Method for preparing highly nitrogen-doped mesoporous carbon composites

A method of preparing macroscopic composites made of a macroscopic support coated with a thin layer of highly nitrogen-doped mesoporous carbon phase, said method comprising:

• (a) providing an aqueous solution of (i) (NH4)2CO3;
• (ii) a carbohydrate as carbon source, selected from aldose monosaccharides and glycosilated forms thereof, disaccharides and oligosaccharides or dextrine deriving from biomass conversion, and (iii) a carboxylic acid source selected from citric acid, and any other mono-, di-, tri-, and poly-carboxylic acid or their ammonium mono-, di-, tri- and poly-basic forms;
• (b) providing a macroscopic support made of carbon-, silicon- or aluminum-based material, or binary mixtures thereof;
• wherein the macroscopic support is a single object or an assembly of smaller objects, wherein the overall dimension of the support ranges from 0.1 μm to 100 cm in three orthogonal directions;
• optionally subjecting the maccroscopic support of step (b) to a passivation process comprising steps of:
• (a1) providing an aqueous solution of citric acid and a carbohydrate as carbon source, selected from aldose monosaccharides and glycosilated forms thereof, disaccharides and oligosaccharides;
• (b1) prior to step (c), immerging/soaking or impregnating the macroscopic support of step (b) in the aqueous solution of step (a1) for a suitable amount of time;
• (c1) optionally removing the immerged macroscopic support from the aqueous solution of step (a1) if an excess aqueous solution is used in step (b1);
• (d1) optionally subjecting the resulting macroscopic support to a gentle thermal treatment under air at low temperatures from 45 to 55° C.;
• (e1) subjecting the resulting macroscopic support to a first thermal treatment under air at moderate temperatures from 110-150° C.±5° C.;
• and
• (f1) subjecting the thermally treated macroscopic support to a second thermal treatment under inert atmosphere at higher temperatures from 600-800° C.±10° C.;
• thereby generating a macroscopic composite coated with a carbon layer;
• (c) immerging/soaking or impregnating the macroscopic support of step (b), or the passivated macroscopic support obtained in step (f1) when a passivation process is used, in the aqueous solution of step (a) for a suitable amount of time;
• (d) optionally removing the immerged macroscopic support from the aqueous solution of step (a) if an excess aqueous solution is used in step (c);
• (e′) optionally subjecting the resulting macroscopic support to a gentle thermal treatment under air at low temperatures from 45 to 55° C.;
• (e) subjecting the resulting macroscopic support to a first thermal treatment under air at moderate temperatures from 110-150° C.±5° C.;
• (f) optionally subjecting the thermally treated macroscopic support to a second thermal treatment under air at higher temperatures:
• from 400-500° C.±10° C., or
• at 300° C.±10° C. for 2 to 4 hours;
• thereby generating a macroscopic composite composed of a macroscopic support coated with a 20-200 nm thick layer of highly N-doped mesoporous carbonaceous material;
• wherein the N atom % in the mesoporous carbonaceous material is 25-40%;
• and
• (g) optionally subjecting the macroscopic composite obtained in step (e) or (f) to a third thermal treatment by heating it to a temperature ranging between 600 to 900° C.±10° C. under inert atmosphere;
• thereby generating a macroscopic composite composed of a macroscopic support coated with a 10-100 nm thick layer of highly N-doped mesoporous carbonaceous material;
• wherein the N atom % in the mesoporous carbonaceous material is 2-35%;
• wherein the method comprises at least one of steps (f) or (g).