Tailoring Hydrogen Evolution Performance: Size and Phase Engineering of Ruthenium Nanoparticles

Ruthenium-based nanomaterials have seen increased interest as an alternative to platinum electrocatalysts for the hydrogen evolution reaction (HER). In this study, ruthenium nanoparticles supported on a graphene-based composite consisting of expanded graphite and reduced graphene oxide were successfully prepared by using a one-step thermal method. The nanocomposite was optimized for alkaline HER performance by varying the expanded graphite content and annealing temperature, exhibiting an overpotential of 54 mV to achieve 10 mA cm–2, outperforming the benchmark 20% Pt/C. Through surface characterization of the nanocomposite, the high electrocatalytic activity and stability were found to originate from the interconnected microstructure, optimized porosity, tuned Ru particle size, and homogeneous particle dispersion, revealing the key roles of each component. Using X-ray absorption and X-ray total scattering techniques, the electrochemical performance of the nanocomposite was found to depend on a balance between the size and quality of the ruthenium nanoparticles. The catalyst design principles demonstrated in this work can be applied to streamline and simplify the processes used to develop advanced HER electrocatalysts and other energy storage and conversion materials.