Ultrathin γ-Al2O3 nanofibers with large specific surface area and their enhanced thermal stability by Si-doping

Abstract

A series of ultrathin boehmite nanofibers with large specific surface area (302–385 m² g⁻¹) were synthesized via a parallel flow co-precipitation method using cheap NaAlO₂ and Al₂(SO₄)₃ as reactive agents and then transformed into γ-Al₂O₃ by calcination at 500 °C. The resultant γ-Al₂O₃ possesses similar nanofibrous morphology with a length of over 100 nm and a transverse size of ∼2 nm, large specific surface area of up to 419 m² g⁻¹ and relatively high thermal stability, and still retain a specific surface area of 132, 104 and 70 m² g⁻¹ after being calcined at 1000, 1100 and 1200 °C, respectively. Moreover, the thermal stability could be further improved by doping Si for inhibiting the phase transformation and the specific surface area of Si-doped γ-Al₂O₃ nanofibers could be up to 113 m² g⁻¹ at 1200 °C.