Mesoporous Pd@Ru Core–Shell Nanorods for Hydrogen Evolution Reaction in Alkaline Solution

The activity and stability of bimetallic nanocatalysts strongly depend on their structures, compositions, and interfaces. Here, we report the synthesis of mesoporous Pd@Ru core-shell bimetallic nanorods composed of face-centered cubic Pd and hexagonal close-packed Ru. The nanorods have two types of cavities with diameters of 3.0 ± 0.9 and 20.3 ± 8.1 nm. The mutual diffusion process between Ru and Pd is characterized by the high-angle annular dark-field scanning transmission electron microscopy, energy-dispersive X-ray spectroscopy mapping, and the synchrotron radiation photoemission spectroscopy measurements. The mesoporous Pd@Ru nanorods exhibit superior catalytic performance and stability for hydrogen evolution reactions (overpotentials of 30 mV at 10 mA·cm-2 in 1.0 M KOH solution and 37 mV at 10 mA·cm-2 in 0.5 M H2SO4 solution).