Free-standing highly ordered mesoporous carbon–silica composite thin films

Abstract

Free-standing mesoporous carbon–silica composite films with different silica contents are successfully prepared with a crack-free morphology, square centimeter size, and a highly ordered mesostructure. The films are first synthesized on Al₂O₃-coated Si substrates by spin-coating of a tri-constituent solution, in which triblock copolymer Pluronic F127, resin and tetraethoxylsilane (TEOS) are used as the template, carbon and silica precursors, respectively. After the organic–inorganic assembly, calcination, and etching of the intermediate Al₂O₃ layer, the free-standing mesoporous carbon–silica composite films are obtained. The mechanical property, water wettability and electrical conductivity are well adjusted with different carbon–silica ratios. Furthermore, the free-standing carbon or silica films are also prepared by hydrofluoric acid etching of the carbon–silica composite film or calcination in air, owing to the three-dimensional (3D) interpenetrated frameworks of their parental carbon–silica composite films. The surface area of the obtained free-standing carbon film is extremely high up to ∼2030 m² g⁻¹, which is ∼4 times larger than that of its parental carbon–silica composite thin film.