Hollow Ru Nanoparticles for Electrocatalytic Hydrogen Evolution

The development of highly efficient and robust Pt-free electrocatalysts toward the hydrogen evolution reaction (HER) is facing increasing demand. Herein, we demonstrate a hollow Ru nanostructure (h-RuNP) that is fabricated with an ultrasmall Ru nanoparticle of similar to 1.72 nm and is resistant to oxidation. The construction of h-RuNP was done using preformed Ni nanocrystals as reducing agents in dimethylformamide (DMF) without the need of any inert gas atmosphere (such as N-2) or stabilizing agents. Studies indicate that both the solvent DMF and the ultrasmall Ru nanoparticles help to prevent the surface oxidation of Ru. The as-synthesized h-RuNP possesses robust catalytic activity toward HER in acidic media, which is superior to that of recently reported pure Ru and Ru-based nanocatalysts and close to that of the commercial 20% Pt/C catalyst. The h-RuNP also exhibits exceptional long-term stability under natural ambient conditions (no nitrogen is added to remove oxygen). The enhanced performance of h-RuNP mainly arose from the strong surface oxidation resistance and antiaggregation effect of unsupported ultrasmall Ru nanoparticles.