Nitrogen-doped graphene aerogel-supported ruthenium nanocrystals for pH-universal hydrogen evolution reaction

The design and synthesis of high-performance and low-cost electrocatalysts for the hydrogen evolution reaction (HER), a key half-reaction in water electrolysis, are essential. Owing to their modest hydrogen adsorption energy, ruthenium (Ru)-based nanomaterials are considered outstanding candidates to replace the expensive platinum (Pt)-based HER electrocatalysts. In this study, we developed an adsorption-pyrolysis method to construct nitrogen (N)-doped graphene aerogel (N-GA)-supported ultrafine Ru nanocrystal (Ru-NC) nanocomposites (Ru-NCs/N-GA). The particle size of the Ru-NCs and the conductivity of the N-GA substrate can be controlled by varying the pyrolysis temperature. Optimal experiments reveal revealed that 10 wt% Ru-NCs/N-GA nanocomposites require overpotentials of only 52 and 36 mV to achieve a current density of 10 mA cm−2 in 1 mol/L HClO4 and 1 mol/L KOH electrolytes for HER, respectively, which is comparable to 20 wt% Pt/C electrocatalyst. Benefiting from the ultrafine size and uniform dispersion of the Ru-NCs, the synergy between Ru and the highly conductive substrate, and the anchoring effect of the N atom, the Ru-NCs/N-GA nanocomposites exhibit excellent activity and durability in the pH-universal HER, thereby opening a new avenue for the production of commercial HER electrocatalysts.