Fluorine‐Engineered RuO ₂ Nanohybrids for Stable Acidic Oxygen Evolution in Proton Exchange Membrane Water Electrolysis

The instability of ruthenium dioxide (RuO 2 ) poses a significant challenge for the oxygen evolution reaction (OER) in proton exchange membrane (PEM) water electrolysis. Herein, we present a synergistic strategy combining fluorine engineering with conductivity modulation to significantly enhance both the stability of RuO 2 . RuO 2 nanoparticles (≈3 nm in diameter) were prepared via a sol–gel method and supported on carbon nanotubes (CNTs) to form a RuO 2 /CNT composite, which was subsequently fluorinated at 200°C to obtain RuO 2 /CNT‐F. Systematic investigations reveal that F incorporation modulates the electronic structure of RuO 2 and mitigates proton accumulation during OER, while the conductive CNT matrix facilitates efficient charge transfer. The optimized RuO 2 /CNT‐F catalyst exhibits exceptional acidic OER activity, requiring an overpotential of only 209 mV to achieve a current density of 10 mA cm −2 in 0.5 M H 2 SO 4 , along with remarkable stability exceeding 300 h in a three‐electrode system. Notably, the catalyst also demonstrates outstanding durability in a PEM electrolyzer, maintaining stable operation for over 2000 h at 10 mA cm −2 and sustaining an industrially relevant current density of 500 mA cm −2 for 50 h. This work provides an effective strategy for designing high‐performance acidic OER catalysts through synergistic electronic modulation and nanostructure engineering.