Two-dimensional crystals of mesoporous silica SBA-15 nanosheets with perpendicular and open channels

A preparation of mesoporous silica SBA-15 thin sheets with perpendicular nanochannels (SBA(⊥)) and open ends is reported here. At a synthesis condition of pH = 2 where the silica condensation is extremely slow, micron-sized single-crystal-like hexagonally faceted nanosheets (SBA(⊥)-pH2) with aspect ratio of 10-50 were formed. The nanosheets can attach to each other in sideway to extend the thin sheet. At pH = 5, multi-domain SBA(⊥)-pH5 nanosheets are formed, and stacking attachment of sheets is preferred. Vivid Moiré patterns are observed in large areas of stacked silica sheets, indicating excellent structure order.