Tailored morphology and controlled structure of bimodal mesopores silicas via additive ammonia amount in the TEOS–CTAB–H2O system

• BMMs with uniform primary mesopore around 2.7 nm were synthesized.
• The secondary mesopores between 15 and 30 nm were controlled via ammonia additive.
• The spherical particles and rod-like morphology were obtained.
• The related cooperative mechanism was proposed.

Bimodal mesopores silicas (designated as BMMs) with tailored morphology and controlled structure have been synthesized via varying additive ammonia amount in the TEOS–CTAB–H2O system based on hydrolysis–condensation behaviors of silicate species (TEOS) and coefficient principles of cetyltrimethylammonium bromide template (CTAB). The spherical BMMs with an average diameter of 25–150 nm were prepared in a relative low ammonia concentration solution, while the rod-like BMMs with an average size of 2 μm in length were obtained under a high ammonia concentration aqueous solution. Meanwhile, their corresponding morphologies and textural properties were characterized by various techniques, such as X-ray diffraction, SEM, TEM, FT-IR, TG, and N2 sorption, and then, the related cooperative mechanism including sol–gel chemistry and self-assembly process was put forward.

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