Dual-Site Synergistic C–F Bond Activation over Fe ₁ /Al ₂ O ₃ for Efficient CF ₄ Decomposition

Alumina (Al2O3)-based catalysts are widely used for the catalytic hydrolysis of CF4, where coordinatively unsaturated Al (AlIII) sites cooperate with surface hydroxyl groups to facilitate C–F bond activation. However, the catalytic performance of conventional Al2O3 is strongly limited by the low abundance of AlIII sites and the insufficient reactivity of hydroxyl species, making high temperatures necessary for complete CF4 conversion. In this study, we report a single-atom Fe modification strategy (Fe1/Al2O3) that promotes CF4 hydrolysis by simultaneously increasing the fraction of AlIII sites and enhancing the Brønsted acidity of surface hydroxyl groups. 27Al magic-angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy showed that the incorporation of isolated Fe atoms increased the proportion of AlIII sites from 2.1% to 9.9%, corresponding to a 4.7-fold enhancement. Pyridine-IR (Py-IR) results further indicated that the Brønsted acidity associated with surface −OH species on Fe1/Al2O3 was 5.4 times higher than that of pristine Al2O3. In addition, temperature-programmed desorption (TPD) and in situ infrared spectroscopy revealed much stronger CF4 adsorption and C–F bond activation ability over Fe1/Al2O3. Consequently, Fe1/Al2O3 delivered complete CF4 decomposition at 580 °C and maintained stable performance for more than 200 h, whereas pure Al2O3 only achieved 56% conversion and remained stable for 30 h. These findings provide a viable strategy for the rational design of highly active catalysts for low-temperature CF4 hydrolysis.