Effect of nitrogen doping on the pore texture of carbon xerogels based on resorcinol-melamine-formaldehyde precursors

Abstract

N-doped carbon xerogels (CXs) were synthesized from melamine-resorcinol-formaldehyde aqueous gels by evaporative drying and pyrolysis at 800 °C. The pore texture of these N-doped CXs ranged from micro-mesoporous to micro-macroporous depending on the initial pH of the precursors solution. For different pH values, while the specific surface area varied slightly from 500 to 600 m2 g−1, the total void volume changed from 0.6 to 1.6 cm3 g−1. Furthermore, N-doped CXs showed a wide interval of average pore diameters ranging from 19 to 1200 nm. The nitrogen amount in N-doped CXs varied from 4 to 11 wt. % and XPS analysis showed that nitrogen was mainly incorporated into the carbon network as pyridine or quaternary nitrogen groups. These results indicate that this doping approach is suitable to tune the pore texture, pore size and chemical composition by adjusting the initial pH value or the amount of nitrogen precursor. Taking into account the properties mentioned above, N-doped CXs can be tailored to find applications as adsorbents, catalyst supports, materials for energy generation and storage.