📄 Abstract
This study introduces a method for fabricating ultra-high-performance catalysts designed for the oxygen evolution reaction (OER), employing a combination of ball-milling, autoclave heat treatment procedures, and a two-step heat treatment approach. This method produces catalysts characterized by an atomic dispersion of ruthenium on nitrogen-doped carbon sheets (Ru–O/N–C–NH3). The Ru–O/N–C–NH3 catalyst exhibits exceptional OER activity in alkaline conditions, achieving a mass activity of 16842 A g−Ru1 at 1.52 V, and a minimal overpotential of 290 mV at a current density of 10 mA cm−2. Moreover, this catalyst demonstrates enduring stability, showing no significant decay after a 100-h stability test in anion exchange membrane water electrolysis (AEMWE), with a mass activity approximating 62000 A g−PGM1. This is nearly three orders of magnitude greater than the AEMWE that utilizes commercial IrO2 as an anode. The atomic dispersion and the Ru–O/N bonding of the catalyst are substantiated to contribute to the notable enhancement in OER activity.
🔬 Five Key Findings
1
Innovative synthesis of atomically dispersed Ru catalyst: Combining ball-milling, autoclave heat treatment, and a two-step heat treatment with ammonia atmosphere, atomically dispersed Ru on nitrogen-doped carbon sheets (Ru–O/N–C–NH3) was successfully fabricated with Ru loading as low as 0.17 wt%.
2
Exceptional OER activity: The 0.34-Ru–O/N–C–NH3 catalyst achieves an overpotential of only 290 mV at 10 mA cm−2 and a record-breaking mass activity of 16842 A g−Ru1 at 1.52 V — 191× and 495× higher than commercial IrO2 and RuO2, respectively.
3
Outstanding long-term stability: In an AEMWE device, the 0.34-Ru–O/N–C–NH3||Pt/C assembly operated at 2.0 V for 100 hours with stable mass activity of ~62000 A g−Ru1 and no observable decay, far superior to IrO2||Pt/C (~40 hours before degradation).
4
Structural and bonding characterization: HAADF-STEM and XAS confirm atomic-scale dispersion of Ru with both Ru–N and Ru–O bonds. XPS reveals that the Ru–O bond proportion increases from 18.4% to 35.2% after heat treatment (16.8% increase), which is critical for OER activity.
5
Synergistic mechanism: The synergistic effect between Ru–O/Ru–N bonds and Ru clusters, combined with the electron-donating ability of pyridinic-N, facilitates electron transfer to the π-bond and enhances OER activity. The higher formation rate of Ru–O bonds compared to Ru–N bonds leads to a higher oxidation state of Ru, beneficial for water electrolysis.
