Fabrication of multi-compartmentalized mesoporous silica microspheres through a Pickering droplet strategy for enhanced CO2 capture and catalysis

It is a long-standing dream to fabricate micron-sized inorganic spheres that have nanocompartments enclosed by a permeable shell and thus resemble the shape of natural cells. Here, we demonstrate a novel synthesis protocol to attain this goal for the first time. This protocol unprecedentedly harnesses interfacial sol-gel growth around Pickering droplets coupled with a surfactant assembly-directed sol-gel process within droplet-confined spaces. This protocol enables us to fabricate novel mesoporous silica microspheres (MSMs) with tunable interior architectures, such as hollow MSMs, hollow nanosphere-containing MSMs (hn@MSMs), nanosphere-containing MSMs (n@MSMs), yolk-shell-structured MSMs (y@MSMs) and solid MSMs. The obtained multi-compartmentalized MSMs exhibit good permeability to external molecules and good mechanical strength against stress. Moreover, their structural features benefit practical applications of CO2 capture and enzymatic reactions. Due to the high dispersion of tetraethylenepentamine and enzyme in the spatially separated nanocompartments, the developed CO2 sorbents and catalysts exhibit significantly enhanced CO2 capture efficiency and catalysis efficiency. Meanwhile, owing to the encapsulation of these nanocompartments inside the hollow micron-sized spheres, these CO2 sorbents and catalysts can be packed directly in fixed-bed reactors, which is unattainable for nanoparticle materials.