Post-synthesis functionalisation of nanostructured carbons byphosphoric acid

摘要

Nanostructured carbons have been obtained by template method using silica gel as structure directing substance. Surface chemistry was altered by high temperature treatment in argon with and without phosphoric acid Porous structure and surface chemistry was investigated by nitrogen adsorption and acid-base titration methods. It has been shown that nanostructured carbon obtained by template method contains relatively high amount of acid groups (1.2 mmol/g) that make surface acid with PZC 3.4. Heat treatment of nanostructured carbon at 1000 °C in inert atmosphere did not change porous structure while decreasing concentration of surface groups (0.7 mmol/g) making PZC 8.6. High temperature treatment with phosphoric acid significantly increased concentration of surface groups introducing phosphate, carboxylic and phenol groups (2.4 mmol/g) and making very surface acidic (PZC = 1.7). High temperature treatment with phosphoric acid significantly changed porosity of nanostructured carbon - it increased (1.5 times) micropore volume and decreased (4 times) mesopore volume. XRD patterns indicated increase of long-range order though the orientation of graphene layers became less perfect. High temperature treatment with phosphoric acid could be regarded as a method for functionalisation of carbonaceous materials.