Face-centered cubic structured RuCu hollow urchin-like nanospheres enable remarkable hydrogen evolution catalysis

Ruthenium (Ru) is one of the most promising metals for its versatility in driving a wide range of catalytic reactions. However, owing to the intrinsic preference of hexagonal close-packed (hcp) phase for bulk Ru, currently, it is still challenging to construct Ru-based nanomaterials with face-centered-cubic (fcc) phase for optimizing their performance towards potential applications. Herein, we report a facile wet-chemical method to directly create unconventional fcc-structured Ru-copper hollow urchin-like nanospheres (fcc-RuCu HUNSs) as a class of efficient pH-universal hydrogen evolution reaction (HER) electrocatalyst. Interestingly, this synthetic strategy can be expanded to prepare other fcc-Ru-based alloy nanomaterials. Significantly, the novel fcc-RuCu HUNSs exhibit superior HER performance with the overpotential of only 25, 34, 40, and 26 mV to reach the current density of 10 mA cm−2 in 0.5 M H2SO4, 0.05 M H2SO4, 0.1 M KOH, and 1 M KOH, respectively, much lower than those of hcp-RuCu HUNSs and commercial Pt/C. Density functional theory (DFT) calculations further indicate that their excellent pH-universal HER performance results from the optimized adsorption free energy of H and work functions. Our work highlights the importance of phase control to design high-efficiency nanocatalysts for relevant catalytic reactions in energy conversion.