Various strategies are employed to synthesize hierarchically porous materials:
Template Methods: Using hard or soft templates to create pores of different sizes. Hard templates like silica spheres can be used for macropores, while surfactants can create mesopores. Sol-gel Processes: Controlling the sol-gel chemistry can lead to the formation of hierarchical structures. Post-synthesis Modifications: Techniques such as acid etching, steam treatment, or thermal treatments can modify the pore structure of already synthesized materials. Self-assembly: Utilizing the self-assembly of block copolymers or other organic-inorganic hybrids to create multi-scale porosity.
