Free-Standing Mesoporous Silica/Carbon Composite Films with Crystalline Silica Wall from Ethylene-Bridged Organosilane

Abstract

Free-standing periodic mesoporous organosilica (PMO) films were grown at the interface of an ethylene-bridged organosilica and surfactant template via a self-assembly process. After the pyrolysis of the PMO films with ethylene-bridged organosilica moieties in the pore walls under an Ar flow at temperatures ranging from 400 to 900 °C, free-standing mesoporous silica/carbon composite films were obtained. The composite films had a highly ordered periodic mesostructure with a hexagonal closed-packed arrangement of channels running parallel to the surface. The mesopore walls of the films pyrolyzed above 700 °C in the presence of alkali metal ions had a cristobalite structure at the pore walls. When the pyrolysis temperature was between 400 and 900 °C, the pore diameter, surface area, and pore volume of the silica/carbon composite films were 18.2−30.5 Å, 172−690 m2 g−1, and 0.18−0.64 cm3 g−1, respectively