high catalytic activity for ammonia borane (AB) hydrolytic dehydrogenation have been prepared by dealloying Fe₂₅Ni_xCo_40-xRu₅B₃₀ (x = 0–40) high-entropy amorphous alloys with low Ru content. The np-RuNiFeCo are composed of an amorphous/hexagonal close-packed Ru nanocrystalline dual-phase structure and exhibit a uniform nanopore/ligament bicontinuous architecture. The morphology, composition, and AB hydrolysis catalytic properties of the np-RuNiFeCo can be regulated by varying the Ni/Co content in the precursors, and the best catalytic activity with a high turnover frequency value of 148.2 ${\text{mol}}_{H2}{\text{mol}}_{\text{Ru}}^{‐1}{\min }^{‐1}$ and a low apparent activation energy of 25.3 $\text{kJ}{\text{mol}}^{‐1}$ was obtained when x = 30. Density functional theory simulations indicate that the presence of Ni, synergizing with Fe and Co, promotes electron transfer to Ru and enhances the adsorption energies of both AB and H₂O molecules while reducing the activation barrier for cleaving the H₂O molecule, leading to enhanced intrinsic catalytic activity of the alloy. The exceptional catalytic performance of the np-RuNiFeCo arises from the synergy of multiple principal elements, nanoporous morphology, and amorphous/nanocrystalline heterogeneous interface. In addition, the mechanisms of dealloying and nanoporous structure formation have been discussed based on surface diffusion.