Hierarchical Architectures by Hybridizing Ru Nanoparticles with Nitrogen/Oxygen Dual-Doped Carbon Nanotubes for Advanced Hydrogen Evolution Reaction Performance

Developing highly efficient and stable electrocatalysts is critical for advancing hydrogen evolution reactions (HER) for hydrogen production. Herein, we report a facile approach to fabricating a hierarchical catalyst featuring ruthenium (Ru) nanoparticles uniformly integrated with nitrogen/oxygen co-doped carbon nanotube aerogels (Ru-NOCAs). Heteroatoms N and O-modified CNTs can result in a negatively charged surface to effectively trap Ru³⁺ ions. Ru-NOCAs exhibit a well-defined hierarchical morphology facilitated by the self-assembly of functional groups on the surface of CNTs, which enhances the interaction between Ru nanoparticles and CNTs. Due to the synergistic effect of hierarchical structure and strong interaction formation, Ru-NOCAs show excellent catalytic activity and stability. Ru-NOCAs catalyst demonstrates a remarkable overpotential of 41 mV at 10 mA cm⁻² with a Tafel slope of 57 mV dec⁻¹ in 1 M KOH and an overpotential of 68 mV with a Tafel slope of 65.8 mV dec⁻¹ in 0.5 M H₂SO₄. These results indicate superior catalytic efficiency and enhanced charge transfer kinetics compared to the control samples. This study highlights the effectiveness of incorporating hierarchical structures and tailored surface chemistries in electrocatalyst design, offering new avenues for optimizing HER performance and advancing hydrogen fuel technology.