Template-free synthesis of highly porous silica-doped alumina with exceptional stability via intercalation–exfoliation of boehmite into two-dimensional nanosheets

Porous alumina with high specific surface area (SSA) and large pore volume (PV) is highly desired in various applications; however, its synthesis without an organic template faces a great challenge. Herein, we propose a novel template-free strategy based on intercalation-exfoliation with silica to weaken boehmite (alumina precursor) interlayer forces and achieve the exfoliation of boehmite into two-dimensional (2D) nanosheets, which can easily be scaled up. The as-prepared 2D nanosheets with 2-nm thickness could be assembled to form boehmite with 542 m2 g−1 SSA and 2.43 cm3 g−1 PV. The porous alumina obtained from the thermal/hydrothermal treatment of the 2D nanosheets at different temperatures possesses a hierarchical porous structure superior to most of the reported alumina synthesized with organic templates, exhibiting excellent performance in the adsorption of large organic molecules. This research provides a new strategy for synthesizing 2D boehmite nanosheets and porous alumina materials, demonstrating great potential in catalysis and adsorption.