Porous carbon supported ruthenium single atom and ruthenium nanoclusters catalysts for efficient hydrogen evolution reaction

The preparation of electrocatalyst for high efficiency hydrogen evolution reaction (HER) is of great significance to the large-scale promotion of hydrogen energy. In this paper, using sodium carboxymethyl cellulose (CMC-NA) and RuCl₃ as raw materials, Ru-CMC-Na hydrogel was prepared by the coordination of Ru ions with CMC-Na in solution. Then, porous carbon supported Ru single atom and Ru nanocluster catalyst Ru_SA+NC/C-2 was prepared by freeze-drying, high temperature annealing and pickling. The catalyst Ru_SA+NC/C-2 shows excellent HER activity and stability in both acidic and alkaline electrolytes, reaching 10 mA·cm⁻² current density at 20 mV and 23 mV, respectively. After 12 h chronoamperometry test, the activity of Ru_SA+NC/C-2 shows no obvious attenuation. The mass activity of Ru_SA+NC/C-2 is 5.8 times that of commercial Pt/C when the overpotential is 0.05 V in 1 mol/L KOH electrolyte. The physical characterization of Ru_SA+NC/C-2 catalyst shows that the porous structure and large specific surface area of Ru_SA+NC/C-2 catalyst can expose more active sites. Ru single atom and Ru nanocluster structure improve the utilization rate of Ru atom. XPS analysis shows that there is a strong interaction between Ru and carbon support, resulting in the formation of electron-deficient Ru, thus improving HER activity of the catalyst.