Chemical state of nitrogen in carbon aerogels issued from phenol–melamine–formaldehyde gels

Chemical states of nitrogen in the carbon aerogels synthesized from phenol-melamine-formaldehyde were investigated by elemental analysis, X-ray photoelectron spectroscopy and nitrogen adsorption. It is found that the carbon aerogels are rich in mesopores and the nitrogen content of the carbon aerogels increases from 1.6 to 3.1 wt. % with increasing melamine to phenol ratios. Over two-thirds of nitrogen are on periphery of graphene layers (pyridinic-N, pyrrolic-N and/or pyridonic-N, pyridine N-oxide) and less than one-third in central position of graphene layers (quaternary-N). Polymerisation at low pH might cause a preferred location of nitrogen on periphery of graphene layer.