Buckling of Two-Dimensional Colloidal Nanoplatelets in Confined Space To Design Heterogeneous Catalysts

We report the buckling of two-dimensional (2D) colloidal ceria nanoplatelets in oil-in-water emulsions. The buckling process in a drying oil droplet is found to be controlled by the size of the nanoplatelets and the Janus bilayer formed on the surface of the nanoplatelets. The buckling of the nanoplatelets can generate multiple cavities after the evaporation of the oil phase. Thus, we develop a general process for the encapsulation of heterogeneous metal nanoparticles (Au, Ag, Pt, and Pd) into the hierarchically self-assembled 2D ceria nanoplatelets. The spatially compartmentalized metal nanoparticles exhibit excellent catalytic performances toward 4-nitrophenol reduction and CO oxidation reactions. Thus, the method can be potentially extended to other colloidal 2D materials. More generally, these findings encourage to explore other buckled 2D materials to design advanced materials by combing the best of different ingredients in one ultimate material.