A highly active iron-nitrogen-doped carbon nanotube catalyst for the oxygen reduction reaction (ORR) is produced by employing vertically aligned carbon nanotubes (VA-CNT) with a high specifi c surface area and iron(II) phthalocyanine (FePc) molecules. Pyrolyzing the composite easily transforms the adsorbed FePc molecules into a large number of iron coordinated nitrogen functionalized nanographene (Fe-N-C) structures, which serve as ORR active sites on the individual VA-CNT surfaces. The catalyst exhibits a high ORR activity, with onset and halfwave potentials of 0.97 and 0.79 V, respectively, versus reversible hydrogen electrode, a high selectivity of above 3.92 electron transfer number, and a high electrochemical durability, with a 17 mV negative shift of E 1/2 after 10 000 cycles in an oxygen-saturated 0.5 M H 2 SO 4 solution. The catalyst demonstrates one of the highest ORR performances in previously reported any-nanotube-based catalysts in acid media. The excellent ORR performance can be attributed to the formation of a greater number of catalytically active Fe-N-C centers and their dense immobilization on individual tubes, in addition to more effi cient mass transport due to the mesoporous nature of the VA-CNTs.

The cooperative effect of hydrogen and halogen bonds on the two-dimensional (2D) molecular arrangement on highly oriented pyrolytic graphite (HOPG) was studied by scanning tunneling microscopy. The terephthalic acid (TPA) molecule, which has two carboxyl g roups attached at the para positions of a benzene ring, formed a one-dimensional (1D) linear non-covalent network structure on HOPG by hydrogen bonds between the carboxyl groups of neighboring molecules. However, unlike the TPA molecule, Br substituted TPA molecules were found to form different non-covalent network structures. Owing to Br … O halogen and hydrogen bonds, bromo-substituted TPA (2-bromoterephthalic acid) formed a 1D ladder-like non-covalent network structure, whereas dibromo-substituted TPA (2,5-dibromoterephthalic acid) formed a 2D non-covalent lattice network on HOPG. These results strongly indicate that Br … O halogen significantly contribute to determine the molecular assembly as well as hydrogen bonds for molecules containing bromine groups and hydrogen bonding groups. These results provided deep fundamental insight into the cooperative effect of halogen and hydrogen bonds in 2D molecular assembly. In addition, we have demonstrated that these interactive bonds are promising for the precise design of 2D molecular architectures.