Facile synthesis of hexagonally ordered mesoporous aluminum oxide thin films with high catalytic activity

Facile synthesis of hexagonally ordered mesoporous aluminum oxide thin films on glass has been reported using a modified aluminum alkoxide precursor and a triblock co-polymer (P123) in ambient condition. The fast hydrolysis rate of aluminum alkoxide can be effectively controlled using a complexing agent acetyl acetone (acac). The slow and controlled hydrolysis and condensation reactions of such partially acac complexed aluminum alkoxide in presence of P123 yielded well-organized mesostructures originating from the self-assembling of micelles in sols. The symmetry of mesopores, thermal stability and catalytic activity of these films were studied. X-ray diffraction studies and transmission electron microscopy (TEM) at different temperatures of these mesoporous films confirmed the ordered nature of mesopores with hexagonal p6mm symmetry and retention of the ordered arrangement up to a high temperature of 900 °C where the transformation of amorphous to γ-alumina took place. The films heat-treated at 500 °C with hexagonally ordered pore arrangement showed much better catalytic activity in the decomposition of toxic KMnO4 to MnO2 nanoparticles in aqueous solution compared to its disordered analogue of similar thickness and porosity.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Ordered mesoporous alumina films with p6mm symmetry. ► Films are thermally stable as well as crack-free and transparent. ► Ordered films show enhanced catalytic activity towards decomposition of KMnO4 to MnO2.