First-principles study of transition metal adsorbed on porphyrin-like motifs in pyrrolic nitrogen-doped carbon nanostructures

Abstract

First-principles density functional theory calculations were performed on a porphyrin-like motif into the lattice of carbon nanotubes and graphene. The porphyrin-like motif was generated by applying the Stone-Thrower-Wales (STW) transformation twice on two consecutive carbon bonds in a semiconducting (10 0) single-walled carbon nanotube (SWCNT) and graphene, resulting in a porphyrin-like motif that contained an octagon surrounded by four pentagons, two hexagons, and two heptagons. When one carbon atom of each pentagon is substituted by nitrogen (N-pyrrolic doping), the motif mimics the skeleton of a porphyrin molecule (DSTW-N4-porphyrin-like motif). Transition metals (TMs) (Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn) are incorporated to the double Stone-Thrower-Wales (DSTW)-N4-porphyrin motif. The band-structure, electronic density of states, binding energy, formation energy, and wave functions were calculated. The binding and formation energy calculations demonstrated that the proposed TM-DSTW-N4 defects are stable and energetically competitive with other types of defects. The calculated systems exhibit spin-dependent semiconducting band gap and half-metallicity. Our investigations offered insights into how TM atoms are adsorbed by sp2 carbon materials doped with N-pyrrolic. The interplay between the type of nitrogen doping (pyridine, substitutional, and pyrrolic) and structural defects in sp2 carbon materials are crucial for tailoring the electronic, magnetic, and catalytic properties.