Face-Centered Cubic Ruthenium Nanocrystals with Promising Thermal Stability and Electrocatalytic Performance

The rational design of Ru nanocrystals with a metastable face-centered cubic (fcc) structure is highly important for catalytic applications and yet remains a challenge. Herein, we have successfully prepared a unique core–shell structure consisting of structurally disordered Cu2O (core) and fcc Ru (shell) (Cu2O@Rufcc) via a facile chemical method. The experimental investigations show that Cu2O, which is formed in the initial stage and becomes disordered in the subsequent structural evolution, plays a pivotal role in Ru stacking into the fcc structure. Benefiting from the distinct structural advantage, the fcc Ru structure of Cu2O@Rufcc shows good thermal stability with preserving the phase transition temperature up to 500 °C according to the in situ measurement, which is much better than those of Rufcc, Cu@Rufcc, and most reported materials. The X-ray absorption spectroscopy (XAS) analysis identifies the strong interaction of disordered Cu2O and fcc Ru. Further theoretical calculation reveals that the phase stability of Cu2O@Rufcc mainly originates from the strong interfacial interaction of the core and shell. When used as an electrocatalyst, the Cu2O@Rufcc exhibits superior performance over the Rufcc, Ruhcp, and commercial Pt/C in both the alkaline hydrogen evolution reaction and hydrogen oxidation reaction. This work highlights a potential strategy for designing fcc Ru nanocrystals with favorable properties and promising applications.