Highly-efficient CoRuO_x nanocatalysts for acidic oxygen evolution: The merit of optimum ordering degree of carbon nanotube support

Hydrogen production from proton exchange membrane water electrolysis is constrained by the sluggish kinetics of the anodic oxygen evolution reaction. RuO2 has attracted considerable attention due to its low reaction overpotential, but its inferior stability remains a major challenge. Herein, a strategy is proposed to enhance the catalytic activity and stability of CoRuOx nanoparticles by doping Co and regulating the ordering degree of carbon nanotubes (CNTs) by air annealing. It was found that the CoRuOx@CNTs-30 0 catalyst exhibited the best catalytic activity and stability when the annealing temperature was 300 degrees C. At the current density of 10 mA cm(-2), the overpotential of this catalyst was only 201 mV, which was nearly 100 mV lower than that of commercial RuO2 (300 mV). Surprisingly, there was no significant increase in the overpotential when tested at a current density of 10 mA cm(-2) for 50 h. The density functional theory calculations indicate that the high activity of the catalyst is due to the electronic coupling of CoRuOx nanoparticles and CNTs, and that the introduction of Co and CNTs improves the electronic structure and solvation energies of the Ru in the active site, dramatically increasing the structural stability. (c) 2024 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.