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.