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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