Organic-free synthesis of boehmite nanofibers by Al₂(SO ₄)₃·18H₂O with high pore volume

Nanofibrous boehmite materials with controlled morphology were synthesized without use of any surfactant by careful tuning of the pH value of the precursor, temperature, and time length of the hydrothermal treatment, followed by a series of characterizations. When the pH value was controlled at 9.5 and hydrothermal treatment temperature was controlled at 90 C for 12 h, the surface area and the pore volume of boehmite reached significantly large values of 367.9 m²/g and 1.01 cm³/g, respectively. The acquired fibrous morphology can be well kept at 600 C in the procedure of transformation into γ-Al₂O₃. The heat treatment at higher temperatures will result in a morphology change accompanied by the formation of θ- Al₂O₃ or α- Al₂O₃. The approach of the present study achieves precise control of the size and morphology of the boehmite nanofibers at low temperatures.