Hierarchical Architectures Based on Ru Nanoparticles/Oxygen‐Rich‐Carbon Nanotubes for Efficient Hydrogen Evolution

Highly active and durable electrocatalysts are essential for producing hydrogen fuel through the hydrogen evolution reaction (HER). Here, a uniform deposition of Ru nanoparticles strongly interacting with oxygen‐rich carbon nanotube architectures (Ru‐OCNT) through ozonation and hydrothermal approaches has been designed. The hierarchical structure of Ru‐OCNT is made by self‐assembly of oxygen functionalities of OCNT. Ru nanoparticles interact strongly with OCNT at the Ru/OCNT interface to give excellent catalytic activity and stability of the Ru‐OCNT, as further confirmed by density functional theory. Owing to the hierarchical structure and adjusted surface chemistry, Ru‐OCNT has an overpotential of 34 mV at 10 mA cm−2 with a Tafel slope of 27.8 mV dec−1 in 1 M KOH, and an overpotential of 55 mV with Tafel slope of 33 mV dec−1 in 0.5 M H2SO4. The smaller Tafel slope of Ru‐OCNT than Ru‐CNT and commercial Pt/C in both alkaline and acidic electrolytes indicates high catalytic activity and fast charge transfer kinetics. The as‐proposed chemistry provides the rational design of hierarchically structured CNT/nanoparticle electrocatalysts for HER to produce hydrogen fuel. Hydrogen at high or low pH: Hierarchical oxygen‐rich carbon nanotube architectures strongly trap Ru nanoparticles, and a Ru−O−C bond is formed from the strong interaction at Ru/OCNT interfaces. The obtained catalyst shows excellent catalytic activity and stability for the HER in both alkaline and acid electrolytes, and the high activity of the catalyst is further confirmed by density functional theory.