Synthesis of mesoporous clusters of AlO(OH)· αH 2O by a surface hydrolysis reaction of pure Al-metal with nascent-surface in water

Abstract

A catalytic surface induced hydrolysis of nascent surfaces of a thin Al-metal plate in water results in mesoporous clusters of oxidized aluminum into AlO(OH)· αH 2O at room temperature (RT). Their bulk density ρ=1.85 g/cm 3 is observed to be ∼18% lower over the 2.25 g/cm 3 theoretical value. The clusters are in an ellipsoidal shape with major axis as long as 30 nm. On heating in a calorimeter or in a thermogravimetric (TG) machine at moderate rate, 40 K/min or lower, they desorb off the internal water αH 2O followed by OH group in two successive steps over 300–810 K in a controlled manner with an ultimate product of mesoporous Al 2O 3 clusters. TG analysis of loss in mass of the sample in the two desorption steps confirms its molecular composition with α=0.7. Its molecular structure with AlO and OH characteristic groups is analyzed with its IR spectrum. They exhibit two strong IR bandgroups at 950–1150 cm −1 and 3200–4000 cm −1, respectively.