Two-dimensional porous γ-AlOOH and γ-Al2O3 nanosheets: hydrothermal synthesis, formation mechanism and catalytic performance†
Abstract
Novel two-dimensional (2D) γ-AlOOH porous nanosheets have been successfully prepared in a mixed system consisting of oleic acid (OA), dodecylamine (DDA), urea, and 1-octadecene. OA acted as a reaction reagent to form the Al-carboxyl precursor, DDA acted as a soft template and induced the γ-AlOOH sheet structure, and urea acted as a porogen. Porous γ-Al2O3 nanosheets were obtained by thermal decomposition of the γ-AlOOH. Furthermore, the obtained sheet-like γ-Al2O3 was used as a support to prepare a monodisperse Ag/γ-Al2O3 nanocatalyst. This catalyst exhibited superior catalytic activity compared to γ-Al2O3 nanosheets, pure Ag nanocrystals (NCs) and Ag/amorphous Al2O3 for the hydrogenation of nitroaromatic compounds, which can be explained by a higher concentration of Lewis type basic sites on sheet-like γ-Al2O3 leading to a higher concentration of nitrobenzene and more efficient hydrogenation.