Interfacial co-assembly strategy towards gradient mesoporous hollow sheet for molecule filtration

Gradient porous structures enable the fast capillary-directed mass transport and enhance the chemical reaction rate with optimal efficiency and minimal energy consumption. Rational design and facile synthesis of functional mesoporous materials with sheet structure and gradient mesopores still face challenges of stacked structures and unadjustable pore sizes. Herein, an interfacial co-assembly strategy for gradient mesoporous hollow silica sheets is reported. The modulated oil-water interface allows the assembly of gradient mesoporous silica layers on the water-removable ammonium sulfate crystals. The obtained mesoporous silica layers possess narrow pore size distributions (~2.2 nm and ~6.6 nm). Owing to the good mono-dispersity, sheet structure and proper pore size, the designed gradient mesoporous hollow silica sheets can serve as flexible building blocks for fabricating nanoscale molecule filtration device. Experiments reveal that the obtained nanofiltration device shows remarkable gradient rejection rates (range from 23.5 to 99.9%) for molecules with different sizes (range from 1.2 to 4.4 nm).