Solvothermal synthesis of disordered mesoporous materials based on a Si–N framework in ionic liquids

• Novel preparation method for porous silicon–nitrogen materials in ionic liquids.
• Ionic liquid remains occluded in the as-prepared materials acting as a template.
• Possibility of tailoring the pore size by changing the experimental conditions.
• High quantity of Si–NH species in the bulk and on the materials surface.

Silicon–nitrogen network based porous materials have been synthesized by a novel method based on the preparation of silicon diimide gel by the ammonolysis of silicon tetrachloride using an ionic liquid as solvent followed by a heating process. The resulting materials contain ionic liquid molecules occluded inside the framework, which can be remove by heat treatment at 600 °C under flowing ammonia leading to microporous and mesoporous materials with high surface areas. The pore size of the materials is tailored by the variation of the experimental conditions.STEM investigations reveal a disordered porous structure with pores with an average diameter of 10 nm in the mesoporous samples. A N/Si molar ratio higher than 2 is obtained for all the ammonia-calcined materials and FTIR and XPS measurements indicate a high number of Si–NH groups, both in the bulk and on the materials surface.

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