Highly porous and mechanically robust Al2O3-based foams with self-wrinkled and rough aperture surfaces via binary colloidal self-assembly of nanoparticle/gelation network

Porous materials with wrinkled surfaces could have broad applications in catalysis and adsorption. However, designing cellular ceramics with similar structures is challenging. Herein, we demonstrated the binary colloidal self-assembly of γ-Al 2 O 3 nanoparticle/silica gelation network for constructing such materials. The competitive effect between volume shrinkage and surface bend during water evaporation of silica gel contributed to wrinkled aperture surface. During calcination , silica nanoparticles were highly active to react with alumina to form mullite nanocrystals , bringing about high compressive strength at low relative densities. After calcining at 1350 °C, resultant products with hierarchical structure exhibited an outstanding compressive strength of 4.2 MPa, a relatively high surface area of 7.23 m 2 /g at a porosity level of 83.3%. The current strategy provides a feasible and affordable approach for producing high performance ceramic foams towards practical application fields in catalysis and adsorption.