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 nanocasting 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 m2 g–1; Fe2O3, 163 m2 g–1; CeO2, 211 m2 g–1; CuO x -CeO y catalyst, 237 m2 g–1; CuO x -CoO y -CeO z catalyst, 203 m2 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.

No abstract

For industrial catalysis, a simple and green process for catalyst synthesis has always been pursued. In this regard, we utilized NaCl, one of the most common salts, as a template to prepare transitional metal oxide catalysts with both abundant porosity and well-dispersed noble metal species. Interestingly, this dispersion by NaCl was realized by solid-state grinding. Importantly, those catalysts afforded excellent performance in redox processes.

Metal-free oxidation, a green chemistry process, has drawn significant attention from catalysis researchers.