In the first funding period, we gained extensive experience in the preparation of graphene on metal substrates and the chemical modification of graphene with nitrogen and boron leading to heterographene, that is, doped graphene. The formation of these carbon allotropes is achieved via
a CVD process using precursors that contain the heteroatom, or by low energy ion implantation. The heterographenes were characterized with photoemission spectroscopy, accompanied by density functional theory calculations. While boron insertion leads to the expected p
-doped material, nitrogen insertion results, depending on the functionality in the graphene sheet, in p
– or n
-doping, for pyridinic or substitutional nitrogen atoms in the graphene lattice, respectively. Extrinsic doping was achieved by means of p-stacking porphyrins and porphycenes onto the basal plane of graphene. In a “molecular” approach, porphyrin derivatives as inherently N
-doped carbon-rich species were deposited on surfaces. Stepwise dehydrogenation led to a proof-of-concept that graphyrins or intermediates on the way to graphyrins can be made at specific conditions. Carefully controlled ESI experiments clearly showed the successful synthesis of graphyrins in the gas phase. In parallel to these approaches towards heterographenes, controlled chemical synthesis starting from carefully designed heteroatom-containing polyaromatic precursors (allowing to vary the size, shape, and periphery of the resulting heterographenes), such as polyphenylated porphyrins and bridged triarylamines, were pursued both in solution and on surfaces.