Platinum-based catalysts are widely used in hydrogen evolution reactions; however, their applications are restricted because of the cost-efficiency trade-off. Here, we present a thermodynamics-based design strategy for synthesizing an Al 73 Mn 7 Ru 20 (atomic %) metal catalyst via combinatorial magnetron co-sputtering. The new electrocatalyst is composed of ~2 nanometers of medium-entropy nanocrystals surrounded by ~2 nanometers of amorphous regions. The catalyst exhibits exceptional performance, similar to that of single-atom catalysts and better than that of nanocluster-based catalysts. We use aluminum rather than a noble metal as the principal element of the catalyst and ruthenium, which is cheaper than platinum, as the noble metal component. The design strategy provides an efficient route for the development of electrocatalysts for use in large-scale hydrogen production. Moreover, the superior hydrogen reaction evolution created by the synergistic effect of the nano-dual-phase structure is expected to guide the development of high-performance catalysts in other alloy systems.

Thermal stability determines a material's ability to maintain its performance at desired service temperatures. This is especially important for aluminum (Al) alloys, which are widely used in the commercial sector. Herein, an ultra‐strong and heat‐resistant Al‐Cu composite is fabricated with a structure of nano‐AlN and submicron‐Al2O3 particles uniformly distributed in the matrix. At 350 °C, the (8.2AlN+1Al2O3)p/Al‐0.9Cu composite achieves a high strength of 187 MPa along with a 4.6% ductility under tension. The high strength and good ductility benefit from strong pinning effect on dislocation motion and grain boundary sliding by uniform dispersion of nano‐AlN particles, in conjunction with the precipitation of Guinier–Preston (GP) zones, enhancing strain hardening capacity during plastic deformation. This work can expand the selection of Al–Cu composites for potential applications at service temperatures as high as ≈350 °C.