Facile Synthesis of Highly Porous Metal Oxides by Mechanochemical Nanocasting

Metal oxides with high porosity usually exhibit better performance in many applications, as compared with the corresponding bulk materials. Template-assisted method is generally employed to prepare porous metal oxides. However, the template-assisted method is commonly operated in wet conditions, which requires solvents, soluble metal oxide precursors, and a long time for drying. To overwhelm those drawbacks of the wet procedure, a mechanochemical nano casting method is developed in the current work. Inspired by solid-state synthesis, this strategy proceeds without solvents, and the ball milling process can enable pores replicated in a shorter time (60 min). By this method, a series of highly porous metal oxides were obtained, with several cases approaching the corresponding surface area records (e.g., ZrO2, 293 m(2) g(-1); Fe2O3, 163 m(2) g(-1); CeO2, 211 m(2) g(-1); CuOx-CeOy catalyst, 237 m(2) g(-1); CuOx-CoOy-CeOz catalyst, 203 m(2) g(-1)). Abundant nanopores with clear lattice fringes in metal oxide products were witnessed by scanning transmission electron microscopy (STEM) in high angle annular dark field (HAADF). By combination of mechanochemical synthesis and nanocasting, current technology provides a general and simple pathway to porous metal oxides.